Cathaica

A remarkable new species of Aegistohadra Wu, 2004 from Guizhou, southwest China (Gastropoda: Stylommatophora: Camaenidae)

贵州省脐厚螺属一新种（腹足纲：柄眼目：坚螺科）

1 Parasitology and Vectors Lab, Department of Veterinary Biosciences, Faculty of Science, The University of Melbourne, Parkville VIC 3010, Australia.

[墨尔本大学理学院兽医科学系寄生虫及媒介实验室 帕克维尔 VIC 3010 澳大利亚]

2 Department of Life Sciences, Natural History Museum, London SW7 5BD, UK.

[伦敦自然历史博物馆自然科学部 伦敦 SW7 5BD 英国]

 https://orcid.org/0000-0002-4150-8906; Email: chenzheyu1998@163.com

Published on 23 November 2024        DOI: https://doi.org/10.5281/zenodo.14196707

ZooBank Code: http://zoobank.org/urn:lsid:zoobank.org:pub:D379F5BC-621F-46CD-89F5-1D46AD4AD5FF

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Abstract: Aegistohadra jiangrixini Z.-Y. Chen, sp. nov. is described and illustrated from Maolan National Nature Reserve, Guizhou Province, China. The new species can be distinguished from other members of the genus by its smaller size, depressed conical shell, and the pattern of bands. This new species represents the first report of Aegistohadra Wu, 2004 in Guizhou Province.

摘  要：本文报道了产自贵州茂兰国家级自然保护区的脐厚螺属 Aegistohadra Wu, 2004 一新种：姜氏脐厚螺 Aegistohadra jiangrixini Z.-Y. Chen, sp. nov.。该新种系脐厚螺属在贵州的首次报道。与同属其他物种相比，姜氏脐厚螺具有较小的壳体、扁锥形的贝壳及其特有的色带形态等显著的区分特征。

Key words. New species, morphology, taxonomy, land snail, new provincial record

关键词：新种，形态学，分类学，陆生贝类，省级新纪录

Introduction

Aegistohadra Wu, 2004 is a small genus of the family Camaenidae with 12 known species from Southwest China, North Vietnam and Laos (Wu, 2004, 2023; Jirapatrasilp et al., 2022; Lee, 2022). Aegistohadra Wu, 2004, was originally established as a monotypic genus based on the type species Aegistohadra delavayana (Heude, 1885) with its anatomical features (Wu, 2004). However, only recently has the high shell variability of Aegistohadra been revealed through anatomical and molecular phylogenetic studies, leading to the reassignment of some species, previously classified under Amphidromus Albers, 1850 and Camaena Albers, 1850, into this genus (Jirapatrasilp et al., 2022; Wu, 2023). The shell general shape of Aegistohadra species ranges from elongate conical to heliciform. In this paper, I describe a new species of Aegistohadra from Guizhou Province, China. 

Materials and methods

Images of living animal and shell habitus were taken using a Canon® 5D Mark IV digital camera with Canon® EF 100mm f/2.8L IS USM macro lens. Images of the microstructures were taken using a Canon® 5D Mark IV digital camera with a Canon® MP-E 65 mm f/2.8 1–5X macro lens. A Godox® MF12 flash was used as the light source. Zerene Stacker® (version 1.04) was used for image stacking. All images were modified and assembled into plates using Adobe Photoshop® 2021. Whorls were counted as described by Kerney and Cameron (1979). Specimens are deposited in the Mollusks collection of Museum of Hebei University (HBUMM, Baoding, China) and Mianyang Normal University (MYNU, Mianyang, China).

Systematics

Family Camaenidae Pilsbry, 1895

Genus Aegistohadra Wu, 2004

Aegistohadra Wu, 2004: 112.

Aegistohadra – Jirapatrasilp et al., 2022: 264; Wu, 2023: 60.

Type species. Nanina delavayana Heude, 1885, by original designation.

Aegistohadra jiangrixini Z.-Y. Chen, sp. nov.

姜氏脐厚螺

(Figure 1, 2, 3B)

Type materials. Holotype. HBUMM, Shishang Forest Scenic spot [石上森林], Maolan National Nature Reserve [茂兰国家级自然保护区], Libo County [荔波县], Qiannan Buyi and Miao Autonomous Prefecture [黔南布依族苗族自治州], Guizhou Province, China. 2024.X.15, leg. Ri-Xin Jiang. Paratypes. HBUMM (3 shells), MYNU (2 shells), Botanical Garden, Shishang Forest Scenic spot [石上森林], Maolan National Nature Reserve [茂兰国家级自然保护区], Libo County [荔波县], Qiannan Buyi and Miao Autonomous Prefecture [黔南布依族苗族自治州], Guizhou Province, China. 2019.VI.16. 780m. leg. Lu Qiu.

Etymology. This species is named after entomologist Ri-Xin Jiang, the collector of the holotype.

Diagnosis. A small Aegistohadra with a depressed sinistral shell and rounded periphery, a broad band along the periphery, a dark and narrow band on each side of the peripheral band, and an uppermost band attached to the suture.

Description. Shell (Fig. 1) medium, small size for the genus, sinistral, thin but solid, depressed conical, with 4.75 slightly convex whorls separated by impressed suture. Protoconch (Fig. 2A) consisting of 1.5 whorls, very fine radial structure present near the suture. Shell surface with thin spiral furrows starting from protoconch (16–20 per 1 mm on body whorl) and irregular prominent growth lines (Fig. 2B–C). Body whorl peripherally rounded. Shell pale yellow with chestnut bands appearing and deepening about one whorl after the protoconch: one broad band on the periphery, partially covered by lower whorls on upper whorls; one darker, narrower band on each side of the periphery band, with the lower band fully covered by lower whorls, visible only at the body whorl; the most upper one much narrower and attached suture. Aperture oblique, ovate, suddenly descending in front, angulo-palatal margin of the aperture reaches to the lower band. Peristome slightly expanded and reflexed. Columella oblique. Umbilicus small, approximately 1/9 of shell major diameter, slightly covered by reflexed columella.

Measurements. Shell height: 13.0 mm, shell width: 25.5 mm (holotype).

Differential diagnosis. The conchological traits of the new species align with the revised diagnosis of Aegistohadra proposed by Jirapatrasilp et al. (2022). While Aegistohadra exhibits significant variability in shell morphology, there is a general trend among known species where the shell shape transitions from depressed to conical and elongate-conical as shell size decreases. Aegistohadra jiangrixini sp. nov., however, represents a smaller member of the genus with a distinctly depressed shell. This unique morphology sets it apart from other depressed species by size and from conical species of comparable size by shape. The banding pattern of Aegistohadra jiangrixini sp. nov. somewhat resembles that of Aegistohadra jiahei (Yang et al., 2012), Aegistohadra mirifica (Bavay & Dautzenberg, 1909) and Aegistohadra baii Wu, 2023. It features a relatively broad peripheral band that is partially obscured by the suture but becomes visible near the aperture due to its descending aperture.

Remarks. The new species was found in crevices of tree trunks and bark. A photograph of a living juvenile individual shows pigmentation in the head region, but no prominent head wart has developed, which may be associated with the individual not yet reaching sexual maturity.

Distribution. South China: Guizhou. This species is known from the type locality only. This is the first record of Aegistohadra found in Guizhou Province.

 Acknowledgements

Thanks go to Ri-Xin Jiang (Guizhou University) and Lu Qiu (Mianyang Normal University) for sharing the specimens of this species, to Zhong-Guang Chen (Nanchang University) and an anonymous reviewer for their helpful comments on the manuscript. This study was funded by research grants from the Malacological Society of London and the Melbourne Research Scholarship.

References

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Kerney, M. P. & Cameron, R. A. D. (1979) A field guide to the land snails of Britain and north-west Europe. Collins, London, 288 pp.

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