Sinoennea montawana Páll-Gergely & Hunyadi, 2020

Páll-Gergely, Barna, Hunyadi, András, Grego, Jozef, Sajan, Sheikh, Tripathy, Basudev & Chen, Zhe-Yu, 2020, A review of the Diapheridae (Gastropoda: Eupulmonata: Streptaxoidea), with special emphasis on India and Myanmar, Raffles Bulletin of Zoology 68, pp. 682-718 : 709

Sinoennea montawana Páll-Gergely & Hunyadi , new species

( Figs. 18 , 22M )

Type material. Holotype ( H: 2.6 mm, D: 1.3 mm) ( HNHM 104856 ) ( Fig. 18B–K ), Myanmar, Shan State, Taunggyi centre WSW, Montawa Cave , 20°45.282′N, 97°1.057′E, 1,260 m a.s.l. (locality codes: 2018/34 and 20181005C), coll. K. Okubo, J.U. Otani & A. Hunyadi, 05 October 2018 . Paratypes. 1 shell ( H: 2.5 mm, D: 1.3 mm) (Coll. HA), same data as holotype ( Fig. 18A ) .

Additional material. 3 juvenile shells ( Fig. 18L ), same data as holotype, coll. HA .

Diagnosis. A small, ovoid Sinoennea species with elongate oval aperture, four normally developed apertural barriers, narrow, rounded umbilicus, and a moderate periumbilical keel.

Description. Shell shape ovoid to cylindrical, apex domed, the last three whorls the widest in standard apertural view. Shell colourless, semi-transparent, consisting of 5.5–5.75 whorls. Ribs low, fine, rather regularly arranged. Protoconch consisting of 1.5–1.75 whorls, glossy, almost smooth, very finely granular. Teleoconch sculpture glossier than that of protoconch, ribs rather regularly spaced, although the space between them increases on the last whorl towards aperture. Individual ribs look like low waves “pushed” backwards. Suture deep, whorls bulging, although side of body whorl straight with an outer angle of variable strength. Aperture elongate oval or almost rectangular, elongate. Parietal callus distinct, not “smeared” onto preceding whorl. Apertural dentition 4-fold. Parietal lamella moderately developed, nearly straight. Its outer part is slightly bent towards the parietal denticle, its inner part slightly bent towards the columella. Sinulus oval, opens slightly laterally, relatively small, and not conspicuously isolated due to the relatively weak parietal and palatal teeth. Palatal wall with two blunt, but well-developed denticles that are situated close to each other. Upper one situated on the peristome edge, lower one slightly lower in position and deeper. The inner one is slightly more elevated than the outer one. Columellar lamella situated relatively deep, but clearly visible from apertural view, rather low, elongated ridge-like, oblique to shell axis. Peristome strongly thickened and expanded, not reflected, relatively weak around the sinulus. Basal swelling very slightly indicated, nearly absent, situated relatively close to peristome. Depression anterior to basal swelling on the outer side very shallow (corresponding with the inner palatal tooth). Inner (umbilical) side with a slight depression corresponding with the columellar lamella. Umbilicus open, narrow, rounded. Periumbilical keel moderate, but relatively clearly visible from umbilical view, especially due to the slight furrow on the outer side.

Juveniles with a strong parietal and columellar lamella, and a lower palatal tooth ( Fig. 18L ).

Differential diagnosis. Only two Sinoennea species are known from Myanmar: S. fartoidea and S. woodthorpei . The former is more ovoid, has a closed umbilicus, lacks the columellar lamella, and has a very weak lower palatal tooth. Sinoennea woodthorpei is larger with stronger ribbing and its parietal callus is smeared onto the penultimate whorl.

Figures

Fig. 18. Paratype (A), holotype (B–K), and juvenile shell (L) of Sinoennea montawana Páll-Gergely & Hunyadi, new species.

Fig. 22. Apertures of Streptaxidae (A) and Diapheridae (B–P). A, Gulella (Huttonella) bicolor (Hutton, 1834); B, Rowsonia beddomei (W.T. Blanford, 1881); C, Platylennea subcostulata (W.T. Blanford, 1881); D, Pupennea planguncula (Benson, 1863); E, Diaphera polita, Páll-Gergely new species; F, Diaphera cylindrelloidea (Stoliczka, 1871); G, Bruggennea cf. bongi (Dance, 1970), H, Parasinoennea ovulum (Bavay & Dautzenberg, 1912); I, Sinoennea otostoma Páll-Gergely, A. Reischütz & Maassen in Páll-Gergely, Reischütz, Maassen, Grego & Hunyadi, 2020; J, Sinoennea infantilis Páll-Gergely & Grego in Páll-Gergely et al., 2020; K, Sinoennea variabilis Páll-Gergely & Grego in Páll-Gergely et al., 2020; L, Sinoennea sutchariti Páll-Gergely & Hunyadi in Páll-Gergely et al., 2020; M, Sinoennea montawana Páll-Gergely & Hunyadi, new species; N, Sinoennea angustistoma Páll-Gergely, A. Reischütz & Maassen in Páll-Gergely et al., 2020, O, Sinoennea woodthorpei (Peile, 1929); P, Sinoennea fartoidea (Theobald, 1870). Not to scale.