Diaphera polita Páll-Gergely, 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 : 690

Diaphera polita Páll-Gergely , new species

( Figs. 7 , 22E )

Ennea (Diaphora) cylindrelloidea — W.T. Blanford & Godwin- Austen, 1908: 18.

Type material. Holotype ( H: 4 mm, D: 1.3 mm) ( NHMUK 1891.3.14.480), Damotha, Moulmein, coll. Hungerford.

Diagnosis. A small, smooth Diaphera species with relatively weak apertural barriers.

Description. Shell spindle-shaped, rather matte, colourless, although fresh specimens might have a light brownish colour, as indicated on the last whorl of the holotype. Shell wall slightly semi-transparent, nearly smooth, except for the last ca. half whorl. Some very fine spiral striation is visible on the teleoconch, although it does not consist of raised threads, but seemingly part of the lower shell layers. The last quarter whorl is very finely ribbed and free from the penultimate whorl. Ribs gradually disappearing towards the earlier whorls. Ribs low, fine, equally spaced, looking as if they were “pushed” backwards (= away from the aperture). Entire shell consisting of 7 whorls. Apex rounded, protoconch cylindrical, consisting of 3 whorls, smooth. Teleoconch gradually widening, the widest whorl being the penultimate one from standard apertural view. Therefore, the cylindrical protoconch is consciously narrower than the first and second teleoconch whorls. Suture somewhat deep, whorls rather bulging. Aperture subcircular with a rather wide sinulus. Apertural dentition 4-fold; parietal lamella moderately developed, moderately elevated, outer portion slightly bent in palatal direction, with a blunt end. Inner portion rather low, rounded, slightly bent towards columella. Sinulus rounded, opens slightly laterally, moderately isolated (tips of parietal lamella and upper palatal tooth situated rather far from each other). Palatal wall with a slight upper palatal tooth situated on the peristome, and a deeply situated, knob-like inner parietal tooth. There is seemingly no connection between the two parietal teeth. Columellar lamella situated rather close to the peristome, blunt, short, oblique to the shell axis. Peristome strongly thickened, expanded, and slightly reflected, weakest (thinnest) around the slightly laterally opening sinulus. Basal swelling not indicated. There is a small depression on the shell wall, behind the peristome, corresponding with the inner palatal tooth. Columellar lamella also corresponds with a slit-like, elongated depression that runs as a continuation of the umbilicus and stops before the peristome. Umbilicus absent due to the free last quarter whorl.

Differential diagnosis. Diaphera seatoni is far larger than the new species and has a strongly protruding aperture. Both D. brevicollis and D. cylindrelloidea are equally, strongly ribbed, whereas S. polita , new species, is smooth. Furthermore, D. cylindrelloidea has a more strongly protruding aperture, a more elevated parietal lamella, and a strong, sharp palatal ridge that connects the outer denticle, which is situated on the peristome, and the inner denticle.

Etymology. This new species is named after its smooth shell, which distinguishes it from its congeners.

Remarks. The holotype specimen was mentioned under D. cylindrelloidea by Blanford & Godwin-Austen (1908). They recognised that it was a new species, but refrained from describing it.

Figures

Fig. 7. Diaphera polita Páll-Gergely, new species, NHMUK 1891.3.14.480 (holotype).

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.