Gyliotrachela muangon Panha & Burch, 2004

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

Gyliotrachela muangon Panha & Burch, 2004

Figs 11 , 13O

Gyliotrachela muangon Panha & Burch in Panha et al. 2004: 67, 68, fig. 7. Type locality. Muangon Cave, San Kam Pang District, Chiangmai Province, Thailand. Panha and Burch 2005: 76, 77, fig. 66. Gojšina et al. 2022: 138, fig. 6.

Material examined.

Yum Cave , Kalaw City, Shan State, Myanmar (locality code KW1; 20°37'18.1"N, 96°29'8.3"E; 854 m a.s.l.): CUMZ 14385 (1 shell; Fig. 11A, B ); CUMZ 14408 (6 shells); CUMZ 14409 (12 shells; measured); CUMZ 14410 (2 shells; Figs 11C , 13O ) .

Description.

Shell broadly ovate-conical, reddish brown in colour, moderate spire, and 4¾ -5 widely convex whorls. Shell height 1.8-2.0 mm and shell width (including tuba) 2.5-2.9 mm. Appex blunt; protoconch 1¾ whorls, wrinkled with roundish pits. Teleoconch with wrinkles and irregular growth lines crossed by conspicuous spiral ridges throughout; suture well impressed and deep. Last whorl widely angular, tuba short and ~ 10-12 degrees angled upward. Peristome widely expanded; lip reddish brown. Aperture roundly triangular and many aperture dentitions. Parietal lamella large, tall, strong, blunt and slightly deep inside aperture. One or two minute infraparietal lamellae may be present. Angular lamella strong and reaching peristome. Upper palatal plica strong; sometimes very small suprapalatal plicae present. Lower palatal plica tall and strong; one or two small interpalatal plicae and infrapalatal plicae usually present. Columellar lamella very strong, distinct and horizontal; very low and weak supracolumellar and subcolumellar lamellae present. All dentitions generally with very fine spines on surface. Umbilicus perforate, ~ 1/4 of shell width, rounded, deep, and surrounded by blunt periumbilical keel.

Distribution.

This species was originally described from Chiangmai Province, northern Thailand ( Panha et al. 2004). Later, a few specimens were collected from Hsi Hseng Township, Taunggyi District, Shan State ( Gojšina et al. 2022). Recently, several specimens were collected from Kalaw Township, Taunggyi District, Shan State.

Differential diagnosis.

Gyliotrachela muangon can be distinguished from G. tianxingqiaoensis from China and Myanmar, and G. plesiolopa Inkhavilay & Panha, 2016 from Laos by having weak spiral striae, five strong major lamellae and plicae (parietal, angular, columellar, and upper and lower palatals). In contrast, G. tianxingqiaoensis lacks spiral striation on the teleoconch, has a more elevated aperture, a narrower umbilicus and has more numerous teeth in the aperture; G. plesiolopa has a more expanded peristome, and a slightly weaker peripheral keel, which is also less upturned and flatter on the lower side ( Inkhavilay et al. 2016; Gojšina et al. 2022).

The three species from Thailand ( G. saraburiensis Panha & Burch in Burch et al. 2003, G. muangon and G. cultura Tanmuangpak & Dumrongrojwattana, 2022) are very similar to G. muangon in the turbinate shell form, the short and slightly descending tuba, the weakly angulated last whorl, the spiral striae on the teleoconch, and by having five major apertural dentitions. The significant distinction among them is mainly the number of accessory plicae and lamellae. Specifically, G. muangon possesses two infraparietals, two interpalatal and two infrapalatals, while G. saraburiensis has three infraparietals, three interpalatals and five infrapalatals, and G. cultura exhibits one infraparietal, one interpalatal and two infrapalatals ( Burch et al. 2003; Panha et al. 2004; Panha and Burch 2005; Tanmuangpak and Dumrongrojwattana 2022).

Remarks.

The examined specimens from Myanmar show minor variability in terms of apertural dentition from the type specimen from Thailand. Two interpalatal plicae are observed in the Myanmar specimens, while the type specimen has only one interpalatal plica.

Figures

Figure 11. Gyliotrachela muangon from Kalaw City, Shan State A, B specimen CUMZ 14385 from Kalaw City, Shan State, (A) shell and (B) protoconch C specimen CUMZ 14410 from Kalaw City, Shan State. Abbreviations: a: angular lamella, c: columellar lamella, ip: infraparietal lamella, itpl: interpalatal plica, ifpl: infrapalatal plica, lpl: lower palatal plica, p: parietal lamella, sbc: subcolumellar lamella, spc: supracolumellar lamella, sppl: suprapalatal lamella, upl: upper palatal plica.

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.