Cathaica

A new species of Trichelix Ancey, 1887 from northeast Guangxi, China (Gastropoda, Stylommatophora, Camaenidae)

广西壮族自治区东北部绒粒螺属一新种记述

（腹足纲：柄眼目：坚螺科）

1 State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Agriculture, South China Agricultural University, Guangzhou 510642, China

[华南农业大学农学院 亚热带农业生物资源保护与利用国家重点实验室 广州 510642 广东省 中国]

https://orcid.org/0009-0009-3422-1438; Email: linranxi2001@163.com

224 Fengdanbailu, 185 Xiufeng Road, Jin’an District, Fuzhou 350012, China;

[枫丹白鹭 秀峰路185号 晋安区 福州 350012 福建省 中国]

 https://orcid.org/0000-0001-9467-6893

Published on 15 April 2025        DOI: https://doi.org/10.5281/zenodo.15206364

ZooBank Code: http://zoobank.org/urn:lsid:zoobank.org:pub:6C68BD2C-9D5C-4602-B23D-13E23BA8A0E3

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Abstract: A new species of camaenid land snail, Trichelix yao n. sp., is described from Guangxi, China, based on its morphological characteristics. Trichelix yao n. sp. differs from all known congeners by its distinctly depressed, non-biconcave shell with prominent furrows, a palatal fold that does not extend to the aperture, a basal fold that reaches the aperture and forms a tooth. This discovery extends the known distribution of Trichelix in southern China and helps bridge the distribution gap of this genus in Guangxi.

摘  要：本文基于形态学特征，记述了产自广西大瑶山国家级自然保护区的陆生贝类一新种：瑶绒粒螺Trichelix yao n. sp.。该新种可通过以下特征与已知同属种相区分：壳形明显扁平且非双凹型；具两个腭褶，对应的深沟在壳表清晰可见：上腭褶不延伸至壳口，基褶则延伸至壳口并形成齿突。这一新物种的发现拓展了绒粒螺属Trichelix Ancey, 1887在中国南方的分布范围。

Key words. Taxonomy, land snails, Guangxi, new species, new provincial record

关键词：新种，形态学，分类学，陆生贝类，省级新纪录 

Introduction

The genus Trichelix Ancey, 1887 is a group of small to medium-sized land snails, characterized by a slightly flattened to concave shell with a hairy periostracum, which will fall off when the shells reach full maturity for some species, the elevated parietal callus, and the descending anteriorly last whorl with external furrows (Ancey, 1887; Sutcharit et al., 2020; Lin & Lin, 2022).

Trichelix currently includes seven species distributed across East Asia and continental Southeast Asia (Sutcharit et al., 2020; Lin & Lin, 2022). Trichelix horrida (Pfeiffer, 1863) occurs in northern Laos and Vietnam (Sutcharit et al., 2020). Trichelix eucharista (Pilsbry, 1901), Trichelix diminuta (Pilsbry & Hirase, 1905) and Trichelix tokunoensis (Pilsbry & Hirase, 1905) are restricted to the Amami Islands in the central Ryukyu Islands, Japan (Sutcharit et al., 2020). The remaining three species are found in southern China: Trichelix biscalpta (Heude, 1885) from Chongqing, Trichelix hiraseana (Pilsbry, 1905) from Taiwan, and Trichelix xiaoxiang Lin & Lin, 2022 from Hunan (Sutcharit et al., 2020; Lin & Lin, 2022).

In this study, Trichelix yao n. sp. is described and illustrated as a species new to science from Guangxi Zhuang Autonomous Region, China. This discovery fills a gap in the distribution records of Trichelix in Guangxi and suggests that additional, yet-undiscovered species of this genus may occur in this region. 

Materials and methods

Living specimens were first submerged in pure water for 6 h, then immersed in boiling water for 1 min. The separated animal tissues were fixed in 70% ethanol, while the corresponding empty shells were cleaned and air-dried. Shells were photographed using a Nikon D80 camera with a Laowa 60 mm F2.8 Macro 2:1 lens. The number of shell whorls was counted according to Kerney & Cameron (1979). Specimens were deposited in the Mollusk Collection, Museum of Hebei University (HBUMM, Baoding, China).

Systematics

Family Camaenidae Pilsbry, 1895

Genus Trichelix Ancey, 1887

Trichelix Ancey, 1887: 64; Schileyko, 2003: 1513; Sutcharit et al., 2020: 68.

Helix (Stegodera) [Trihelix] Pilsbry, 1890: 6 (as a group of subgenus, incorrect subsequent spelling); Pilsbry, 1895: 289.

Moellendorffia (Trihelix) – Pilsbry, 1905: 65. (incorrect subsequent spelling)

Moellendorffia (Trichelix) – Zilch, 1960: 612.

Type species. Helix horrida Pfeiffer, 1863, by monotypy.

Trichelix yao R.-X. Lin & L.-W. Lin, n. sp.

瑶绒粒螺

(Figures 1, 2)

Type materials. Holotype: HBUMM 10076, mature shell, Lianhuashan scenic area [莲花山景区], Dayaoshan National Nature Reserve [大瑶山国家级自然保护区], Jinxiu Yao Autonomous County [金秀瑶族自治县], Laibin City [来宾市], Guangxi Zhuang Autonomous Region [广西壮族自治区], China, 110°7’15”E, 24°9’16”N, 18 July 2024, leg. Wen-Yong Feng; Paratypes: HBUMM 10077, two subadult shells, other information same as holotype.

Etymology. The species is named after the Yao people, a minority ethnic group in China and continental Southeast Asia. Type locality of the new species, Dayao Mountain, is one of their traditional settlement areas.

Diagnosis. Shell medium-sized, depressed. Shell surface with long hairs but usually worn away upon maturity. Two palatal folds present, with corresponding deep furrows present distinctly on the shell surface. Upper palatal fold prominent, extending from ¼ of the body whorl from aperture to a distance behind the aperture. Basal palatal fold extends from umbilical suture at ¼ of the body whorl before aperture to just behind the aperture, weaker than former. Aperture oval, strongly downward sloping.

Description. Shell (Fig. 1) dextral, medium-sized, depressed with rounded periphery, consisting of 4.5 reddish brown and rather thick whorls separated by shallow suture. Protoconch composed of 1.5 smooth to somewhat glossy whorls. Shell surface with long and sparse periostracal hairs, distinct in subadults but usually worn away upon maturity, leaving only blurred periostracal folds. Teleoconch surface with small tubercles arranged in oblique rows along the lines of growth, distinct on the dorsal side and around umbilical region. Two palatal folds present, highest parts oppositely positioned, with corresponding deep furrows present distinctly on the shell surface. Upper palatal fold prominent, situated along the periphery, extending from ¼ of the body whorl from aperture to a distance behind the aperture, internally highest at its midpoint. Basal palatal fold extends from umbilical suture at ¼ of the body whorl before aperture to just behind the aperture, weaker than former. Body whorl strongly descending about ⅛ of a whorl behind the aperture. Aperture oval, strongly downward sloping, forming an angle with shell axis. Peristome expanded and very slightly reflexed, with a yellowish white margin. Parietal callus thicken but not expand. Umbilicus open and wide, approximately ⅕ of shell diameter, with protoconch visible inside.

Genitalia (Fig. 2A). Atrium short. Penis medium in length, consistent swelled, with longitudinal, thin, smooth pilasters internally. Epiphallus medium in length, distinctly inflated, longer than penis. Penis retractor muscle long, thick at the ends. Flagellum short and slightly thick, tapering distally. Vas deferens long and moderately thin. Vagina short and slightly thick. Spermoviduct cylindrical, shorter and thinner than vagina. Bursa copulatrix oval and thin, with a long and tapering pedunculus. Bursa copulatrix duct long, the middle part thinner than the ends.

Measurements. Adult: Shell height = 9.8 mm, shell width = 23.7 mm (holotype), subadult shells: shell height = 11.3–16.9 mm, shell width = 6.1–8.1mm (paratypes).

Remarks. The new species can be distinguished from Trichelix species that lack lamellar teeth, which are primarily distributed in Vietnam and Laos, by the presence of such teeth. Among Trichelix species with lamellar teeth, the new species differs from those without a biconcave shell shape mainly by having more shell whorls and deeper palatal folds, with the exception of Trichelix biscalpta (Heude, 1885) and Trichelix hiraseana (Pilsbry, 1905). Trichelix biscalpta is characterized by a long and strong upper palatal lamella that extends to the aperture, resulting in a curved aperture, which distinguishes it from the new species. While the new species shares some similarities with Trichelix hiraseana, it has a more rounded aperture and a basal lamella that is notably longer and deeper than that of the latter.

Distribution and ecology. This species is known from the type locality only, where it is typically active in leaf litter or humus. 

Acknowledgements

We thank Yu-Tong Ding [丁雨桐] (Durham University) for sharing specimens of this species. Zhe-Yu Chen [陈哲宇] (The University of Melbourne) is greatly appreciated for his invaluable assistance with the genitalia images. Thanks go to Zhong-Guang Chen [陈重光] (Nanchang University) and an anonymous reviewer for their helpful comments on the manuscript. Special thanks are also due to the Biodiversity Heritage Library (www.biodiversitylibrary.org) for granting access to a wealth of rare literature.

References

Ancey, C. F. (1887) Description of new genera or subgenera of Helicidæ. The Conchologists’ Exchange. 1(9–10): 53–54; 1(11): 64; 1(12): 75–76; 2(2):22–23; 2(3): 38–39.

Heude, P.-M. (1882–1890) Notes sur les mollusques terrestres de la vallée du Fleuve Bleu. Mémoires concernant l’histoire naturelle de l’Empire chinois, 1882: 1–84; 1885: 89–132; 1890: 125–188.

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.

Lin, R.-X. & Lin, L.-W. (2022) Two new Moellendorffia species and one new Trichelix species (Gastropoda, Eupulmonata, Camaenidae) from southern China. Journal of Conchology, 44(4): 335–341.

Pfeiffer, L. (1863) Descriptions of thirty-six new land shells, from the collection of H. Cuming, Esq. Proceedings of the zoological Society of London, 30 (17–18) [“1862”]: 268–278, pl. 36.

Pilsbry, H. A. (1890–1891) Manual of conchology, structural and systematic, with illustrations of the species. Ser. 2, Pulmonata. Vol. 6: Helicidae, Vol. 4. Conchological Section, Academy of Natural Sciences, Philadelphia, pp. 1–324, pls 1–69. [pp. 1–64, pls 1–15, 27 May 1890; pp. 65–128, pls 16–30, 12 Aug 1890; pp. 129–192, pls 31–47, 16 Dec 1890; pp. 193–324, pls 48–69, 19 May 1891].

Pilsbry, H. A. (1893–1895) Manual of conchology, structural and systematic, with illustrations of the species. Ser. 2, Pulmonata. Vol. 9: Helicidae, Vol. 7, Guide to the study of Helices. Conchological Section, Academy of Natural Sciences, Philadelphia, pp. i–xlviii, 1–366, pls 1–71. [pp. 1–48, pls 1–14, 16 Nov 1893; pp. 49–112, pls 15–28, 19 Mar 1894; pp. 113–160, pls 29–40, 27 Jul 1894; pp. 161–366, pls 41–71, i–xlviii, 2 Feb 1895; index 1–126, April 1895].

Pilsbry, H. A. (1901) New land Mollusca from Japan and the Loo Choo Islands. Proceedings of the Academy of Natural Sciences of Philadelphia, 53: 344–353.

Pilsbry, H. A. (1905) Notes on Moellendorffia and Stegodera. The Nautilus, 19(6): 63–67.

Pilsbry, H. A. & Hirase, Y. (1905). New land mollusks of the Japanese Empire. Proceedings of the Academy of Natural Sciences of Philadelphia, 57: 705–719.

Schileyko, A. A. (2003) Treatise on recent terrestrial pulmonate mollusks. Part 11: Trigonochlamydidae, Papillodesmidae, Vitrinidae, Limacidae, Bielziidae, Agriolimacidae, Boettgerillidae, Camaenidae. Ruthenica, Supplement 2: 1467–1626.

Sutcharit, J., Inkhavilay, K. & Panha, S. (2020) Taxonomic note on Trichelix horrida (Pfeiffer, 1863) from Laos, with a type catalogue of Moellendorffia, Trichelix, and Moellendorffiella (Heterobranchia, Camaenidae). ZooKeys, 952: 65–93.

Zilch, A. (1959–1960) Gastropoda, Euthyneura. In: Schindewolf, O. H. (ed.) Handbuch der Paläozoologie, Band 6, Gastropoda. Gebrüder Borntraeger, Berlin, 835 pp. [Iss. 1: 1–200, Iss. 2: 201–400, 1959; Iss. 3: 401–600, Iss. 4: 601–835, 1960]