Zoological Studies最新文献

A new stygobitic amphipod species of the genus Spelaeogammarus is described from a cave in the municipality of Morro do Chapéu, in Bahia, northeastern Brazil, increasing the total number of species in the genus to eleven. Spelaeogammarus quilombola sp. nov. shares similarities primarily with Spelaeogammarus spinilacertus, S. bahiensis, and S. trajanoae, but can be distinguished from its congeners by specific morphological and morphometric traits. An updated comparative table highlighting the diagnostic characteristics of Spelaeogammarus species are also provided. Additionally, we offer a supplementary description of S. bahiensis da Silva Brum, 1975, the type species of the genus. Finally, we discuss the habitat characteristics and the threats facing both species addressed in this study. Given its high endemism, this new species holds particular significance for biogeographical and conservation studies.

Spiders play a pivotal role in ecosystems, serving as predators to regulate populations of small organisms. They commonly exhibit body color polymorphism which could be due to a combination of environmental factors, adaptation, or genetic drift from population subdivision. This polymorphism, in turn, could affect their behavior and prey capture efficiency. Certain morphological traits may be unique to specific subregions, suggesting possible subspecies classification. In this study, we examined morphological polymorphism in the giant wood spider, Nephila pilipes, in Thailand, particularly focusing on leg variation and genetic variation at the cytochrome c oxidase I (COI) gene. We used partial sequence of the COI gene for our samples and constructed a phylogenetic tree by including other species. We explored the relationship between morphological polymorphism, COI genotype, and geographic distribution. Our findings categorized female N. pilipes into seven types based on legs I and IV, with no correlation to geographic region. The N. pilipes specimens formed two clades, each containing all leg types and collection regions, consistent with low genetic differentiation within the species. Trichonephila antipodiana specimens formed three clades while all Argyrodes flavescens specimens were grouped into a monophyletic clade. Additionally, Nephila kuhli, previously suggested to be a melanic morph of N. pilipes, was also included in the N. pilipes cluster, with a low genetic distance. Our results suggest that the leg variants in N. pilipes represent polymorphism within the species rather than distinct biospecies.

The function of ecdysone in promoting molting is widely known in arthropods. Moreover, in insects, ecdysone synthesis in the ovary is involved in reproduction and development. In crustaceans, some studies conducted in species with the molt linked to mating have shown that ecdysone produced by the Y organ stimulates ovarian maturation, but scarce evidence about the capacity of the ovary itself to synthesize ecdysone is currently available. The present study provides the first evidence of the expression of a putative shadow gene (sad, cytochrome P450 CYP315A1), involved in the ecdysone synthesis pathway, in the ovary of the estuarine crab Neohelice granulata, considered a derived species with the molt not linked to mating. The obtained results provide the first evidence for future studies testing the hypothesis that during the intermolt period, the mature ovary of females synthesizes ecdysone to locally act on the female vulvae to promote its decalcification, allowing mating. These results are discussed considering phylogenetic relationships among Arthropoda.

Caenorhabditis species diversity has been surveyed in several places around the world and tends to be higher in subtropical and tropical regions. Vietnam is a long country with complex topography and a climate largely influenced by the northeast monsoon from the Siberian plateau. Here, we report the first Caenorhabditis survey in Ta Kou Nature Reserve located in south-central Vietnam, where we have found two isolates of a new species, Caenorhabditis sp. 71. Whole genome skimming of one isolate using a combination of the Oxford Nanopore Technologies MinION long read and Illumina short read sequencing platforms allowed us to assemble a complete mitochondrial genome that is 13,654 bp in length. Annotation of the mitochondrial genome revealed 12 protein coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and 1 control region. Phylogenetic analysis, based on the concatenated sequences of the 12 mitochondrial protein coding genes, suggests that Caenorhabditis sp. 71 is the sister species to C. imperialis. Our findings not only contribute to the understanding of Caenorhabditis diversity in Vietnam but also highlight the ecological significance of isolated habitats, such as Ta Kou Mountain. These fragile environments are essential for biodiversity conservation and require dedicated protection to preserve their unique and diverse ecosystems.

We describe the complete larval development of the pedunculated barnacle Capitulum mitella, using both light microscopy and scanning electron microscopy. This includes all six naupliar instars and the final cypris stage. Many previous accounts on the development of barnacle larvae suffer from a shortage in detail and habitually use terminologies that are either inconsistent or hard to compare with those used for other crustaceans. We therefore propose and use a new, completely standardized terminology to enable comparison both within barnacles and with larvae of other crustaceans. Rather than a stage-by-stage description, our account follows changes in specific features during larval development. The morphological, ecological and phylogenetic significance of these characters is discussed. Special attention is paid to the feeding apparatus and how it may have undergone adaptive evolution in response to changes in the availability of food items through geological time. C. mitella is universally agreed to be placed lower in the barnacle phylogeny than acorn barnacles (Balanomorpha), and fossil forms very similar to this species can be traced back to the Upper Jurassic. This makes C. mitella central to understanding the large-scale evolution within barnacles.

In recent decades, taxonomy has been significantly improved by integrating molecular techniques with classical morphological methods, leading to the discovery of cryptic species. On the other hand, molecular datasets by themselves are ineffective in several types of research without basic taxonomic studies, as the ecological and biological roles of a given species cannot be determined without an accurate name. DNA barcoding libraries are widely used as identification tools by non-specialists to overcome the taxonomic impediment, but they fail when basic taxonomic studies are insufficient and faunistic inventories are lacking. South European microlepidoptera are poorly studied, with the exception of a few families such as Depressariidae. We tested the effectiveness of the DNA barcoding library for this family to identify 174 specimens collected in southern Italy, where faunistic studies are very limited. All specimens were successfully barcoded, and 95% of them were assigned to 47 species, 43 of which correspond to a Barcode Index Number (BIN). Four additional species shared a BIN but were still clearly separated into different clusters at within-BIN resolution. Only seven specimens belonging to four BINs remain unnamed, and ad hoc studies are needed to clarify their status. The regional fauna was enriched by 37 species, three of which are new for the Italian mainland and 21 for peninsular Italy, demonstrating the usefulness of the DNA barcoding library in assessing local diversity and overcoming the taxonomic impediment. Improving taxonomic studies is crucial for utilizing molecular datasets to depict ongoing macroecological dynamics, highlight species richness trends, and identify changes in species assemblages.

Epifaunal communities inhabiting seaweeds are key components of temperate rocky reef ecosystems, playing vital roles in nutrient cycling and biodiversity maintenance. However, limited research has addressed their seasonal dynamics in the semi-enclosed Sea of Japan. This study examined the seasonal changes in epifaunal communities associated with two dominant brown algae, Sargassum macrocarpum and S. patens, in Tsukumo Bay, Noto Peninsula. Over the course of one year, we recorded fluctuations in seaweed biomass and associated epifaunal abundance and composition. The wet weight of both host seaweed species peaked in spring and winter and declined during summer and autumn, reflecting their life history traits. Seasonal changes in epifaunal communities were more pronounced than differences between host species. Caprellid and gammarid amphipods exhibited synchronized abundance peaks with seaweed growth in spring and winter, while gastropods remained relatively stable year-round, likely favoring understory habitats. Bivalves increased in summer on S. macrocarpum, potentially due to structural differences facilitating larval settlement. Multivariate analyses (PERMANOVA and nMDS) revealed clear seasonal shifts in community composition, with caprellids, gammarids, and gastropods contributing most to these patterns. Our findings highlight the strong coupling between macroalgal phenology and epifaunal dynamics, suggesting that algal bed seasonality significantly shapes coastal community structure.

Stylochoposthia Faubel, 1983 is a genus of acotylean polyclads, and its family-level assignment is controversial. In this study, we inferred the phylogenetic position of the genus represented by Stylochoposthia sp. using the combined data generated from partial sequences of nuclear 18S and 28S ribosomal DNA, mitochondrial 16S ribosomal DNA, and the cytochrome c oxidase subunit I gene. The phylogenetic analysis revealed that Stylochoposthia sp. was nested in a robust clade comprising the species of four genera within Planoceridae Stimpson, 1857 (Aquaplana Hyman, 1953, Heteroplanocera Oya & Kajihara, 2021, Paraplanocera Laidlaw, 1903, and Planocera Blainville, 1828). Specifically, Stylochoposthia sp. was closely related to Planocera pellucida (Mertens, 1833), with high support values. This study revealed that an eversible cirrus with hard structures (numerous spines, thorns, or teeth) in the male copulatory apparatus, a diagnostic characteristic of Planoceridae, has been lost in the lineage of Stylochoposthia.

Based on a comprehensive literature review, we present an analysis of the richness of the subfamily Scarabaeinae and its distribution in Mexico's Chiapas state. The reviewed works provided information from 185 localities where 134 species belonging to 24 genera were recorded. Fourteen species (10.4%) are endemic to Chiapas, mainly restricted to montane forests. The number of species places Chiapas as one of the regions with the highest species richness in Mexico, representing 39.2% of the Scarabaeinae diversity known in the country. Although the sampling effort is relatively high compared to other regions, there is a strong sampling bias, with localities unevenly distributed in the state territory, most of them concentrated in easily accessible areas, with extensive regions with little or no representativeness, including mountainous areas and several natural protected areas. This information may constitute a valuable contribution to future projects on the taxonomy and biodiversity of dung beetles, so considering poorly explored regions constitutes a niche of opportunities that would allow expanding the knowledge on Scarabaeinae at a regional level.

This study describes two new species of Glyptothorax from the Mekong River drainage in Cambodia and Laos. Glyptothorax carnatus can be distinguished from Mekong congeners by its deep body relative to the caudal peduncle (caudal peduncle depth 2.8-3.6 times in body depth at dorsal-fin origin vs. 1.9-3.0) and combination of characters in color pattern, thoracic adhesive apparatus (TAA) morphology, nuchal plate shape, and morphometry. Glyptothorax rhadinus can be distinguished from Mekong congeners by its very slender TAA (width 1.9-2.2 times in its length vs. 1.1-1.9) and a combination of characters in color pattern, thoracic adhesive apparatus (TAA) morphology, nuchal plate shape, and morphometry. Both species have been previously confused with G. fuscus and G. lampris, and comparisons with these two species are provided.