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| Ichthyophis griseivermis Poyarkov, Skorinova, Bragin, Kolchanov, Gorin, Trofimets, Yuzefovich, Le, Nguyen & Skutschas, 2025 |
Abstract
Herein we examined the cranial osteology of 15 species of Ichthyophis (I. asplenius, I. beddomei, I. glutinosus, I. kohtaoensis, I. larutensis, I. mindanaoensis, I. multicolor, I. nguyenorum, I. nigroflavus, I. sikkimensis, I. singaporensis, I. supachaii, I. tricolor, I. weberi, and Ichthyophis sp. from northern Vietnam) with a special emphasis on the temporal region. We presented the first detailed description of the cranium and the atlas of an Ichthyophis species based on micro-CT scanning data. We discuss the implications of temporal region composition for the systematics of this group and the evolution of the cranium in Gymnophiona as a whole. We further provided comments on a jaw-closing mechanism and reported on the presence of phylogenetically basal cranial features in ichthyophiids that are also found in stem caecilians. Our detailed morphological description was based on a specimen from a previously unknown population of unstriped Ichthyophis from northern Vietnam. We consequently described this population as a new species based on morphological and molecular (3967 bp from cyt b, 12S rRNA, and 16S rRNA mitochondrial DNA genes) lines of evidence. We provide comparisons of external morphological traits of the new species with its congeners and further compare its cranial osteological features with other Ichthyophis for which skull descriptions exist. The new species differs from the morphologically similar species I. yangi and I. chaloensis by a significant divergence in cyt b and 16S rRNA mitochondrial DNA gene sequences (p = 6.5%–6.9% and p = 4.5%, respectively). The new species is currently known only from evergreen forests of Xuan Lien National Park (Thanh Hoa Province) and Pu Hoat (Nghe An Province) Nature Reserve, northern Vietnam, and was recorded at elevations of 700–800 m asl. We suggest the new species be considered Data Deficient (DD), following the IUCN’s Red List categories.
Keywords: Ichthyophis griseivermis sp. nov., micro-CT scanning, molecular analyses, morphology, Nghe An, osteology, Pu Hoat, taxonomy, Thanh Hoa, Xuan Lien
Family Ichthyophiidae Taylor, 1968
Genus Ichthyophis Fitzinger, 1826
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| Details of external morphology of the holotype of Ichthyophis griseivermis sp. nov. in life (ZMMU A-8208, adult female). A Lateral view of the head, right side; B lateral view of the head, right side; C dorsal view of the head; D ventral view of the head; E lateral view of the tail, left side; F lateral view of the tail, right side; G dorsal view of the tail; H ventral view of the tail. Scale bar equals 5 mm (all photographs shown in one scale). Photographs by A. M. Bragin. |
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| The holotype of Ichthyophis griseivermis sp. nov. in life in situ (ZMMU A-8208, adult female). Photograph by A. M. Bragin. |
Ichthyophis griseivermis sp. nov.
Diagnosis. The new species Ichthyophis griseivermis sp. nov. differs from other members of the genus Ichthyophis by the following combination of the morphological characters: unstriped body lacking lateral yellow stripe; adult total length 206–242 mm (based on two available specimens); snout blunt and rounded (snout length/head length ratio 0.06–0.08); tentacle aperture located closer to eye than to naris (tentacle aperture-naris distance/tentacle aperture-eye distance ratio 2.1–2.2); premaxillary and maxillary teeth 44–48, vomero-palatine teeth 43–48, dentary teeth 38, inner mandibular teeth 25–33; tail very short, acuminate, ending in a nipple-like cap; annuli angulate, total 301–306 (dorsal count), four interupted by cloacal disc, one posterior to cloacal disc, the degree of annuli angulation decreasing from head to cloaca with grooves appearing almost orthoplicate at mid-body and posteriorly; vertebrae 111–112; scales in one series per annulus (dosolaterally), present only in the posterior half of body.
Etymology. The specific name “griseivermis” is a Latin noun in the nominative singular, given in apposition, derived from the Latin adjective “griseus” for “grey” and the Latin noun “vermis” for “worm.” The new species is named in reference to its characteristic uniform grey body coloration. The specific epithet also alludes to Grey Worm, the commander of the Unsullied, the warrior-eunuchs of Astapor with an unparalleled reputation for combat in George R. R. Martin’s fictional work “A Song of Ice and Fire” (also known as “Game of Thrones”). We suggest the following common names for the new species: “Grey Worm Caecilian” (in English), “ếch giun xám ___” (in Vietnamese), and “Seryi rybozmey” (“____,” in Russian).
Nikolay A. Poyarkov, Dana D. Skorinova, Andrey M. Bragin, Veniamin V. Kolchanov, Vladislav A. Gorin, Alexey V. Trofimets, Alexander P. Yuzefovich, Dac Xuan Le, Tan Van Nguyen and Pavel P. Skutschas. 2025. Integrative Taxonomy reveals A New unstriped Ichthyophis Fitzinger, 1826 from Vietnam and provides new data on diagnostic osteological traits for Asian tailed caecilians (Gymnophiona: Ichthyophiidae). Vertebrate Zoology. 75: 405-440. DOI: doi.org/10.3897/vz.75.e149399
