Arthropoda

Seven new species of the genus Cherax from the western region of Western New Guinea, Indonesia, are described and illustrated. All new species—Cherax veritas n. sp. from the southeastern part of Misool Island of Raja Ampat Regency, Southwest Papua; Cherax arguni n. sp. and Cherax kaimana n. sp. from the northern part of Kaimana Regency, West Papua; Cherax nigli n. sp. from the southeastern part of Kaimana Regency, West Papua; Cherax bomberai n. sp. from the northeastern part of the Fakfak Regency, West Papua; Cherax farhadii n. sp. and Cherax doberai n. sp. from the Teluk Bintuni Regency, West Papua—belong to the northern group of Cherax. The new species are compared with their closest relatives, from which they can all be easily distinguished by morphological characters, such as the shape of the chelae, rostrum, body, and by their coloration. A molecular phylogeny based on a mitochondrial gene fragment, 16S, supports the morphology-based description of the seven new species, which can also be clearly distinguished by sequence differences. Full article

The nine-banded armadillo, Dasypus novemcinctus, is one of only two species of armadillo found in Mexico. Among the ectoparasites reported on this mammal are ticks of the genus Amblyomma. Between December 2022 and April 2024, 52 ticks of different developmental stages (females, males, and nymphs) were collected from five D. novemcinctus. All ticks were morphologically identified as A. auricularium. This study reports for the first time the presence of this tick species in the Municipality of Santiago Llano Grande, Oaxaca. Full article

A new genus of Ectinosomatidae is recorded in association with an Ascidia from a permanent submerged coral community in Barra Beach, Salvador City, Bahia State (Brazil). The new taxon belongs to a smaller group of genera in the family Ectinosomatidae based on the geniculate maxilla and the prehensile first swimming leg. This group is composed of Bradiellopsis, Chaulionyx, Halophytophilus, and Sigmatidium. The new genus differs from the others due to distinct aspects of the mandible gnathobasis, which features sharp processes on the pars incisiva and pars molaris followed by a short spinulated area and a serrulated seta; the presence of a two-segmented endopod of the first swimming leg, with the first endopodal segment longer than all exopodites combined; and a short, quadratic second endopodal segment with two strong curved claws. In addition, it differs from other genera due to the distinct armature of the first to fourth swimming legs and the presence of fused exopod and baseoendopod on the fifth swimming leg. Cruscollatus gen.nov. lives specifically within the digestive tract of Eudistoma vannamei Millar, 1977, an Ascidia species endemic to northeastern Brazil. This study reports the first documented association between a harpacticoid copepod of the family Ectinosomatidae (order Harpacticoida) and ascidian hosts (Ascidia). Full article

Although it has its advantages for the development of urban areas, road construction is among the greatest threats to biodiversity, due to fragmentation, habitat loss, and changes in landscape structure. This study investigated the effects of different traffic intensities on the understory spider assemblage in the Brazilian Atlantic Forest. Understory spiders were collected between 09:00 h–16:00 h using beating tray samples on roadside vegetation on roads with and without traffic. In total, 1616 spiders belonging to 24 families and 317 morphospecies were collected. The families Araneidae and Theridiidae were more abundant and showed a higher number of morphospecies on both roads. Understory spiders were classified into seven guilds. However, no significant differences were found in functional and taxonomic richness and abundance between the roads. These results indicate that understory spider assemblages showed no significant response to traffic intensity, suggesting potential resilience to this disturbance in the studied context. Additionally, the proximity between locations may result in the founder effect, with spiders migrating from the preserved site to the impacted site. Overall, this study indicates that traffic presence does not significantly impact the diversity and composition of understory spider assemblages in the studied region. Full article

The genus Troglorhopalurus (Scorpiones: Buthidae) is endemic to northeastern Brazil and comprises cave-dwelling species with limited distributions. Based on newly collected specimens, this study provides a description of a new cave-dwelling Troglorhopalurus species and the first detailed description of the male hemispermatophore of the genus. Troglorhopalurus iuiu n. sp. is diagnosed based on morphometric characters, distinct carapace granulation, and differences in the pedipalps and metasomal carinae and peg sensillae shape. The hemispermatophore of Troglorhopalurus is like other Centruroidinae species, with internal, external, and basal lobes. Additionally, we discuss the distribution and conservation status of Troglorhopalurus species. Troglorhopalurus lacrau distribution range is extended based on additional epigean and hypogean records. This species may be reassessed from data deficient to least concern. Based on the limited localities and declining habitat quality, we propose that T. iuiu n. sp. be considered endangered. This research underscores the importance of further sampling to explore species-specific variations and promote conservation efforts for these ecologically specialized scorpions. Full article

Here, we confirm the presence of two species of caridean shrimps for the first time in Brazil: Latreutes parvulus and Ambidexter cochensis. During active samplings conducted in December 2023, April 2024 and September 2024 on the rocky shore of Prainha da USP (Ubatuba municipality, São Paulo state, southeastern Brazil), we captured five ovigerous females of L. parvulus and fifteen individuals of A. cochensis (five males, three non-ovigerous females and seven ovigerous females). All the females of L. parvulus exhibited eyestalks with small, truncated processes separating the cornea from the stalk, a unique feature of this species. On the other hand, all specimens of A. cochensis exhibited a unique combination of characteristics: a rostrum with an apex bifid, a stylocerite bearing a lateral spinule and a transverse row of setae between the anterior pair of spines, and three longitudinal rows of setae on the telson. Also, males of A. cochensis had the tip of their appendix masculina armed with four simple apical setae and another two setae positioned below them. All analyzed shrimps had fully developed gametes in their reproductive systems, indicating breeding populations in this area. This is the first record of L. parvulus on the Atlantic coast of South America and a new meridional distribution limit for A. cochensis. Full article

The palaemonid shrimp genus Pseudopalaemon Sollaud, 1911, is endemic to South America, comprising seven freshwater and low salinity species. This study aimed to compile an overview of the genus, including an illustrated identification key for species and updated distributional data. Diagnostic morphological characters of the species were analyzed using specimens from several museums and other scientific collections. Current knowledge about the genus reveals significant knowledge gaps, particularly in species ecology. The data and insights from this study support future research and highlight a need for further studies on this group. Full article

Trilobites, as typical euarthropods, possess compound eyes. In 1901, Lindström was the first to describe them in detail; on the one hand, we reconsider his descriptions of the different modes of trilobite eyes; on the other hand, we expand this by compiling the observations that have been possible in recent years. There are two, perhaps three kinds of trilobite compound eyes. The first are the primordial holochroal eyes, which are actually apposition compound eyes, similar to those of many modern diurnal crustaceans and insects. The abathochroal eyes, often referred to as the second form, are probably a subtype of the holochroal eyes. Consequently, the second is the schizochroal eye of phacopid trilobites, which are hyper-compound eyes composed of numerous small compound eyes below each of the big lenses, which appear from outside as one big lateral eye each. Thirdly, one may call the maculae light-sensitive organs, but this is still uncertain. Comparing what are probably the oldest trilobite eyes described so far with other forms, it is possible to conclude that the sensory apparatus is much older than the fossil record of trilobite eyes and probably developed in Precambrian times. The refractive apparatus, however, was developed later and separately within the systematic groups. This explains why, for example, the mandibulates have a lens and a crystalline cone. Still, the chelicerate xiphosurans, such as horseshoe crabs or eurypterids, possess a lens cylinder with an index gradient but no crystalline cone. Furthermore, this can explain why the calcite character of trilobites is unique in the arthropod kingdom. An important discovery is the probably epidermal, lens-building cells encompassing a prospective lens of Schmidtiellus reetae Bergström 1973 from the early Lower Cambrian of Estonia. We reconsider the morphology of hypostome maculae and interpret them as a potential phylogenetic relict and a potential predecessor of all arthropod ommatidial compound eyes. It will be of great relevance for future research to understand the evolution of compound eyes and vision because we witness the emergence of the first lenses in the trilobite, if not the arthropod kingdom. Full article

Mastigoproctus Pocock, 1894, is the most speciose genus in the thelyphonid subfamily Mastigoproctinae Speijer, 1933, with eighteen described species distributed from the Southern United States to Colombia and Venezuela. Ten of these species occur in Mexico. In the present contribution, Mastigoproctus spinifemoratus, sp. nov., is described based on an adult male and two juveniles from Eastern Nuevo León and Southwestern Tamaulipas, Mexico. It differs from five other species of Mastigoproctus, in which spiniform tubercles are present on the retrolateral surface of the pedipalp femur, in the ventrally directed epistome of the carapace, and the absence of an accessory spine on the prodorsal margin of the pedipalp trochanter. The new species raises the number of Mastigoproctus species to nineteen and the number in Mexico to eleven. Full article

Rock shrimps (Sicyonia dorsalis and Sicyonia typica) are commonly caught as bycatch during shrimp trawling along the Brazilian coast, but are not commercially exploited due to their small size and hard carapace. This study evaluated their spatio-temporal distribution, size classes, and sex ratio near the Almada River Estuary, Ilhéus, Bahia, Northeastern Brazil, and tested correlations between environmental factors and species abundance. Samples were collected monthly using double-rig trawl nets in the estuary and along transects at depths of 5–35 m. Bottom water and sediment samples were obtained for analyses of environmental factors. In total, 5336 individuals of S. dorsalis and 303 individuals of S. typica were collected. No individuals were recorded in the estuary. Both species were significantly more abundant between 25 and 35 m, where fine sediment with high levels of organic matter occurred. Considering the temporal variation, their abundance decreased during the rainy season, coinciding with increased river flow. Organic matter content, salinity, and water transparency were the primary environmental factors influencing abundance. Females were generally larger and predominant compared to males, likely due to life cycle dynamics. Despite being congeneric and sympatric, the species exhibited distinct population patterns, possibly to avoid niche overlap and competition. Full article

Two new species of the genus Cherax are described and illustrated. Cherax rayko n. sp., endemic to the Bian River drainage basin in the Muting District, in the northern part of the Merauke Regency, South Papua, Indonesia, is described, figured, and compared with its closest relatives, Cherax alyciae, Lukhaup, Eprilurahman & von Rintelen, 2018, and Cherax peknyi Lukhaup & Herbert, 2008. The new species may be easily distinguished from both by the shape of the rostrum, the shape of the chelae, the shape of the scaphocerite, and the coloration. Cherax phing n. sp., endemic to the Kali Ombak River drainage basin in the western part of the Kepala Burung (Vogelkop) Peninsula, Southwest Papua, Indonesia, is described, figured, and compared with its closest relatives, Cherax pulcher Lukhaup, 2015a, Cherax boesemani Lukhaup & Pekny, 2008, Cherax wagenknechtae Lukhaup and Eprilurahman, 2022, and Cherax gherardii Patoka, Bláha & Kouba, 2015. The new species may be easily distinguished from the latter species by the shape of the chelae, rostrum, and body and by the coloration. A molecular phylogeny based on a mitochondrial gene fragment, 16S, supports the morphology-based description of the two new species, which can also be clearly distinguished by sequence differences. Full article

Parasitoidism strongly influences the structure of the spiders’ populations, and it can be affected by environmental factors such as those caused by anthropogenic actions. We studied the prevalence of parasitoids in egg sacs and the proportion of eggs parasitized in each egg sac of two synanthropic spider species, one native to the American continent (Parasteatoda tepidariorum) and another recently introduced to the Americas (Latrodectus geometricus). We conducted the study at two scales, along an urban gradient (from highly urbanized to rural sites) and in the vegetation surrounding each sampling site (microscale). We expected to find a larger prevalence of parasitoids in the most urbanized sites and around sampling sites with more vegetation. However, we saw more parasitized egg sacs at the intermediate urbanized site for both species, and the vegetation surrounding the sampling sites did not affect the number of parasitized egg sacs. Therefore, conditions in the site with intermediate urban development favored parasitoids. We also found more parasitized egg sacs in P. tepidariorum than in L. geometricus, which is likely a consequence of native parasites not being adapted to a new host. The proportion of eggs parasitized was similar for both species in all sites, which may be related to the behavior (e.g., searching behavior) and number of spider eggs a female parasitoid can parasitize. Full article

Eighteen new cases of teratology and other abnormalities within scorpions are presented, representing new cases of metasomal duplication, mesosomal anomaly, telson anomaly, albinism, and abnormal pigmentation. Furthermore, recently published literature on other scorpion anomalies are tabulated to update the recent 2023 checklist of scorpion teratology which charted all known literature up to the aforementioned work. Full article

The red spider mite, Tetranychus macfarlanei, is a serious pest of many cultivated crops in Bangladesh and other East-Asian and South-East Asian countries, in the Afrotropical, Oriental, and Palearctic regions. Sublethal concentration of pesticides, such as LC₁₅ and LC₃₀ (the concentrations that result in 15 and 30 percent lethality, respectively) impact reproduction, behavior, development, and physiology. This study assessed the effects of different concentrations of spirotetramat, an insecticide that disrupts lipid production, on the biological traits of T. macfarlanei. The LC₁₅, LC₃₀, LC₅₀, and LC₉₀ values were 2.16, 6.57, 20.54, and 332.81 mg·L⁻¹, respectively. Sublethal concentrations (LC₁₅ and LC₃₀) slightly reduced female fecundity but did not significantly affect development duration, pre-oviposition, oviposition period, or longevity compared to the untreated control group. Life table parameters differed between the treated and control groups, with significant reductions in the intrinsic rate of increase (r), the net reproductive rate (R₀), and the finite rate of increase (λ) for LC₁₅ and LC₃₀. LC₁₅ and LC₃₀ had negative effects on the intrinsic rate of increase for females. This study demonstrated that lower lethal concentrations of spirotetramat compromised survivability and negatively impacted the life-table parameters of subsequent generations of T. macfarlanei. These findings highlight the importance of sublethal effects in pest control, offering valuable insights for developing more effective and sustainable integrated pest management strategies. Full article

Invertebrates, including Asellidae, are part of the natural ecosystem of the drinking water distribution system (DWDS) and are known to cause a nuisance to consumers. In addition, recently, the potential role of the species Asellus aquaticus (L. 1758) in the regrowth of Aeromonas bacteria was published. Aeromonas is included in the Dutch drinking water guidelines as a process parameter, and the guideline values are regularly exceeded. Although neither A. aquaticus nor Aeromonas is associated with health risks, the Evides drinking water utility shows a strong interest in the possible reasons for these exceedances and possible control measures. In surface waters, Asellidae feed mainly on decaying leaves that are abundantly present. These food sources are not present in the DWDS. Therefore, we determined suitable food sources for A. aquaticus in the DWDS. Laboratory experiments show that A. aquaticus individuals survive on biofilm on pipe wall material and loose deposits (sediments) collected from DWDS. Growth and survival rates on these loose deposits were even higher than on the positive control (decaying leaves). As the basis of these loose deposits is inorganic (iron deposits, sand, and pipe particles), the organic matter (living and decaying bacteria, protozoans, fungi, and invertebrates) must be their substrate. These experiments validate hypotheses that Asellidae can grow and survive on organic matter in deposits in DWDS. Full article

Lyme disease, the leading vector-borne ailment in the U.S., annually affects an estimated 476,000 individuals, predominantly in the Northeast and Upper Midwest. Despite its increasing incidence, the evaluation of risk within U.S. cities, including natural public lands, remains inadequate. This study focuses on blacklegged tick occurrences and Borrelia burgdorferi infection prevalence in 24 Staten Island parks, aiming to assess Lyme disease exposure risk. Monthly acarological risk index (ARI) calculations from 2019 to 2022 revealed elevated values (0.16–0.53) in specific parks, notably Wolfe’s Pond Park, High Rock Park, Clay Pit Pond Park, Clove Lake Park, and Fair View Park. June (0.36) and November (0.21) consistently exhibited heightened ARIs, aligning with peak tick collection months. Despite stable yearly infection rates at 28.97%, tick densities varied significantly between parks and years. Identifying a high transmission risk in specific parks in Staten Island, a highly urbanized part of New York City, emphasizes the continuous necessity for Lyme disease risk management, even within the greenspaces of large cities. Full article

The family Atyidae is composed of species whose existence has been known since the seventeenth century. Widely found in the Caribbean, Atya lanipes is a freshwater scraper/filter feeder shrimp with an amphidromous complex life cycle. Hunte (1975) described the first larval (zoeal) stage of the species. However, no scientific study has described the early larval development of this species after the first stage. This study aimed to document the early larval development of Atya lanipes under laboratory conditions and compare its larval development with other previously described species of the Atyidae family. Larval development was recorded by taking daily photos and videos of larval (zoeal) growth using a stereo microscope. Larvae were also preserved in ethanol for further morphological analysis. The results revealed that the best conditions for Atya lanipes development were 30 ppm water salinity, constant gentle aeration, and 27 °C water temperature. Nine stages were identified for the description of the early larval development of Atya lanipes. Early larval stages differ primarily in interstage larval size, the appearance and development of the telson, appendage appearance, growth of antennae and antennules, and pigmentation. The present contribution represents the first study that describes the larval development of the Caribbean shrimp Atya lanipes. Full article

Limb anomalies are widespread and diversified in arthropods. From trilobites to insects, they range from the loss to the addition or fusion of legs and may appear congenitally or be induced experimentally (e.g., amputation or injury). Basal chelicerates pycnogonids, or sea spiders, also show deformities. Despite being understudied compared to other arthropods, quite a high diversity of limb malformations has been reported in the literature. The present study reports the leg anomalies of two adult females Ammothea hilgendorfi (Böhm, 1879) observed with duplicated leg podomeres. Both individuals were described ethologically and morphologically. Although the current knowledge on pycnogonids is limited, the anomaly is likely due to a problem in the molting process; the specimens were unable to totally remove their old exuviae, which then stacked after the proximal leg segments. The second specimen also showed other leg deformities, hinting at a problem during the molting process itself. The discussion emphasizes that understanding how pycnogonids normally molt would not only help our understanding of how the abnormal patterns appeared but also put pycnogonids into perspective with other arthropods, a phylum in which they have a key taxonomic position. Full article