Taphrenalla dalli 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 : 56-57

Taphrenalla dalli Pholyotha & Panha , sp. nov.

( figs 1 , 3 , 5, 8D, E, 9D–F, table 6)

Type material examined. Holotype: CUMZ 7183 ( fig. 8D ). Paratypes. Same data as holotype: CUMZ 7184 (31 shells and nine specimens in ethanol), CUMZ 7188 (one shell), NHMUK (two shells) and SMF (two shells) .

Other material examined. Wat Khiri Rat Phatthana, Wiang Sa District, Surat Thani (8°31’36.5” N 99°23’00.2” E): CUMZ 7185 (63 shells and 88 specimens in ethanol) . Wat Na San, Ban Na San District, Surat Thani, Thailand (8°48’30.7” N 99°22’16.1” E): CUMZ 7186 (four shells and 11 specimens in ethanol) and CUMZ 7187 (11 shells and 24 specimens in ethanol) . Wat Tham Kanlayanamit, Tham Phannara District, Nakhon Si Thammarat (8°30’49.3” N 99°22’53.9” E): CUMZ 7189 ( fig 8E ; 39 shells and 27 specimens in ethanol). Wat Tham Thong Panara, Tham Phannara District, Nakhon Si Thammarat (8°25’19.1” N 99°22’48.4” E): CUMZ 7190 (20 shells and one specimen in ethanol) .

Type locality. Limestone outcrop at Tham Lord, Nopphitam District, Nakhon Si Thammarat, Thailand (8°47’16.7” N 99°38’29.9” E) .

Etymology. This species is named after William Healey Dall, an American malacologist, who discovered the first species of Crown Snail, T.diadema .

Diagnosis. Shell with a very wide channel-shaped suture and with deep and short radial grooves. Epiphallic caecum straight. Penial caecum very short. Inner sculpture of proximal penis with very small, irregular and longitudinal folds, and then with obliquely and wrinkled to very fine pilasters distally. Dart apparatus connected on vagina. Spermatophore with two spines on tail filament close to sperm sac.

Description

Shell ( figs 8D, E ). Shell depressed conic to globosely depressed, medium-sized (width up to 18.3 mm; height up to 11.3 mm) and pale to dark brown. Whorls 5–6; suture very wide, deep and channeled-shape. Upper shell surface with strong and short radial grooves continuing from suture to inconspicuous at periphery and then disappear below periphery. Radial grooves beginning between whorl 3 to 4 and having 23–37 grooves at last whorl (n = 33; fig. 5). Spire depressed conic; apex raised with a spire angle of about 135–155°. Last whorl shouldered and well-rounded at periphery. Aperture lip simple; umbilicus narrowly opened.

Genital organs (figs 9D–F). Atrium slightly short. Penis elongate cylindrical and nearly two times that of total vagina length; penial caecum present. Inner sculpture of proximal penial wall supported by penial pilasters starting proximally with very small irregular longitudinal folds, then gradually, obliquely, wrinkled pilasters in middle, to very fine pilasters surrounding penial verge. Epiphallus slender tube, approximately one and a half times total penis length. Epiphallic caecum slightly prolonged, and attached with thick penial retractor muscle (prm). Flagellum enlarged at base and tapering with irregular shape to tip. Vas deferens slender tube. Vagina long and cylindrical tube. Dart apparatus located on proximal vagina away from penis joining to atrium. Spermatophore long and needle-shaped. Tail filament very long tube; region close to sperm sac bearing two spines; spine close to sperm sac shorter than the other.

External features ( fig. 3 ). Animal dark gray in body colour with three pale orange stripes running from head to caudal horn. One stripe at middle of the body and others two stripes on side of body close to foot sole; stripes on tail wider than anterior.

Remarks. Shell morphology of this new species looks similar to T. diadema , but can be distinguished by having a wider base of the suture than in T. diadema . In comparison, T. dalli sp. nov. shows a small penial caecum, shorter flagellum, and large and coarse penial sculpture pilaster at the middle of penis. Whereas, T. diadema has a large penial caecum, longer flagellum, and inner wall of penis is sculptured with very fine wrinkled pilasters. In addition, the penial sculpture at the middle of the penis of T. dalli sp. nov. has larger, more obliquely wrinkled pilasters than T. diadema .

This new species shows variation in size and shell sculpture, the like of which also appears in T. diadema . However, the shell suture and genitalia of all variants are identical, and are also clustered together in the T. dalli clade in the molecular analysis.

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.

Figure 8 Shells.A–C.Taphrenalla diadema. A.specimen CUMZ 7175.B. specimen CUMZ 7177.C.specimen CUMZ 7171 showing channel-shaped suture with wide bottom.D, E.T.dalli sp. nov. D. holotype CUMZ 7183.E. specimen CUMZ 7189 showing channel-shaped suture with very wide bottom. Inset SEM image showing shell sculpture of each species.