Petraeomastus markamensis Chen & Zhou & Dai & Wu & Ouyang 2024, comb. n.
Creators: name: Chen, Zhong-Guang
name: Zhou, Yi
name: Dai, Yu-Ting
name: Wu, Xiao-Ping
name: Ouyang, Shan
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Stylommatophora
Enidae
Petraeomastus
Petraeomastus markamensis

description: Petraeomastus markamensis (Chen and Zhang, 2001) comb. n.
(Figures 1, 2 (F–H), 4(E,F), 6)
Ena (Petraeomastus) desgodinsi: Yen 1938: 442. Misidentification
Petraeomastus desgodinsi: Yen 1942: 254. Misidentification
Ena markamensis Chen and Zhang, 2001: 13
Material examined
n = 1. NHMUK 1912.6.27.22–25, Batang, west China, identified by T. C. Yen; n = 10, 24_NCU_XPWU_AN036–75, 1 km west of Jinshajiang River Bridge [金沙江大桥以西 1 km], Mangkang County [芒康县], Changdu City [昌都市], Xizang Autonomous Region [西藏自 治区], China, 99.000°E, 29.761°N, collected by Zhong-Guang Chen, Meng-Hua Li and Jin-Sheng Mou, 16 August 2023; n = 45, 24_NCU_XPWU_AN76–120, Langdaquka [朗达曲卡], Batang County [巴塘县], Ganzi Tibetan Autonomous Prefecture [甘孜藏族自治州], Sichuan Province [四川省], China, 99.041°E, 29.871°N, collected by Zhong-Guang Chen, Meng-Hua Li and Jin-Sheng Mou, 17 August 2023.
Diagnosis
Shell sinistral, width <12 mm, multicoloured, with multiple indistinct small and white spots on teleoconch, apex region reddish brown, gradually transitioning to pinkish white downwards; umbilicus slit-shaped. Penial caecum present, subglobular. Bursa copulatrix ovoid, with stalk, well defined. Habitat is mossy ground.
Description
Shell. (Figure 2 (F–H)) n = 55. Shell cylindrical-conic with apex abruptly pointed; shell most swollen (broadest) at body whorl, sinistral, large, medium width (width <12 mm), thick, solid, opaque, sub-glossy, speckled, not spirally grooved; 7.75–9.0 whorls. Whorls rather flattened, not shouldered. Protoconch smooth, polished. Post-nuclear teleoconch smooth. Growth lines distinct. Suture shallow, without narrow band beneath it. Body whorl gradually ascending towards aperture, rounded at periphery. Aperture in a plane, truncate-ovate, oblique, without tooth, without angular tubercle, completely adnate to body whorl. Peristome connected, with a shallow channel at upper insertion; white, thickened, expanded, slightly reflexed. Parietal callus distinct. Columellar margin reflexed. Umbilicus slit-shaped. Shell multicoloured, with multiple indistinct small and white spots on teleoconch, apex region reddish brown, gradually transitioning to pinkish white downwards.
Genitalia. (Figure 6) n = 5. Vas deferens long, slightly tapering distally; entering epiphallus apically with distinct demarcation. Epiphallus long; cylindrical; straight; externally smooth. Epiphallic caecum present; blunt apically; located near vas deferens entrance. Flagellum long; tubular; proximally normal; with tip pointed. Penis with terminal entrance of epiphallus; clavate; distally enlarged. Penial caecum present, subglobular. Penial appendix long; branched off from penis at some distance from atrium; divided into sections including A-1 + A-2, A-3 and A-4 + A-5. A-1 and A-2 fused. A-2 and A-3 not fused. Boundary between A-4 and A-5 indistinct. A-5 long; convoluted. Appendicular retractor and penial retractor long; biramous; attaching to penis proximally and to A-2 of penial appendix; with penial retractor arms arising from diaphragm close to each other. Additional retractor other than penial or appendicular absent. Muscular band connecting vagina and epiphallus absent. Atrium short; without retractor. Free oviduct longer than vagina. Vagina short; not swollen; straight; unpigmented. Bursa copulatrix duct long; proximally straight. Bursa copulatrix ovoid, with stalk; without apical ligament; normal in size; with long neck; well defined. Diverticle normally present; longer than bursa copulatrix; unexpanded. Bursa copulatrix and diverticle distinguishable; forked more distally from their base.
Measurements
n = 55. Shell height 25.5–33.0 mm, width 9.5–10.8 mm; aperture height 9.3–10.5 mm, width 7.3–8.0 mm.
Distribution and ecology
Petraeomastus markamensis is distributed in Mangkang County and Batang County on both banks of the Jinshajiang River (Figure 1 (C)). It inhabits mossy ground but hibernates at the base of shrubs (Figure 4 (E,F)). Juveniles are covered in mud.
Remarks
For comparison to other Petraeomastus, see remarks of P. desgodinsi. Chen and Zhang (2001) described Ena markamensis from Mangkang, Xizang. However, the genus Ena Turton, 1831 is restricted to Europe and should not be distributed in China (Schileyko 1998; Wu 2018). Based on morphology (eg the shell is cylindrical-conic), E. markamensis is reclassified here as Petraeomastus markamensis comb. n. This species is widely distributed on both banks of the Jinshajiang River; the specimens from the left bank are usually a bit larger and thicker than those from the right bank.
description: Published as part of Chen, Zhong-Guang, Zhou, Yi, Dai, Yu-Ting, Wu, Xiao-Ping & Ouyang, Shan, 2024, A review of three taxonomically confused species of Petraeomastus Möllendorff, 1901 (Gastropoda: Stylommatophora: Enidae) from the Jinshajiang River Valley, with the description of a new species, pp. 11-28 in Journal of Natural History 59 (1 - 4) on pages 20-23, DOI: 10.1080/00222933.2024.2435550, http://zenodo.org/record/14764931