Hunyadiscus saurini Pall-Gergely

Pall-Gergely, Barna, Muratov, Igor V. & Asami, Takahiro, 2016, The family Plectopylidae (Gastropoda, Pulmonata) in Laos with the description of two new genera and a new species, ZooKeys 592, pp. 1-26 : 10-11

Taxon classification Animalia Pulmonata Plectopylidae

Hunyadiscus saurini Pall-Gergely sp. n. Figures 3A, 4C, 5 A–B, 11A

Hunyadiscus saurini 1953 Plectopylis laomontana , Saurin, Journal de Conchyliologie, 93 (4), 113.

Type material.

Laos, Pa Hia (Ancienne province Tran Ninh), Coll. Saurin, MNHN 24947 (holotype), MNHN 24948/7 paratypes + 5 juvenile shells (also paratypes), HNHM 97470/2 paratypes; Laos, Pah Xieng Tong, Pa Hia, Prov. Tran Ninh, Coll. Saurin, MNHN 249479/1 paratype + 1 juvenile shell (also paratype, protoconch figured: Fig. 4C); Laos, Pa Ka Tai, Prov. Tran Ninh, Coll. Saurin, MNHN 24950/5 paratypes, HNHM 97471/1 paratype; Laos, Pa Xieng Tong, Pa Hia, Prov. Tran Ninh, Coll. Saurin MNHN 24951/3 paratypes; Laos, Pa Hia (Tran Ninh), Coll. Saurin, MNHN 24952/1 juvenile shell (paratype).

Diagnosis.

A dextral, medium-sized or large species with a relatively sharp upper keel and a blunt lower keel on the body whorl. On the parietal wall there is a single oblique lamella with a horizontal plica below it.

Description.

The shell is yellowish or corneous (the type material consists mainly of weathered shells). The protoconch is very large, with regular riblets and spiral lines; the radial and spiral lines are approximately of the same strength. The 5.25-6 whorls are separated by a shallow suture. The umbilicus is wide but moderately deep. The body whorl has a prominent upper keel and a less conspicuous lower keel. The apertural margin is slightly thickened. The parietal callus is blunt, not well developed and is only clearly apparent in older specimens.

Three shells were opened. On the parietal wall there is a single curved lamella that is oblique, its upper end situated much more anteriorly than the lower end. A short, but thick vertical plica is situated below and anteriorly of the lamella. On the palatal wall there are six more-or-less parallel plicae, with some additional short plicae. The most prominent additional plica is situated above the posterior end of the last plica. The fifth plica is usually S-shaped.

Measurements

(in mm). D= 16.3-21.3, H= 6.7-8.6. (n=4, shells from different samples).

Differential diagnosis.

Hunyadiscus saurini sp. n. is smaller than Hunyadiscus andersoni , its keel is situated higher (this results a more angular body whorl), has weaker parietal callus, a lower horizontal plica on the parietal wall which is absent in Hunyadiscus andersoni . Naggsia laomontana has a rounded body whorl and weaker spiral striation on its protoconch.

Etymology.

The species is named in honour of the French geologist and malacologist Edmond Saurin (1904-1977) who collected it.

Type locality.

Laos, Pa Hia (Ancienne province Tran Ninh).

Distribution.

This species is known only from Southern Laos.

Remarks.

This new species shows considerable diversity in terms of shell size. However, the other shell characters are stable within and between samples.

The village "Pa Hia" or "Pah Hia" is located 100 km south from Xieng-Khouang, the capital of Tran Ninh Province (see Saurin 1953: 113). However, the exact locality could not be determined ( Nordsieck 2002, Páll-Gergely 2014, Páll-Gergely 2015c). A geological report ( Marutani 2006), mentioned the name "Ban Namthong" in brackets after "Pa Hia". The two names are probably identical, but the origin of this information could not be traced. Marutani (2006) gave the following GPS coordinates for Ban Namthong: 19.05000°N, 103.28330°E. This location is situated approximately 75 km southwest from Xiangkhoang city. Google Earth placed "Ban Namthong" 7.6 km in southwest direction (18° 59'N, 103° 16'E), which agrees with the 1:50.000 map printed by the National Geographic Directorate, Vietnam, in 1965. We provisionally identify the village Pah Hia with Ban Namthong, because we could not locate the name Pah Hia on the maps available to us.