Zoosystematics and Evolution

This study documents the northernmost record of Egglestonichthys melanoptera in the South China Sea (Hainan Island, China), thereby extending its distribution in the Indo-Pacific region from the Indian Ocean, and confirms the sympatric occurrence of E. bombylios . The morphological characteristics of E. melanoptera are described in detail, and measurable data is presented. The complete mitochondrial genomes of both species have been presented for the first time (17,743 bp for E. bombylios , 17,350 bp for E. melanoptera ), revealing a conserved gobiid genomic architecture with a pronounced A+T bias (60.3–62.7%) and codon position-specific nucleotide preferences. A further objective of this study was to construct a phylogeny of 110 species of the family Gobiidae, extending previous studies. Phylogenetic analyses resolved E. melanoptera within Gobiidae, supported by osteological synapomorphies (single epural; pterygo-phore formula 3-22110), and placed Egglestonichthys within the Priolepis lineage. The validity of Benthophilinae remains contentious due to conflicting swim bladder and spine morphology, necessitating integrative reassessment. Comparative mitogenomic analyses reveal that the mitochondrial genome currently attributed to Oxyurichthys formosanus in GenBank (accession: KC237282) does not represent the genus Oxyurichthys but should be reassigned to Cryptocentrus yatsui . A revised diagnostic key has been synthesised, synthesising historical descriptions with novel morphological-molecular data, giving taxonomy for Egglestonichthys species. These findings contribute to our understanding of the evolutionary trajectories of gobiid fish, emphasising the synergy of mitogenomic and morphological approaches in resolving complex marine fish systematics.

The genus Murina Gray, 1842, recently had four new species discovered in China over the last four years, suggesting its diversity may have been previously underestimated. Herein, we describe four new species—Murina beibengensissp. nov., Murina medogensissp. nov., Murina milinensissp. nov., and Murina yadongensissp. nov.—based on morphological and genetic evidence from specimens collected during bat diversity surveys conducted in the Xizang Autonomous Region of China over the past three years. Each of these four new species forms an independent lineage on a phylogenetic tree reconstructed using the mitochondrial COI and Cyt b genes, and each is genetically distinct from its congeners. Morphologically, the new species can be distinguished from the 43 recognized congeners by features including forearm length, hair color, and skull morphology. We elevated M. huttoni rubella from a subspecies of M. huttoni to a species based on morphological and genetic evidence. The new species discussed herein increase the number of species in the genus Murina to four worldwide and from 23 to 28 in China. This study not only enriches our understanding of bat species diversity but also underscores the importance of conducting bat surveys in the specialized highland habitats of the Himalayas.

Traccatichthys punctulatus is here described from the Liu-Jiang flowing into the Xi-Jiang of the Pearl River basin at Jinxiu County, Guangxi Zhuang Autonomous Region, southern China. It is distinguished from all congeners by having a unique body coloration of a series of brown spots along the lateral line and dorsal-fin. Other diagnostic characters, not unique to this new species, are caudal-fin and lateral body colorations, and absence of pectoral-fin tuberculation. Its validity is further confirmed by its monophyly recovered in a molecular phylogenetic analysis based on mitochondrial COI and Cyt b gene sequences and species-level divergence between the new species and its closest relatives.

The tube-nosed bats (genus Murina) are small insectivorous mammals that are primarily distributed in South, East, and Southeast Asia. The Qinghai-Tibet Plateau (QTP) has long been an understudied region in bat surveys, especially for species of small arboreal bats, including Murina. In 2023, we surveyed the southeastern QTP and collected seven individual specimens of Murina. The specimens were identified using combined morphological and molecular data (the mitochondrial Cyt b gene). Phylogenetic analyses identified three unknown clades: Murina sp1, Murina sp2, and Murina sp3. Murina sp1 was most closely related to M. pluvialis, with a genetic distance of 0.09. Murina sp2 was most closely related to M. shuipuensis, with a genetic distance of 0.13, and Murina sp3 was most closely related to M. chrysochaetes, with a genetic distance of 0.15. All three species delimitation methods supported the partitioning of Murina sp1, Murina sp2, and Murina sp3. Herein, we describe a new species, Murina chayuensissp. nov. (Murina sp1.), that is similar to M. annamitica and M. lorelieae. Owing to the limited number of specimens, Murina sp2 and Murina sp3 are not described in this study. Our results highlight the overlooked diversity of bats in the southeastern QTP, and thus this group warrants further surveys and taxonomic studies.

During a survey of small mammals in Sichuan and southern Xizang, China, three species of Neodon were collected that did not match to any described species. Therefore, we conducted phylogenetic analyses of the entire genus based on two mitochondrial genes (CYTB and ND2) and three nuclear genes (IRBP, GHR, and RAG1). Morphological analyses were based on skull characteristics and male genitalia. The main results were as follows: 1) Three new taxa consistently formed three distinct clades in the molecular phylogenetic trees; 2) the Kimura 2-Parameter (K2P) distances between these three new taxa and other known species of Neodon ranged from 9.0% to 15.5%, indicating interspecific divergence; 3) both automatic barcode gap discovery (ABGD) and Bayesian posterior probability (BPP) analyses indicated that the three new taxa were independent species; 4) principal component analysis (PCA) and discriminant analysis showed clear separation in scatterplots from morphologically similar species; and 5) these three new taxa had distinct glans penis morphologies. Accordingly, three new taxa were described as N. minorsp. nov., N. kulakangriasp. nov., and N. konggordoussp. nov.

Brachistosternus pehuenchesp. nov. (Scorpiones, Bothriuridae) is described from the Mauline Andean forests of the northern Chilean Patagonia, located within the upper basin of the Maule Valley. Its unique geography and the discovery of this partial isolation, as a result of the surrounding higher altitudes, support the role of this valley as a biodiversity hotspot, fostering a variety of endemic epigean arthropods. The discovery of this third endemic scorpion species highlights the area’s ecological uniqueness. The species is most similar to Brachistosternus negrei, a species found in the southern Chilean forests, but distinct morphological traits, such as pigmentation patterns and metasomal structures, clearly separate the two. This study underscores the ecological value of the Maule Valley, which, despite its high endemism, remains unprotected and is subject to significant anthropogenic pressures, including agriculture, hydropower projects, and international transit routes. The need for conservation initiatives in this region is critical to preserve its exceptional biodiversity. This work not only adds to the taxonomy of Brachistosternus but also raises fundamental questions about the processes driving endemism in the Andes and the broader implications for the conservation of montane ecosystems.

Corrigendum: Three new species and a new record of pheretimoid earthworms (Crassiclitellata, Megascolecidae) from Misamis Oriental, Philippines, with data from the mitochondrial genome. Dr. Csaba Csuzdi, earthworm scientist from Hungary, contacted us after noticing the incongruity of the scientific names of our species presented in Figs 6, 7 in contrast to what is presented in the Results and Discussion. We realized that the figures that were submitted to the journal were still the old versions where the scientific names of the new species have not been revised yet. We present here the corrected versions of the figures. Moreover, we certify that the sequences that were submitted to GenBank are correct and the species names have not been misiden-tified: Polypheretima andresi-Accession No. PP266606; Pheretima elnorroae-Accession No. PP266605; Phere-tima naawanensis-Accession No. PP266607; Metaphire bahli-Accession No. PP266604.

Capitellidae is a family of marine annelids commonly found in coastal to deep-sea sediments. These annelids are characterized by capillary chaetae at the anterior and long-handled hooks at the posterior part. Although mitochondrial genomes (mtgenomes) are widely used in phylogenetic analyses of invertebrates, their application is limited in many marine annelid families, particularly in Capitellidae. In this study, we obtained complete or nearly complete (except control region) mtgenomes through high-throughput sequencing of eight species across five genera of Capitellidae: Barantolla sp., Capitella teleta, Mediomastus sp., Notodasus sp. A, Notodasus sp. B, Notodasus sp. C, and Notomastus sp. A and Notomastus sp. B. Our results indicate that species from genera with fewer capillary chaetae (Barantolla and Mediomastus) exhibit a relatively conserved mitochondrial gene order, while those from other genera show significant gene order rearrangements. Group II intron in cox1 is found in newly sequenced Notomastus sp. B and Notodasus sp. A & C. Phylogenetic analysis based on the 13 protein-coding genes (PCGs) or 37 mitochondrial genes (mtgenes) revealed three distinct clades for nine capitellid worms with the mtgenome: Clade 1 includes Mediomastus and Barantolla; Clade 2 consists of Notodasus and Capitella; and Clade 3 comprises Notomastus. Notably, Clade 2 is sister to Clade 3, and both form the sister group to Clade 1. In contrast, a phylogenetic tree constructed from nuclear genes (ncgenes; 18S, 28S, and H3) identified Capitella as an early branching clade within Capitellidae. The tree based on 37 mtgenes + ncgenes identified the Capitella as the sister taxon of Notodasus + Notomastus. Additionally, the Ka/Ks ratios of 13 PCGs in Mediomastus and Barantolla were much lower than those in Notodasus or Notomastus. Together, our results indicate different trajectories of mtgenome evolution in the Capitellidae.

While taxonomy of the odorous frog genus Odorrana has made considerable progress recently, far less attention was given to those newly-described karst-associated species. In this study, the taxonomic status of Odorrana lipuensis group, species living in karst environments, was revisited. Combining the scrutiny of previous literature, molecular analyses using two mitochondrial DNA fragments (i.e. 16S rRNA and CO1) and morphological analyses including a series of additional specimens, we defined the O. lipuensis group and revised the taxonomic accounts of recognised species. Based on these data, we described a new species, O. calciphilasp. nov. from the karst regions in northern Guangdong, China. Apart from this new species, the O. lipuensis group currently contains three other species distributed in southern China and northern Vietnam, namely O. concelata, O. liboensis and O. lipuensis. Morphological comparisons between this group and other congeners, together with a dichotomous identification key for each species within this group, were also presented. Finally, the known distribution, implications of morphological distinctiveness, ecological and evolutionary significances and existing taxonomic issues of these species were also discussed.

Three new Anoplodesmus species are described from northern Vietnam, namely A. lobussp. nov., A. bilobussp. nov., and A. gladiussp. nov. All three species belong to the A. elongissimus group, showing the relatively to extremely long gonopod solenophore. The phylogenetic relationships among Anoplodesmus species and other sulciferinin genera are also discussed.

Gordius wulingensissp. nov., a newly described horsehair worm, parasitizes Tachycines (Orthoptera, Rhaphidophoridae). Free-living specimens are mainly found in karstic cave puddles. In recent years, a total of 37 creamy white horsehair worms were collected from various caves in the Wuling Mountains. Characteristic for the species is that males exhibit concentrated bristles at the tips of the inner lobes and scattered bristles along the posterior half of the caudal lobe. The inner wall of the cloacal opening displays honeycombed areoles. The body cuticle contains dense bristles in the anterior and posterior ends; the density of bristles is decreasing in the mid-body. Distinct longitudinal sharp ridges are visible on the ventral and dorsal surfaces. Adults are present in caves year-round, while the entire life cycle is completed within the caves. In the laboratory, specimens can be kept alive for more than 3 months.

Ichnotropis is a genus of small and elusive ground-dwelling lizards mostly distributed in the savannas and woodlands south of the Congo River. The genus comprises six nominal species and three subspecies; however, the phylogenetic hypothesis of this group and the taxonomical status of several taxa remain unresolved. Among these species, Ichnotropis microlepidota stands out, as it is only known from the type series since its discovery in the 1950s in the crop of a Chanting Goshawk in Mount Moco, in the central highlands of Angola. Consequently, due to the lack of a precise locality and its similar morphology to other species, the taxonomic status of this species has been debated by several authors. Thanks to the collection of new material across the Angolan territory, we take the opportunity to revise the group, using molecular and morphological techniques. Thus, we here provide the first phylogenetic hypothesis of the group in Angola and therefore a phylogenetic placement of I. microlepidota. As a result, we validate the taxonomic status of this elusive species and demonstrate that it represents a distinct taxon within the bivittata group, differing by 14.99% 16S uncorrected p-distance from I. bivittata. Furthermore, we undertake an updated description of this species, providing additional external and internal (i.e., cranial osteology) morphological features that can be used to compare I. microlepidota with other members of the group. Finally, we identified two candidate new species from Angola and corroborated the importance of the central highlands of Angola as an important center of endemism in the western slope of Central Africa.

A new stenothoid species, Metopa propodasp. nov., is described from a seamount of the Western Pacific. The new species differs from all other congeneric species by the mature males having a large rectangular notch in the palmar corner of the gnathopod 2. One mitochondrial gene (COI) was used to analyze the validity of Metopa propodasp. nov. An identification key of the Pacific Metopa species, including this new species, is provided.

Integrative taxonomy provides a valuable approach to discover and unravel even morphologically almost indiscernible species, such as those forming “cryptic” species complexes. The six members of the recently discovered Haploniscus belyaevi species complex (short: belyaevi-complex) from the abysso-hadal Kuril-Kamchatka Trench (KKT) region in the Northwest Pacific Ocean are taxonomically described herein. The eponymous Haploniscus belyaevi is redescribed alongside new descriptions of the five closely related species Haploniscus apaticussp. nov., H. erebussp. nov., H. hadessp. nov., H. kerberossp. nov., and H. nyxsp. nov. The morphological differences between these species are most eminent in the rostral and pleotelson morphology of the adult males. Alongside light-microscopical drawings, CLSM scans, and 16S and COI barcodes, these species descriptions are complemented by the first genomic data of deep-sea haploniscid isopods. Geometric morphometrics was applied to quantify interspecific and intraspecific morphological differences of the pleotelson considering the pronounced sexual dimorphism. The distributional range of the belyaevi-complex covers a large geographical area, ranging across the greater KKT region and extending beyond large-scale geomorphological barriers such as the KKT and the Kuril Island Ridge, turning these into promising species to study differentiation processes in the deep sea.

A new species of cypriniform fish was discovered during studies of the riverine fish fauna of the Caspian Sea basin, employing an integrative taxonomy approach. The Ural gudgeon is herein described as a new species from the Ural River system, which is considered a geographical boundary between Europe and Asia. The new species is distinguished from the other gudgeon species by a combination of morphological characters and genetic data. Morphologically, it is very similar to Gobio volgensis from the Volga basin. Genetically, however, it is closer to G. acutipinnatus, which occurs in the upper Irtysh River (Ob’ River system), and to G. multipunctatus from the Lake Alakol basin in Central Asia (p-distance = 0.037; COI mtDNA). Therefore, the Ural gudgeon, which is endemic to the Ural River system, is of Asian rather than European origin. The biogeography of freshwater aquatic animals in the region is discussed in relation to paleogeographic events and connections between the Caspian Sea and Ob’ drainages.

A new genus and species of freshwater mussels, Guiunio rarus Chen, Li, Dai & Wu, gen. et sp. nov., is described from the Pearl River Basin in China based on comparative morphology and molecular phylogeny. The new taxon belongs to the tribe Gonideini and can be distinguished from other genera by a unique combination of characteristics: shell medium-sized, moderately thick, flat, long, sub-glossy, opaque; anterior small, rounded and short; posterior extremely expanded, wide and long, with an indistinct obtuse angle in the middle of posterior margin; papillae on flap margin highly degraded. The validity of it is further supported by the molecular phylogenetic analysis based on COI, 16S and 28S sequences.

To explore the taxonomic status of a tropical sea cucumber species with controversy, we conducted an investigation into its morphological characteristics (external form and ossicles) and mitochondrial genome and rearranged the historical materials of the species and its confusing species. The species was first described in the middle of the 18th century but later synonymized with Bohadschia ocellata Jaeger, 1833, Holothuria hamata Pearson, 1913, or Holothuria kurti Ludwig, 1891, by different scholars. The observed ossicles encompassed multiple types, including buttons, C-shaped ossicles, rods, and tables, with a distinct subtype identified as tack-like tables. Ventral and dorsal body walls exhibited similar table and button ossicle shapes. The mitogenome contained 13 protein-coding genes (PCGs), 2 ribosomal RNAs (rRNAs), and 22 transfer RNA (tRNA) genes, with a sequence length of 15,797 bp. Subsequent construction of a phylogenetic tree using Bayesian inference (BI) and maximum likelihood (ML) methods indicated that the species was grouped into a separate branch firstly with Holothuria (Theelothuria) spinifera Théel, 1886, so suggesting its taxonomic classification under subgenus Theelothuria Deichmann, 1958. Based on the data of this study and previous literature, we suggested that the Latin name for this species should tentatively be “Holothuria ocellata Jaeger, 1833 sensuThéel 1886.” The morphologic and genomic information in the current study could be valuable in further biological studies of this sea cucumber species.

Mussels of the genus Idas (Bathymodiolinae) are small bivalves inhabiting organic falls and cold seep ecosystems. Despite their ecological significance, the taxonomy and phylogeny of Idas remain understudied. In this study, 30 Idas specimens were collected from a piece of sunken wood in the East China Sea at depths of 460–550 m. DNA barcoding and phylogenetic analysis revealed three distinct clades: 23 specimens matched Idas sp. ESU D, previously reported from Japan and the Philippines, five samples clustered with Idas iwaotakii (Habe, 1958), and two samples formed a new clade related to I. iwaotakii. These findings resulted in the description of two new species, Idas sinensissp. nov. and Idas pacificussp. nov. We present the complete mitochondrial genomes for both species and investigate the diversity of their symbiotic microbes through full-length 16S rRNA amplicon sequencing. Phylogenetic analyses of mitochondrial genomes further support the taxonomic placement of the new species. The gill-associated microbial communities of these mussels include sulfur-oxidizing SUP05 bacteria, suggesting chemosynthetic symbiosis.

Freyastera represents the most derived form in the deep-sea starfish order Brisingida, known only at below 2500 m to over 6000 m depth, adapting to the great depth by small body size, reduced number of arms, and simplified body form. Long being remote and rarely investigated, newly collected specimens from the last decade revealed high species diversity of the genus. In this study, a new species, Freyastera jiaolongisp. nov., is described from the southern part of the Kyushu-Palau Ridge. Freyastera giardicomb. nov. and Freyastera loricatacomb. nov., formerly belonging to genus Freyella, are reassigned to Freyastera. The genus is hence revised to include ten species. Key characters of nine Freyastera species as well as Freyella benthophila (formerly Freyastera benthophila) are described and discussed based on an examination of type specimens and new specimens, and a key to Freyastera species is provided, aiding in the future identification of Freyastera. Phylogenetic analysis using four DNA barcoding genes retrieves a monophyletic Freyastera, providing solid support for interspecific phylogeny except at three nodes. Species delimitation analysis results in 11 species units within Freyastera, including seven unnamed species pending description. A high diversity of Freyastera revealed in the present study suggests a successful adaptation and radiation of the genus at great depth.

A new tribe, genus, and species of freshwater mussels, Globunionini Dai, Chen, Huang & Wu, tribe nov. and Globunio mirificus Chen, Dai, Huang & Wu, gen. et sp. nov., is described from the Changjiang River Basin in China based on comparative morphology and molecular phylogeny. The species presence of a special small-sized and elongated globular, which distinguishes it from all other tribes. The discovery increases the diversity of freshwater mussels in the Changjiang River Basin.

A survey of the mimetids of Central Guizhou Province, China, is presented. A total of five species are addressed, raising the number of species of the genus Mimetus Hentz, 1832, known from this province from four to eight, making Guizhou the province with the most Mimetus species in China. Two of the taxa are new species: M. guiyang J. S. Zhang, Yu & Xu, sp. nov. and M. lanmeiae Liu, Yu & Xu, sp. nov., both from Guiyang City, provincial capital of Guizhou. The other three known species include two new records from Guizhou, M. caudatus Wang, 1990, and M. sinicus Song & Zhu, 1993, as well as a species, M. testaceus Yaginuma, 1960, that was previously recorded from the province. The female of M. caudatus is described for the first time, based on the new material from Duyun City. Detailed descriptions, diagnoses, and photographs of the two new species and M. caudatus, as well as photographs of M. sinicus and M. testaceus, are provided. The DNA barcodes of M. lanmeiaesp. nov., M. sinicus, and M. testaceus were obtained for species delimitation, matching of sexes, and future use.

Two new species of Homatula are herein described from the Wu-Jiang of the upper Chang-Jiang Basin in Guizhou Province, China. Homatula xiangzhi and H. shexiang are respectively assigned to the scaleless group and the partially scaled group of the genus. Homatula xiangzhi differs from all other species of the scaleless group in having a complete lateral line, an adipose crest along the dorsal mid-line of the caudal peduncle anteriorly terminating behind the middle of the anal-fin base, nine branched dorsal-fin rays, vertebrae 4+42-43 and no median notch on the lower jaw. Homatula shexiang is similar to H. longidorsalis in having nine branched dorsal-fin rays rather than seven or eight in all other species of the partially scaled group, but differs from it in having an adipose crest along the dorsal mid-line of the caudal peduncle anteriorly terminating behind the middle of the anal-fin base, a deeper head and a slender caudal peduncle. The validity of the two new species is further corroborated in a molecular phylogenetic analysis, based on the Cytb gene.

The first obligatory troglobitic Claea species, Claea scet, is described from a subterranean river in a cave connected to the Yangtze River in Hulu Town, Shawan District, Leshan City, Sichuan Province, southern China. C. scet differs from all congeners by the following combination of characters: Body pale without pigmentation; eye vestigial, diameter of eye 3.8–5.9% SL; short anal fin, anal fin height 7.0–8.4% SL. Molecular phylogenetic analysis supported the validity of the new species and revealed a close relationship between Claea and hypogean Triplophysa species.

The Yellow River drainage is a biodiversity hotspot for the Gobio group, but no one has yet reviewed these species systematically. This study examined the type specimens of the species in the Gobio group and numerous newly captured specimens in the Yellow River drainage for an overall morphological comparison. A phylogenetic tree of those species based on mitochondrial cytochrome-b sequences was also constructed. Our results indicate the presence of four species, i.e., Gobio guentheri (this was described as Acanthogobio guentheri), G. rivuloides, G. coriparoides, and G. huanghensis. Morphological and molecular phylogenetic analyses indicated that G. tchangi is a junior synonym of G. huanghensis, while G. meridionalis is a junior synonym of G. rivuloides. Additionally, the phylogenetic analysis showed that the genus Acanthogobio is nested within Gobio. In order to maintain the monophyly of Gobio, this study suggests that the genus Acanthogobio should be a junior synonym of Gobio, and the type species A. guentheri should be treated as Gobio guentheri. Furthermore, the type specimens of Romanogobio johntreadwelli and R. amplexilabris were checked, and this study confirmed that these two species are junior synonyms of G. rivuloides. Therefore, the genus Romanogobio is not distributed in the Yellow River drainage. The Gobio species are primarily distributed in the upper and middle reaches of the Yellow River drainage, from Qushian Township, Qinghai Province, to Sanmenxia City, Henan Province, at an average elevation above 300 meters. A diagnostic key for four valid Gobio species in the Yellow River drainage is provided.

Inle Lake, located on the Shan Plateau of Myanmar, is the only ancient lake on the Indochinese Peninsula and a biodiversity hotspot of freshwater fauna with high diversity and endemism, including molluscs. However, recent research on its biodiversity remains limited. Based on morphological, anatomical, and molecular studies, we systematically revise the freshwater snails of the family Bithyniidae from the Inle Lake basin. We provide an updated re-description of four bithyniid species within three genera from the Inle Lake basin, including one new record, Digoniostoma iravadicacomb. nov. The endemic genus Parabithyniasyn. nov. with one endemic species of Inle Lake, Hydrobioides physcuscomb. rev., is considered a synonym of Hydrobioides. Gabbia nanacomb. nov. is assigned to Gabbia based on shell morphology and molecular phylogeny. Hydrobioides dautzenbergistat. rev. from Thailand is recognised as a valid species rather than a synonym of Hydrobioides nassa, which is endemic to Shan State of Myanmar. There are altogether seven bithyniid species recorded from the Inle Lake basin and surrounding area, including four endemic species.