Four New Species of Hesionidae (Annelida, Polychaeta, Phyllodocida) from Eastern Pacific Chemosynthetic Habitats and Reinstatement of Vrijenhoekia †
Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0202, USA
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Author to whom correspondence should be addressed.
†
LSID urn:lsid:zoobank.org:pub:92292DEC-A341-4721-BE0B-A5778C5E4DBD.
Diversity 2025, 17(2), 121; https://doi.org/10.3390/d17020121
Submission received: 4 January 2025
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Revised: 4 February 2025
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Accepted: 4 February 2025
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Published: 8 February 2025
(This article belongs to the Special Issue 2024 Feature Papers by Diversity’s Editorial Board Members)
Abstract
:Hesionid polychaetes are well known at hydrothermal vents, methane seeps, and unusual habitats such as whale falls. In 1985, Sirsoe grasslei was the first hesionid to be named from a hydrothermal vent. Vrijenhoekia was erected in 2008 for a closely related species from a whale fall. Further species of Sirsoe and Vrijenhoekia were described in the following decade and the genera were recovered as reciprocally monophyletic with DNA data. However, Sirsoe was made a senior synonym of Vrijenhoekia when 10 further new species from the clade were named from off the coast of Brazil. To further evaluate the status of Sirsoe and Vrijenhoekia, we present the first DNA data for the type species of Sirsoe, S. grasslei. Our results allow the reinstatement of Vrijenhoekia and emended diagnoses for Sirsoe and Vrijenhoekia. Four new species, three in Sirsoe and one in Vrijenhoekia, are also described.
1. Introduction
Hesionidae Grube, 1850 (Annelida) is a globally distributed clade of polychaetes with members found in marine environments from the intertidal to a range of deep-water habitats [1]. Some hesionid taxa are abundant in chemosynthetic environments such as hydrothermal vents, methane seeps, and whale falls [2,3,4,5,6,7,8,9]. Orseis grasslei Blake, 1985 is the earliest named of these species, described from a hydrothermal mound in the Guaymas Basin, Gulf of California, Mexico [2]. The “iceworm”, Hesiocaeca methanicola Desbruyères and Toulmond, 1998 was subsequently described after being found living in high densities on methane hydrates in the Gulf of California [9]. Pleijel [10], in his major monograph on Hesionidae, established the genus Sirsoe Pleijel, 1998 for O. grasslei and noted similarities between S. grasslei and the then unpublished H. methanicola, referring to it as the undescribed Sirsoe A. Desbruyères and Toulmond [9] rejected this view and placed their new species in Hesiocaeca Hartman, 1965 [11].
Pleijel et al. [3] formally placed Hesiocaeca methanicola in Sirsoe and published the first DNA sequences for Sirsoe methanicola. Molecular data for the type species, Sirsoe grasslei, were not available at that time. Vrijenhoekia balaenophila Pleijel, Rouse, Ruta, Wiklund and Nygren, 2008 was described in the same study from specimens collected at a whale fall off the coast of California. Vrijenhoekia balaenophila was recovered as the sister taxon to Sirsoe methanicola and considered as a separate genus based on the absence of an obvious median antenna, presence of glandular lip pads (GLPs), and lack of developed neuropodial lobes on segment three. Subsequently a further three species of Vrijenhoekia and a new Sirsoe were described from eastern Pacific whale falls, as well as an undescribed Vrijenhoekia sp. A [4]. Sirsoe and Vrijenhoekia formed reciprocally monophyletic clades in that study but, unlike V. balaenophila, all the new Vrijenhoekia had a median antenna and lacked GLPs, as found in Sirsoe. In 2018, Rouse et al. [5] described two more Sirsoe from methane seeps off Costa Rica and Mexico, with Sirsoe and Vrijenhoekia still being recovered as sister clades. In 2019 (and 2021), Shimabukuro et al. [8] used DNA data and morphology to describe a further 10 hesionid species from Brazilian whale falls. They recognized three major clades, placing them all within Sirsoe and stated that their analyses showed that “Sirsoe constitutes a monophyletic group only with the inclusion of Vrijenhoekia species”, and that “recognition of Vrijenhoekia renders both genera non-monophyletic” [8]. According to these arguments, they classified Vrijenhoekia as a junior synonym of Sirsoe. Examination of their phylogenetic results show that they could have recognized reciprocally monophyletic Sirsoe (Clade I) and Vrijenhoekia (Clades II and III) if they had classified most of their new species as members of Vrijenhoekia. Three further new Sirsoe were described recently from the South China Sea and were all in Clade I [7]. A new Vrijenhoekia was also named recently from a whale fall off Australia, where the synonymy under Sirsoe was ignored [6].
To further evaluate the status of Sirsoe and Vrijenhoekia, we present the first molecular data for type species of Sirsoe, S. grasslei, collected from hydrothermal vents in the Pescadero Basin, Mexico, south of the original type locality. Three new species of Sirsoe are also described here for specimens collected from the Pescadero Basin and Alaska. The previously informally named Vrijenhoekia sp. A. for a single specimen from the Guaymas seeps [4] is described incorporating new material from Costa Rican methane seeps. Our results allow the reinstatement of Vrijenhoekia and emended diagnoses for Sirsoe and Vrijenhoekia.
2. Materials and Methods
2.1. Specimen Collection
The specimens described in this study were collected from six cruises. Specimens from to the Gulf of California, Mexico, were collected with R/V Falkor and ROV SuBastian on cruises FK181031 (2018) and FK210922 (2021). Specimens from Costa Rica were collected with R/V Atlantis and HOV Alvin on cruises AT15-44 (2009), AT37-13 (2017), and AT42-03 (2018). Specimens from Alaska were collected on cruise AT50-24 (2024). Specimens from Mexico were collected under CONAPESCA permits PPFE/DGOPA-200/18 (2018) and PPFE/DGOPA-090/21 (2021). Specimens from Costa Rica were under permits issued by CONAGEBIO (Comisión Nacional para la Gestión de la Biodiversidad), INCOPESCA (Instituto Costarricense de Pesca y Acuicultura), and SINAC (Sistema Nacional de Áreas de Conservación) under MINAE (Ministerio de Ambiente y Energía), Government of Costa Rica: INCOPESCA-CPI-003-12-2018, R-070-2018-OT-CONAGEBIO, SINAC-CUSBSE-PI-R-032-2018, and SINAC-SE-CUS-PI-R-035-2017.
2.2. Specimen Fates and Morphology
Specimens were recovered from the submersibles and after sorting in cold sea water were relaxed with 7% magnesium chloride and photographed live under a stereomicroscope (Leica MZ9.5 or MZ12.5, Wetzlar, Germany) with a digital camera (Canon EOS M6, Rebel T6i or Rebel T7i, Tokyo, Japan). Whole specimens or tissue subsamples for DNA sequencing were preserved in 95% ethanol. Voucher specimens were preserved in 10% formalin in seawater for morphological analysis. Additional post-preservation morphological photographs were taken with one of the stereomicroscopes and specimens post-stained with ShirlastainA© (SDL Atlas sdlatlas.com, Rock Hill, SC, USA) and chaetae were documented with a Leica DMR interference contrast microscope and Canon EOS Rebel T6i camera. Depth date and locality information can be found in Table 1.
Specimens are deposited at the Scripps Institution of Oceanography, Benthic Invertebrate Collection (SIO-BIC), La Jolla, CA, USA; Museo de Zoología, Universidad de Costa Rica (MZUCR), San Jose Costa Rica; and the Colección Regional de Invertebrados Marinos Estación Mazatlán UNAM, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México (ICML-EMU), Mazatlán, Sinaloa, Mexico.
2.3. Molecular Data
DNA were extracted with the Zymo Research DNA-Tissue Mini- and Microprep kit following the manufacturer’s protocol. COI was sequenced for initial species delimitation. Nuclear marker genes (28S rRNA and 18S rRNA) and an additional mitochondrial gene (16S rRNA) were then sequenced from a representative of each of the taxa newly included here. DNA was amplified with 12.5 µL Apex 2.0× Taq DNA Polymerase, 1 µL each of the forward and reverse primers for each gene, 8.5 µL of water, and 2 µL of DNA. The primers and profiles used are the same as used in [4]. PCR products were cleaned with ExoSAP-IT and sent to Eurofins Genomics (Louisville, KY, USA) for Sanger sequencing. Sequences were trimmed on Geneious Prime 2023.0.4 (http://www.geneious.com). GenBank accession numbers for relevant species and localities are found in Table 1. Additional GenBank numbers for COI data generated for this study are listed with the material examined.
2.4. Molecular Data Analyses
Sequences for a terminal listed on GenBank as Hesiospina vestimentifera (Blake, 1985) were used as an outgroup based on previous studies [5,6]. Sequences were aligned using MAFFT [12] with the G-INS-i option via Mesquite v.3.81 [13]. COI, 16S, 18S, and 28S genes were aligned individually and concatenated using SequenceMatrix [14] into a single matrix. The data were then evaluated with maximum likelihood (ML) inference using RaxML-NG [15] with RAxML GUI v2.0.10 [16] with the GTR+I+G model for all partitions, selected using ModelTest-NG [17]. Support was evaluated by bootstrapping with 1000 replicates. FigTree 1.4.4 [18] was used to visualize the maximum likelihood tree with bootstrap values. A COI uncorrected distance matrix was constructed with PAUP* 4a (build 168) [19]. COI haplotype networks were created with PopArt [20] using the TCS [21] network option. Morphological transformations for three characters were mapped onto the ML tree topology (with branch length information) via Mesquite using likelihood transformations under the Mk1 model [22]. The three characters traced were as follows:
- Median antenna: 0. Absent, 1. Present, 2. Present as mediodorsal tubercle.
- Frontal tubercle: 0. Absent, 1. Present prominent, 2. Present inconspicuous.
- Glandular lip pads: 0. Absent, 1. Present.
Scoring for these characters was based on the original descriptions [2,3,4,5,6,7,8,9,10]. We note that the mediodorsal tubercle described for Vrijenhoekia balaenophila [3] is positionally in the same place as a median antenna and so may represent a reduced form of this structure. We used the median antenna state ‘Present as mediodorsal tubercle’ to reflect this. Unfortunately for most recently described Sirsoe and Vrijenhoekia that have been regarded as having no median antenna [7,8], the quality of the preservation and imagery is not adequate to determine if a mediodorsal tubercle may be present. These taxa are scored with median antenna absent. The frontal tubercle, also known as a facial tubercle, is found in a range of hesionids, including other Psamathinae such as Nereimyra and some Hesiospina [10]. We note here that the frontal tubercle described as present for Sirsoe alucia Shimabukuro, Carrerette, Alfaro-Lucas, Rizzo, Halanych, and Sumida, 2021 [8] and Sirsoe maximiano Shimabukuro, Carrerette, Alfaro-Lucas, Rizzo, Halanych, and Sumida, 2021 [8] is hardly evident in their labelled figures (Figures 7C,E and 10C,D in [8]). We therefore added a state ‘Present inconspicuous’ for this character. Also, Sirsoe methanicola has previously been regarded as having a frontal tubercle [3,10], but this feature was not noted nor visible in the original description and figures [9] and was scored as absent here.
3. Results
3.1. Phylogeny
Allowing for additional taxon sampling here, the maximum likelihood analysis showed three major clades, as also recovered in recent analyses [6,7,8], which are marked as Clades I, II and III (Figure 1).
Clade I is referred to here as Sirsoe and contains the type species S. grasslei. Clades II and III formed a clade that is referred to as the reinstated Vrijenhoekia. Support values for Vrijenhoekia and Clades II and III were high (bootstrap (BS) 97 or above), while that for the Sirsoe Clade I was lower, with BS 73 (Figure 1). Three of the new species described here were found in the Sirsoe Clade I. Two of the new species, Sirsoe pleijeli n. sp. and Sirsoe shastae n. sp. formed a clade with reasonable support (BS 78) and this clade was the sister group to S. grasslei, though with low support. These three taxa formed a well-supported clade with Sirsoe munki. The third new Sirsoe species, Sirsoe sapote n. sp. formed a well-supported clade with S. dalailama. The Vrijenhoekia species previously known as Vrijenhoekia sp. A and described here as Vrijenhoekia mindiae n. sp., was recovered as the sister group to the unnamed species from Brazil called here Vrijenhoekia BioSuOr (previously called Sirsoe BioSuOr [8]), though with low support.
3.2. Haplotype Networks
Two haplotypes were present for Sirsoe pleijeli n. sp. (Figure 2) among the 21 specimens sequenced for 596 bases of COI. Only one base differed between the specimens found off the Aleutian Archipelago, Alaska, and in the Gulf of California, Mexico. 19 of the sequences were the same haplotype, which were found at both sites. The specimens from Mexico were from around 3700 m at hydrothermal vents, while those from Alaska were from a methane seep at around 2000 m. The sampling sites were over 5500 km apart.
Vrijenhoekia mindiae n. sp. was found at seeps in the Gulf of California, Mexico, and off the Pacific coast of Costa Rica from depths of 1000 to 1500 m. Among the 15 specimens sequenced for 597 bases of COI, six haplotypes were recovered, with one haplotype dominating (Figure 3). The single specimen from the Gulf of California differed by a minimum of eight bases from the Costa Rican haplotypes, which differed by no more than five bases from each other.
3.3. Transformations
The transformations of the three morphological characters are shown on the ML tree topology in Figure 4, Figure 5 and Figure 6. Figure 3 shows the transformation for the median antenna and under a maximum likelihood model it appears the feature has evolved twice and been lost several times. It appears as apomorphic for subclades within Sirsoe and Vrijenhoekia, with losses in each of these subclades. The mediodorsal tubercle form of the median antenna, which has only been seen in Vrijenhoekia balaenophila to date, appeared within a clade of Vrijenhoekia where the median antenna is otherwise absent (Figure 4).
The frontal tubercle character transformation (Figure 5) shows that this feature, which is present in the outgroup, may be plesiomorphic for the Sirsoe+Vrijenhoekia clade.
If this scenario is accepted, then the frontal tubercle has been lost in the Sirsoe clade and would represent an apomorphic state. Vrijenhoekia members can be distinguished by its presence, though this may be plesiomorphic. A less likely scenario is that the presence of the frontal tubercle in Vrijenhoekia is apomorphic and its absence in Sirsoe is plesiomorphic. The scoring of the frontal tubercle character as ‘small’ showed up independently twice within the Sirsoe clade and supports the idea that this is not homologous to the frontal tubercles seen in Vrijenhoekia. The glandular lip pad character transformation (Figure 6) suggests that this feature has appeared once or twice within the Vrijenhoekia clade. This could either be apomorphic for Clade II, with a subsequent loss for the V. alphadelphini n. comb. + V. besnard n. comb. Clade, or independently appearing twice in Clade II.
3.4. COI Distances
The minimum pairwise distances for COI are shown in Table 2.
Of the new species described here, S. shastae n. sp. had the smallest uncorrected pairwise COI distance of 4% to S. grasslei and these specimens were found in close proximity to each other at the Pescadero Basin vents. This COI distance is slightly more than the 3% distance between S. alucia and S. polita, which are very widely separated geographically. Sirsoe pleijeli n. sp. was 8% distant from S. grasslei and also 8% from S. shastae n. sp. but was found to be the sister group to the latter in the multigene phylogeny (Figure 1). The single specimen of Sirsoe sapote n. sp. was 5% divergent from Sirsoe dalailamai described from Costa Rican seeps. Vrijenhoekia mindiae n. sp. was 15% divergent from the undescribed Vrijenhoekia BioSuOr.
3.5. Taxonomy
3.5.1. Sirsoe
Type species: Orseis grasslei Blake, 1985 (p. 78, Figure 6) [2].
Diagnosis (emended)
Psamathinae with or without dorsally inserted median antenna, eyes absent, frontal tubercle and glandular lip pads absent. Notopodial hooks absent.
Remarks:
Pleijel, 1998 [10] diagnosed Sirsoe as ‘Psamathini with dorsally inserted median antenna and eyes absent’. Pleijel et al., 2008 [3] did not revise the diagnosis for Sirsoe when they erected Vrijenhoekia and there was no revision with subsequent Sirsoe descriptions [4,5]. Shimabukuro et al., 2019 [8] emended the diagnosis for Sirsoe when they made it a senior synonym of Vrijenhoekia to ‘Psamathinae with reduced small depression-like nuchal organs not projected on posterior margin of prostomium, frontal tubercle present with or without dorsally median antenna, eyes absent, with or without glandular lip pads’. Notably, they did not account for the frontal tubercle also being absent in many of the species in their genus, which would have been classified as Sirsoe sensu stricto in previous studies [4,5]. Based on the restriction here of Sirsoe to Clade I, which includes the type species S. grasslei, and the information provided in the morphology transformation (Figure 4, Figure 5 and Figure 6), we have removed the possible presence of the frontal tubercle and glandular lip pads as diagnostic for the genus. We also removed the shape of the nuchal organs, as this is difficult to document without scanning electron microscopy. The absence of notopodial hooks helps distinguish Sirsoe from Hesiospina, which also may lack eyes, median antenna, and a frontal tubercle [10].
3.5.2. Sirsoe grasslei
Orseis grasslei: Blake, 1985 [2] (p. 78, Figure 6)
Sirsoe grasslei: Pleijel, 1998 [10] (pp. 124–126, Figure 18)
Material Examined
Voucher: SIO-BIC A13989, Z vent, Auka Vent Field, Gulf of California, 23.956° N, 108.861° W, 3684 m depth, anterior 10% SW formalin-fixed, preserved in 50% ethanol, posterior fixed in 95% ethanol, used for DNA sequencing, 30 October 2021, ROV SuBastian dive S0471, collector Greg Rouse [GenBank: COI = PQ774161; other sequences listed in Table 1].
Diagnosis
Smaller Sirsoe species with a median antenna and prostomium with a similar width to following segments. Terminal proboscis ring without ventral incision. Enlarged ventral cirri on segments 1–2, ventral cirri of segment 3 short but with distinct cirrophores. Neuropodial lobes and neurochaetae start on segment 2; ~50 or more neurochaetae in chaetiger 12 parapodia. Compound chaetal blades quite straight. Ventral cirri five times longer than base width.
Description
Mature specimen with 30 or more segments (Figure 7A,B).
Gametes (oocytes) found in coelom from segment 5 to most posterior segments. Adult length 8 mm or greater. Body anteriorly truncate, prostomium similar width to following segments, posterior body tapered. Pigmentation restricted to whitish prostomium and small white spots on dorsal midbody, otherwise translucent. Prostomium rounded. Facial tubercle absent. Palps biarticulated; palpophores as wide as long, cylindrical; palpostyles much longer and thinner, evenly tapering to a point (Figure 7C,D and Figure 8A).
Lateral antennae cirriform, lateral to palps, tapering slightly shorter than palps, lacking ceratophores (Figure 7C,D and Figure 8A). Median antenna inserted on dorsal prostomium, posteriorly; median antennal furrows absent (Figure 7C and Figure 8A). Eyes absent. Nuchal organs separated, brown patches in life (Figure 7A). Prostomium without distinct incision posteriorly. Glandular lip pads absent. Terminal proboscis ring with 10 papillae; ventral incision absent (Figure 8B); jaws absent. Anterior dorsal cirri and cirrophores not obviously differing from following ones (Figure 7A–C and Figure 8A); enlarged ventral cirri on segments 1–2 (Figure 8B), ventral cirri of segment 3 short but differ from following cirri in having distinct cirrophores (Figure 7D and Figure 8B). Notopodial lobes and notochaetae absent. Neuropodial lobes and neurochaetae absent on segment 1 (Figure 7C,D). Dorsal cirri weakly annulated, very long, up to 4 mm long in life, cylindrical; elongated cirrophores absent (Figure 7A and Figure 8C,D). Dorsal cirri alternation unknown. Notopodial hooks absent. Neuropodia triangular, with rounded prechaetal lobe distally (Figure 8C,D). Aciculae transparent, notopodial, and neuropodial (Figure 8D). Neurochaetae ~50 in chaetiger 12, all compound with distinctly internally chambered shafts (Figure 8D), ending in rounded hooked tip, superior (dorsal) and median blades up to 3 times longer than inferior (ventral) ones, in all cases blades quite straight (Figure 8D–F). Ventral cirri subdistally inserted on neuropodium, without cirrophores, five times longer than base width (Figure 8B–D). Paired pygidial cirri present (Figure 7A,B), like dorsal cirri; median pygidial papilla absent.
Distribution
Hydrothermal vents in the Gulf of California, Mexico.
Remarks
This redescription is largely based on Pleijel’s 1998 [10] study of the type specimens from the Guaymas Basin, several hundred kilometers north of the Pescadero Basin vents where the single specimen we had available for study was obtained. Our specimen (SIO-BIC A13989) matched Pleijel’s redescription in all respects and allowed for some further observations since the animal was observed alive and was a mature female. Blake [2] stated the lateral antennae had ceratophores, but did not draw this, and we see no evidence of this (Figure 7C,D) and the point was not commented on by Pleijel [10]. We provide here the first DNA sequences for Sirsoe grasslei and its placement in Clade I (Figure 1) is valuable in delineating the membership of Sirsoe. Obtaining sequence data for Sirsoe grasslei from the type locality in the Guaymas Basin would be valuable. It is notable that there is a precedent for polychaete species to have been found at the Pescadero vents at 3700 m and those at ~2000 m in the Guaymas Basin. Zhang et al. described Ophryotrocha marinae from both sites in 2023 and provided molecular evidence to support this [23]. Other annelids such as Branchiplicatus cupreus and Riftia pachyptila are also known from both sites [24]. Sirsoe grasslei showed a COI distance of 4–8% from its closest relatives S. pleijeli n. sp. and S. shastae n. sp. (Table 2). It differs from Sirsoe pleijeli n. sp. in having cirrophores on the ventral cirri of segment 3, compound chaetae with straight rather than curved blades and shorter ventral cirri. Sirsoe shastae n. sp. is most like S. grasslei but can be distinguished from it owing to having fewer chaetae per parapodium, and the ventral cirri are much longer in proportion to the width.
3.5.3. Sirsoe pleijeli New Species
Material Examined
Holotype: ICML-EMU 13999, Bejeweled Mound, south of the JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.936° N, 108.853° W, 3635–3646.0 m depth, anterior 10% SW formalin-fixed, preserved in 50% ethanol, posterior fixed in 95% ethanol, used for DNA sequencing, 7 November 2021, ROV SuBastian dive S0479, collector Greg Rouse [GenBank: COI = PQ774173]. Paratypes: SIO-BIC A13998A, Z Vent, Auka Vent Field, Pescadero Basin, Gulf of California, 23.956° N, 108.862° W, 3684 m depth, fixed in 95% ethanol, 21 October 2021, ROV SuBastian dive S0472, collector Greg Rouse [GenBank: COI = PQ774166]; SIO-BIC A13998B, A13998C, Z Vent, Auka Vent Field, Pescadero Basin, Gulf of California, 23.956° N, 108.862° W, 3684 m depth, fixed in 95% ethanol, 21 October 2021, ROV SuBastian dive S0472, collector Greg Rouse [GenBank: COI = PQ774167; other sequences listed in Table 1, PQ774168]; SIO-BIC A13991, Z Vent, Auka Vent Field, Pescadero Basin, Gulf of California, 3.956° N, 108.862° W, 3684 m depth, anterior 10% SW formalin-fixed, preserved in 50% ethanol, posterior fixed in 95% ethanol, used for DNA sequencing, 30 October 2021, ROV SuBastian dive S0471, collector Greg Rouse [GenBank: COI = PQ774169]; SIO-BIC A14074A, A14074B, Matterhorn and Z vent, Auka Vent Field, Pescadero Basin, Gulf of California, 23.957° N, 108.860° W, 3635–3664 m depth, fixed in 95% ethanol, 8 November 2021, ROV SuBastian dive S0480, collector Greg Rouse [GenBank: COI = PQ774170, PQ774171]; SIO-BIC A14001, Midway between Auka and JaichMaa ‘ja’ag Vent Fields, Pescadero Basin, Gulf of California, 23.949° N, 108.858° W, 3687 m depth, anterior 10% SW formalin-fixed, preserved in 50% ethanol, posterior fixed in 95% ethanol, used for DNA sequencing, 1 November 2021, ROV SuBastian dive S0473, collector Greg Rouse [GenBank: COI = PQ774172]; SIO-BIC A14050, Sisters, JaichMaa ’ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.943° N, 108.856° W, 3695 m depth, fixed in 95% ethanol, 6 November 2021, ROV SuBastian dive S0478, collector Greg Rouse [GenBank: COI = PQ774174]; SIO-BIC W10406A, W10406B, W10406C, W10406D, Sanak Islands seep, Aleutian Archipelago, Alaska, 53.748° N, 162.589° W, 2014 m depth, fixed in 95% ethanol, 31 May 2024, HOV Alvin dive AD5278, collectors Tina Treude and Emily Klonicki [GenBank: COI = PQ774175, PQ774176, PQ774177, PQ774178]; SIO-BIC W10501A, Sanak seep, Aleutian Archipelago, Alaska, 53.748° N, 162.589° W, 2014 m depth, fixed in 95% ethanol, 1 June 2024, HOV Alvin dive 5279, collectors Victoria Orphan and Shana Goffredi [GenBank: COI = PQ774179]; SIO-BIC A10631, Top of Matterhorn red bacterial mat, Auka Vent Field, Pescadero Basin, Gulf of California, 23.954° N, 108.863° W, 3650 m depth, fixed in 95% ethanol, 14 November 2018, ROV SuBastian dive S0193, collectors Greg Rouse and Ekin Tilic [GenBank: COI = PQ800517]; SIO-BIC A9984, Two Sisters Mounds, JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.943° N, 108.856° W, 3684 m depth, anterior 10% SW formalin fixed, preserved in 50% ethanol, posterior fixed in 95% ethanol, used for DNA sequencing, November 16 2018, ROV SuBastian dive S0195, collectors Greg Rouse and Ekin Tilic [GenBank: COI = PQ800518]; SIO-BIC A10032, A10637, A10638, A10639, A10640, A10641, Z Mound area, Auka Vent Field, Pescadero Basin, Gulf of California, 23.956° N, 108.861° W, 3687 m depth, fixed in 95% ethanol, 21 November 2018, ROV SuBastian dive S0200, collectors Greg Rouse and Ekin Tilic [GenBank: COI = PQ800524, PQ800523, PQ800519, PQ800522, PQ800521, PQ800520]; SIO-BIC A10632, A10633, A10634, Weey ’kual (Red Hill), JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.940° N, 108.856° W, 3674 m depth, fixed in 95% ethanol, 20 November 2018, ROV SuBastian dive S0199, collectors Greg Rouse and Ekin Tilic [GenBank: COI = PQ800528, PQ800526, PQ800525]; SIO-BIC A14080A, Red Hill (Weey ’kual), JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.940° N, 108.856° W, 3682 m depth, fixed in 95% ethanol, 9 November 2021, ROV SuBastian dive S0481, collector Greg Rouse [GenBank: COI = PQ800527]. SIO-BIC A13998D, A13998E, Z Vent, Auka Vent Field, Pescadero Basin, Gulf of California, 23.956° N, 108.862° W, 3684 m depth, fixed in 95% ethanol, 21 October 2021, ROV SuBastian dive S0472, collector Greg Rouse [GenBank: COI = PQ826244, PQ826245]. Other materials: SIO-BIC A10015, Weey ’kual (Red Hill), JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.940° N, 108.856° W, 3674 m depth, 10% SW formalin-fixed, preserved in 50% ethanol, November 20 2018, ROV SuBastian dive S0199, collectors Greg Rouse and Ekin Tilic; SIO-BIC A13998F-H, Z Vent, Auka Vent Field, Pescadero Basin, Gulf of California, 23.956° N, 108.862° W, 3684 m depth, fixed in 95% ethanol, 21 October 2021, ROV SuBastian dive S0472, collector Greg Rouse; SIO-BIC A13998I, Z Vent, Auka Vent Field, Pescadero Basin, Gulf of California, 23.956° N, 108.862° W, 3684 m depth, 10% SW formalin-fixed, preserved in 50% ethanol, October 21 2021, ROV SuBastian dive S0472, collector Greg Rouse; SIO-BIC A13998J, Z Vent, Auka Vent Field, Pescadero Basin, Gulf of California, 23.956° N, 108.862° W, 3684 m depth, frozen for isotopes, 21 October 2021, ROV SuBastian dive S0472, collector Greg Rouse; SIO-BIC A14074C, A14074D, Matterhorn and Z vent, Auka Vent Field, Pescadero Basin, Gulf of California, 23.957° N, 108.861° W, 3635–3664 m depth, fixed in 95% ethanol, 8 November 2021, ROV SuBastian dive S0480, collector Greg Rouse; SIO-BIC A14074E, A14074F, Matterhorn and Z vent, Auka Vent Field, Pescadero Basin, Gulf of California, 23.957° N, 108.861° W, 3635–3664 m depth, 10% SW formalin-fixed, preserved in 50% ethanol, 8 November 2021, ROV SuBastian dive S0480, collector Greg Rouse; SIO-BIC W10406E, Sanak Islands seep, Aleutian Archipelago, Alaska, 53.748° N, 162.588° W, 2014 m depth, 10% SW formalin-fixed, preserved in 50% ethanol, 31 May 2024, HOV Alvin dive 5278, collectors Tina Treude and Emily Klonicki; SIO-BIC W10406F, Sanak Islands seep, Aleutian Archipelago, Alaska, 53.748° N, 162.589° W, 2014 m depth, frozen for isotopes, May 31, 2024, HOV Alvin dive 5278, collectors Tina Treude and Emily Klonicki; SIO-BIC W10501B, W10501C, Sanak Islands seep, Aleutian Archipelago, Alaska 53.748° N, 162.589° W, 2014 m depth, fixed in 95% ethanol, 1 June 2024, HOV Alvin dive 5279, collectors Victoria Orphan and Shana Goffredi; SIO-BIC A9973, Top of Matterhorn red bacterial mat, Auka Vent Field, Pescadero Basin, Gulf of California, 23.954° N, 108.863° W, 3650 m depth, 10% SW formalin-fixed, preserved in 50% ethanol, 14 November 2018, ROV SuBastian dive S0193, collectors Greg Rouse and Ekin Tilic; SIO-BIC A14080B - H, Red Hill (Weey ’kual), JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.940° N, 108.856° W, 3682 m depth, fixed in 95% ethanol, 9 November 2021, ROV SuBastian dive S0481, collector Greg Rouse.
Diagnosis
Moderate-sized Sirsoe species with a median antenna, prostomium similar width to following segments. Terminal proboscis ring without ventral incision. Enlarged ventral cirri with cirrophores on segments 1–2, thereafter ventral cirri short, without distinct cirrophores. Neuropodial lobes and neurochaetae start on segment 2. Compound chaetal blades curved. Ventral cirri 7–8 times longer than base width.
Description
Holotype with 32 segments, mature female, 16 mm long in life (Figure 9A). Gametes (sperm) found in coelom from segment 7 to most posterior segments.
Body anteriorly and posteriorly tapered. Pigmentation restricted to brownish patches on prostomium and small brown spots on dorsal midbody, otherwise translucent with red blood vessels visible in life (Figure 9A,B). Prostomium rectangular, narrower than segments behind (Figure 9A,B). Facial tubercle absent. Palps biarticulated; palpophores as wide as long, cylindrical; palpostyles much longer and thinner, evenly tapering to a point (Figure 9C,D). Lateral antennae cirriform, lateral to palps, tapering slightly shorter than palps, lacking ceratophores (Figure 9B,C). Median antenna inserted on dorsal prostomium, posteriorly; median antennal furrows absent (Figure 9C).
Eyes absent. Nuchal organs not distinct. Prostomium without distinct incision posteriorly. Glandular lip pads absent. Terminal proboscis ring ciliated with 10 papillae; ventral incision absent (Figure 9C,D and Figure 10A); jaws absent. Anterior dorsal cirri and cirrophores not obviously differing from following ones, all extremely long (Figure 9A,C,D); enlarged ventral cirri on segments 1–2 (Figure 9D and Figure 10A,B), ventral cirri of segment 3 short, like following cirri in having no cirrophores (Figure 10B). Notopodial lobes and notochaetae absent. Neuropodial lobes and neurochaetae absent on segment 1 (Figure 9D and Figure 10B). Dorsal cirri weakly annulated, very long, up to 8 mm in life, cylindrical; cirrophores present but not elongated (Figure 9A and Figure 10C,D). Dorsal cirri alternation unknown. Notopodial hooks absent. Neuropodia triangular, with rounded prechaetal lobe distally (Figure 10C,D). Aciculae transparent, notopodial and neuropodial (Figure 10D). Neurochaetae ~30 in chaetiger 12 all compound with distinctly internally chambered shafts (Figure 10D), ending in rounded tip, superior (dorsal) and median blades up to four times longer than inferior (ventral) ones, in all cases blades curved (Figure 10D–F). Ventral cirri subdistally inserted on neuropodium, without distinct cirrophores (Figure 10C,D). Paired pygidial cirri present (not shown), very long, like dorsal cirri; median pygidial papilla absent.
Variation
As seen in the haplotype network (Figure 2) there was very little variability on COI among the 21 specimens sequenced across a 5500 km range, with the same haplotype found in both Mexico and Alaska. Paratypes were generally smaller than the holotype, usually less than 10 mm and with ~24 segments. They ranged in size from 3 to 11 mm and with 19–36 segments. Some specimens had less brown pigmentation on the prostomium than the holotype and the brown pair of curved nuchal organs was visible.
Distribution
Hydrothermal vents at ~3700 m in the Pescadero Basin, Gulf of California, Mexico, and methane seeps at ~2000 m off the Sanak Islands, Aleutian Archipelago, Alaska.
Etymology
This species is named for Fredrik Pleijel who erected the genus Sirsoe and devoted much time to the study of Hesionidae.
Remarks
Sirsoe pleijeli n. sp. was found to be the sister group to another of the new species described here, S. shastae n. sp., and is additionally very similar to S. grasslei. Apart from the COI distance of 8% in each case (Table 2), Sirsoe pleijeli n. sp. can be easily distinguished from both species by its lack of a cirrophore on the ventral cirri of segment 3 (Figure 10B), extremely long dorsal cirri, and compound chaetae with curved blades. It differs also from S. grasslei in that the ventral cirri are proportionally longer.
3.5.4. Sirsoe shastae New Species
Material Examined
Holotype: ICML-EMU 14001, Weey ’kual (Red Hill), JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.940° N, 108.856° W, 3674 m depth, fixed in 95% ethanol, 20 September 2018, ROV SuBastian dive S0199, collectors Greg Rouse and Ekin Tilic [GenBank: COI = PQ774162; other sequences listed in Table 1]. Paratypes: SIO-BIC A14065A, A14065B, A14065C, Bejeweled Mound, south of the JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.936° N, 108.8534° W, 3635–3646 m depth, fixed in 95% ethanol, 7 September 2021, ROV SuBastian dive S0479, collector Greg Rouse [GenBank: COI = PQ774163, PQ774164, PQ774165]. Other materials: SIO-BIC A14065D, A1406E, Bejeweled Mound, south of the JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.936° N, 108.853° W, 3635–3646 m depth, 10% SW formalin-fixed, preserved in 50% ethanol, 7 September 2021, ROV SuBastian dive S0479, collector Greg Rouse; SIO-BIC A14065F Bejeweled Mound, south of the JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.936° N, 108.853° W, 3635–3646 m depth, frozen for isotopes, 7 September 2021, ROV SuBastian dive S0479, collector Greg Rouse; SIO-BIC A10016A, Weey ’kual (Red Hill), JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.940° N, 108.856° W, 3674 m depth, 10% SW formalin-fixed, preserved in 50% ethanol, September 20 2018, ROV SuBastian dive S0199, collectors Greg Rouse and Ekin Tilic; SIO-BIC A10016B, Weey ’kual (Red Hill), JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.940° N, 108.856° W, 3674 m depth, RNAlater, 20 September 2018, ROV SuBastian dive S0199, collectors Greg Rouse and Ekin Tilic; SIO-BIC A10635, Weey ’kual (Red Hill), JaichMaa ‘ja’ag Vent Field, Pescadero Basin, Gulf of California, 23.940° N, 108.856° W, 3674 m depth, fixed in 95% ethanol, 20 September 2018, ROV SuBastian dive S0199, collectors Greg Rouse and Ekin Tilic.
Diagnosis
Small-sized Sirsoe species with a median antenna, prostomium similar width to following segments. Enlarged ventral cirri on segments 1–2, ventral cirri of segment 3 short, with distinct cirrophores. Neuropodial lobes and neurochaetae start on segment 2; ~30 or more neurochaetae in chaetiger 12 parapodia. Compound chaetal blades straight. Ventral cirri ten times longer than base width.
Description
Holotype with 30 segments, length 11 mm in life; gametes (oocytes) found in coelom from segment 7 to most posterior segments (Figure 11A). Body anteriorly truncate, prostomium similar width to following segments, posterior body tapered. Pigmentation restricted to yellowish gut, otherwise translucent. Prostomium rounded. Facial tubercle absent. Palps biarticulated; palpophores as wide as long, cylindrical; palpostyles much longer and thinner, evenly tapering to a point (Figure 11C and Figure 12B). Lateral antennae cirriform, lateral to palps, tapering slightly shorter than palps, lacking ceratophores (Figure 11B,C and Figure 12A). Median antenna inserted on dorsal prostomium, posteriorly; median antennal furrows absent (Figure 11B,C and Figure 12A). Eyes absent. Nuchal organs separated, brown patches in life (Figure 11A). Prostomium without distinct incision posteriorly. Glandular lip pads absent. Terminal proboscis not observed. Anterior dorsal cirri and cirrophores not obviously differing from following ones (Figure 11A,B); enlarged ventral cirri on segments 1–2 (Figure 12B), ventral cirri of segment 3 (and segment 4?) short but differ from following cirri in having distinct cirrophores (Figure 12B).
Notopodial lobes and notochaetae absent. Neuropodial lobes and neurochaetae absent on segment 1 (Figure 11B,C). Dorsal cirri weakly annulated, very long, up to 4.7 mm in life, cylindrical; cirrophores present but not elongated (Figure 11A,B and Figure 12C,D). Dorsal cirri alternation unknown. Notopodial hooks absent. Neuropodia triangular, with rounded prechaetal lobe distally (Figure 12C,D). Notopodial and neuropodial aciculae transparent (Figure 12D). Neurochaetae ~30 in chaetiger 12, all compound with distinctly internally chambered shafts (Figure 12E,F), ending in rounded hooked tip, superior (dorsal) and median blades up to 3 times longer than inferior (ventral) ones, in all cases blades quite straight (Figure 12D–F). Ventral cirri subdistally inserted on neuropodium, without cirrophores, up to ten times longer than base width (Figure 12B–D). Paired pygidial cirri present (not shown), like dorsal cirri; median pygidial papilla absent.
Distribution
Hydrothermal vents at ~3700 m in the Pescadero Basin, Gulf of California.
Variation
The four COI sequences obtained here of the holotype of Sirsoe shastae n. sp. and three paratypes varied by less than 1%. Paratypes ranged in size from 5 to 11 mm and with 22–27 segments.
Etymology
This species is named after one of the first author’s female cats for the cirri’s similarities to her whiskers.
Remarks
Sirsoe shastae n. sp. was found to be a sister group to S. pleijeli n. sp. (Figure 1), from which it is 8% divergent with COI (Table 2). It can be distinguished from S. pleijeli n. sp. by its cirrophore on the ventral cirri of segment 3, shorter dorsal cirri, and straight compound chaetal blades. However, S. shastae n. sp. is most similar to S. grasslei morphologically and is only 4% divergent from it with COI (Table 2). Sirsoe shastae n. sp. can be distinguished from S. grasslei in that it has fewer chaetae per parapodium, and the ventral cirri are much longer in proportion to the width.
3.5.5. Sirsoe sapote
Material Examined
Holotype: ICML-EMU 14000, Matterhorn and Z Vent, Auka Vent Field, Pescadero Basin, Gulf of California, 23.954° N, 108.863°, 3655 m depth, 10% SW formalin-fixed, preserved in 50% ethanol piece fixed in 95% ethanol for DNA sequencing, 8 November 2021, ROV SuBastian dive S0480, collector Greg Rouse [GenBank: COI = PQ774180; other sequences listed in Table 1].
Diagnosis
Large-sized Sirsoe species with a median antenna, prostomium similar width to following segments. Enlarged ventral cirri on segments 1–3 with distinct cirrophores. Segment 3 lacking small triangular neuropodial lobe dorsal to each ventral cirrus. Neuropodial lobes and neurochaetae start on segment 4. Proboscis opening mid-ventrally with distinct incision and small rounded knob. Compound chaetal blades straight.
Description
Holotype with at least 28 segments, at least 30 mm long in life (Figure 13A). Body anteriorly truncate, prostomium similar width to following segments, but shape obscured by everted proboscis. Pigmentation bright orange in life with whitish gut visible through body wall; fixed specimen white. Facial tubercle absent. Palps biarticulated; palpophores cylindrical and palpostyles tapering, palpostyles much shorter than palpophores (Figure 13A,C). Lateral antennae cirriform, lateral to palps, tapering slightly, shorter, much thinner than palps, lacking ceratophores (Figure 13C). Median antenna inserted on dorsal prostomium, posteriorly; median antennal furrows absent (Figure 13C). Eyes absent. Nuchal organs forming two short slits postero-laterally on prostomium. (Figure 13A). Prostomium without distinct incision posteriorly. Glandular lip pads absent. Proboscis with 10 tapering papillae situated on dorsal half of the proboscis opening; papillae elongated, tapering, decreasing in size towards the ventral side. Proboscis opening mid-ventrally with distinct incision and small rounded knob (Figure 13A,B,D).
Anterior dorsal cirri and cirrophores not obviously differing from following ones (Figure 13A,C,D); enlarged ventral cirri on segments 1–3 (Figure 13D), all with distinct cirrophores. Notopodial lobes and notochaetae absent on all segments. Neuropodial lobes and neurochaetae absent on segment 1–3, first chaetiger segment 4 (Figure 13D). Segment 3 also without small triangular (neuropodial?) lobes dorsal to ventral cirri. Dorsal cirri weakly annulated, very long, up to 8 mm in life, cylindrical; elongated cirrophores absent (Figure 13A,D and Figure 14A). Dorsal cirri alternation unknown. Notopodial hooks absent. Neuropodia triangular, with rounded prechaetal lobe distally (Figure 14A,B). Noto- and neuro-aciculae not visualized owing to thickness of parapodia. Neurochaetae ~25 in chaetiger 12, all compound with distinctly internally chambered shafts (Figure 14C,D), ending in rounded hooked tip, superior (dorsal) and median blades up to three times longer than inferior (ventral) ones, in all cases blades quite straight (Figure 14C,D). Ventral cirri subdistally inserted on neuropodium, without cirrophores, up to five times longer than base width (Figure 14A,B). Paired pygidial cirri present (not shown), like dorsal cirri; median pygidial papilla absent.
Distribution
Hydrothermal vents at ~3700 m in the Pescadero Basin, Gulf of California.
Etymology
This species is named as a noun in apposition for sapote, a type of fruit native to Mexico. The mamey sapote, Pouteria sapota, has an orange flesh like the color in life of the S. sapote n. sp.
Remarks
Sirsoe sapote n. sp. was found to be the sister group to S. dalailamai known from Costa Rican methane seeps (Figure 1) and this clade was then the sister group to Sirsoe methanicola (Gulf of Mexico). Sirsoe sapote n. sp. was found to be 5% divergent from S. dalailamai with COI and 10% from Sirsoe methanicola (Table 2). It is morphologically very similar to S. dalailamai, even with regards to color in life. Rouse at al. 2018 [5] could not provide any obvious differences between S. dalailamai and S. methanicola and the erection of the former was justified on molecular and geographical divergence. Here we can distinguish Sirsoe sapote n. sp. from S. dalailamai in that segment 3 lacks a small triangular neuropodial lobe dorsal to each ventral cirrus and it has fewer chaetae (~25 compared to 30–50) in midbody parapodia. A clear difference distinguishing Sirsoe sapote n. sp. and S. dalailamai from S. methanicola is that both have far fewer neurochaetae in the parapodia than the more than 90 reported for the latter species [9].
3.5.6. Vrijenhoekia Pleijel, Rouse, Ruta, Wiklund and Nygren, 2008 [3]
Type species: Vrijenhoekia balaenophila Pleijel, Rouse, Ruta, Wiklund and Nygren, 2008 [3] (p. 78, Figure 6)
Diagnosis (emended)
Psamathinae with or without dorsally inserted median antenna, may be present as mediodorsal tubercle, eyes absent, frontal tubercle present, glandular lip pads absent or present. Notopodial hooks absent.
Remarks
Pleijel et al. [3] did not traditionally diagnose (a mixture of apomorphies and plesiomorphies) Vrijenhoekia when they established the genus for V. balaenophila, but instead listed a proposed set of apomorphic features as follows: ‘Three pairs of large glandular lip pads surrounding mouth opening, papilla-shaped neuropodial lobes on segment 3, very long dorsal cirri, and growth pattern with up to about 35 segments where after segments increase in size but no new segments are added’. In their remarks they did note that Vrijenhoekia lacked a median antenna compared to members of Sirsoe, which also had developed neuropodial lobes on segment 3, while lacking glandular lip pads. Species of Vrijenhoekia and Sirsoe that were described later introduced more variability in terms of the presence or absence of the median antenna and glandular lip pads (Figure 4 and Figure 5) and led in part to Shimabukuro et al. [8] arguing for Vrijenhoekia to be a junior synonym of Sirsoe. Here our revised diagnosis of Vrijenhoekia allows for clear identification of members of the Vrijenhoekia clade (Figure 1) by the presence of an obvious frontal tubercle, which is arguably absent in members of Sirsoe (Figure 5).
3.5.7. Vrijenhoekia mindiae New Species
Vrijenhoekia sp. A: Summers et al., 2015 [4] (pp. 120–121, Figure 3H)
Vrijenhoekia sp. A: Seid et al., 2025 [25] (p. 29, Figure 11B).
Holotype: SIO-BIC A9606, Mound 12, bone, wood, and chips deployment, Costa Rica, 8.93° N, 84.312° W, 992 m depth, anterior 10% SW formalin-fixed, preserved in 50% ethanol, posterior fixed in 95% ethanol, used for DNA sequencing, October 20, 2018, HOV Alvin dive AD4974, collectors Lisa Levin and Kyle Metcalfe [GenBank: COI = PQ800508].
Paratypes: SIO-BIC A3255 (to be ICML-EMU 14002), seep at Pinkie’s ‘Vent’ Guaymas Basin, Mexico, 27.588° N 111.474° W, 1565 m depth, anterior 10% SW formalin-fixed, preserved in 50% ethanol, posterior fixed in 95% ethanol, used for DNA sequencing, 15 April 2012, ROV Doc Ricketts dive 388, collectors G. Rouse and S. Katz, [GenBank: COI = KP745533; other sequences listed in Table 1]; SIO-BIC A1406, Parrita Seep, Costa Rica, 9.030° N, 84.623° W, 1419 m depth, on wood, posterior, and anterior 10% SW formalin-fixed, preserved in 50% ethanol, midpiece fixed in 95% ethanol, used for DNA sequencing, 1 March 2009, HOV Alvin dive 4508, collectors Andrew Thurber and Jason Waggoner [GenBank: COI = PQ814685]; (MZUCR-1530-01, was SIO-BIC A9608A), A9608C, A9608D, Mound 12, bone, wood, and chips deployment, Costa Rica, 8.930° N, 84.312° W, 992 m depth, fixed in 95% ethanol, 20 October 2018, HOV Alvin dive 4974, collectors Lisa Levin and Kyle Metcalfe [GenBank: COI = PQ800507, PQ800509, PQ800510]; SIO-BIC A8101A, Mound 12, Costa Rica, 8.930° N, 84.313° W, 990–999 m depth, fixed in 95% ethanol, 22 May 2017, HOV Alvin dive AD4907, collector Lisa Levin and Charlotte Seid [GenBank: COI = PQ834250]; SIO-BIC A9612A-F, Mound 12, bone, wood, and chips deployment, Costa Rica, 8.930° N, 84.312° W, 992 m depth, fixed in 95% ethanol, 20 October 2018, HOV Alvin dive 4974, collectors Lisa Levin and Kyle Metcalfe [GenBank: COI = PQ800506, PQ800511, PQ800512, PQ800513, PQ800514, PQ800515]; SIO-BIC A9615, Mound 12, bone, wood, and chips deployment, Costa Rica, 8.930° N, 84.312° W, 992 m depth, fixed in 95% ethanol, 20 October 2018, HOV Alvin dive 4974, collectors Lisa Levin and Kyle Metcalfe [GenBank: COI = PQ800505]; SIO-BIC A9926A, Mound 11, naturally occurring wood fall, Costa Rica, 8.922° N, 84.304° W, 1010 m depth, fixed in 95% ethanol, 3 November 2018, HOV Alvin dive 4988, collectors Victoria Orphan and Hang Yu [GenBank: COI = PQ800504]. Other materials: SIO-BIC A9608B, Mound 12, bone, wood, and chips deployment, Costa Rica, 8.93° N, 84.311° W, 992 m depth, 1 fixed in 95% ethanol, October 20, 2018, HOV Alvin dive 4974, collectors Lisa Levin and Kyle Metcalfe; SIO-BIC A9608E - G, Mound 12, bone, wood, and chips deployment, Costa Rica, 8.930° N, 84.312° W, 992 m depth, 10% SW formalin-fixed, preserved in 50% ethanol, October 20, 2018, HOV Alvin dive AD4974, collectors Lisa Levin and Kyle Metcalfe; SIO-BIC A9926B, Mound 11, naturally occurring wood fall, Costa Rica, 8.922° N, 84.304° W, 1010 m depth, fixed in 95% ethanol, 3 November 2018, HOV Alvin dive AD4988, collectors Victoria Orphan and Hang Yu.
Diagnosis
Moderate-sized Vrijenhoekia species with a median antenna, prostomium similar width to following segments. Proboscis lacking terminal papillae, jaws, or teeth. Enlarged ventral cirri on segments 1–3, ventral cirri with distinct cirrophores segments 1–5. Segment 3 with small triangular neuropodial lobes dorsal to ventral cirri and neurochaetae. Compound chaetal blades straight.
Description
Holotype with at least 33 segments, 12 mm long, though other specimens reach 15 mm in life (Figure 15A,B).
Body stout anteriorly, tapering steadily to posterior. Prostomium rounded rectangular, much wider than long, posterior incision absent. In life, anterior body in pharyngeal region translucent followed by bright orange gut wall visible through body wall, posteriorly turning to white (Figure 15A,B); fixed specimens white. Facial tubercle present (Figure 15C and Figure 16A).
Biarticulated palps: palpophores cylindrical, longer than wide, slightly longer than palpostyles, which taper (Figure 15C). Lateral antennae cirriform, lateral to palps, tapering slightly, shorter, much thinner than palps, lacking ceratophores (Figure 15C). Median antenna inserted on dorsal prostomium, posteriorly; median antennal furrows absent (Figure 16A). Eyes absent. Nuchal organs not discernable with light microcopy. Proboscis without terminal papillae, jaws, or teeth. Proboscis opening mid-ventrally without distinct incision or small rounded knob (Figure 16B,C). Glandular lip pads absent. Anterior dorsal cirri and cirrophores not obviously differing from following ones (Figure 15A–C and Figure 16A); enlarged ventral cirri on segments 1–3 (Figure 16C), all with distinct cirrophores. Segments 4–5 with shorter cirri and distinct cirrophores, remaining ventral cirri without cirrophores (Figure 16C). Notopodial lobes and notochaetae absent on all segments. Neuropodial lobes and neurochaetae absent on segment 1–2, first chaetiger segment 3 (Figure 13D). Segment 3 with small neuropodial lobe dorsal to ventral cirri. Dorsal cirri weakly annulated, very long, up to 5 mm in life, cylindrical; elongated cirrophores absent (Figure 15A,B and Figure 17A). Dorsal cirri alternation unknown.
Notopodial hooks absent. Neuropodia triangular, with rounded prechaetal lobe distally inserted (Figure 17A). Noto- and neuro-aciculae present. Neurochaetae ~40 in chaetiger 12, all compound with distinctly internally chambered shafts (Figure 17B,C), ending in rounded hooked tip, superior (dorsal) and median blades up to five times longer than inferior (ventral) ones, in all cases blades quite straight (Figure 17B,C). Ventral cirri subdistally inserted on neuropodium, without cirrophores, up to 10 times longer than base width (Figure 17A). Paired pygidial cirri present (Figure 15A), like dorsal cirri; median pygidial papilla not observed.
Variation
As seen in the haplotype network (Figure 3) there was very little variability on COI among the 15 specimens sequenced from Costa Rica and the Gulf of California (Mexico), with the most divergent haplotype coming from Mexico. Preserved paratypes ranged in size from 1.5 to 12 mm and with 12–33 segments.
Distribution
Methane seeps at ~990–1400 m off the Pacific coast of Costa Rica and at ~1500 m in the Guaymas Basin, Gulf of California, Mexico.
Etymology
This species is named in honor of Mindi Summers for her work on Sirsoe and Vrijenhoekia and who first informally led the description of this species as Vrijenhoekia sp. A [4].
Remarks
Vrijenhoekia mindiae n. sp. was originally described but not named from a single specimen from the Guaymas Basin seeps [4]. Owing to there being only a single specimen in poor condition, the authors chose to refer to it as Vrijenhoekia sp. A and published several sequences for the species that clearly showed it belonging in Vrijenhoekia. The acquisition of many more specimens, all associated with wood or bone on the seafloor at seep locations off the coast of Costa Rica, has allowed for the species to now be described. The haplotype network for this species showed six haplotypes for the 15 specimens sequenced (Figure 3). The single Guaymas Basin haplotype was separated by at least six base pairs from the Costa Rican specimens, which showed little variation. The description here largely matches the original informal description but the newly acquired specimens here were mostly much larger. Vrijenhoekia mindiae n. sp. is the sister group to the as yet undescribed Vrijenhoekia BioSuOr from bones deployed off the Brazilian coast. It was 15% divergent on COI (Table 2). Vrijenhoekia mindiae n. sp. lies in the clade of Vrijenhoekia (Clade III, Figure 1), which mainly have a median antenna and lack glandular lip pads. Like V. ketea and V. timoharai, it lacks the terminal proboscis papillae [4] that is seen in Sirsoe spp. and in V. balaenophila, V. besnard n. comb., V. alphacrucis n. comb., V. alphadelphini n. comb., V. nadir n. comb., and V. yokosuka n. comb. [3,8], all members of Vrijenhoekia Clade II. Only one member of Vrijenhoekia Clade III has been described as having terminal papillae; V. ungava n. comb. [8]. Vrijenhoekia mindiae n. sp. appears to be unique in having ventral cirri on segments 1–5 with cirrophores.
4. Discussion
The availability of an appropriately fixed and recently collected specimen of Sirsoe grasslei, the type species for the genus [10], allowed for it to be sequenced and placed into a molecular phylogeny (Figure 1). This facilitated a reassessment of the recent proposal to make Vrijenhoekia a junior synonym of Sirsoe [8]. In their arguments for synonymy, the authors erroneously stated that Sirsoe could only be monophyletic with the inclusion of the Vrijenhoekia species and that recognition of Vrijenhoekia made both genera non-monophyletic. Examination of their phylogenetic results showed that, allowing for the new species included, their tree was not markedly different from the previously published phylogeny [5] showing reciprocally monophyletic Sirsoe and Vrijenhoekia. Their Clade I could have been retained as Sirsoe and their Clades II and III (sister taxa) as Vrijenhoekia. Concerns about the diagnosis of each genus also seemed to be an issue and the authors opted for an expanded genus with a diagnosis with a series of variable features (see Section 3.5.1). This synonymy was unfortunate, in that four species changed genus name from Vrijenhoekia to Sirsoe when a main goal of taxonomy is the stability of taxon names.
The phylogenetic results here show Sirsoe grasslei clearly falls (Figure 1) into what was previously regarded as Sirsoe [3,5], which is not surprising given its morphological similarity to taxa such as Sirsoe methanicola. As the type species for Sirsoe, this subjectively allows for members of Clade I alone to be in the genus (Figure 1), a decision we follow here. We additionally reinstate a monophyletic Vrijenhoekia here to Clades II and III, also a subjective decision. Our new diagnoses for each genus are clear and should hopefully allow for morphological identification (see Section 3.5.1 and Section 3.5.6) in the absence of DNA data. An unfortunate consequence of this is that eight species named as Sirsoe will now be referred to as Vrijenhoekia (Figure 1), but hopefully, with the two genera stabilized, there will be long term stability.
Author Contributions
Conceptualization, G.W.R.; methodology, G.W.R.; formal analysis, G.W.R. and R.K.; investigation, G.W.R. and R.K. resources, G.W.R.; data curation, R.K. and G.W.R.; writing—original draft preparation, R.K.; writing—review and editing, G.W.R. and R.K.; visualization, G.W.R. and R.K.; supervision, G.W.R.; funding acquisition, G.W.R. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by the US National Science Foundation for Alaskan specimens (NSF-OCE 2048481) and Costa Rican specimens (NSF-OCE 0826254, 0939557, and 1634172). Specimens from the Pescadero Basin were collected on cruises funded by the Schmidt Ocean Institute.
Institutional Review Board Statement
Not applicable.
Data Availability Statement
All new data have been lodged on GenBank.
Acknowledgments
Thanks to Shana Goffredi for the invitation to Alaska to GWR and to the Schmidt Ocean Institute for cruises FK181031 and FK210922. We thank the crews, captains, and technicians of the R/V Falkor and the R/V Atlantis and to the pilots of the ROV SuBastian and HOV Alvin for their expertise. We are also grateful to the chief scientists and parties of each expedition. Thanks to Avery Hiley, Marina McCowin, and Kate Burns for their assistance in the lab and initial sequencing of specimens. We also thank Charlotte Seid of the Benthic Invertebrate Collection (SIO-BIC) at the Scripps Institution of Oceanography for her help with specimen management. We thank the two anonymous reviewers for their valuable comments on the initial submission. This paper and the resurrection of Vrijenhoekia is dedicated to Bob Vrijenhoek for his outstanding contributions to deep sea biology.
Conflicts of Interest
The authors declare no conflicts of interest.
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Figure 1.
Maximum likelihood (ML) phylogenetic tree from concatenated and partitioned mitochondrial (COI and 16S) and nuclear (18S and 28S) genes. New species are in bold and values on nodes represent ML bootstrap values with an asterisk indicating support of 100%.
Figure 1.
Maximum likelihood (ML) phylogenetic tree from concatenated and partitioned mitochondrial (COI and 16S) and nuclear (18S and 28S) genes. New species are in bold and values on nodes represent ML bootstrap values with an asterisk indicating support of 100%.
Figure 2.
TCS haplotype network for COI from 21 individuals of Sirsoe pleijeli n. sp. from seeps off the Sanak Islands, Alaska, and hydrothermal vents in the Pescadero Basin, Gulf of California, Mexico.
Figure 2.
TCS haplotype network for COI from 21 individuals of Sirsoe pleijeli n. sp. from seeps off the Sanak Islands, Alaska, and hydrothermal vents in the Pescadero Basin, Gulf of California, Mexico.
Figure 3.
TCS haplotype network for COI from 15 individuals of Vrijenhoekia mindiae n. sp. From seeps in the Guaymas Basin, Gulf of California, Mexico, and Costa Rican seeps.
Figure 3.
TCS haplotype network for COI from 15 individuals of Vrijenhoekia mindiae n. sp. From seeps in the Guaymas Basin, Gulf of California, Mexico, and Costa Rican seeps.
Figure 4.
Transformation for the median antenna character mapped onto the ML tree topology (with branch length information), visualized in Mesquite 3.81 using likelihood ancestral state reconstruction on ball and sticks tree form with the Mk1 probability model. Values at some nodes show the maximum likelihood score out of 100 for the most likely state indicated by the pie chart.
Figure 4.
Transformation for the median antenna character mapped onto the ML tree topology (with branch length information), visualized in Mesquite 3.81 using likelihood ancestral state reconstruction on ball and sticks tree form with the Mk1 probability model. Values at some nodes show the maximum likelihood score out of 100 for the most likely state indicated by the pie chart.
Figure 5.
Transformation for the frontal tubercle character mapped onto the ML tree topology (with branch length information), visualized in Mesquite 3.81 using likelihood ancestral state reconstruction on ball and sticks tree form with the Mk1 probability model. Values at some nodes show the maximum likelihood score out of 100 for the most likely state indicated by the pie chart.
Figure 5.
Transformation for the frontal tubercle character mapped onto the ML tree topology (with branch length information), visualized in Mesquite 3.81 using likelihood ancestral state reconstruction on ball and sticks tree form with the Mk1 probability model. Values at some nodes show the maximum likelihood score out of 100 for the most likely state indicated by the pie chart.
Figure 6.
Transformation for the glandular lip pad character mapped onto the ML tree topology (with branch length information), visualized in Mesquite 3.81 using likelihood ancestral state reconstruction on ball and sticks tree form with the Mk1 probability model. Values at some nodes show the maximum likelihood score out of 100 for the most likely state indicated by the pie chart.
Figure 6.
Transformation for the glandular lip pad character mapped onto the ML tree topology (with branch length information), visualized in Mesquite 3.81 using likelihood ancestral state reconstruction on ball and sticks tree form with the Mk1 probability model. Values at some nodes show the maximum likelihood score out of 100 for the most likely state indicated by the pie chart.
Figure 7.
Light microscopy images of Sirsoe grasslei (SIO-BIC A13989) from hydrothermal vents in the Pescadero Basin, Gulf of California, Mexico. (A) Dorsal view of live, mature, female specimen. (B) Ventral view of whole specimen. (C) Dorsal view of anterior of preserved specimen stained with ShirlastainA©. (D) Lateral view of preserved specimen stained with ShirlastainA©. Legend: 1, 2, 3: first three segments; a—lateral antenna; cp—cirrophore; ma—median antenna; no—nuchal organ; oo—oocytes; p—palp.
Figure 7.
Light microscopy images of Sirsoe grasslei (SIO-BIC A13989) from hydrothermal vents in the Pescadero Basin, Gulf of California, Mexico. (A) Dorsal view of live, mature, female specimen. (B) Ventral view of whole specimen. (C) Dorsal view of anterior of preserved specimen stained with ShirlastainA©. (D) Lateral view of preserved specimen stained with ShirlastainA©. Legend: 1, 2, 3: first three segments; a—lateral antenna; cp—cirrophore; ma—median antenna; no—nuchal organ; oo—oocytes; p—palp.
Figure 8.
Light microscopy images of Sirsoe grasslei (SIO-BIC A13989) from hydrothermal vents in the Pescadero Basin, Gulf of California, Mexico. (A) Dorsal view of preserved specimen stained with ShirlastainA©. (B) Ventral view of preserved specimen with 10 terminal papillae in the proboscis stained with ShirlastainA©. (C) Segment 12. (D) Parapodium of segment 12. (E) Superior (dorsal) neurochaetae of segment 12. (F) Inferior (ventral) neurochaetae of segment 12. Legend: 1–10: terminal papillae of proboscis; a—lateral antenna; ac—aciculae; cp—cirrophores; dc—dorsal cirrus; ma—median antenna; p—palpophores; S1, S2, S3—segments 1–3; vc—ventral cirrus.
Figure 8.
Light microscopy images of Sirsoe grasslei (SIO-BIC A13989) from hydrothermal vents in the Pescadero Basin, Gulf of California, Mexico. (A) Dorsal view of preserved specimen stained with ShirlastainA©. (B) Ventral view of preserved specimen with 10 terminal papillae in the proboscis stained with ShirlastainA©. (C) Segment 12. (D) Parapodium of segment 12. (E) Superior (dorsal) neurochaetae of segment 12. (F) Inferior (ventral) neurochaetae of segment 12. Legend: 1–10: terminal papillae of proboscis; a—lateral antenna; ac—aciculae; cp—cirrophores; dc—dorsal cirrus; ma—median antenna; p—palpophores; S1, S2, S3—segments 1–3; vc—ventral cirrus.
Figure 9.
Light microscopy images of Sirsoe pleijeli n. sp. (A) Holotype (ICML-EMU 13999), dorsal view of live specimen. (B) Holotype, dorsal view of anterior living specimen. (C) Paratype (SIO-BIC A14080A) dorsal view of anterior of live specimen with everted proboscis. (D) Paratype (SIO-BIC A14080A) lateral view of live specimen with everted proboscis and first three ventral cirri labeled. Legend: 1, 2, 3: first three segments; a—lateral antenna; ch—chaetae of segment 2; ma—median antenna; p—palp.
Figure 9.
Light microscopy images of Sirsoe pleijeli n. sp. (A) Holotype (ICML-EMU 13999), dorsal view of live specimen. (B) Holotype, dorsal view of anterior living specimen. (C) Paratype (SIO-BIC A14080A) dorsal view of anterior of live specimen with everted proboscis. (D) Paratype (SIO-BIC A14080A) lateral view of live specimen with everted proboscis and first three ventral cirri labeled. Legend: 1, 2, 3: first three segments; a—lateral antenna; ch—chaetae of segment 2; ma—median antenna; p—palp.
Figure 10.
Light microscopy of Sirsoe pleijeli n. sp. (A) Paratype (SIO-BIC A14074) ventral view of preserved specimen with everted proboscis and 10 terminal papillae stained with ShirlastainA©. (B) Specimen SIO-BIC A13998 ventral view of preserved specimen stained with ShirlastainA©. (C) Holotype (ICML-EMU 13999), segment 12. (D) Holotype, segment 12 parapodium. (E) Holotype, superior (dorsal) neurochaetae segment 12. (F) Holotype, inferior (ventral) neurochaetae segment 12. Legend: 1, 2, 3: first three segments; ac—aciculae; dc—dorsal cirrus; S1, S2, S3—segments 1–3; vc—ventral cirrus.
Figure 10.
Light microscopy of Sirsoe pleijeli n. sp. (A) Paratype (SIO-BIC A14074) ventral view of preserved specimen with everted proboscis and 10 terminal papillae stained with ShirlastainA©. (B) Specimen SIO-BIC A13998 ventral view of preserved specimen stained with ShirlastainA©. (C) Holotype (ICML-EMU 13999), segment 12. (D) Holotype, segment 12 parapodium. (E) Holotype, superior (dorsal) neurochaetae segment 12. (F) Holotype, inferior (ventral) neurochaetae segment 12. Legend: 1, 2, 3: first three segments; ac—aciculae; dc—dorsal cirrus; S1, S2, S3—segments 1–3; vc—ventral cirrus.
Figure 11.
Light microscopy images of Sirsoe shastae n. sp. from the Pescadero Basin hydrothermal vent fields. (A) Holotype (ICML-EMU 14001), dorsal view of live specimen. (B) Holotype, dorsal view of anterior of living specimen. (C) Paratype (SIO-BIC A14065A) prostomium of live specimen in frontal view. Legend: 1, 2, 3: first three segments; a—lateral antenna; ma—median antenna; no—nuchal organ; oo—oocytes; p—palp.
Figure 11.
Light microscopy images of Sirsoe shastae n. sp. from the Pescadero Basin hydrothermal vent fields. (A) Holotype (ICML-EMU 14001), dorsal view of live specimen. (B) Holotype, dorsal view of anterior of living specimen. (C) Paratype (SIO-BIC A14065A) prostomium of live specimen in frontal view. Legend: 1, 2, 3: first three segments; a—lateral antenna; ma—median antenna; no—nuchal organ; oo—oocytes; p—palp.
Figure 12.
Light microscopy images of preserved holotype (ICML-EMU 14001) of Sirsoe shastae n. sp. (A) Dorsal view, stained with ShirlastainA©. (B) Ventral view, stained with ShirlastainA©. (C) Segment 12. (D) Segment 12 parapodium. (E) Superior (dorsal) neurochaetae segment 12. (F) Inferior (ventral) neurochaetae segment 12. Legend: 1, 2, 3: first three segments; a—lateral antenna; ac—aciculae; cp—cirrophore; dc—dorsal cirrus; ma—median antenna; p—palp; vc—ventral cirrus.
Figure 12.
Light microscopy images of preserved holotype (ICML-EMU 14001) of Sirsoe shastae n. sp. (A) Dorsal view, stained with ShirlastainA©. (B) Ventral view, stained with ShirlastainA©. (C) Segment 12. (D) Segment 12 parapodium. (E) Superior (dorsal) neurochaetae segment 12. (F) Inferior (ventral) neurochaetae segment 12. Legend: 1, 2, 3: first three segments; a—lateral antenna; ac—aciculae; cp—cirrophore; dc—dorsal cirrus; ma—median antenna; p—palp; vc—ventral cirrus.
Figure 13.
Holotype (ICML-EMU 14000), of Sirsoe sapote n. sp. from hydrothermal vents of the Pescadero Basin, Gulf of California, Mexico. (A) Dorsal view of live specimen with everted proboscis. (B) Ventral view of everted proboscis of preserved holotype with 10 terminal papillae stained with ShirlastainA©. (C) Anterior dorsal view of preserved holotype stained with ShirlastainA©. (D) Lateral view of preserved holotype stained with ShirlastainA©. Legend: 1–10: terminal papillae of proboscis; a—lateral antenna; k—knob; ma—median antenna; no—nuchal organ; pp—palpophore; ps—palpostyle; S1, S2, S3, S4: first four segments; vi—ventral incision of proboscis.
Figure 13.
Holotype (ICML-EMU 14000), of Sirsoe sapote n. sp. from hydrothermal vents of the Pescadero Basin, Gulf of California, Mexico. (A) Dorsal view of live specimen with everted proboscis. (B) Ventral view of everted proboscis of preserved holotype with 10 terminal papillae stained with ShirlastainA©. (C) Anterior dorsal view of preserved holotype stained with ShirlastainA©. (D) Lateral view of preserved holotype stained with ShirlastainA©. Legend: 1–10: terminal papillae of proboscis; a—lateral antenna; k—knob; ma—median antenna; no—nuchal organ; pp—palpophore; ps—palpostyle; S1, S2, S3, S4: first four segments; vi—ventral incision of proboscis.
Figure 14.
Holotype (ICML-EMU 14000), of Sirsoe sapote n. sp. from hydrothermal vents in the Pescadero Basin, Gulf of California, Mexico. (A) Segment 12. (B) Segment 12 parapodium. (C) Superior (dorsal) neurochaetae segment 12. (D) Inferior (ventral) neurochaetae segment 12. Legend: dc—dorsal cirrus; vc—ventral cirrus.
Figure 14.
Holotype (ICML-EMU 14000), of Sirsoe sapote n. sp. from hydrothermal vents in the Pescadero Basin, Gulf of California, Mexico. (A) Segment 12. (B) Segment 12 parapodium. (C) Superior (dorsal) neurochaetae segment 12. (D) Inferior (ventral) neurochaetae segment 12. Legend: dc—dorsal cirrus; vc—ventral cirrus.
Figure 15.
Collection site and individual representative of Vrijenhoekia mindiae n. sp. (A) Paratype SIO-BIC A9615 in situ on decaying vertebrate bone fragment at Costa Rica seep at 992 m depth. (B) Holotype (SIO-BIC A9606) dorsal view of live, relaxed specimen. (C) Anterior end of holotype. Legend: 1, 2, 3, 4: first four segments; a—lateral antenna; ch—chaetae of segment 3; ft—frontal tubercle; p—palp.
Figure 15.
Collection site and individual representative of Vrijenhoekia mindiae n. sp. (A) Paratype SIO-BIC A9615 in situ on decaying vertebrate bone fragment at Costa Rica seep at 992 m depth. (B) Holotype (SIO-BIC A9606) dorsal view of live, relaxed specimen. (C) Anterior end of holotype. Legend: 1, 2, 3, 4: first four segments; a—lateral antenna; ch—chaetae of segment 3; ft—frontal tubercle; p—palp.
Figure 16.
Paratype (SIO-BIC A9612F) of Vrijenhoekia mindiae n. sp. stained with ShirlastainA©. (A) Dorsal view of preserved specimen anterior region. (B) Ventral view of partially everted proboscis and anterior segments. (C) Lateral view showing partially everted proboscis and anterior segments. Legend: 1, 2, 3, 4, 5: first five segments; a—lateral antenna; ch—chaetae; ft—frontal tubercle; ma—median antenna; p—palp.
Figure 16.
Paratype (SIO-BIC A9612F) of Vrijenhoekia mindiae n. sp. stained with ShirlastainA©. (A) Dorsal view of preserved specimen anterior region. (B) Ventral view of partially everted proboscis and anterior segments. (C) Lateral view showing partially everted proboscis and anterior segments. Legend: 1, 2, 3, 4, 5: first five segments; a—lateral antenna; ch—chaetae; ft—frontal tubercle; ma—median antenna; p—palp.
Figure 17.
Holotype (SIO-BIC A9606) of Vrijenhoekia mindiae n. sp. (A) Segment 12. (B) Superior (dorsal) neurochaetae segment 12. (C) Inferior (ventral) neurochaetae segment 12. Legend: ac—aciculae; dc—dorsal cirrus; vc—ventral cirrus.
Figure 17.
Holotype (SIO-BIC A9606) of Vrijenhoekia mindiae n. sp. (A) Segment 12. (B) Superior (dorsal) neurochaetae segment 12. (C) Inferior (ventral) neurochaetae segment 12. Legend: ac—aciculae; dc—dorsal cirrus; vc—ventral cirrus.
Table 1.
GenBank accession numbers and catalog numbers of specimens referenced in this study. New data in bold. Abbreviations: AM—Australian Museum; MZUSP—Museu de Zoologia, Universidade de São Paulo; SY—Repository of the Second Institute of Oceanography; SIO-BIC—Scripps Institution of Oceanography, Benthic Invertebrate Collection; SMNH—Swedish Museum of Natural History. Vrijenhoekia mindiae n. sp. is what was formerly referred to as Vrijenhoekia sp. A in Summers et al. [4]. Vrijenhoekia BioSuOr was previously referred to as Sirsoe BioSuOr [8]. Other COI data generated for this study are listed with the material examined.
Table 1.
GenBank accession numbers and catalog numbers of specimens referenced in this study. New data in bold. Abbreviations: AM—Australian Museum; MZUSP—Museu de Zoologia, Universidade de São Paulo; SY—Repository of the Second Institute of Oceanography; SIO-BIC—Scripps Institution of Oceanography, Benthic Invertebrate Collection; SMNH—Swedish Museum of Natural History. Vrijenhoekia mindiae n. sp. is what was formerly referred to as Vrijenhoekia sp. A in Summers et al. [4]. Vrijenhoekia BioSuOr was previously referred to as Sirsoe BioSuOr [8]. Other COI data generated for this study are listed with the material examined.
| Species | Voucher | Locality | COI | 16S | 18S | 28S |
|---|---|---|---|---|---|---|
| Hesiospina vestimentifera | SIO-BIC A2510 | Fiji | JN631310 | JN631320 | JN631330 | JN631343 |
| Sirsoe alucia | MZUSP 3359 | SW Atlantic | MH935127 | MH935204 | - | - |
| Sirsoe dalailamai | SIO-BIC A1767 | Costa Rica | MG517498 | MG523357 | MG649240 | MG649245 |
| Sirsoe feitiana | SY 398007 | South China Sea | OR126117 | OR129662 | - | - |
| Sirsoe grasslei | SIO-BIC A13989 | Gulf of California | PQ774161 | PQ771110 | PQ771116 | PQ771120 |
| Sirsoe maximiano | MZUSP 3371 | SW Atlantic | MH935151 | MH935157 | - | - |
| Sirsoe methanicola | - | Gulf of Mexico | DQ513295 | DQ442582 | JN631332 | DQ442611 |
| Sirsoe nanhaiensis | SY 396P01 | South China Sea | OR126101 | OR129656 | - | - |
| Sirsoe pleijeli n. sp. | SIO-BIC A13998B | Gulf of California | PQ774167 | PQ771113 | PQ771119 | PQ771123 |
| Sirsoe polita | SY 400001 | South China Sea | OR126114 | OR129671 | - | - |
| Sirsoe sapote n. sp. | ICML-EMU-14000 | Gulf of California | PQ774180 | PQ771112 | PQ771117 | PQ771121 |
| Sirsoe shastae n. sp. | ICML-EMU-14001 | Gulf of California | PQ774162 | PQ771113 | PQ771118 | PQ771122 |
| Sirsoe sirikos | SIO-BIC A2323 | California | JN571829 | JN571882 | JN571893 | JN571902 |
| Vrijenhoekia ahabi | SIO-BIC A2327 | California | JN571876 | JN571887 | JN571898 | JN571907 |
| Vrijenhoekia balaenophila | SMNH 6305 type | California | DQ513296 | DQ513301 | JN631333 | DQ513306 |
| Vrijenhoekia cf. balaenophila | SMNH 6307 | California | DQ513297 | DQ513302 | - | DQ513307 |
| Vrijenhoekia mindiae n. sp. | SIO-BIC A3255 | Gulf of California | KP745533 | KP745536 | KP745539 | KP745542 |
| Vrijenhoekia ketea | SIO-BIC A2341 | California | JN571838 | JN571885 | JN571896 | JN571905 |
| Vrijenhoekia falenothiras | SIO-BIC A2345 | California | JN571875 | JN571886 | JN571897 | JN571906 |
| Vrijenhoekia nadir n. comb. | MZUSP 3361 | SW Atlantic | MH935129 | MH935200 | - | - |
| Vrijenhoekia besnard n. comb. | MZUSP 3370 | SW Atlantic | MH935147 | MH935199 | - | - |
| Vrijenhoekia alphadelphini n. comb. | MZUSP 2272 | SW Atlantic | MH935132 | MH935203 | - | - |
| Vrijenhoekia alphacrucis n. comb. | MZUSP 3363 | SW Atlantic | MH935140 | MH935191 | - | - |
| Vrijenhoekia yokosuka n. comb. | MZUSP 3369 | SW Atlantic | MH935141 | MH935196 | - | - |
| Vrijenhoekia ypupiara n. comb. | MZUSP 3357 | SW Atlantic | MH935119 | MH935179 | - | - |
| Vrijenhoekia pirapuan n. comb. | MZUSP 3455 | SW Atlantic | MH935102 | MH935189 | - | - |
| Vrijenhoekia ungava n. comb. | MZUSP 3369 | SW Atlantic | MH935145 | MH935160 | - | - |
| Vrijenhoekia BioSuOr | - | SW Atlantic | MH935146 | MH935161 | - | - |
| Vrijenhoekia timoharai | AM W.53702 | Australia | OQ801445 | OQ820995 | OQ803244 | - |
Table 2.
Minimum uncorrected pairwise distances for COI for all currently known Sirsoe and Vrijenhoekia species. Orange highlighted cell shows the 3% distance between S. alucia from the South Atlantic Ocean and S. polita from the South China Sea. The green highlighted cells show distances discussed in the text.
Table 2.
Minimum uncorrected pairwise distances for COI for all currently known Sirsoe and Vrijenhoekia species. Orange highlighted cell shows the 3% distance between S. alucia from the South Atlantic Ocean and S. polita from the South China Sea. The green highlighted cells show distances discussed in the text.
| Species | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 |
| 1. S_alucia | ||||||||||||||||||||||||||||
| 2. S_dalailamai | 0.19 | |||||||||||||||||||||||||||
| 3. S_feitiana | 0.18 | 0.15 | ||||||||||||||||||||||||||
| 4. S_grasslei | 0.20 | 0.12 | 0.15 | |||||||||||||||||||||||||
| 5. S_maximiano | 0.20 | 0.16 | 0.16 | 0.14 | ||||||||||||||||||||||||
| 6. S_methanicola | 0.21 | 0.10 | 0.17 | 0.14 | 0.16 | |||||||||||||||||||||||
| 7. S_munki | 0.22 | 0.14 | 0.17 | 0.08 | 0.15 | 0.13 | ||||||||||||||||||||||
| 8. S_nanhaiensis | 0.21 | 0.16 | 0.11 | 0.16 | 0.16 | 0.19 | 0.19 | |||||||||||||||||||||
| 9. S_pleijeli n. sp. | 0.20 | 0.12 | 0.15 | 0.08 | 0.14 | 0.13 | 0.10 | 0.16 | ||||||||||||||||||||
| 10. S_polita | 0.03 | 0.19 | 0.18 | 0.20 | 0.20 | 0.21 | 0.21 | 0.20 | 0.20 | |||||||||||||||||||
| 11. S_sapote n. sp. | 0.19 | 0.05 | 0.15 | 0.13 | 0.16 | 0.10 | 0.13 | 0.16 | 0.13 | 0.18 | ||||||||||||||||||
| 12. S_shastae n. sp. | 0.20 | 0.13 | 0.15 | 0.04 | 0.14 | 0.13 | 0.09 | 0.16 | 0.08 | 0.19 | 0.13 | |||||||||||||||||
| 13. S_sirikos | 0.21 | 0.15 | 0.16 | 0.15 | 0.08 | 0.15 | 0.14 | 0.16 | 0.13 | 0.21 | 0.15 | 0.14 | ||||||||||||||||
| 14. V_ahabi | 0.21 | 0.20 | 0.18 | 0.20 | 0.20 | 0.22 | 0.22 | 0.18 | 0.20 | 0.21 | 0.19 | 0.20 | 0.20 | |||||||||||||||
| 15. V_alphacrucis n. comb. | 0.23 | 0.19 | 0.20 | 0.19 | 0.19 | 0.22 | 0.20 | 0.20 | 0.19 | 0.24 | 0.20 | 0.20 | 0.18 | 0.17 | ||||||||||||||
| 16. V_alphadelphini n. comb. | 0.23 | 0.21 | 0.23 | 0.21 | 0.23 | 0.24 | 0.24 | 0.23 | 0.22 | 0.24 | 0.22 | 0.22 | 0.23 | 0.18 | 0.19 | |||||||||||||
| 17. V_balaenophila | 0.19 | 0.20 | 0.17 | 0.19 | 0.20 | 0.20 | 0.21 | 0.19 | 0.21 | 0.20 | 0.19 | 0.19 | 0.19 | 0.16 | 0.14 | 0.18 | ||||||||||||
| 18. V_cf._balaenophila | 0.22 | 0.19 | 0.18 | 0.19 | 0.21 | 0.21 | 0.21 | 0.20 | 0.20 | 0.21 | 0.20 | 0.19 | 0.19 | 0.16 | 0.16 | 0.18 | 0.08 | |||||||||||
| 19. V_besnard n. comb. | 0.21 | 0.18 | 0.20 | 0.19 | 0.21 | 0.22 | 0.20 | 0.19 | 0.20 | 0.21 | 0.20 | 0.19 | 0.19 | 0.17 | 0.18 | 0.16 | 0.16 | 0.16 | ||||||||||
| 20. V_falenothiras | 0.23 | 0.20 | 0.20 | 0.19 | 0.19 | 0.20 | 0.21 | 0.20 | 0.20 | 0.22 | 0.19 | 0.20 | 0.19 | 0.16 | 0.17 | 0.20 | 0.17 | 0.18 | 0.19 | |||||||||
| 21. V_ketea | 0.23 | 0.21 | 0.20 | 0.21 | 0.21 | 0.20 | 0.22 | 0.21 | 0.20 | 0.23 | 0.21 | 0.21 | 0.22 | 0.18 | 0.20 | 0.19 | 0.18 | 0.18 | 0.20 | 0.14 | ||||||||
| 22. V_mindiae n. sp. | 0.22 | 0.20 | 0.20 | 0.20 | 0.21 | 0.22 | 0.23 | 0.18 | 0.20 | 0.22 | 0.19 | 0.20 | 0.20 | 0.15 | 0.19 | 0.18 | 0.17 | 0.18 | 0.20 | 0.16 | 0.18 | |||||||
| 23. V_nadir n. comb. | 0.22 | 0.21 | 0.20 | 0.21 | 0.21 | 0.22 | 0.23 | 0.20 | 0.22 | 0.22 | 0.21 | 0.22 | 0.20 | 0.19 | 0.20 | 0.18 | 0.17 | 0.18 | 0.19 | 0.20 | 0.20 | 0.19 | ||||||
| 24. V_pirapuan n. comb. | 0.22 | 0.20 | 0.18 | 0.19 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | 0.22 | 0.20 | 0.19 | 0.20 | 0.17 | 0.16 | 0.18 | 0.07 | 0.06 | 0.17 | 0.18 | 0.19 | 0.17 | 0.18 | |||||
| 25. V_timoharai | 0.22 | 0.20 | 0.18 | 0.20 | 0.21 | 0.21 | 0.21 | 0.17 | 0.19 | 0.21 | 0.19 | 0.20 | 0.19 | 0.06 | 0.17 | 0.18 | 0.15 | 0.15 | 0.18 | 0.16 | 0.19 | 0.15 | 0.17 | 0.15 | ||||
| 26. V_ungava n. comb. | 0.23 | 0.18 | 0.19 | 0.20 | 0.20 | 0.20 | 0.21 | 0.19 | 0.20 | 0.23 | 0.19 | 0.20 | 0.20 | 0.17 | 0.15 | 0.20 | 0.16 | 0.16 | 0.19 | 0.11 | 0.14 | 0.16 | 0.17 | 0.16 | 0.17 | |||
| 27. V_yokosuka n. comb. | 0.21 | 0.19 | 0.20 | 0.21 | 0.20 | 0.23 | 0.22 | 0.19 | 0.22 | 0.22 | 0.20 | 0.21 | 0.20 | 0.15 | 0.11 | 0.17 | 0.13 | 0.14 | 0.16 | 0.17 | 0.18 | 0.18 | 0.18 | 0.14 | 0.15 | 0.15 | ||
| 28. V_ypupiara n. comb. | 0.22 | 0.21 | 0.18 | 0.20 | 0.21 | 0.21 | 0.21 | 0.21 | 0.21 | 0.21 | 0.21 | 0.20 | 0.21 | 0.17 | 0.17 | 0.18 | 0.08 | 0.08 | 0.17 | 0.19 | 0.19 | 0.18 | 0.20 | 0.06 | 0.17 | 0.17 | 0.15 | |
| 29. V_BioSuOr | 0.21 | 0.20 | 0.20 | 0.20 | 0.20 | 0.21 | 0.22 | 0.20 | 0.21 | 0.22 | 0.20 | 0.21 | 0.21 | 0.16 | 0.18 | 0.20 | 0.16 | 0.18 | 0.19 | 0.15 | 0.19 | 0.15 | 0.19 | 0.17 | 0.15 | 0.17 | 0.16 | 0.18 |
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Kroesche, R.; Rouse, G.W. Four New Species of Hesionidae (Annelida, Polychaeta, Phyllodocida) from Eastern Pacific Chemosynthetic Habitats and Reinstatement of Vrijenhoekia. Diversity 2025, 17, 121. https://doi.org/10.3390/d17020121
AMA Style
Kroesche R, Rouse GW. Four New Species of Hesionidae (Annelida, Polychaeta, Phyllodocida) from Eastern Pacific Chemosynthetic Habitats and Reinstatement of Vrijenhoekia. Diversity. 2025; 17(2):121. https://doi.org/10.3390/d17020121
Chicago/Turabian StyleKroesche, Rachel, and Greg W. Rouse. 2025. "Four New Species of Hesionidae (Annelida, Polychaeta, Phyllodocida) from Eastern Pacific Chemosynthetic Habitats and Reinstatement of Vrijenhoekia" Diversity 17, no. 2: 121. https://doi.org/10.3390/d17020121
APA StyleKroesche, R., & Rouse, G. W. (2025). Four New Species of Hesionidae (Annelida, Polychaeta, Phyllodocida) from Eastern Pacific Chemosynthetic Habitats and Reinstatement of Vrijenhoekia. Diversity, 17(2), 121. https://doi.org/10.3390/d17020121
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