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Article

Uncovering the Evolutionary History in Lineage of Caribbean Octocorals: Phylogenomics Reveals Unrecognized Diversity in Eunicea †

by
Adriana Sarmiento
1,2,
Iván Calixto-Botía
2,3,
Tatiana Julio-Rodríguez
1,
Andrea M. Quattrini
4 and
Juan A. Sánchez
1,*
1
Laboratory of Marine Molecular Biology (BIOMMAR), Department of Biological Sciences, Universidad de Los Andes, Bogotá 111711, Colombia
2
Center of Excellence in Marine Sciences (CEMarin), Bogotá 111311, Colombia
3
Laboratorio de Estudios Moleculares de la Orinoquia -LEMO-, Universidad Internacional del Trópico Americano -Unitropico-, Yopal 850002, Colombia
4
Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, 10th and Constitution Ave NW, Washington, DC 20560, USA
*
Author to whom correspondence should be addressed.
†
urn:lsid:zoobank.org:act:262AFAA2-62AB-46FD-B8E8-14159E4AFE70; urn:lsid:zoobank.org:act:F59458C7-12A8-41AA-AB4A-F49C86FE51E6.
Diversity 2025, 17(3), 173; https://doi.org/10.3390/d17030173
Submission received: 27 November 2024 / Revised: 23 February 2025 / Accepted: 24 February 2025 / Published: 27 February 2025
(This article belongs to the Section Marine Diversity)
Browse Figures
Versions Notes

Abstract

:
The evolutionary history of the Caribbean candelabrum octocorals from the genus Eunicea (Plexauridae: Octocorallia) remains unknown despite their high diversity and abundance in reef environments. Understanding the evolutionary relationships between and within the Eunicea species is critical to accurately measuring the group diversity. Furthermore, this group has a high potential for cryptic diversity and new species, particularly given the rich morphological variability. Conventional molecular markers, however, have not provided a precise positioning for the species inside the genus. Here, we provide the first phylogenomic reconstruction of these candelabrum octocorals employing NextRAD, a reduced-representation sequencing technique, to generate thousands of SNPs. We include 15 morphospecies sampled between valid and new species throughout the Caribbean. At large, the phylogeny is well supported and resolved. In total, 13 species-level clades are discernible, including two lineages with demonstrated genetic and morphological variation that are considered and described as two new species, Eunicea criptica sp. nov. and E. colombiensis sp. nov., both previously assigned as E. clavigera and the second as the “thick morphotype”, thereby increasing the diversity of the group. Understanding the magnitude of species diversity within Eunicea is essential for directing conservation initiatives and clarifying the biological processes in reef ecosystems.

Graphical Abstract

1. Introduction

No universal properties can be used to delimit a species. However, different characteristics, such as morphological distinctness, reproductive isolation, and monophyly, manifested throughout distinct evolutionary paths, are reliable indicators that help define species [1,2,3]. This search for species delimitation has uncovered vast unrecognized cryptic diversity, encompassing two or more taxa categorized under a single name due to indistinguishable morphology [4]. The extent and distribution of cryptic species comprise the most elusive problem in the search for diversification patterns in marine fauna, where human perception to categorize species poses unique difficulties, especially when compared to those encountered in terrestrial ecosystems. Other intrinsic and widespread elements that obscure the current patterns of diversification across benthic marine fauna are the common sympatric scenarios for gene flow reduction, diagnostic characters based on labile traits of colonial forms, repetitive patterns of adaptive radiation, morphological characteristics overlapping across clines, and non-recognizable phenotype plasticity of particular traits [5,6].
Octocorals, commonly known as gorgonian and soft corals, are diverse and abundant in reef communities [7,8,9]. They play a crucial role in Caribbean reef formation, often exhibiting greater diversity and biomass than scleractinian corals [10]. Among octocorals, the genus Eunicea Lamouroux, 1816 (Cnidaria: Anthozoa: Octocorallia: Plexauridae), commonly known as sea candelabrum, comprises the most diverse and abundant group in the Tropical Western Atlantic [11]. All species have a mutualistic relationship with symbiotic dinoflagellates, Symbiodiniaceae, limiting their habitat to the photic zone [11,12]. The group’s success on Caribbean reefs is partly attributed to their efficiency as colonial photosynthetic suspension feeders [11], with E. flexuosa and E. tourneforti as the most abundant species. This group has a high potential to find new species, particularly given the rich morphological variability among and within species. The primary reason for this has been sympatric species, which has exacerbated the challenge of species identification due to the overlap of morphological characteristics among multiple species [11].
There are few phylogenetic studies of Eunicea. Gerhart [13] published the first phylogenetic hypotheses proposed for the genus Eunicea based on the chemical compounds they produce, including only five species, and found that the genus should be split into two groups. Wirshing et al. [14] proposed a phylogeny using the mitochondrial genes ND2 and mtMutS, including only eight Eunicea species, and suggested a diversification of Eunicea into at least two incipient groups corresponding to the known subgenus Eunicea and Euniceopsis Verrill, 1907. Other studies based on RNA secondary structures of the Internal Transcribed Spacer 2 (ITS2) suggested that the genus is a monophyletic group [15,16]. Most recently, some presently recognized Eunicea species, plus two morphotypes, were included, and molecular (ITS2) and morphological data were used to infer a phylogeny [17]. Though these studies confirmed the monophyletic state of the group, they lack robust support and seem inconclusive for certain phylogenetic relationships in the group. These unresolved phylogenies and the large morphological variation point towards hidden diversity among the Eunicea group and the potential of finding undescribed species.
To elucidate the evolutionary relationships among species from the genus Eunicea [11], we (1) employed a phylogenomic approach using NextRAD, a reduced-representation sequencing (RRS), to generate genome-wide sequencing data and obtain a large number of polymorphic SNPs across the group, and (2) delved into unrecognized diversity. Here, we provide the first Eunicea phylogeny constructed from genome-scale data, resolve the evolutionary history of ancestor-descendant relationships for 15 Eunicea morphospecies, and moreover describe two new species.

2. Materials and Methods

2.1. Sample Collection and Morphospecies Identifications

Eunicea colonies were collected with SCUBA at five locations in the Caribbean: Florida Keys, Panama, Cartagena, San Andrés, and Curaçao (Figure 1, Table S1). Sampling was performed in shallow and mesophotic reefs within a depth range of 5 to 45 m. A minimum of three colonies were sampled per site, for a total of 202 samples collected (Table S1). After collection, a small piece of tissue from each colony was further preserved in DMSO solution for posterior DNA extraction, a remaining fragment of each collected colony was dried, and vouchers were deposited in the Museo de Historia Natural ANDES (University of Los Andes, Colombia). For taxonomic identification, a small portion of each colony was treated with diluted bleach to isolate the sclerites for microscopic observations following the terminology, identification key, and descriptions by Bayer [18].

2.2. DNA Extraction, Library Construction and Sequencing

Total genomic DNA was extracted following the phenol–chloroform protocol from Coffroth et al. [19] with slight modifications to reduce mechanical stress on processed tissue and avoid DNA degradation (e.g., no vortex steps). Qubit Fluorometer (Thermo-Fisher, Dietikon, Switzerland), and agarose gel (0.7%) electrophoresis were used to measure DNA quality and concentration. Individualized SNP sequencing was performed by SNPsaurus company (Eugene, OR, USA) (University of Oregon, Eugene, OR, USA) using the NextRAD genotyping-by-sequencing library methodology [20]. With this RADseq-modified methodology, 7 ng of each genomic DNA was fragmented and ligated to short adapters with Nextera reagent (Illumina, Inc., San Diego, CA, USA). DNA segments were then amplified for 26 cycles at 73 degrees, with one of the primers matching the adapter and extending nine nucleotides into the genomic DNA with the selective sequence GTGTAGAGG. Thus, only fragments starting with a sequence that the selective sequence of the primer can hybridize were efficiently amplified. The nextRAD libraries were sequenced on a HiSeq 4000 with 150 bp single-end reads.

2.3. Data Cleaning and De Novo Assembly

A mixed-read analysis was performed to detect the presence of Symbiodiniaceae [21], bacterial contamination, mitochondrial DNA, and other contaminant reads by randomly sampling 1000 reads from each sample and carrying out a blast [22] of each read to the NCBI nucleotide (nt) database.
To align reads and call SNPs, we used the de novo reference pipeline in ipyRAD 0.9.82 [23]. This program considers indel variation to detect homologous regions on highly divergent sequences. First, read quality was checked with FastQC [24] and cleaned with the cutadapt [25] module inside ipyRAD for low-quality bases (Q < 20), adapters, significant proportion of N’s, and reads shorter than 35 bp. Then, a branching process for the assembly was implemented to reduce paralogous loci while maximizing informativeness. Accordingly, dataset combinations were assessed for clustering threshold (0.80, 0.85), minimum number of taxa per locus (10%, 25%, 50%), and maximum shared heterozygous loci (0.25 and 0.5) using default values for the rest of parameters.

2.4. Phylogenomic Analysis and Species Delimitation

The IQ-Tree v. 2 software [26] was implemented to infer maximum likelihood (ML) phylogenomic trees on the 12 combinations of datasets from ipyRAD. The best model was chosen based on the AIC criterion from the IQ-Tree integrated ModelFinder algorithm (286 DNA models) [27]. Trees were run with ultrafast bootstrapping (UFBoot) [28] using 1000 replicates. Finally, the visualization and editing of trees were performed in the online version of iTOL 6.5.8 [29].
From the ipyRAD dataset chosen to obtain the phylogeny, the genetic structure was explored. The .vcf file was transformed to structure format using PGDSpider v 2.1.1.5 [30] to perform a Bayesian model-based clustering analysis in Structure v. 2.3.4 [31] through the web-based software Structure Harvester v. 0.6.9 [32], CLUMPP v. 1.1.2 [33], and DISTRUCT v. 1.1 software [34]. For all runs, the admixture model was applied with the correlated model of allele frequencies due to the expected closeness and considering priors with an alpha of 0.5 as recommended by Wang [35] for unbalanced-size samples. Burnin was set to 50,000 and 100,000 MCMC repeats, with 10 runs for each K assessed. F-statistics were calculated in R with the “hierfsat” package [36]. An SNP subset dataset was taken to perform the clustering analyses described above and explore the genetic structure for Clade A.

2.5. Morphological Analysis from New Eunicea Species

For taxonomic identification, external morphological characters of the colony were analyzed from photographs under a stereoscope of samples previously sequenced. For internal characters, a small portion of the tissue colony was treated with diluted bleach to isolate sclerites from polyps and coenenchyme. The dissociated sclerites were thoroughly washed with distilled water, dehydrated in 100% ethanol, and dried. The sclerites were documented using a digital light microscope (Olympus CX21) and photographed with a SWIFTCAM camera and the SwiftImaging application for detailed observation and further description. For scanning electron microscopy (SEM), sclerites were mounted on SEM stubs with double-stick carbon tape and silver paint and sputter-coated with gold. Images were captured with a Tescan Vegas 4 SEM at the MicroCore Microscopy Core at the Universidad de Los Andes. Other sclerites were coated in an 80:20 high-purity gold–palladium alloy using a LEICA EM ACE600. The samples were imaged using a Thermofisher APEREO Field Emission Scanning Electron Microscope at the Centre for Imaging, Smithsonian National Museum of Natural History. Sclerite measurements were taken from optical and SEM images. Taxonomic terminology followed Bayer et al. [37] (see Appendix A for more details).

3. Results

3.1. Data Cleaning and De Novo Assembly

NextRAD library sequencing produced approximately 4 million reads per individual (up to 9.4 million reads). After no mixed-read detection of Symbiodiniaceae or another microorganism and the filtering steps from cutadapt and ipyRAD, 183 individuals were retained from the initial 202 sampled. The number of individuals per a priori morphospecies, site, and depth is shown in Table 1.

3.2. Variant Calling and Filtering

A total of 12 datasets were produced from the ipyRAD de novo branching assemblies (Table 2). The numbers of loci and missingness at two different clustering thresholds, three different levels of taxon occupancy per locus, and two different levels of shared polymorphic sites are shown in Table 2. In general, the number of loci and the number of SNPs obtained increased when the number of shared polymorphic sites and the clustering threshold were increased, and the taxon occupancy decreased. Accordingly, the dataset with the highest number of SNPs retained, with a total of 328.314 SNPs, occurred when the clustering threshold was 0.85, the taxon occupancy was 10%, and the shared polymorphic sites were 0.5 (Table 2).

3.3. Phylogenomic Inference and Species Delimitation

A maximum likelihood tree was obtained from IQ-Tree with a clustering threshold of 0.85, taxon occupancy of 10% and shared polymorphic sites of 0.5 RADseq dataset (Figure 2). A GTR + F + R2 model suggested by the Akaike Information Criterion (AIC = 14,302,211) was used. Nevertheless, all IQ-Tree phylogenies obtained with the 12 RADseq datasets had identical topologies and similar support values regarding evolutionary relationships between species (Figures S1–S11). The majority of the Eunicea species formed strongly supported monophyletic clades (bootstrap values of 100%), which is congruent with the morphospecies assignment. The phylogenomic analyses recovered 13 well-supported clades. In the case of E. laciniata and E. tourneforti, species that show high intra-specific morphological variation, a broad sampling effort was undertaken to include samples of different morphotypes, yet all samples previously assigned to each morphospecies were included in the respective well-supported clades without evidencing any grouping by morphotype. Only one clade (Figure 2—Yellow clade) comprises samples from different morphospecies, E. mammosa, E. succinea, and E. palmeri, with no discernible discrimination based on morphospecies assignment, depth, or sampling location.
The structure analyses supported the assignment of morphospecies across most of the phylogeny. The optimal number of clusters suggested by the greatest ∆K was 13, which aligns well with the number of well-supported clades observed in the phylogeny. The Structure plot shows low to no admixture among the species E. flexuosa, E. pinta, E. fusca, E. tayrona, and E. laciniata (Figure 3). Meanwhile, individuals of E. knighti and E. calyculata exhibited admixture with the species E. tayrona and E. laciniata. Additionally, the species E. succinea, E. palmeri, and E. mammosa that are mixed in one clade (yellow) show low to no admixture with the other species but display high admixture within these three species. Finally, the high genetic admixture among the morphospecies E. tourneforti, E. asperula, E. clavigera, E. criptica sp. nov., and E. colombiensis sp. nov. is evident despite them being in separate clades.
  • Clade A
This clade includes the morphospecies E. tourneforti, E. asperula, and E. clavigera, along with two new species E. criptica sp. nov. and E. colombiensis sp. nov.; from now on, we will refer to it as Clade A (Figure 3). Although in the phylogeny, each morphospecies forms a well-supported clade (UF Boostrap > 90), the Structure plot for the total phylogeny shows that the morphospecies from Clade A has a high genetic admixture. Thereby, a separate approximation for genetic structure and genetic variance among the morphospecies included in this clade was run. For the structure analyses, K values were tested from 2 to 5 (Figure 3), assuming 5 as the optimal number of clusters in the clade suggested by the phylogeny (congruent clades with morphospecies) and supported by the Fst values, implying a degree of differentiation among clusters (Table 3). However, the Structure plot performed with different K values demonstrated high admixture among the clade species.
The Eunicea criptica sp. nov. clade consists exclusively of samples from Curaçao and exhibits subtle morphological differences from E. clavigera (Figure 4, Tables S2 and S3). This clade forms a well-supported independent group (ultrafast bootstrap 100), compelling evidence that it represents an undescribed cryptic species. Notably, the E. clavigera clade comprises samples exhibiting the typical morphology described for the “slender morphotype” [18]. In contrast, the E. colombiensis sp. nov. clade includes samples that align with the previously described “thick morphotype” of E. clavigera [11]. Our phylogenomic findings and the distinct morphological differences between morphotypes (slender and thick) (Figure 4, Tables S2 and S3) support the assignment of the new species. Given the evidence, the two new species within Eunicea are described below.
The descriptions of the new species E. criptica sp. nov. and E. colombiensis sp. nov., both previously assigned as E. clavigera, are focused on comparisons with E. clavigera, the closest morphospecies in the phylogeny, with similar colony characteristics and sclerites. The Systematics section provides a diagnosis (not intended to be a redescription) of E. clavigera based on the holotype, paratype, and sequenced specimens to aid in the species comparisons. This inclusion does not imply a redescription of the species, as we believe the original description by Bayer [18] accurately reflects what we identified as E. clavigera.
This publication and the new species described herein are registered in ZooBank under the Life Science Identifier (LSID) urn:lsid:zoobank.org:pub:F2E439E7-3586-4F9D-9165-6AAF78901508.

3.4. Systematics

Subphylum Anthozoa Ehrenberg, 1834 [38]
Class Octocorallia Haeckel, 1866 [39]
Order Malacalcyonacea McFadden, van Ofwegen & Quattrini, 2022 [40]
Family Plexauridae Gray, 1859 [41]
Genus Eunicea Lamoroux, 1816 [42]
Eunicea clavigera Bayer, 1961 [18]
  • Examined Material:
USNM 50265, Holotype (70% ETOH). Locality: Caracas Baai, Curaçao, Netherlands Antilles. Collection date: 22 April 1955, on Chain Buoy for 15+ years, submerged several meters deep. Collector: Zaneveld J.S. and P.W. Hummelinck. USNM 50076 Paratype. Locality: Bermuda, North Rock. Collection date: 23 July 1951. Collector: collected by diver for E. Deichmann, donated by MCZ, Harvard. ANDES-IN 7561, sequenced specimen deposited in the Invertebrate Collections of the Museo de Historia Natural Universidad de los Andes (Bogotá, Colombia). Locality: Montañita (Cartagena), Colombia; Latitude: 10.26 N, Longitude: 75.16 W; Depth: 15–26 m; Collection date: 15 June 2018; Collector: Adriana Sarmiento; Sample ID: CAR304. ANDES-IN 7602; sequenced specimen deposited in the Invertebrate Collections of the Museo de Historia Natural Universidad de los Andes (Bogotá, Colombia). Locality: West View (San Andres), Colombia; Latitude: 12.59 N, Longitude: 81.03 W, Depth: 7–12 m, Collection date: 30 January 2019; Collector: Juan Sánchez; Sample ID: SAI1740.
  • Diagnosis:
Colonies of Eunicea clavigera can exceed 1 m in height, with some branches reaching up to 50 cm without branching. A distinct dark holdfast marks the base of the colony. The terminal branches are clavate, approximately 5 mm in diameter. In preserved specimens (either in alcohol or dry), the colonies appear brown, with cylindrical branches about 3.5 mm in diameter. The calyx is low and elongated, with the lower lip pointing upwards, and is lighter in color compared to the adjacent tissue in dry specimens. Live colonies tightly close their calyces. The coenenchyme is black, while the calyx aperture is pale. The colony exhibits about three branching orders, though most branches are longer than 20 cm. The calyces are tubular and prominent, with a semi-hermetic aperture, and the lower lip is longer than the upper lip, forming an enlarged lobule. The calyx tube is whiter than the rest of the colony. The tentacles are generally pale brown. The paratype USNM 50076 exhibits the slender morphotype typical of E. clavigera (Figure 5A). Another notable feature of E. clavigera is the size of its extended polyps, which are larger than those of other Eunicea species.
The surface layer contains tiny foliate club sclerites with irregular curvatures, ranging from 0.07 to 0.19 mm in length (Figure 5B). The polyp’s anthocodial armature includes robust rods ranging from 0.12 to 0.35 mm and smaller rods measuring between 0.08 and 0.12 mm) (Figure 5C). There are typically a few club sclerites, mostly small, measure around or below 1 mm (Figure 5D). The middle layer sclerites consist of strong, robust spindles, ranging from 0.41 to 1.26 mm in length and 0.4 to 0.8 mm in diameter (Figure 5E). In the axial layer, the sclerites are intricate spindles with lavender or purple hues and irregular bodies. Club-like torch sclerites are rare in this species, in contrast to E. criptica, where such sclerites are abundant. Additionally, the polyp contains minute sclerite bodies and octoradiate formations within its tentacles.
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Figure 5. Eunicea clavigera. (A) Paratype USNM 50076 dry colony. (B–E) Eunicea clavigera, holotype USNM 50265 SEM sclerites. (B) Rod sclerites from the anthocodial crown/armature of the polyps. (C) Axial sheath spicules. (D) Club sclerites (foliate). (E) Ornamented spindle sclerites from the middle layer.
Figure 5. Eunicea clavigera. (A) Paratype USNM 50076 dry colony. (B–E) Eunicea clavigera, holotype USNM 50265 SEM sclerites. (B) Rod sclerites from the anthocodial crown/armature of the polyps. (C) Axial sheath spicules. (D) Club sclerites (foliate). (E) Ornamented spindle sclerites from the middle layer.
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Distribution and habitat: Antilles, Central America, and the Caribbean coast of South America, probably widespread in Caribbean. Semi-exposed reef terraces and slopes between 10 and 40 m depths.
  • Material examined:
ANDES-IN 8720, Holotype, deposited in the Invertebrate Collections of the Museo de Historia Natural Universidad de Los Andes, Bogotá, Colombia. Locality: Water Factory Reef (Aqualectra), Curaçao; Latitude: 12.10 N, Longitude: 68.93 W; Depth: 15–20 m; Collection date: 25 September 2014; Collector: Juan Sánchez; Sample ID: CUR728. ANDES-IN 8721, Paratype, deposited in the Invertebrate Collections of the Museo de Historia Natural Universidad de Los Andes, Bogotá, Colombia. Locality: Water Factory Reef (Aqualectra), Curaçao; Latitude: 12.10 N, Longitude: 68.93 W; Depth: 15–20 m; Collection date: 25 September 2014; Collector: Juan Sánchez; Sample ID: CUR729.
  • Type locality:
Curaçao, Caribbean Sea, at depths 15–20 m.
  • Diagnosis:
Colonies are candelabrum-like, with few long, thin branches branching mainly in one plane. They are brown, with low calyces paler than the surrounding tissue. Polyps have a brown coloration, and some are not entirely retractable. The middle layer sclerites are robust spindles with spaced ornaments in the middle layer. The axial sheath features colored spicules with four discernible tips, spicules with different ornamentation with denser tips, and spicules curved with unilaterally spiny forms and tip ornamentations. The axial layer sclerites feature ornate curved purple spindles or irregular bodies. The surface layer contains small, foliate, and irregular clubs and distinctive sclerite are torch-like clubs with short and ornate handles (Figure 7D). The polyps anthocodial armature consists of small and robust rods. The tentacles have little sclerite bodies and octoradiate sclerites.
  • Description:
The holotype is a fragment of dried colony stands at 42 cm in height with thin cylindrical branches of 0.6 mm in diameter or less. Brown colony branched in a single plane, with few branches, and a small holdfast (Figure 6A–C). Coenenchyme is dark with low but distinct pale to white calyces. Small and brown polyps without noticeable pigmentation; some are not entirely retractable in dry state. Numerous low calyces are disposed uniformly with a projecting lower tip. The calyx tube is short and can reach up to 0.18 mm in height with irregular edges paler than the surrounding tissue (Figure 6D). The polyp armature comprises rod sclerites ranging from 0.15 to 0.39 mm (Figure 7A). Axial layer sclerites with ornate spindles or irregular bodies between 0.2 mm and 0.4 mm in length and axial sheath spicules curved with unilaterally spiny forms and tip ornamentations (Figure 7B). The surface layer contains irregular clubs not elongated ranging from 0.6 and 1.2 mm in length (Figure 7C) and torched club sclerites with short and ornate handles between 0.9 mm and 1.6 mm in length (Figure 7D). The middle layer sclerites are robust, with spaced ornamented spindles ranging from 1.3 to 3 mm long and 0.02 to 0.3 mm in width (Figure 7E,F). The tentacles have small octoradiated sclerites. The characteristics of the paratypes are very consistent with those of the holotype.
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Figure 6. Eunicea criptica sp. nov. (A) Holotype ANDES-IN 8720. (B) Holotype ANDES-IN 8720 underwater view of the colony alive. (C) Holotype ANDES-IN 8720, underwater view of the colony alive with extended polyps. (D) Holotype ANDES-IN 8720, detailed dry colony. (E–K) Holotype sclerites. (E) Spindles. (F) Axial sheath spicules. (G) Axial sheath spicules with pink coloration. (H) Axial sheath spicules with unilaterally spined forms (left) and tip ornamentations (right). (I) Torch sclerites. (J) Club sclerites. (K) Anthocodial spicules, including rod sclerites.
Figure 6. Eunicea criptica sp. nov. (A) Holotype ANDES-IN 8720. (B) Holotype ANDES-IN 8720 underwater view of the colony alive. (C) Holotype ANDES-IN 8720, underwater view of the colony alive with extended polyps. (D) Holotype ANDES-IN 8720, detailed dry colony. (E–K) Holotype sclerites. (E) Spindles. (F) Axial sheath spicules. (G) Axial sheath spicules with pink coloration. (H) Axial sheath spicules with unilaterally spined forms (left) and tip ornamentations (right). (I) Torch sclerites. (J) Club sclerites. (K) Anthocodial spicules, including rod sclerites.
Diversity 17 00173 g006
Diversity 17 00173 g007
Figure 7. Eunicea criptica sp. nov., holotype ANDES-IN 8720 SEM sclerites. (A) Rod sclerites from the anthocodial crown/armature of the polyps. (B) Axial sheath spicules. (C) Club sclerites (foliate). (D) Torch-like club sclerites. (E) Details of wart ornamentations of spindles. (F) Ornamented spindle sclerites from the middle layer.
Figure 7. Eunicea criptica sp. nov., holotype ANDES-IN 8720 SEM sclerites. (A) Rod sclerites from the anthocodial crown/armature of the polyps. (B) Axial sheath spicules. (C) Club sclerites (foliate). (D) Torch-like club sclerites. (E) Details of wart ornamentations of spindles. (F) Ornamented spindle sclerites from the middle layer.
Diversity 17 00173 g007
  • Etymology:
The species was named after the Spanish feminine adjective ‘criptica’ (from the Greek root kryptikós) due to its cryptic and concealed morphology similar to E. clavigera, emphasizing the difficulty of telling this species apart.
  • Distribution:
Semi-exposed shallow reefs and slope edge (8–15 m). Curaçao; probably is widespread in the Caribbean.
  • Species comparisons:
This species is considered a cryptic species, with some sclerites overlapping in shape with species such as E. clavigera and E. asperula. The comparison of sclerites revealed the abundance of torched sclerites with short and ornate handles sets E. criptica sp. nov. apart from E. clavigera (Figure 7D—Table S4). Moreover, there are subtle differences in colony morphology (Figure 4—Table S3). Compared to E clavigera, E. criptica sp. nov. has thinner branches, a higher polyp density, and shorter polyps when extended. It is very compelling that the type locality of E. clavigera is also Curaçao, so the claim for cryptic species was properly raised by comparing the type material for both species. Compared to E. asperula colonies, darker in living and dry colonies, its calyces have curved and upward lower lips. Unlike other Eunicea species, such as E. fusca, E. laciniata, E. asperula, and E. tayrona, which have some pigmentation in the polyps, E. criptica sp. nov. stands out with its complete absence of pigmentation.
  • Eunicea colombiensis sp. nov.
Eunicea clavigera Sánchez, 2009: 248.
  • Material examined:
ANDES-IN 7544, Holotype, deposited in the Invertebrate Collections of the Museo de Historia Natural Universidad de los Andes (Bogotá, Colombia). Locality: Montañita (Cartagena), Colombia; Latitude: 10.26 N, Longitude: 75.16 W; Depth: 15–26 m; Collection date: 15 June 2018; Collector: Adriana Sarmiento; Sample ID: CAR302. ANDES-IN 7586, Paratype, deposited in the Invertebrate Collections of the Museo de Historia Natural Universidad de los Andes. Locality: West View (San Andrés), Colombia; Latitude: 12.59 N, Longitude: 81.03 W; Depth: 35–40 m; Collection date: 30 January 2019; Collector: Juan Sánchez; Sample ID: SAI1718.
  • Type locality:
Cartagena, Colombia, Caribbean Sea, at depths 15–26 m.
  • Diagnosis:
Colonies are candelabrum-like, with irregular branching of long, thick, and robust branches. The cylindrical branches are around 6 mm wide and 12 mm in diameter with the calyces. Colonies color pale gray, with prominent long calyces paler than the surrounding tissue (Figure 8D). Polyps colored pale brown are retractile into tubular calyces. The middle layer sclerites are robust and densely ornamented spindles, the longest observed among Eunicea species, even visible at the colony’s surface. The spicules of the colored axial sheath have different forms, with some featuring forked ends that form tripod-shaped spicules. The axial layer sclerites feature ornate purple spindles and irregular bodies. The surface layer contains elongated, small, foliate, and irregular clubs. The polyps anthocodial armature consists of robust rods. Additionally, the anthocodial spicules vary greatly as tripod-shaped, and needle-like, and some have four tips. Tentacular sclerites are mostly octoradiate sclerites.
  • Description:
The holotype is a fragment of dried colony 34 cm tall and exhibits long, thick, robust branches (Figure 8A–C) with irregular branching. Holdfast is unnoticeable or buried. Colony in alcohol or dry is dark with pale to white tubular calyces (Figure 8D). Polyps are retractile into tubular and prominent calyces up to 3 mm tall. It possesses a semi-hermetic aperture, never tightly closed where anthocodial remains exerted, and features an expanded lobule with a larger bottom lip in comparison to the upper lip (Figure 8D). Extended tentacles exhibit a pale brown coloration (Figure 8C). Polyp armature comprises smaller sturdy rods ranging from 0.1 to 0.4 mm (Figure 9A). Sclerites in the axial layer exhibit intricate purple spindles and irregular bodies. The axial sheath spicules vary greatly as needle-like (Figure 9B). The surface layer contains small foliate and irregular clubs measuring between 0.09 and 0.14 mm in length (Figure 9C) and torched clubs with short and ornate handles between 0.06 mm and 0.24 mm in length (Figure 9D). The middle layer sclerites are densely ornamented, slightly curved spindles ranging from 1.5 to 4.3 mm long and 0.08 to 0.8 mm wide (Figure 9E,F). The tentacles have small octoradiated sclerites. The characteristics of the paratypes are very consistent with those of the holotype.
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Figure 8. Eunicea colombiensis sp. nov. (A) Holotype ANDES-IN 7544. (B) Holotype ANDES-IN 7544 underwater view of the alive. (C) Holotype ANDES-IN 7544, underwater view of the colony alive with extended polyps. (D) Holotype ANDES-IN 7544, detailed dry colony. (E–I) Holotype sclerites. (E) Spindles, which are visible at the surface of the colony. (F) Axial sheath spicules. (G) Club sclerites. (H) Octoradiate sclerite. (I) Anthocodial spicules, including rod sclerites.
Figure 8. Eunicea colombiensis sp. nov. (A) Holotype ANDES-IN 7544. (B) Holotype ANDES-IN 7544 underwater view of the alive. (C) Holotype ANDES-IN 7544, underwater view of the colony alive with extended polyps. (D) Holotype ANDES-IN 7544, detailed dry colony. (E–I) Holotype sclerites. (E) Spindles, which are visible at the surface of the colony. (F) Axial sheath spicules. (G) Club sclerites. (H) Octoradiate sclerite. (I) Anthocodial spicules, including rod sclerites.
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Figure 9. Eunicea colombiensis sp. nov., holotype ANDES-IN 7544 SEM sclerites. (A) Rod sclerites from the anthocodial crown/armature of the polyps. (B) Axial sheath spicules. (C) Club sclerites (foliate). (D) Torch-like club sclerites. (E) Details of wart ornamentations of spindles. (F) Ornamented spindle sclerites from the middle layer.
Figure 9. Eunicea colombiensis sp. nov., holotype ANDES-IN 7544 SEM sclerites. (A) Rod sclerites from the anthocodial crown/armature of the polyps. (B) Axial sheath spicules. (C) Club sclerites (foliate). (D) Torch-like club sclerites. (E) Details of wart ornamentations of spindles. (F) Ornamented spindle sclerites from the middle layer.
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  • Etymology:
The species was named after the country Colombia, where it is widespread, with the suffix demonym ensis.
  • Distribution:
Antilles, Central America, and the Caribbean coast of South America. It is widespread in the Caribbean in semi-exposed reef terraces and slopes between 10 and 40 m depths.
  • Species comparisons:
This morphospecies can be differentiated from E. clavigera because its calyx is longer (up to 3 mm) (Figure 4 and Figure 8, Table S3). When alive, E. clavigera has longer extended polyps, while E. colombiensis sp. nov. has densely packed polyps. Branches are usually longer in E. clavigera, generally branching near the base, whereas E. colombiensis sp. nov. is less branched but with less regular branching and includes shorter and stubbier branches. The comparison of sclerites revealed that the middle layer sclerites are the longest spindles observed among Eunicea species, even visible at the colony’s surface (Figure 8 and Figure 9, Table S4). Compared to E. clavigera, the colored axial sheath spicules present different forms, as they have forked ends that produce tripods, and the spindles are visible at the colony’s surface.
  • Additional taxonomic remarks:
Eunicea clavigera was described by Bayer [18] as part of his work on the octocorals from the West Indies, including the wider Caribbean region. He examined all the literature and type material available on Eunicea. The synonymy is ample in this genus but concentrated in a few taxa, such as E. calyculata, with over seven distinct names, followed by E. tourneforti and E. mammosa. In the original description of E. clavigera, there is one likely name, E. turgida [43], examined both by Bayer [18] and Verrill [43]. Bayer states that “It is possible that E. clavigera will fall into synonymy with some previously described species, perhaps E. turgida (Verril, 1864)”, but the material now at hand cannot be assigned definitely to any of the species in the literature. Verrill describes it as a large colony, up to a meter high, and “unable to detect any difference between this species and Plexaura dichotoma, the type of Plexaura Lamouroux, P. homomalla, and P. flexuosa”, which means the absence of notorious calyces such as E. colombiensis sp. nov. or E. criptica sp. nov. It is worth highlighting the robustness of Bayer’s taxonomic and morphologic work because when E. tayrona was described [11], the closest species morphologically according to Bayer’s work was E. fusca. The surface clubs from E. tayrona looked similar but smaller compared to E. fusca’s sclerites, so E. fusca’s type material was examined, deposited in Turin, and the difference with both shape and size from both species and especially the accuracy from Bayer observations were corroborated. Nonetheless, as seen in our phylogeny, E. tayrona and E. fusca are both monophyletic and not closely related, as expected. Morphology in Eunicea is highly labile, and some characters are polyphyletic; therefore, reciprocal monophyly based on thousands of molecular markers supported the discovery of new and cryptic species.

4. Discussion

With more than 3500 species, octocoral biodiversity remains underestimated, and it is highly complicated to identify the number of species and differentiate boundaries across taxa that appear to be similar morphologically [44] and coexist in sympatry, such as the genus Eunicea [11]. The incongruence between the taxonomic classification and molecular phylogenetic hypotheses is usual in some octocoral taxa [44]. In addition, unresolved or unsupported phylogenies continue to represent issues that must be addressed to unveil an accurate diversity estimation. Recently, the use of next-generation sequencing to elucidate evolutionary relationships and objective species boundaries in octocorals has increased [45,46,47], becoming an efficient tool for solving these concerns. Here, we demonstrate the utility and efficiency of using RADseq to work at the species level, resolving the evolutionary relationships in this problematic octocoral group and deciphering its cryptic diversity. Our phylogenomic analyses provided a robust and well-resolved phylogeny, solving previous problems in the phylogenies proposed for the genus, such as low support values of branches and unclear relationships among taxa that used few nuclear and mitochondrial markers.
In general, the majority of the morphospecies have well-supported monophyletic clades, and the evolutionary relationships of the group have been illuminated based on a large amount of genomic information. Congruently with the phylogenetic hypotheses previously proposed for the group, the phylogeny here inferred exhibits a clade that comprises the species E. mammosa, E. succinea, and E. palmeri and another clade (Clade A) that includes the species E. clavigera, E. asperula, and E. tourneforti; these sub-groups correspond to the proposed sub-genera Eunicea and Euniceopsis [12,13,14,15,43]. However, our phylogeny revealed the evolutionary relationships between most of the species of the genus, revealing the presence of clades that are monophyletic and divergent concerning the other morphospecies. Hence, E. criptica sp. nov. and E. colombiensis sp. nov. are defined as new species, consistent with the presence of undescribed species suggested in previous studies [10,43]. The morphospecies E. tourneforti, E. asperula, E. clavigera, E. criptica sp. nov., and E. colombiensis sp. nov. included in the Clade A display short branch lengths within the phylogeny, emphasizing their rapid and perhaps recent divergence. Additionally, the clade shows evidence of low genetic structure among morphospecies, which could be interpreted as a recent diversification process that has not yet restricted gene flow, having incomplete separation of lineages, a reasonable result under coexistence in sympatry, where without geographic or environmental barriers exists the possibility to interbreed. Nonetheless, addressing all potential hypotheses is imperative to elucidate the diversification process fully.
Cryptic diversity is common in cnidarians [44,48,49]. Often, cryptic taxa are closely related, occur sympatrically, and, therefore, have the opportunity to maintain infrequently to constant gene flow [6,50,51]. This is especially common in marine environments, where the speciation process with gene flow occurs in several marine taxa without barriers blocking the genetic flow between incipient species [52,53]. The diversification process with gene flow has been documented in octocorals, especially in cases of depth-mediated population divergence [54,55]. In these cases, differentiation has been framed by the depth gradient, and although there is evidence of genetic exchange, it has also been observed that there are periods in which this exchange has stopped [56]. However, depth is not a possible ecological driver in the diversification process of the Eunicea group because there is co-occurring sympatry at the same depth, which makes it necessary to explore possible intrinsic variables that are promoting the diversification of the group, such as holobiont composition and feeding preferences. However, from our results, it is impossible to differentiate what gene flow scenery is reflected: ancient gene flow, secondary contact, or continuous gene flow. Therefore, it remains uncertain whether the development of partial reproductive barriers among these species is due to a gradual decrease in gene flow or intermittent historical barriers to gene flow and secondary contact.
Given the array of genetic data, Fst matrix, and insights drawn from the phylogenomic tree, our current taxonomic understanding demands a rigorous re-evaluation. When comparing the Fst values, which highlight varying levels of genetic differentiation between morphospecies, there is a plausible assertion that we might be dealing with more distinct genetic lineages than the species currently recognized. The cryptic species E. criptica sp. nov. presents a compelling case of cryptic diversity, as highlighted by our comprehensive datasets. Based on the Fst values, there is a discernible differentiation of around 0.1 between morphospecies. Such values underscore significant genetic differentiation, highlighting its singular evolutionary trajectory and hinting that these may not merely be variants but represent distinct genetic lineages. The phylogenomic tree supports this narrative where E. criptica sp. nov. is a separate clade with robust nodal support (above 90%), underscoring its evolutionary divergence. Marrying these insights—the stark genetic differentiation evidenced by Fst values and distinct branching in the phylogenomic tree—it is well founded to postulate that E. criptica sp. nov. represents a separate cryptic species.
On the contrary, the morphospecies E. colombiensis sp. nov. shows evident morphological differences with the other morphospecies included in Clade A, especially with E. clavigera, of which it was a previously described morphotype. Additionally, analysis of Fst values reveals a discernible differentiation of approximately 0.1 between these morphospecies, indicating significant genetic divergence and suggesting that they may not simply be variants but distinct genetic lineages. This is further supported by the phylogenomic tree, where E. colombiensis sp. nov. forms a separate and well-supported clade (around 90%) that underlines its evolutionary divergence. Considering the morphological differences, the genetic differentiation indicated by the Fst values, and the independent branch in the phylogenomic tree, it is cogent to propose that E. colombiensis sp. nov. represents a distinct species.
Field identification of Eunicea species is exceptionally challenging because their distinction is based on numerous morphological characters, and definitive identification needs microscopic sclerite analyses. Although not entirely explored, polyp shape, size, and color patterns are new morphological traits that distinguish most Eunicea octocorals in the field. Even the most abundant species in shallow waters, such as E. fusca, can be easily mistaken for E. tayrona, E. flexuosa, and E. asperula. All these species, under certain environmental conditions, can have short colonies that display a disorganized and slim branching, sometimes propagating clonally. New polyp pigmentation patterns have been consistently observed in Eunicea through repeated expeditions at Curaçao and Colombian reefs. These polyp pigmentation patterns may be viewed as another valuable diagnostic characteristic for field identification (Figure 10). For instance, E. fusca polyps show eight distinctive inter-tentacular black spots that none of its closely related species have. Other dark-pigmented polyps include E. asperula, E. laciniata, E. tayrona, and E. tourneforti. Although E. tourneforti and E. laciniata have similar polyp pigmentation, the colony morphology is distinctive. E. clavigera and the two new species lack dark-pigmented spots and show a lighter tone around the oral cavity. E. mammosa also has colorless polyps with lighter oral cavities. The uniform brown color corresponds to dense zooxanthellate polyps, which, in some cases, such as E. calyculata, contrast with the white polyp sclerites. E. asperula and E. tayrona have little dark spots in the tentacles and pinnules. This new trait has the potential to facilitate underwater identification in this genus. However, since this group has several polyp pigmentation patterns, it is still necessary to survey its entire variation across species, locations, and environments.
In conclusion, our study elucidates the intricate evolutionary history and undescribed diversity within the genus Eunicea. Through comprehensive phylogenomic analysis, we have provided compelling evidence for the presence of distinct genetic lineages and newly described species, E. criptica sp. nov. and E. colombiensis sp. nov. Our findings highlighted the importance of integrating molecular insights into taxonomic considerations, emphasizing the need for a rigorous re-evaluation of species classifications. The congruence between morphological and molecular data in our phylogenetic analysis highlights the robustness of our approach in elucidating the evolutionary relationships within Eunicea. Finally, it is essential to continue exploring the evolutionary dynamics and ecological drivers shaping the diversification of Eunicea to understand the complete panorama that promotes its high diversity.

Supplementary Materials

The following are available online at https://www.mdpi.com/article/10.3390/d17030173/s1: Table S1: List of Eunicea morphospecies samples included in our phylogenomic analyses and associated locality data. Table S2: Morphological measures on morphospecies E. criptica sp. nov., E. colombiensis sp. nov., and E. clavigera colonies. Table S3. Comparison of morphological measures on morphospecies E. criptica sp. nov., E. colombiensis sp. nov., and E. clavigera colonies. Table S4: Measures of the sclerites of E. criptica sp. nov., E. colombiensis sp. nov., and E. clavigera. Average, standard deviation, minimum, and maximum size of type sclerites. Table S5: Sclerite measures of E. criptica sp. nov., E. colombiensis sp. nov., and E. clavigera. Figure S1–S11: Phylogenomic tree for Eunicea species from ipyRAD datasets. Midpoint-rooted maximum likelihood (ML) phylogenies. Circles represent UF bootstrap support values. Parameter combination of clustering threshold, taxon occupancy, and shared polymorphic sites. Figure S12: Phylogenomic tree for Eunicea species from ipyRAD datasets. Midpoint-rooted maximum likelihood (ML) phylogenies. Circles represent ultrafast bootstrap support values > 80. Sample ID at the end of each branch.

Author Contributions

Conceptualization, A.S., I.C.-B., A.M.Q. and J.A.S.; methodology, A.S., I.C.-B., T.J.-R., A.M.Q. and J.A.S.; validation, A.S., I.C.-B., A.M.Q. and J.A.S.; formal analysis, A.S., I.C.-B. and T.J.-R.; research, A.S., I.C.-B., A.M.Q. and J.A.S.; resources, A.S. and J.A.S.; data curation, A.S. and J.A.S.; writing—original draft preparation, A.S. and I.C.-B.; writing—review and editing, A.S., I.C.-B., A.M.Q. and J.A.S.; visualization, A.S., I.C.-B. and T.J.-R.; supervision, J.A.S.; project administration, A.S. and J.A.S.; funding acquisition, A.S. and J.A.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by MinCiencias Colombia (Programa Doctorados Nacionales call 757 to A. Sarmiento), Universidad de Los Andes, Colombia (STAI, Vicerrectoría de Investigaciones and Facultad de Ciencias) and CEMarin (Center of Excellence in Marine Sciences).

Institutional Review Board Statement

The sampling complies with the current laws of the countries in which it was performed. Study permit provided to the Universidad de Los Andes by the Ministerio de Medio Ambiente (grant number Resolución 1177 del 09 de octubre de 2014—IDB 0359). Study permit provided to the Universidad de los Andes under the project “IRES—Taxonomía de Anthozoa” by the Ministerio de Ambiente de Panamá (grant number SE/A-21-19). Curaçao samples were exchanged between the CARMABI Foundation (CITES institution code AN 001) and Universidad Nacional de Colombia (CITES institution code CO 001) as part of a research collaboration.

Data Availability Statement

RADseq reads are available on SRA under Bioproject number PRJNA1106038.

Acknowledgments

Thanks to Minciencias-Colombia (Programa Doctorados Nacionales to A. Sarmiento), Universidad de Los Andes, Colombia (STAI, Vicerrectoría de Investigaciones and Facultad de Ciencias). Adriana Sarmiento and Ivan Calixto thank CEMarin (Center of Excellence in Marine Sciences). Thanks to the BIOMMAR group, especially Diana Vergara, for field and laboratory support. Thanks to the Octocoral Workshop 2019 (H. Lasker, M.A. Coffroth, C. McFadden, P. Edmunds, R. Richmond) carried out in the Marine Key Lab (Florida, USA) and the Caribbean Research and Management of Biodiversity—CARMABI (M. Vermeij, Curaçao). The authors acknowledge the instruments and scientific and technical assistance of the MicroCore Microscopy Core at the Universidad de Los Andes, a facility that is supported by the vicepresidency for research and creation.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Appendix A

The morphological comparison carried out in the description of the new species E. criptica sp. nov. and E. colombiensis sp. nov. to highlight their morphological differences from E. clavigera (the closest morphospecies in the phylogeny, with similar colony features and sclerites) was a focus on polyp density and colony girth, which are external characters of the colonies with evident differences and sclerite sizes (Table S2–S5). For colony morphology, the measures were obtained from photographs of five randomly selected colonies previously sequenced for each morphotype. The pictures were processed in ImageJ v. 1.52 [57] to measure area and colony girth. Later, the same images were examined with Photoshop to quantify the number of polyps per colony. Colony girth was determined through multiple measurements taken at five different randomized points, encompassing the calyxes of the colony. Polyp density was calculated as the number of polyps per square millimeter. On the other hand, sclerite measurements were taken from optical and SEM images from E. criptica sp. nov. and E. colombiensis sp. nov. holotypes, and from E. clavigera holotype USNM 50265 (Figure 5). A Kruskal–Wallis test was conducted in R [58] using the command stats:krukal.test to assess potential differences among the morphotypes studied about the variables (polyp density, colony girth, spindle length, club length, and rod length), followed by Dunn’s multiple comparison test. Furthermore, a principal component analysis (PCA) was conducted using the command prcomp [59], and a visual representation of how these variables interact across the morphotypes was obtained with ggplot2 [59]. The morphological comparison shows differences in polyp density (Kruskal–Wallis test: Chi-squared = 86.075, df = 4, p-value < 2.2 × 10−16), colony girth (Kruskal–Wallis test: Chi-squared = 91.852, df = 4, p-value < 2.2 × 10−16), and sclerites (Kruskal–Wallis test: Chi-squared = 120.11, df = 9, p-value < 2.2 × 10−16). The pairwise comparisons showed differences between the morphospecies (Table S3).

References

  1. Hausdorf, B. Progress Toward a General Species Concept. Evolution 2011, 65, 923–931. [Google Scholar] [CrossRef] [PubMed]
  2. De Queiroz, K. Species Concepts and Species Delimitation. Syst. Biol. 2007, 56, 879–886. [Google Scholar] [CrossRef] [PubMed]
  3. Edwards, D.L.; Knowles, L.L. Species Detection and Individual Assignment in Species Delimitation: Can Integrative Data Increase Efficacy? Proc. R. Soc. B Biol. Sci. 2014, 281, 20132765. [Google Scholar] [CrossRef] [PubMed]
  4. Bickford, D.; Lohman, D.J.; Sodhi, N.S.; Ng, P.K.L.; Meier, R.; Winker, K.; Ingram, K.K.; Das, I. Cryptic Species as a Window on Diversity and Conservation. Trends Ecol. Evol. 2007, 22, 148–155. [Google Scholar] [CrossRef] [PubMed]
  5. Sánchez, J.A. Diversity and Evolution of Octocoral Animal Forests at Both Sides of Tropical America. In Marine Animal Forests: The Ecology of Benthic Biodiversity Hotspots; Rossi, S., Bramanti, L., Gori, A., Orejas, C., Eds.; Springer International Publishing: Cham, Switzerland, 2017; pp. 111–143. ISBN 978-3-319-21012-4. [Google Scholar]
  6. Potkamp, G.; Fransen, C.H.J.M. Speciation with Gene Flow in Marine Systems. Contrib. Zool. 2019, 88, 133–172. [Google Scholar] [CrossRef]
  7. Ruzicka, R.; Colella, M.; Porter, J.; Morrison, J.; Kidney, J.; Brinkhuis, V.; Lunz, K.; Macaulay, K.; Bartlett, L.; Meyers, M.; et al. Temporal Changes in Benthic Assemblages on Florida Keys Reefs 11 Years after the 1997/1998 El Niño. Mar. Ecol. Prog. Ser. 2013, 489, 125–141. [Google Scholar] [CrossRef]
  8. Edmunds, P.J.; Lasker, H.R. Cryptic Regime Shift in Benthic Community Structure on Shallow Reefs in St. John, US Virgin Islands. Mar. Ecol. Prog. Ser. 2016, 559, 1–12. [Google Scholar] [CrossRef]
  9. Tsounis, G.; Edmunds, P.J. Three Decades of Coral Reef Community Dynamics in St. John, USVI: A Contrast of Scleractinians and Octocorals. Ecosphere 2017, 8, e01646. [Google Scholar] [CrossRef]
  10. Sánchez, J.A.; Diaz, J.; Zea, S. Gorgonian Communities in Two Contrasting Environments on Oceanic Atolls of the Southwestern Caribbean. Bull. Mar. Sci. 1997, 61, 453–465. [Google Scholar]
  11. Sánchez, J.A. Systematics of the Candelabrum Gorgonian Corals (Eunicea Lamouroux; Plexauridae; Octocorallia; Cnidaria). Zool. J. Linn. Soc. 2009, 157, 237–263. [Google Scholar] [CrossRef]
  12. Sánchez, J.A.; González-Zapata, F.L.; Dueñas, L.F.; Andrade, J.; Pico-Vargas, A.L.; Vergara, D.C.; Sarmiento, A.; Bolaños, N. Corals in the Mesophotic Zone (40–115 m) at the Barrier Reef Complex From San Andrés Island (Southwestern Caribbean). Front. Mar. Sci. 2019, 6, 536. [Google Scholar] [CrossRef]
  13. Gerhart, D.J. The Chemical Systematics of Colonial Marine Animals: An Estimated Phylogeny of the Order Gorgonacea Based on Terpenoid Characters. Biol. Bull. 1983, 164, 71–81. [Google Scholar] [CrossRef]
  14. Wirshing, H.H.; Messing, C.G.; Douady, C.J.; Reed, J.; Stanhope, M.J.; Shivji, M.S. Molecular Evidence for Multiple Lineages in the Gorgonian Family Plexauridae (Anthozoa: Octocorallia). Mar. Biol. 2005, 147, 497–508. [Google Scholar] [CrossRef]
  15. Aguilar, C. Phylogenetic Hypotheses of Octocorals Species Using Predicted RNA Secondary Structures of the Internal Transcribed Spacer 2 (ITS2). Master’s Thesis, Universidad de los Andes, Bogotá, Colombia, 2006. [Google Scholar]
  16. Grajales, A.; Aguilar, C.; Sánchez, J.A. Phylogenetic Reconstruction Using Secondary Structures of Internal Transcribed Spacer 2 (ITS2, rDNA): Finding the Molecular and Morphological Gap in Caribbean Gorgonian Corals. BMC Evol. Biol. 2007, 7, 90. [Google Scholar] [CrossRef]
  17. Sarmiento, A.; Sánchez, J.A. Phylogenetic Reconstruction of the Eunicea Caribbean Octocorals Using Secondary Structures of Internal Transcribed Spacer 2 (ITS2). Master’s Thesis, Universidad de los Andes, Bogotá, Colombia, 2015. [Google Scholar]
  18. Bayer, F.M. The Shallow-Water Octocorallia of the West Indian Region. Stud. Fauna Curaçao Caribb. Isl. 1961, 12, 1–373. [Google Scholar]
  19. Coffroth, M.A.; Lasker, H.R.; Diamond, M.E.; Bruenn, J.A.; Bermingham, E. DNA Fingerprints of a Gorgonian Coral: A Method for Detecting Clonal Structure in a Vegetative Species. Mar. Biol. 1992, 114, 317–325. [Google Scholar] [CrossRef]
  20. Russello, M.A.; Waterhouse, M.D.; Etter, P.D.; Johnson, E.A. From Promise to Practice: Pairing Non-Invasive Sampling with Genomics in Conservation. PeerJ 2015, 3, e1106. [Google Scholar] [CrossRef]
  21. Titus, B.M.; Daly, M. Reduced Representation Sequencing for Symbiotic Anthozoans: Are Reference Genomes Necessary to Eliminate Endosymbiont Contamination and Make Robust Phylogeographic Inference? bioRxiv 2018. bioRxiv:440289. [Google Scholar] [CrossRef]
  22. Altschul, S.F.; Gish, W.; Miller, W.; Myers, E.W.; Lipman, D.J. Basic Local Alignment Search Tool. J. Mol. Biol. 1990, 215, 403–410. [Google Scholar] [CrossRef]
  23. Eaton, D.A.R.; Overcast, I. Ipyrad: Interactive Assembly and Analysis of RADseq Datasets. Bioinformatics 2020, 36, 2592–2594. [Google Scholar] [CrossRef]
  24. Andrews, S. FastQC A Quality Control Tool for High Throughput Sequence Data. Available online: https://www.bioinformatics.babraham.ac.uk/projects/fastqc/ (accessed on 25 March 2024).
  25. Martin, M. Cutadapt Removes Adapter Sequences from High-Throughput Sequencing Reads. EMBnet.journal 2011, 17, 10–12. [Google Scholar] [CrossRef]
  26. Minh, B.Q.; Schmidt, H.A.; Chernomor, O.; Schrempf, D.; Woodhams, M.D.; von Haeseler, A.; Lanfear, R. IQ-TREE 2: New Models and Efficient Methods for Phylogenetic Inference in the Genomic Era. Mol. Biol. Evol. 2020, 37, 1530–1534. [Google Scholar] [CrossRef] [PubMed]
  27. Kalyaanamoorthy, S.; Minh, B.Q.; Wong, T.K.F.; von Haeseler, A.; Jermiin, L.S. ModelFinder: Fast Model Selection for Accurate Phylogenetic Estimates. Nat. Methods 2017, 14, 587–589. [Google Scholar] [CrossRef] [PubMed]
  28. Minh, B.Q.; Nguyen, M.A.T.; von Haeseler, A. Ultrafast Approximation for Phylogenetic Bootstrap. Mol. Biol. Evol. 2013, 30, 1188–1195. [Google Scholar] [CrossRef]
  29. Letunic, I.; Bork, P. Interactive Tree Of Life (iTOL) v5: An Online Tool for Phylogenetic Tree Display and Annotation. Nucleic Acids Res. 2021, 49, W293–W296. [Google Scholar] [CrossRef]
  30. Lischer, H.E.L.; Excoffier, L. PGDSpider: An Automated Data Conversion Tool for Connecting Population Genetics and Genomics Programs. Bioinformatics 2012, 28, 298–299. [Google Scholar] [CrossRef]
  31. Pritchard, J.K.; Stephens, M.; Donnelly, P. Inference of Population Structure Using Multilocus Genotype Data. Genetics 2000, 155, 945–959. [Google Scholar] [CrossRef]
  32. Earl, D.A.; vonHoldt, B.M. Structure Harvester: A Website and Program for Visualizing STRUCTURE Output and Implementing the Evanno Method. Conserv. Genet. Resour. 2012, 4, 359–361. [Google Scholar] [CrossRef]
  33. Jakobsson, M.; Rosenberg, N.A. CLUMPP: A Cluster Matching and Permutation Program for Dealing with Label Switching and Multimodality in Analysis of Population Structure. Bioinformatics 2007, 23, 1801–1806. [Google Scholar] [CrossRef]
  34. Rosenberg, N.A. Distruct: A Program for the Graphical Display of Population Structure. Mol. Ecol. Notes 2004, 4, 137–138. [Google Scholar] [CrossRef]
  35. Wang, X.; Liew, Y.J.; Li, Y.; Zoccola, D.; Tambutte, S.; Aranda, M. Draft Genomes of the Corallimorpharians Amplexidiscus Fenestrafer and Discosoma sp. Mol. Ecol. Resour. 2017, 17, e187–e195. [Google Scholar] [CrossRef] [PubMed]
  36. Goudet, J. Hierfstat, a Package for r to Compute and Test Hierarchical F-Statistics. Mol. Ecol. Notes 2005, 5, 184–186. [Google Scholar] [CrossRef]
  37. Bayer, F.M.; Grasshoff, M.; Verseveldt, J. Illustrated Trilingual Glossary of Morphological and Anatomical Terms Applied to Octocorallia; Brill: Leiden, The Netherlands, 1983. [Google Scholar]
  38. Ehrenberg, C.G. Beiträge Zur Physiologischen Kenntniss Der Corallenthiere Im Allgemeinen, Und Besonders Des Rothen Meeres, Nebst Einem Versuche Zur Physiologischen Systematik Derselben. Abh. K. Akad. Wiss. Berl. 1834, 1, 225–380. [Google Scholar]
  39. Haeckel, E. Generelle Morphologie der Organismen; Reimer, G., Ed.; De Gruyter: Berlin, Germany,, 1866; ISBN 978-3-11-084828-1. [Google Scholar]
  40. McFadden, C.S.; van Ofwegen, L.P.; Quattrini, A.M. Revisionary Systematics of Octocorallia (Cnidaria: Anthozoa) Guided by Phylogenomics. Bull. Soc. Syst. Biol. 2022, 1. [Google Scholar] [CrossRef]
  41. Gray, J.E. XLV.—On the Arrangement of Zoophytes with Pinnated Tentacles. Ann. Mag. Nat. Hist. 1859, 4, 439–444. [Google Scholar] [CrossRef]
  42. Lamouroux, M. Histoire Des Polypiers Coralligènes Flexibles, Vulgairement Nommés Zoophytes; Impr. de F. Poisson: Caen, France, 1816. [Google Scholar]
  43. Verrill, A. List of the Polyps and Corals Sent by the Museum of Comparative Zoology to Other Institutions in Exchange, with Annotations. Bull. Mus. Comp. Zool. Harv. Coll. 1864, 1, 29–60. [Google Scholar]
  44. McFadden, C.S.; Sanchez, J.A.; France, S.C. Molecular Phylogenetic Insights into the Evolution of Octocorallia: A Review. Integr. Comp. Biol. 2010, 50, 389–410. [Google Scholar] [CrossRef]
  45. Pante, E.; Abdelkrim, J.; Viricel, A.; Gey, D.; France, S.C.; Boisselier, M.C.; Samadi, S. Use of RAD Sequencing for Delimiting Species. Heredity 2015, 114, 450–459. [Google Scholar] [CrossRef]
  46. Herrera, S.; Shank, T.M. RAD Sequencing Enables Unprecedented Phylogenetic Resolution and Objective Species Delimitation in Recalcitrant Divergent Taxa. Mol. Phylogenet. Evol. 2016, 100, 70–79. [Google Scholar] [CrossRef]
  47. Quattrini, A.M.; Wu, T.; Soong, K.; Jeng, M.-S.; Benayahu, Y.; McFadden, C.S. A next Generation Approach to Species Delimitation Reveals the Role of Hybridization in a Cryptic Species Complex of Corals. BMC Evol. Biol. 2019, 19, 116. [Google Scholar] [CrossRef]
  48. Richards, Z.T.; Berry, O.; van Oppen, M.J.H. Cryptic Genetic Divergence within Threatened Species of Acropora Coral from the Indian and Pacific Oceans. Conserv. Genet. 2016, 17, 577–591. [Google Scholar] [CrossRef]
  49. Bongaerts, P.; Riginos, C.; Ridgway, T.; Sampayo, E.M.; van Oppen, M.J.H.; Englebert, N.; Vermeulen, F.; Hoegh-Guldberg, O. Genetic Divergence across Habitats in the Widespread Coral Seriatopora Hystrix and Its Associated Symbiodinium. PLoS ONE 2010, 5, e10871. [Google Scholar] [CrossRef] [PubMed]
  50. Poliseno, A.; Breedy, O.; Guzman, H.M.; Vargas, S. Hybridization and Cryptic Speciation in the Tropical Eastern Pacific Octocoral Genus Pacifigorgia. bioRxiv 2021. bioRxiv:2021.04.29.442007. [Google Scholar] [CrossRef]
  51. Rippe, J.P.; Dixon, G.; Fuller, Z.L.; Liao, Y.; Matz, M. Environmental Specialization and Cryptic Genetic Divergence in Two Massive Coral Species from the Florida Keys Reef Tract. Mol. Ecol. 2021, 30, 3468–3484. [Google Scholar] [CrossRef]
  52. Matias, A.M.A.; Popovic, I.; Thia, J.A.; Cooke, I.R.; Torda, G.; Lukoschek, V.; Bay, L.K.; Kim, S.W.; Riginos, C. Cryptic Diversity and Spatial Genetic Variation in the Coral Acropora Tenuis and Its Endosymbionts across the Great Barrier Reef. Evol. Appl. 2022, 16, 293–310. [Google Scholar] [CrossRef]
  53. Faria, R.; Johannesson, K.; Stankowski, S. Speciation in Marine Environments: Diving under the Surface. J. Evol. Biol. 2021, 34, 4–15. [Google Scholar] [CrossRef]
  54. Meziere, Z.; Popovic, I.; Prata, K.; Ryan, I.; Pandolfi, J.; Riginos, C. Exploring Coral Speciation: Multiple Sympatric Stylophora Pistillata Taxa along a Divergence Continuum on the Great Barrier Reef. Evol. Appl. 2024, 17, e13644. [Google Scholar] [CrossRef]
  55. Prada, C.; Hellberg, M.E. Long Prereproductive Selection and Divergence by Depth in a Caribbean Candelabrum Coral. Proc. Natl. Acad. Sci. USA 2013, 110, 3961–3966. [Google Scholar] [CrossRef]
  56. Prada, C.; Hellberg, M.E. Speciation-by-Depth on Coral Reefs: Sympatric Divergence with Gene Flow or Cryptic Transient Isolation? J. Evol. Biol. 2021, 34, 128–137. [Google Scholar] [CrossRef]
  57. Rasband, W.S. ImageJ; U.S. National Institutes of Health: Bethesda, MD, USA, 1997–2018; Available online: https://imagej.net/ij/ (accessed on 8 May 2024).
  58. R Core Team. R: A Language and Environment for Statistical Computing; Foundation Statistics and Computing: Vienna, Austria, 2020. [Google Scholar]
  59. Wickham, H. Ggplot2: Elegant Graphics for Data Analysis; Use R! Springer International Publishing: Cham, Switzerland, 2016; ISBN 978-3-319-24275-0. [Google Scholar]
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Figure 1. Collection sites in the Caribbean Sea. Key West, Florida, USA—FLO (orange mark); Curaçao—CUR (violet mark); Cartagena, Colombia—CAR (blue mark); San Andrés Island, Colombia—SAI (yellow mark); Bocas Del Toro, Panama—BDT (green mark). Numbers indicate the samples included in RADseq analysis after filtering steps.
Figure 1. Collection sites in the Caribbean Sea. Key West, Florida, USA—FLO (orange mark); Curaçao—CUR (violet mark); Cartagena, Colombia—CAR (blue mark); San Andrés Island, Colombia—SAI (yellow mark); Bocas Del Toro, Panama—BDT (green mark). Numbers indicate the samples included in RADseq analysis after filtering steps.
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Figure 2. Phylogenomic tree for Eunicea species. Midpoint-rooted maximum likelihood (ML) phylogeny. Circles represent ultrafast bootstrap support values > 80 (photos: J.A.S).
Figure 2. Phylogenomic tree for Eunicea species. Midpoint-rooted maximum likelihood (ML) phylogeny. Circles represent ultrafast bootstrap support values > 80 (photos: J.A.S).
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Figure 3. Maximum likelihood phylogeny of Eunicea species using the ipyRAD dataset with the following parameter combination: clustering threshold 0.85, taxon occupancy 10%, and shared polymorphic sites 0.5. Circles represent ultrafast bootstrap support values. Collection site for each sample is indicated at the end of the branch. Key West, Florida, USA—FLO (orange mark); Curaçao—CUR (violet mark); Cartagena, Colombia—CAR (blue mark); San Andrés Island, Colombia—SAI (yellow mark); Bocas Del Toro, Panama—BDT (green mark). Structure plots are included and show the probability of membership into different K cluster. K = 13 for the total data on phylogeny, and K = 2 to K = 5 only for morphospecies from Clade A. Each color represents a distinct genetic group identified in the dataset.
Figure 3. Maximum likelihood phylogeny of Eunicea species using the ipyRAD dataset with the following parameter combination: clustering threshold 0.85, taxon occupancy 10%, and shared polymorphic sites 0.5. Circles represent ultrafast bootstrap support values. Collection site for each sample is indicated at the end of the branch. Key West, Florida, USA—FLO (orange mark); Curaçao—CUR (violet mark); Cartagena, Colombia—CAR (blue mark); San Andrés Island, Colombia—SAI (yellow mark); Bocas Del Toro, Panama—BDT (green mark). Structure plots are included and show the probability of membership into different K cluster. K = 13 for the total data on phylogeny, and K = 2 to K = 5 only for morphospecies from Clade A. Each color represents a distinct genetic group identified in the dataset.
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Figure 4. Principal component analysis of colony girth, calyx, and polyp density from E. clavigera, E. criptica sp. nov., and E. colombiensis sp. nov.
Figure 4. Principal component analysis of colony girth, calyx, and polyp density from E. clavigera, E. criptica sp. nov., and E. colombiensis sp. nov.
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Figure 10. Close-up underwater images (Nikon 60 mm, 1:1 macro lens) of candelabrum octocoral Eunicea (Octocorallia: Plexauridae) polyps (Willemstad, Curaçao; Aqualectra water factory reef, (10–12 m), except E. calyculata from San Andrés (10 m), Colombia, and E. clavigera, from Barú (18 m), Colombia). (A) Eunicea fusca. (B) E. tayrona. (C) E. mammosa. (D,E) E. tourneforti. (F) E. colombiensis sp. nov. (G) E. criptica sp. nov. (H) E. clavigera. (I) E. calyculata. (J) E.pinta. (K) E. flexuosa. (L) E. asperula. (M) E. knighti. (Photos: J.A.S.)
Figure 10. Close-up underwater images (Nikon 60 mm, 1:1 macro lens) of candelabrum octocoral Eunicea (Octocorallia: Plexauridae) polyps (Willemstad, Curaçao; Aqualectra water factory reef, (10–12 m), except E. calyculata from San Andrés (10 m), Colombia, and E. clavigera, from Barú (18 m), Colombia). (A) Eunicea fusca. (B) E. tayrona. (C) E. mammosa. (D,E) E. tourneforti. (F) E. colombiensis sp. nov. (G) E. criptica sp. nov. (H) E. clavigera. (I) E. calyculata. (J) E.pinta. (K) E. flexuosa. (L) E. asperula. (M) E. knighti. (Photos: J.A.S.)
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Table 1. Eunicea morphospecies included in RADseq analysis after filtering steps. FLO: Florida (USA); SAI: San Andrés Island (Colombia); CUR: Curaçao (Curaçao); BDT: Bocas Del Toro (Panamá); CAR: Cartagena (Colombia). N: samples collected by morphospecies; S: shallow; M: medium; D: deep. Depth range in meters (m).
Table 1. Eunicea morphospecies included in RADseq analysis after filtering steps. FLO: Florida (USA); SAI: San Andrés Island (Colombia); CUR: Curaçao (Curaçao); BDT: Bocas Del Toro (Panamá); CAR: Cartagena (Colombia). N: samples collected by morphospecies; S: shallow; M: medium; D: deep. Depth range in meters (m).
SpeciesNSites CollectedDepth Range (m)
E. flexuosa7FLO, SAI5–15
E. pinta10SAI35–45
E. mammosa14BDT, CUR, FLO, SAI3–15
E. succinea7SAI10–20
E. palmeri5SAI7–20
E. fusca19CAR, CUR, SAI8–34
E. asperula10CAR, CUR, SAI10–26
E. tayrona7BDT, SAI3–17
E. knighti12BDT, SAI3–41
E. laciniata25CAR, CUR, FLO, SAI5–26
E. calyculata8CAR, CUR, FLO, SAI5–26
E. tourneforti19BDT, CAR, CUR, FLO, SAI3–26
E. clavigera12BDT, CAR, SAI3–26
E. criptica sp. nov. 5CUR15–27
E. colombiensis sp. nov.23BDT, CAR, CUR, SAI3–41
Table 2. Eunicea SNP summary statistics of the 12 datasets generated from ipyRAD. The parameter combination for clustering threshold, minimum number of taxa per locus, and maximum shared heterozygous loci. The total number of variable SNPs retained is also included.
Table 2. Eunicea SNP summary statistics of the 12 datasets generated from ipyRAD. The parameter combination for clustering threshold, minimum number of taxa per locus, and maximum shared heterozygous loci. The total number of variable SNPs retained is also included.
Clustering ThresholdTaxon Occupancy
(%)		Shared Polymorphic SitesTotal Filtered LociSequence Matrix SizeMissing Sites (%)SNPs Matrix sizeMissing Sites
(%)
0.8100.2517,6002,455,87981.12241,83079.20
0.518,7772,620,26581.12258,56479.37
250.253303448,56158.7357,72957.23
0.53540482,73459.1561,61457.73
500.2566296,95531.2514,33830.98
0.567699,08231.4014,61131.12
0.85100.2521,5573,049,77481.45305,95879.83
0.523,1083,270,26981.46328,31479.92
250.253877534,59559.3569,20357.87
0.54156575,57659.7273,83258.28
500.25728107,01032.1116,00031.78
0.5749110,19232.3216,43231.98
Table 3. Genetic divergence estimates (Fst) for Eunicea morphospecies from recent Clade A.
Table 3. Genetic divergence estimates (Fst) for Eunicea morphospecies from recent Clade A.
E. clavigeraE. asperulaE. tournefortiE. criptica sp. nov.
E. asperula0.141NA
E. tourneforti0.2220.221NA
E. criptica sp. nov.0.0950.1290.176NA
E. colombiensis sp. nov.0.1030.1980.2070.091
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Sarmiento, A.; Calixto-Botía, I.; Julio-Rodríguez, T.; Quattrini, A.M.; Sánchez, J.A. Uncovering the Evolutionary History in Lineage of Caribbean Octocorals: Phylogenomics Reveals Unrecognized Diversity in Eunicea. Diversity 2025, 17, 173. https://doi.org/10.3390/d17030173

AMA Style

Sarmiento A, Calixto-Botía I, Julio-Rodríguez T, Quattrini AM, Sánchez JA. Uncovering the Evolutionary History in Lineage of Caribbean Octocorals: Phylogenomics Reveals Unrecognized Diversity in Eunicea. Diversity. 2025; 17(3):173. https://doi.org/10.3390/d17030173

Chicago/Turabian Style

Sarmiento, Adriana, Iván Calixto-Botía, Tatiana Julio-Rodríguez, Andrea M. Quattrini, and Juan A. Sánchez. 2025. "Uncovering the Evolutionary History in Lineage of Caribbean Octocorals: Phylogenomics Reveals Unrecognized Diversity in Eunicea" Diversity 17, no. 3: 173. https://doi.org/10.3390/d17030173

APA Style

Sarmiento, A., Calixto-Botía, I., Julio-Rodríguez, T., Quattrini, A. M., & Sánchez, J. A. (2025). Uncovering the Evolutionary History in Lineage of Caribbean Octocorals: Phylogenomics Reveals Unrecognized Diversity in Eunicea. Diversity, 17(3), 173. https://doi.org/10.3390/d17030173

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