Erhaia Davis & Kuo, 1985

Gittenberger, Edmund, Leda, Pema, Wangchuk, Jigme, Gyeltshen, Choki & Bjoern Stelbrink,, 2020, The genera Erhaia and Tricula (Gastropoda, Rissooidea, Amnicolidae and Pomatiopsidae) in Bhutan and elsewhere in the eastern Himalaya, ZooKeys 929, pp. 1-17 : 3

Genus Erhaia Davis & Kuo, 1985

Type species by original designation.

Erhaia daliensis Davis & Kuo, in Davis et al. 1985.

Shells.

The shells vary from conical to more or less ovoid, rarely with a flaring final part of the body whorl. The apex is flattened as in the European amnicolid genus Bythinella Moquin-Tandon, 1856, because of the very low spiral of the protoconch. The peristome is continuous and may be more or less protruding. The parietal and the columellar side of the aperture are about equally long and the regularly curved palatal side of the aperture gradually passes into the basal side, forming a single, regularly curved border. Bythinella cannot be distinguished from Erhaia conchologically, but in some Erhaia species from China the columella has one or two spiral lamellae, that are not known from Bythinella. In Erhaia the protoconch may have spiral striae, which have not been described for any of the Bythinella species.

Distribution.

The genus Erhaia is mainly known from China, where it has been recorded with various species from the province of Yunnan in the west to the provinces of Hunan, Hubei and Fujian in the east ( Davis et al. 1985; Davis and Kang 1995; Davis and Rao 1997; Wilke et al. 2000, 2001; Liu et al. 2014). One species was described from northern India ( Davis and Rao 1997), three from Nepal ( Nesemann et al. 2007) and one from Bhutan ( Gittenberger et al. 2017a). Here we deal with the systematics of only the species occurring in the southern Himalayan foothills in Bhutan, India, and Nepal.