Angustopila fabella Pall-Gergely & Hunyadi, 2015

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 fabella Pall-Gergely & Hunyadi, 2015

Figs 29A, B , 40 , 41

Angustopila fabella Páll-Gergely et al., 2015a: 36, fig. 2.

Angustopila singuladentis Inkhavilay & Panha in Inkhavilay et al. 2016: 224, fig. 5. new synonym.

Angustopila singuladentis - Inkhavilay et al. 2019: 59, fig. 26A.

Type locality.

"China, Guangxi (广西), Chongzuo Shi (崇左市), Longzhou Xian (龙州县), cliffs north of Lenglei (楞垒), north of the Nonggang Nature Reserve (弄岗国家级自然保护区), 220 m, 22°29.161'N, 106°57.357'E " ( A. fabella ); "Xang Lod Cave, Viengxay District, Houaphane Province, Laos (20°24'31.3"N, 104°13'19.7"E), 882 m a.s.l." ( A. singuladentis ).

Type material examined.

Holotype of A. singuladentis , CUMZ 7063 (reimaged for this study Fig. 41 ); paratypes, CUMZ 7064.

Additional material examined.

Wide umbilicus Vietnam • 9 adult + 2 j/b shells; Sơn La Province, Yên Châu District, Xã Chi ềng On, B ản Tr ạm Hốc, Hang Nh ả Nhung , around the cave (locality code: 2020/20); 20°59.48'N, 104°11.27'E; 970 m a.s.l.; 9 Feb. 2020; A. Hunyadi leg.; coll. HA • 1 shell; Sơn La Province, 27 km ESE from centre of Phù Yên, Mư ờng Do, Bàn Han Mȏt, 300 m south of the village (locality code: 2020/7); 21°11.73'N, 104°47.13'E; 810 m a.s.l.; 6 Feb. 2020; A. Hunyadi leg.; coll. HA • 7 adult + 3 j/b shells; Sơn La Province, 10 km from centre of Mộc Châu towards Sơn La, right side of road no. 6, south of Tất Ngo ằng (locality code: 2020/5); 20°52.58'N, 104°35.34'E; 715 m a.s.l.; 5 Feb. 2020; A. Hunyadi leg.; coll. HA • 5 shells; Sơn La Province, Mộc Chau District , Vân H ồ, northwestern edge of Pa C ốp towards Bó Nhàng (locality code: 2020/24); 20°46.00'N, 104°45.20'E; 980 m a.s.l.; 10 Feb. 2020; A. Hunyadi leg.; coll. HA • 3 adult shells; Hòa Bình Province, Tân L ạc District , 1300 m west from Quy H ậu on road no. 6, rock wall (locality code: 2020/28); 20°37.93'N, 105°16.17'E; 150 m a.s.l.; 11 Feb. 2020; A. Hunyadi leg.; coll. HA .

Specimens with wide umbilicus and narrow umbilicus with transitional forms Vietnam • 318 shells; Sơn La Province, Qu ỳnh Nhai district, 20 km north from cross to Thu ận Châu, Chi ềng Khoang , cave above the village (locality code: 2020/9); 21°33.44'N, 103°40.91'E; 315 m a.s.l.; 7 Feb. 2020; A. Hunyadi leg.; coll. HA .

" Regular form " Vietnam • 64 adult + 20 j/b shells; Thanh Hóa Province, Quan Hóa District, Khu di tích Hang Ma , gorge of Sȏng Lu ồng (locality code: 2020/30); 20°23.89'N, 105°04.02'E; 100 m a.s.l.; 12 Feb. 2020; A. Hunyadi leg.; coll. HA • 2 shells; Lạng Sơn Province, vicinity of Chùa Tam Thanh (locality code: 2020/58); 21°51.35'N, 106°44.81'E; 265 m a.s.l.; 21 Feb. 2020; A. Hunyadi leg.; coll. HA • 6 shells; Lạng Sơn Province, H ữu Lũng District, H ữu Liên, cross of roads no. 1B-241, 33.5 km towards Ba Nàng, left side of road (locality code: 2020/52); 21°41.06'N, 106°22.87'E; 220 m a.s.l.; 19 Feb. 2020; A. Hunyadi leg.; coll. HA • 2 shells; Lạng Sơn Province, H ữu Lũng District, H ữu Liên, 1400 m west from Đȏng Lâm along road no. 241 (locality code: 2020/53); 21°41.91'N, 106°21.77'E; 210 m a.s.l.; 19 Feb. 2020; A. Hunyadi leg.; coll. HA • 18 shells; Ninh Binh Province, Cuc Phuong National Park , Prehistorical Man Cave , steep limestone slope with disturbed forest; approx. GPS data: 20°21'N, 105°54'E; 10 Oct. 1998; J.J. Vermeulen & L. Deharveng leg.; JJV 6223 • 134 shells; Thanh Hóa Province, Lang Chanh District , Đ ồng Lương, 9.4 km northeast from centre of Lang Chánh towards Làng Thung (locality code: 2020/32); 20°11.52'N, 105°15.59'E; 300 m a.s.l.; 12 Feb. 2020; A. Hunyadi leg.; coll. HA • 1 adult + 2 broken shells; Thanh Hóa Province, 9.8 km from centre of Ng ọc Lặc towards Lang Chánh, Ng ọc Khê, left side of road (locality code: 2020/34); 20°07.19'N, 105°18.28'E; 115 m a.s.l.; 13 Feb. 2020; A. Hunyadi leg.; coll. HA • 3 shells; Thanh Hóa Province, Như Thanh District , H ải Vân, Hang Lò Cao Kháng Chi ến, vicinity of the cave (locality code: 2020/41); 19°37.08'N, 105°34.63'E; 20 m a.s.l.; 14 Feb. 2020; A. Hunyadi leg.; coll. HA • 1 shell; Sơn La Province, Mộc Châu, Hang Dơi, around the entrance of the cave (locality code: 2020/26); 20°50.96'N, 104°38.34'E; 865 m a.s.l.; 11 Feb. 2020; A. Hunyadi leg.; coll. HA .

Laos • 1 shell; Luang Namtha Province, 19.8 km southeast from centre of Vieng Phou Kha, south from Ban Phou Lek , southern edge of quarry (locality code: 2019/122); 20°32.54'N, 101°07.96'E; 780 m a.s.l.; 8 Oct. 2019; A. Hunyadi leg.; coll. HA • 1 shell; Luang Namtha Province, 48 km southwest from centre of Luang Namtha towards Vieng Phou Kha , Nam Eng , Tham Kao Rao (locality code: 2019/120); 20°43.45'N, 101°09.26'E; 745 m a.s.l.; 7 Oct. 2019; A. Hunyadi leg.; coll. HA • 79 small shells + 7 larger shells + 7 j/b shells (see Suppl. material 3: figs S9-S12); Udomxai Province, 6.5 km southeast from centre of Na Mor towards Udomxai, Ban Nathong , Tham Nathong , below cave spring (locality code: 2019/118); 20°52.37'N, 101°46.98'E; 635 m a.s.l.; 7 Oct. 2019; A. Hunyadi leg.; coll. HA • 21 shells; Udomxai Province, 10 km south of centre of Na Mor , 3.8 km east-southeast of Na Xay , rock wall facing north (locality code: 2019/119); 20°53.37'N, 101°48.96'E; 660 m a.s.l.; 7 Oct. 2019; A. Hunyadi leg.; coll. HA • 1 shell (figured); Luang Prabang province, just NE of Phou Khoun, under rocks in old secondary forest above large cave (locality code: 32L06); 19°26.78'N, 102°26.29'E; 1180 m a.s.l.; 15 Nov. 2006; A. Abdou & I.V. Muratov leg.; MNHN-IM-2014-6413 • 55 concave-conical + 76 low concave-conical + 33 conical + 73 j/b shells; Luang Prabang Province, 2.8 km northeast from Phou Khoun , rock wall above the cave (locality code: 2019/128); 19°26.79'N, 102°26.34'E; 1200 m a.s.l.; 11 Oct. 2019; A. Hunyadi leg.; coll. HA • 6 shells; Vientiane Province, 8.5 km north from centre of Kasi , northwest of the quarry (locality code: 2019/129); 19°16.82'N, 102°13.89'E; 540 m a.s.l.; 12 Oct. 2019; A. Hunyadi leg.; coll. HA • 1 figured shell; Vientiane Province, Tham Pou Kham (cave), W Vang Vieng , at the base of rocks (locality code: La.11); 18°55.60'N, 102°23.71'E; 280 m a.s.l.; Mar. 2010; A. Reischütz leg.; NHMW-MO-112015 • 2 shells; same data as for preceding; NMBE 550645 • 2 shells; same data as for preceding; coll. PGB • 17 shells; same data as for preceding; coll. RE • 57 + 11 j/b shells; Vientiane Province, 7.5 km west from centre of Vang Vieng , Ban Naka , Tham Poukham (locality code: 2019/131); 18°55.61'N, 102°23.77'E; 240 m a.s.l.; 14 Oct. 2019; A. Hunyadi leg.; coll. HA • 1 shell; Bolikhamsay Province , cave entrance above karst spring 500 m N of road from Vieng Thong to Ban Samsok (and Sôp Sang), 16 km from Vieng Thong , 500 m N of the road around large cave entrance above karst spring with travertine cascades (locality code: JG20A); 18°33.06'N, 104°34.19'E; 19 Feb. 2017; J. Grego leg.; coll. JG • 2 shells; Bolikhamsay Province , 1 km SE of Vieng Thong towards Houaykhay on road 1D, caves among boulders at SW bases of rocky cliffs (locality code: JG22); 18°30.28'N, 104°27.47'E; 290 m a.s.l.; 20 Feb. 2017; J. Grego leg.; coll. JG • 11 adult + 2 j/b shells; Bolikhamsay Province, large spring lake at S base of limestone massif 2 km NNE of Na Pavan village, ca. 5 km from Phontan crossing at road 8 (locality code: JG16); 18°13.30'N, 104°44.81'E; 18 Feb. 2017; J. Grego leg.; coll. JG • 1 shell; same data as for preceding; NMBE 550644 • 1 shell; Bolikhamsay Province, NE base of Pha Hông limestone massif 7 km N of Lak Sao (locality code: JG12); 18°13.91'N, 104°56.41'E; 16 Feb. 2017; J. Grego leg.; coll. JG • 1 figured shell; same data as for preceding; NHMUK 20170304 .

Halong Bay area Vietnam • 18 shells; Quang Ninh Province, Halong-Campha area, 4.5 km SW Quang Hanh, limestone hill with regrowth; 20°58.98'N, 107°11.83'E; 29 Sep. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6217 • 1 shell; Haiphong Province, Halong Bay area, unnamed island off E Coast Cat Ba, south facing bay with beach and densely-vegetated limestone scree slope; 20°45.19'N, 107°04.46'E; 1 Oct. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6219 • 1 shell; Quang Ninh Province, Halong Bay area , Tien Ong Cave on Hang Trai Island (locality code: WMVT.0338); 20°48.96'N, 107°07.33'E; 6 Sep. 2003; W.J.M. Maassen leg.; RMNH 347767 .

Large shell with anteriorly situated parietal tooth Laos • 1 shell (figured); Luang Prabang province, ca. 9 km SE of Luang Prabang, on the left side of river Nam Khan , limestone, black soil in limestone pockets, clay, under rocks and logs in secondary forest under cliff (locality code: 15L06); 19°51.38'N, 102°12.46'E; 365 m a.s.l.; 3 Nov. 2006; A. Abdou & I.V. Muratov leg.; MNHN-IM-2014-6414 .

Tiny shell with large variability Vietnam • 4 shells (H: 0.72-0.83 mm, D: 0.70-0.82 mm); Xieng Khouang Province , foot of limestone ridge 3 km NW of Thathom, 800 m S of road 1D crossing a small river (locality code: JG26); 19°00.33'N, 103°34.90'E; 22 Feb. 2017; J. Grego leg.; coll. JG .

Diagnosis.

A small to large, mostly conical or concave-conical (rarely conical-globular) species with a single parietal tooth, shell mostly higher than wide, rarely slightly wider than high. Extremely variable in shell shape across and even within populations.

Measurements (in mm).

H = 0.72-1.16, D = 0.70-1.12, H/D*100 = 87.3-119.8 (n = 99), RUD = 21.4-32.3 (n = 34); H = 1.12, D = 1.19 H/D*100 = 94.1, RUD = 31.9 (15L06).

Differential diagnosis.

Species with conical and concave-conical shells and a single parietal tooth are the following: Angustopila concava , A. babel sp. nov., A. oostoma sp. nov., A. margaritarion sp. nov., A. cavicola sp. nov., A. szekeresi , and A. vandevenderi sp. nov. Among them, A. margaritarion sp. nov., A. cavicola sp. nov., A. szekeresi are sympatric with A. fabella , while A. babel sp. nov., A. oostoma sp. nov., and A. vandevenderi sp. nov. occur in parapatry with A. fabella (i.e., populations of one of those three species occur geographically close to an A. fabella population). For comparisons, see under those species. See also under A. cicatricosa sp. nov.

Distribution.

Known from several localities across northern Laos, northern Vietnam and from one site in Guangxi, China, close to the Vietnamese border (Fig. 42 ).

Remarks.

This is a variable species that is characterised by a conical or concave-conical (in some populations nearly domed) shell and a single parietal tooth. The key traits of the examined populations are compiled in Table 2 . Among the three widely distributed species, the morphological variability of A. fabella is considerably greater than that of the other two species ( A. szekeresi and A. elevata ). This suggests that the samples listed under A. fabella may belong to several distinct species, and species delimitation can only be revealed by molecular phylogenetic means. The following populations should be noted:

The sample 2019/118 contained two ‘morphotypes’, which differed only in shell size. By measuring each shell, it was revealed that the two ‘morphotype’ groups form non-overlapping clusters on the shell diameter vs. shell height diagram. One explanation is that they belong to two morphologically similar species differing only in size. The other explanation is that this is a single species and at the geographically rather broad (ca. 100 meters) collection site, individuals inhabited different microhabitats, which resulted in differences in shell size. In the absence of other conchological characters, we accept the latter hypothesis.

Sample 2019/128 contained three more or less clear ‘morphotypes’: strongly concave-conical with pointed apex and wide umbilicus; concave-conical with blunt apex and wide umbilicus; and conical with broad apex and narrower umbilicus. The allocation of some shells into either group was problematic, indicating that this is a very variable single species.

The single shell from site 15L06 is much larger than that seen in any of the other A. fabella shells whereby the parietal tooth is situated much more anteriorly, so that it reaches the edge of the parietal callus. This shell may well belong to a distinct species. However, given the large morphological variability of A. fabella , the absence of samples from the close vicinity, and the fact that we have only one shell from sample 15L06, we refrain from describing it as new. Angustopila concava possesses a similar, anteriorly positioned (albeit lower) parietal tooth, and a similar large, concave-conical shell, but it has a more oblique aperture.

All A. fabella samples from Sơn La and Hòa Bình Provinces have conical-globular shells with a wide umbilicus except for one sample, which has a conical shell and narrow umbilicus. However, shells from site 2020/9 (Sơn La Province) are extremely variable and there is a continuous variation from conical-globular shells with a wide umbilicus to conical shells with a narrow umbilicus. Therefore, we consider the conical-globular-type shell a local variation of A. fabella , which nonetheless, warrants further attention.

Sample JG26 from Xieng Khouang Province, Laos, contained four shells showing remarkable diversity in terms of shell shape. Moreover, these are the smallest A. fabella shells amongst all examined populations.

Figures

Figure 29. Variability of Angustopila fabella Pall-Gergely & Hunyadi, 2015 in the Halong Bay A JJV 6217 B WMVT. 0338 and Angustopila babel Pall-Gergely & Vermeulen, sp. nov. C JJV 16590 D JJV 17634, Specimen 1 E JJV 17634, Specimen 2.

Figure 40. Synoptic view of Angustopila fabella Pall-Gergely & Hunyadi, 2015.

Figure 41. Angustopila fabella Pall-Gergely & Hunyadi, 2015 (holotype of Angustopila singuladentis Inkhavilay & Panha, 2016). Apertural (A), apical (B), lateral (C) and ventral (D) sides of the shell; microstructure of the protoconch (E), ventral (F) and frontal (G) surface of the body whorl. SEM Images: Chirasak Sutcharit.

Figure 42. Distribution of Angustopila fabella Pall-Gergely & Hunyadi, 2015.