Bensonella anguloobtusa (Inkhavilay & Panha, 2016)

Tongkerd, Piyoros, Lwin, Ngwe, Pall-Gergely, Barna, Chanabun, Ratmanee, Pholyotha, Arthit, Prasankok, Pongpun, Seesamut, Teerapong, Siriwut, Warut, Srisonchai, Ruttapon, Sutcharit, Chirasak & Panha, Somsak, 2024, Contributions of a small collection of terrestrial microsnails (Pupilloidea, Hypselostomatidae) from Myanmar with description of three new species, ZooKeys 1195, pp. 157-197 : 157

Bensonella anguloobtusa (Inkhavilay & Panha, 2016)

Figs 6B , 7A , 13G

Paraboysidia anguloobtusus Inkhavilay & Panha in Inkhavilay et al. 2016: 215-217, figs 2d-f, 4b. Type locality: Kao Rao Cave, Vieng Phouka District, Luang Namtha Province, Laos. Inkhavilay et al. 2019: 61, fig. 26f.

Material examined.

Monastery , Ywangan Township, Taunggyi District, Shan State, Myanmar (locality code SH2; 21°13'43.3"N, 96°33'19.2"E): CUMZ 14398 (1 shell; Fig. 7A ); CUMZ 14399 (87 shells); CUMZ 14400 (12 shells; Fig. 13G ; measured); CUMZ 14401 (1 shell; Fig. 6B ) .

Description.

Shell concave-conical, spire high, yellowish brownish in colour, and 4½ -5 convex whorls. Shell height 1.7-2.1 mm and shell width 1.5-1.7 mm. Apex blunt; protoconch ~ 1½ whorls with wrinkled roundish pits and spiral ridges. Teleoconch with wrinkles, irregular growth lines, and very fine, dense, inconspicuous spiral striae; suture well impressed and deep. Last whorl convex, very slightly shouldered. Aperture subrectangular with eight or nine apertural barriers. Peristome thickened and little expanded, cervical crest absent; lip pale yellowish to brown. Parietal lamella strongly developed, robust, broadly blunt and starting deeper inside aperture than angular lamella; infraparietal lamella very small and sometimes absent. Angular lamella strong and low, as well as long and sinuous upon reaching peristome, increasing in height deeper inside aperture. Palatal tubercle strongly developed with triangular shape. Upper palatal plica long and very thin; interpalatal plicae and lower palatal plicae approximately same size, large and long, tubercle-like. Columellar lamella large, strong, and horizontal; subcolumellar lamella bears small, robust fold. Umbilicus perforate, ~ 1/4 of shell width, rounded and deep.

Distribution.

This species is currently known from the type locality in Luang Namtha Province, Laos. In the recent survey, individuals were collected from the limestone outcrops in Shan State, Myanmar.

Remarks.

This is the first record of the species in Myanmar. The new specimens were collected ~ 480 km away from the type locality. Therefore, more of these snails can be expected to be found in the northeastern part of Myanmar and the northern part of Thailand. The specimens from Shan State all agree well with the type specimen in both shell form and apertural dentition. However, only a very small infraparietal lamella is present in some individuals.

Figures

Figure 6. A Bensonella salwiniana, specimen CUMZ 14393 from Taunggyi District, Shan State B Bensonella anguloobtusa, specimen CUMZ 14401 from Taunggyi District, Shan State. Abbreviations: a: angular lamella, c: columellar lamella, itpl: interpalatal plica, lpl: lower palatal plica, p: parietal lamella, pt: palatal tubercle, sbc: subcolumellar lamella, upl: upper palatal plica.

Figure 7. A Bensonella anguloobtusa, specimen CUMZ 14398 from Taunggyi District, Shan State B Bensonella taiyaiorum sp. nov., holotype CUMZ 14380 from Taunggyi District, Shan State C Bensonella lophiodera sp. nov., holotype CUMZ 14378 from Taunggyi District, Shan State. Abbreviation: ip: infraparietal lamella.

Figure 13. Synoptic view of representatives of hypselostomatid snails recorded from Myanmar A Acinolaemus dayanum, specimen HA Collection B Acinolaemus cryptidentatus, specimen CUMZ 14413 C Anauchen eotvosi, holotype NHMUK 1903.7.1.1227.1 (after Pall-Gergely 2023 a: fig. 1 c) D Angustopila occidentalis, holotype HNHM 103483 (after Pall-Gergely et al. 2023: fig. 70 a) E Angustopila elevata, specimen HNHM 103484 (after Pall-Gergely et al. 2023: fig. 13 a) F Bensonella salwiniana, specimen CUMZ 14393 G Bensonella anguloobtusa, specimen CUMZ 14400 H Bensonella taiyaiorum sp. nov., paratype CUMZ 14403 I Bensonella lophiodera sp. nov., paratype CUMZ 14405 J Clostophis sankeyi, holotype UMZC I. 103320 (after Preece et al. 2022: fig. 70 e) K Clostophis thinbowguensis, holotype MNHN-IM- 2000 - 38057 (after Pall-Gergely et al. 2022: fig. 9 c) L Gyliotrachela bensonianum, syntype NHMUK 20191141 (after Gojsina et al. 2022: fig. 4 a) M Gyliotrachela hungerfordiana, specimen NHMUK collection from Perak, Malaysia N Gyliotrachela tianxingqiaoensis, holotype IZCAS TM 025075 (after Gojsina et al. 2022: fig. 3 a) O Gyliotrachela muangon, specimen CUMZ 14410 P Gyliotrachela aunglini sp. nov., paratype CUMZ 14412 Q Hypselostoma tubiferum, specimen NHMUK 1888.12.4.17 - 22 ex. Theobald collection from Tonduong, Burma.