Angustopila occidentalis Pall-Gergely & Hunyadi, 2023

Pall-Gergely, Barna, Hunyadi, Andras, Vermeulen, Jaap J., Grego, Jozef, Sutcharit, Chirasak, Reischuetz, Alexander, Dumrongrojwattana, Pongrat, Botta-Dukat, Zoltan, Oerstan, Aydin, Fekete, Judit & Jochum, Adrienne, 2023, Five times over: 42 new Angustopila species highlight Southeast Asia's rich biodiversity (Gastropoda, Stylommatophora, Hypselostomatidae), ZooKeys 1147, pp. 1-177 : 1

Angustopila occidentalis Pall-Gergely & Hunyadi sp. nov.

Figs 70 , 71 , 72

Type material.

Holotype: Myanmar • 1 empty shell (H: 0.97 mm, D: 0.93 mm); Shan State, ca. 6 km east from Hsihseng centre, right side of rd. + 400 m on unpaved rd., limestone hill (locality code: 2018/40); 20°07.98'N, 97°18.15'E; 1010 m a.s.l.; 7 Oct. 2018; A. Hunyadi, K. Okubo & J.U. Otani leg.; HNHM 103483.

Paratypes: Myanmar • 18 shells; same data as for holotype; coll. HA • 17 shells; Shan State, 7.4 km from the centre of Hoponh towards Namsang along road no. 4, ca. 5 km north, Parpant Cave (locality code: 2018/36); 20°50.96'N, 97°14.26'E; 1170 m a.s.l.; 6 Oct. 2018; A. Hunyadi, K. Okubo & J.U. Otani leg.; coll. HA • 2 figured shells + 81 shells; Shan State, Pinlaung centre N 7.5 km, Tar Kge, near "Big Bang Cave" (locality codes: 2018/32 and 20181004D); 20°10.27'N, 96°47.44'E; 1540 m a.s.l.; 4 Oct. 2018; A. Hunyadi, K. Okubo & J.U. Otani leg.; coll. HA • 3 shells; Shan State, Hopong, Hopong Spring and cave (locality code: JG/2019/2); 20°49.05'N, 97°13.49'E; 2 Feb. 2019; J. Grego leg.; coll. JG • 5 shells; Kayah State, Hpruso District, Maw Thi Do Village, entrance of Phruno River Cave (locality code: JG/2019/102); 19°22.74'N, 97°02.57'E; 12 Dec. 2019; J. Grego leg.; coll. JG • 59 shells; Kayah State, Hpruso District, Hoyar village, Kyar Yin Cave (locality code: JG/2019/104a); 19°18.10'N, 96°56.40'E; 1100 m a.s.l.; 13 Dec. 2019; Mário Olšavský leg.; coll. JG.

Additional material.

Myanmar • 14 j/b shells; same data as for holotype; coll. HA • 1 juvenile shell (figured with insect in aperture) + 21 j/b shells; Shan State, 7.4 km from the centre of Hoponh towards Namsang along road no. 4, ca. 5 km north, Parpant Cave (locality code: 2018/36); 20°50.96'N, 97°14.26'E; 1170 m a.s.l.; 6 Oct. 2018; A. Hunyadi, K. Okubo & J.U. Otani leg.; coll. HA • 25 j/b shells; Shan State, Pinlaung centre N 7.5 km, Tar Kge, near "Big Bang Cave" (locality codes: 2018/32 and 20181004D); 20°10.27'N, 96°47.44'E; 1540 m a.s.l.; 4 Oct. 2018; A. Hunyadi, K. Okubo & J.U. Otani leg.; coll. HA .

Thailand • 1 figured shell; Chiang Mai Province, northeastern part of Doi Chiang Dao, Wat Tham Chiang Dao northwest 2 km (locality code: 2015/6); 19°24.02'N, 98°54.68'E; 835 m a.s.l.; 7 Feb. 2015; A. Hunyadi leg.; HNHM 100182 .

Diagnosis.

A medium-sized Angustopila species with a relatively low conical shell, a strong parietal tooth and a weak lower palatal tooth (can be absent), and a moderately wide umbilicus.

Description.

Shell of normal size for the genus, slightly higher than wide or slightly wider than high; pale grey, translucent, conical; body whorl widest in standard apertural view; protoconch consists of 1.5 whorls with dense spiral striation on the entire protoconch; teleoconch finely ornamented with irregularly spaced, weak radial growth lines crossed by fine rows of regularly-spaced spiral striae (ca. 17-20 on body whorl from standard apertural view); on both ventral and dorsal surfaces of body whorl spiral lines dominant or spiral and radial lines are of comparable strength; whorls 4-4.25, rounded; aperture oblique to shell axis from lateral view; umbilicus moderately narrow; aperture ovoid or slightly reniform, sinulus wide; peristome expanded, not reflected; parietal callus not conspicuous, somewhat detached from penultimate whorl (aperture not adnate); parietal tooth well-developed, perpendicular to parietal wall; palatal side usually with a blunt lower palatal denticle (often absent, or a second one might be present), which is situated some distance inside from peristome edge.

Measurements (in mm).

H = 0.91-1.03, D = 0.89-1.06, H/D*100 = 88.3-108.5 (Myanmar, n = 16), RUD = 22.8-26.0 (n = 6); H = 1.02, D = 0.89, H/D*100 = 113.5, RUD = 21.9 (Thailand, n = 1).

Differential diagnosis.

Angustopila concava has a concave-conical shell, a wider umbilicus, a smaller parietal tooth, a more strongly oblique aperture, its parietal callus is more detached from the penultimate whorl and lacks a palatal tooth compared to this new species. See also under A. antidomedon sp. nov., A. bathyodon sp. nov., and A. uvula sp. nov.

Etymology.

Named after its geographic distribution compared to other Angustopila species (this is one of the westernmost occurring Angustopila species).

Distribution.

This species is known from one locality in Thailand’s Chiang Mai Province, and five localities from Myanmar’s Shan and Kayah States (Fig. 19 ).

Remarks.

The single shell from Thailand has a higher spire, and a more conical shell than those from Myanmar, and possesses an additional palatal denticle next to the “usual” lower palatal tooth. Thus, additional specimens are needed to infer the intraspecific diversity of that population, and to understand if it is conspecific with A. occidentalis sp. nov. populations of Myanmar. The shells from the populations from Myanmar show no notable conchological variation.

Figures

Figure 19. Distribution of Angustopila species.

Figure 70. Angustopila occidentalis Pall-Gergely & Hunyadi, sp. nov. (holotype, HNHM 103483). Apertural (A), ventral (B), lateral (C) and apical (D) sides of the shell; sculpture on the protoconch (E), ventral (F) and frontal (G) surface of the body whorl.

Figure 71. Variability of Angustopila occidentalis Pall-Gergely & Hunyadi, sp. nov. A-D 2018 / 40, (A holotype B-D paratypes) E-G 2018 / 32 (E and G specimen 1 F specimen 2).

Figure 72. Angustopila cf. occidentalis Pall-Gergely & Hunyadi, sp. nov., Chiang Dao. Apertural (A), ventral (B), apical (C) and lateral (D) sides of the shell; sculpture on the protoconch (E); aperture (F); ventral (G) and frontal (H) surface of the body whorl.