Petraeomastus markamensis ( Chen and Zhang, 2001 ), 2024

Petraeomastus markamensis ( Chen and Zhang, 2001) View in CoL comb. n.

( Figures 1 View Figure 1 , 2 View Figure 2 (F–H), 4(E,F), 6)

Ena (Petraeomastus) desgodinsi : Yen 1938: 442. Misidentification

Petraeomastus desgodinsi View in CoL : Yen 1942: 254. Misidentification

Ena markamensis Chen and Zhang, 2001: 13 View in CoL

Material examined

n = 1. NHMUK 1912.6.27.22–25 , Batang, west China, identified by T. C. Yen; GoogleMaps 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; GoogleMaps 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 GoogleMaps .

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 View 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 View 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 View Figure 1 (C)). It inhabits mossy ground but hibernates at the base of shrubs ( Figure 4 View 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.