Taphrenalla diadema (Dall, 1897)

(figs 1, 3, 5, 8A–C, 9A–C, table 6)

Nanina (Macrochlamys) diadema Dall, 1897: 37–38 . Type locality: Prang, Malay Peninsula; Dall, 1902: 499, pl. 27 figs 1–3; Boss, Rosewater, & Ruhoff, 1968: 104.

Macrochlamys diadema: Gude, 1903: 50 .

Syama diadema: Abbott, 1989: 23, 133 (text figure); Panha, 1996: 102–104, fig. 2b2 (Holotype, USNM 150277); Maneevong, 2000: 28–29, fig. 4-2.

Sarika diadema: Sutcharit & Panha, 2008: 95–100, figs 2a, b, 3a–e, 4a–c.

Material examined. Type material: holotype USNM 150277. Non-type material: Wat Khuha Santayaram (Wat Tham Khao Daeng), Ron Phibun District, Nakhon Si Thammarat (8°14’39.5”N 99°52’00.1”E): CUMZ 7164 (one specimen in ethanol) . Tham Talot, Thung Song District, Nakhon Si Thammarat (8°09’32.3”N 99°40’41.6”E): CUMZ 7165 (16 shells and three specimens in ethanol) . Tham Rad, Thung Song District, Nakhon Si Thammarat (8°02’47.2”N 99°43’45.0”E): CUMZ 7166 (10 shells) and CUMZ 7167 (11 specimens in ethanol) . Wat Tham Phraphut, Ratsada District, Trang (7°57’57.3”N 99°44’41.3”E): CUMZ 7168 (four shells and two specimens in ethanol) . Tham Chang Hai, Mueang District, Trang (7°35’26.6”N 99°40’05.3”E): CUMZ 7169 (nine shells) and CUMZ 7170 (two shells) . Khao Pu Chao Bureau of Monks, Na Yong District, Trang (7°33’53.0”N 99°46’36.2”E): CUMZ 7171 (fig. 8C; 18 shells) and CUMZ 7172 (four shells). Wat Khao Huai Haeng, Huai Yot District, Trang (7°47’36.5”N 99°38’37.0”E): CUMZ 7173 (16 specimens in ethanol) . Wat Tham Sumano, Srinagarindra District, Phatthalung (7°35’14.0”N 99°52’06.8”E): CUMZ 7174 (10 specimens in ethanol) and CUMZ 7175 (fig. 8A; four shells and 33 specimens in ethanol). Khao Ok Talu Khuha Sawan, Mueang District, Phatthalung (7°37’33.7”N 100°05’23.7”E): CUMZ 7176 (three shells) and CUMZ 7177 (fig. 8B; 55 shells and 18 specimens in ethanol). Wat Khuha Sawan, Mueang District, Phatthalung (7°37’15.0”N 100°04’48.7”E): CUMZ 7178 (one shell) . Tham Phaya Hong, Kong Ra District, Phatthalung (7°27’48.4”N 99°57’53.3”E): CUMZ 7179 (36 shells) and CUMZ 7180 (22 shells and 137 specimens in ethanol) . Limestone outcrops at Khlong Chaloem, Kong Ra District, Phatthalung (7°23’50.6”N 99°58’45.2”E): CUMZ 7181 (five shells and 31 specimens in ethanol) . Tham Phra Non, Mueang District, Phatthalung (7°40’52.1”N 100°03’42.4”E): CUMZ 7182 (10 shells) .

Figure 9 Genitalia and spermatophore. A–C. Taphrenalla diadema specimen CUMZ 7180. A. whole reproductive system, B, internal wall of penis with penial verge. C. spermatophore; inset showing two spines located close to sperm sac. D–F. T. dalli sp. nov. paratype CUMZ 7184. D. whole reproductive system; inset showing a small penial caecum. E. internal wall of penis with penial verge. F. spermatophore of T. dalli sp. nov. specimen CUMZ 7186; inset showing two spines located close to the sperm sac.

Remarks. Taphrenalla diadema had been recently re-described and illustrated by Sutcharit & Panha (2008). The distinguishing characters are a depressed conic shell, medium-sized (width up to 17.8 mm; height up to 10.6 mm), a wide and deep channel-shaped suture, and short radial grooves appeared on last about 24–43 grooves (n = 39; figs 5, 8A–C). The genitalia have a short and straight epiphallic caecum, and dart apparatus located on vagina away from vagina and penis junction (figs 9A, B). Spermatophore has one short spine on tail filament close to sperm sac (fig. 9C). Living snail has yellowish stripes on head and tail (fig. 3).

The specimens from Khao Ok Talu, Phatthalung Province (fig. 8B) tended to have a smaller diameter and shallower radial grooves than the other populations (figs 8A, C). However, all the genital characters and spermatophores from all localities appear to be identical. In addition, the molecular data also confirmed that the shell variations were all grouped within the T. diadema clade.