Taphrenalla macrosulcata Pholyotha & Panha,, 2021

Pholyotha, Arthit, Sutcharit, Chirasak, Tongkerd, Piyoros, Jeratthitikul, Ekgachai & Panha, Somsak, 2021, Integrative systematics reveals the new land-snail genus Taphrenalla (Eupulmonata: Ariophantidae) with a description of nine new species from Thailand, Contributions to Zoology 90 (1), pp. 21-69 : 51-53

Taphrenalla macrosulcata Pholyotha & Panha, sp. nov.

( figs 1 , 3 , 5, 6B, 7D–F, table 6)

Type material examined. Holotype: CUMZ 7161 (fig. 6B). Paratypes. Same data as holotype: CUMZ 7162 (15 shells and five specimens in ethanol), CUMZ 7163 (three shells and nine specimens in ethanol), NHMUK (two shells) and SMF (two shells) .

Type locality. Limestone outcrops at Khlong Sok, Phanom District, Surat Thani, Thailand (8°53’20.5”N 98°40’27.7”E) .

Etymology. The specific epithet is derived from ‘ macro ’ (the Greek word ‘ makros ’) meaning ‘long’ and ‘ sulcata ’ (the Latin word ‘ sulcus ’) meaning ‘furrow, groove’ with reference to the characteristic of having numerous long radial grooves on shell sculpture.

Diagnosis. Shell with a narrow and deep impressed suture and deep and long radial grooves. Epiphallic caecum straight and short. Penial caecum short. Inner sculpture of proximal penis with fine wrinkled longitudinal folds; distally with oblique longitudinal folds and transverse-folded surrounding penial verge. Dart apparatus located on vagina. Spermatophore with one spine on tail filament close to sperm sac.

Figure 7 Genitalia and spermatophore. A–C. Taphrenalla asamurai specimen CUMZ 7153. A. whole reproductive system. B. internal wall of penis with penial verge. C. spermatophore; inset showing one spine located close to the sperm sac. D–F. T. macrosulcata sp. nov. paratype CUMZ 7162. D. whole reproductive system. E. internal wall of penis with penial verge. F. spermatophore; inset showing one spine located close to the sperm sac.

Description

Shell (fig. 6B). Shell comparatively depressed conic, medium-sized (width up to 18.7 mm; height up to 9.8 mm) and pale brown. Whorls 5–6; suture deep and narrow impressed. Upper shell surface with strong and long radial grooves continuing from suture, gradually inconspicuous and then disappear below periphery. Radial grooves starting between whorl 3 to 4 and with 42–58 grooves at last whorl (n = 24; fig. 5). Spire depressed conic; apex raised with a spire angle of about 143–164°. Last whorl shouldered and well-rounded at periphery. Aperture lip simple; umbilicus narrowly opened.

Genital organs (figs 7D–F). Atrium short. Penis elongate cylindrical and same length as total vagina length; penial caecum present. Inner sculpture of proximal penial wall has very fine wrinkled, longitudinal penial pilasters, with thick and oblique longitudinal folds in middle, and then transformed to a thin, transverse-folded, surrounded penial verge. Epiphallus slender tube and about two times total penis length. Epiphallic caecum very short; thick penial retractor muscle attached at tip. Flagellum large and irregular slender tube. Vas deferens thin tube. Vagina long and cylindrical tube. Dart apparatus located on vagina away from penis joining to atrium. Spermatophore long and needle-shaped. Tail filament very long tube; region close to sperm sac bearing a very small spine.

External features ( fig. 3 ). Animal dark gray mixed with pale yellow on head and body and monochrome bright yellowish on tail.

Remarks. Taphrenalla macrosulcata sp. nov. is similar to T. asamurai in shell morphology but can be differentiated by a paler brown shell and a pale yellowish soft body. Whereas, T. asamurai has a dark brown shell and reddish to dark red soft body. Regarding the genital anatomy, this new species has a short flagellum, straight epiphallic caecum, and dart apparatus connecting to the vagina away from the penis junction and without thick connective tissue surrounding the proximal end. For comparison, T. asamurai has a long flagellum, bent epiphallic caecum, and dart apparatus located opposite the penis junction and with thick connective tissue at the proximal end.

The presence of one spine on the tail filament of the spermatophore is the remarkable character of T. macrosulcata sp. nov. and T. asamurai , while other Taphrenalla species have two spines.

Figures

Figure 1 Map showing the sampling sites of the 11 Taphrenalla species along Southern Thailand.Each colour of the distribution range follows the phylogenetic tree of all Taphrenalla species in fig.3.

Figure 3 A representative ML tree showing only the Taphrenalla clade.The synopsis of the radial groove on shell sculpture, genitalia showing location of dart apparatus, and live specimens of Taphrenalla spp. Results of species delimitation analyses based on the COI gene using ABGD and PTP.Black circles represent nodes with both ML (when Ē 70%) and BI (when Ē 0.95) support.White circles represent nodes with ML BS support but no BI PP support (when <0.95). Each clade colour refers to the distribution range in fig. 1.