Landouria Godwin-Austen, 1918

Tumpeesuwan, Chanidaporn & Tumpeesuwan, Sakboworn, 2019, First verified record of the genus Landouria Godwin-Austen, 1918 from Thailand (Gastropoda: Stylommatophora: Camaenidae) with description of a new species, Raffles Bulletin of Zoology 67, pp. 298-305 : 301

Genus Landouria Godwin-Austen, 1918

According to Schileyko & Kuznetsov (1998), this genus is distributed in north-eastern India, Nepal, Myanmar (Mandalay and Shan), and China (Yunnan). Only the Nepalese localities have been verified by reproductive anatomy. Thus, the specific and generic identities of shells from other areas remain questionable.

Diagnosis. The anatomical characters of some Nepalese species of Landouria were investigated by Schileyko & Kuznetsov (1998), comprising Landouria savadiensis ( Nevill, 1877) , L. aborensis Godwin-Austen, 1918 , L. dhaulagirica Schileyko & Kuznetsov, 1998 and L. rhododendronis Schileyko & Kuznetsov, 1998 . However, the anatomy of the type species is unknown. The important characters of the genus as suggested by Páll-Gergely et al. (2013) are: depressed shell, last whorl descending in front, and umbilicus open and broad; flagellum possessing a series of distinct tubercles on its surface and internally with an axial canal from which the secondary smaller canals branch off, and ending in superficial tubercles; penis consisting of proximal and distal portions, verge minute. The vagina is long and possesses longitudinal folds on the inner wall. The gametolytic sac is very thin except for the swollen base, and a small globose sac at the distal end; dart apparatus and mucus glands absent.

Remarks. In the original description of the genus Landouria, Godwin-Austen, 1918 included five species from Sri Lanka and the Himalayas (northern and north-eastern India). Schileyko & Kuznetsov (1998) added four species from Nepal to the genus. Other species were described and reported from Indonesia and the Philippines, and have often been mentioned as Landouria ( Rensch, 1931; Zilch, 1966; Marwoto, 2016). However, the systematic positions of these island taxa remain uncertain. By compiling distribution records, Schileyko & Kuznetsov (1998) concluded that the genus is restricted to northern India, Nepal, northern Burma, and Sri Lanka. According to Godwin-Austen (1918), the Sri Lankan L. radleyi showed a short and oval flagellum with an elongated distal end with no sign of tubercles, which are characteristic of other Landouria species. Therefore, L. radleyi probably needs to be reclassified in another possibly undescribed genus.