Naggsia oligogyra, Páll-Gergely, 2018

Páll-Gergely, Barna, 2018, Systematic revision of the Plectopylinae (Gastropoda, Pulmonata, Plectopylidae), European Journal of Taxonomy 455, pp. 1-114 : 74-75

Naggsia oligogyra sp. nov.

urn:lsid:zoobank.org:act:13CE6536-3C26-421E-ACA1-270750697E3A

Figs 31F , 32 G–H

Diagnosis

A large, flat, dextral species with few (5) whorls; parietal wall with a single lamella, and a main plica free from the deeply situated apertural fold.

Differential diagnosis

The shell of the new species resembles N. laomontana , which has about a whorl more and only a single lamella on the parietal wall.

Etymology

The species is named after its few whorls, from the Greek ‘ oligos ’, meaning few and ‘ gyros ’, meaning whorl.

Material examined

Holotype THAILAND: 1 shell (D = 21.0 mm), Chiang Mae Province , Doi Pha San Sao Mountain, 1 km W of Ban Prang Ma-o, 19°25′58.26″ N, 99°4′14.02″ E, 500 m a.s.l., 19 Jun. 1987, F.G. Thompson leg. ( UF 346781).

Paratypes THAILAND: 2 broken shells, same data as for holotype ( UF 448574); 1 broken shell, same data as for holotype ( HNHM 97457).

Description

SHELL. Dextral, flat, with five rapidly increasing whorls, separated by a rather shallow suture; only strongly weathered shells were available for study, and therefore the sculpture could not be observed in detail; protoconch with fine ribs; teleoconch with inconspicuous, irregular riblets and paler reddish transverse stripes; peristome relatively thin, only slightly reflected and thickened; parietal callus low and blunt; apertural fold weak, situated far from parietal callus.

One shell was opened. Parietal wall with a single, straight lamella having slight horizontal extensions above and below in both anterior and posterior directions; main plica free from lamella, starts near upper end of lamella, and does not reach apertural fold. Palatal wall with six plicae; first situated close to upper suture, short; second to fifth oblique, second being the longest; sixth curved, concave.

MEASUREMENTS (in mm). D = 21.0, H = 6.3 (holotype).

Distribution

The new species is known from the type locality only, where it occurs together with C. leiophis ( Fig. 17 ).

Figures

Fig. 31. Shells and protoconchs of species of Hunyadiscus Páll-Gergely, 2016 and Naggsia Páll-Gergely & Muratov, 2016. A. Hunyadiscus saurini Páll-Gergely, 2016, holotype (MNHN IM-2000-24947). B. H. saurini, paratype (MNHN IM-2000-24949). C. Protoconch of H. tigrina sp. nov., holotype (UF 343843). D. Protoconch of H. tigrina sp. nov., paratype (UF 343817). E. Naggsia laomontana from Laos, Luang Praban Province, 20°03.48276′ N, 102°12.79912′ E, 364 m a.s.l., 13 Oct. 2006, K. Ohara leg. (coll. PGB). F. N. oligogyra sp. nov., holotype (UF 346781). Scale bar: A, C, E–F = 10 mm. Images: T. Deli (A, C, E–F) and B. Páll-Gergely (B, D).

Fig. 32. Parietal (A, C, E, G) and palatal (B, D, F, H) plication of species of Hunyadiscus Páll- Gergely, 2016 and Naggsia Páll-Gergely & Muratov, 2016. A–B. Hunyadiscus saurini Páll-Gergely, 2016, paratypes from the type locality (UF 448579). C–D. H. tigrina sp. nov., paratype (UF 448579). E–F. Naggsia laomontana (L. Pfeiffer, 1862) from Laos, Luang Praban Province, 20°03.48276′ N, 102°12.79912′ E, 364 m a.s.l., 13 Oct. 2006, K. Ohara leg. (coll. PGB). G–H. N. oligogyra sp. nov. (UF 346781). Arrows below the letters indicate the direction of the aperture. Not to scale.

Fig. 17. Distribution of plectopylid species in Northern Thailand. Legends: circle = Chersaecia auffenbergi sp. nov.; triangle = Chersaecia leiophis (Benson, 1860) (empty triangle shows the type locality of Plectopylis degerbolae Solem, 1966); empty square = Chersaecia perarcta simplex (Solem, 1966); cross = Chersaecia perarcta perarcta (Blanford, 1865); filled square = Chersaecia scabra sp. nov.; rhomb = Chersaecia densegyrata sp. nov.; the upper filled triangle also shows the locality of Naggsia oligogyra sp. nov.