Erhaia Davis & Kuo in Davis et al., 1985

Gittenberger, Edmund, Gyeltshen, Choki & Stelbrink, Bjoern, 2022, The genus Erhaia (Gastropoda, Truncatelloidea, Amnicolidae), with a new species from Bhutan, ZooKeys 1085, pp. 1-9 : 1

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

Type species by original designation.

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

Synonym.

Pseudobythinella Liu & Zhang, 1979. Not Melville, 1956. Type species by original designation: Pseudobythinella jianouensis Liu & Zhang, 1979.

Description.

Shell ovoid to elongate ovoid or conical, smooth or with spiral microsculpture on the proto- and/or teleoconch. Apex conspicuously and more or less obliquely flattened. Aperture varying from ovoid-elliptical to circular; its palatal side curved and gradually passing into the basal side. Peristome continuous, attached at the parietal side or more or less protruding. Umbilicus minute or closed. Parietal part of the aperture smooth or with a lamella; columella smooth or with 2 spiral lamellae.

Notes.

Molecular data, which are available for only a limited number of the amnicolid species, are inconclusive regarding the status of Erhaia versus Akiyoshia Kuroda & Habe, 1954 Gastropoda, Truncatelloidea , Amnicolidae ) (see also the more comprehensive phylogenetic reconstruction in Gittenberger et al. 2020). No DNA data are known for the type species of these nominal taxa, i.e., E. daliensis Davis & Kuo, 1985 and A. uenoi Kuroda & Habe, 1954. Furthermore, the species that are generally called Erhaia jianouensis (Liu & Zhang, 1979) and Akiyoshia kobayashii Kuroda & Habe, 1958 are sister species (Fig. 7 ) that should be congeneric by definition. At present, their ranges in China and Japan, respectively, have been decisive for the generic classification. Pending additional data that can help solve this problem convincingly, we opted to still use the current, contradictory nomenclature (see also notes under E. norbui sp. nov.).

Distribution.

The genus Erhaia was initially reported from a wide range in southern China, where it has been recorded with various species from the provinces of Yunnan, Sichuan, Guangxi, Hubei, Hunan, and Fujian ( Davis et al. 1985; Davis and Kang 1995; Davis and Rao 1997; Wilke et al. 2000, 2001; Liu et al. 2014). Regarding its occurrence in Japan, see foregoing notes. One species was described from northern India ( Davis and Rao 1997), three additional species were described from Nepal ( Nesemann et al. 2007), and, most recently, three species were described from Bhutan ( Gittenberger et al. 2017, 2020). Here, we describe a fourth species from Bhutan and present, for the first time, a map of all known records of the genus (see Fig. 1 and Table 1 ). As usual, it is unknown where snails may have been looked for in vain and thus our distribution maps (Figs 1 , 6 ) may represent human sampling activity rather than the real range of Erhaia . Contrary to Gittenberger et al. (2020), in the absence of DNA data, we refer to E. chandeshwariensis Nesemann & S. Sharma, 2007 as a species closely related to E. nainatalensis Davis & Rao, 1997. The shells cannot be distinguished, but the type localities are over 600 km apart, which makes conspecificity unlikely in Erhaia . Remarkable facts are the allopatric distribution and diversification in this genus in general, the syntopic occurrence of E. jannei Gittenberger & Stelbrink, 2020 and E. pelkiae Gittenberger & Gyeltshen, 2020 in Bhutan (Fig. 6 ), and that of E. banepaensis Nesemann & S. Sharma, 2007 with either E. chandeshwariensis or E. sugurensis Nesemann, Shah & Tachamo, 2007 in Nepal (Fig. 5 ).

Figures

Figure 1. Distribution of Erhaia species across Asia.

Figure 6. Distribution of Erhaia species described for Bhutan. Note that E. jannei and E. pelkiae were found to occur syntopically.

Figure 7. Maximum likelihood tree reconstructed with RAxML BlackBox (Stamatakis et al. 2008; GTR + G substitution model for each partition and 100 bootstrap replicates) based on the COI and 16 S rRNA dataset of Liu et al. (2014) and Guan et al. (2008), with new data in red. Numbers on branches denote bootstrap values> 50.

Figures 3 - 5. Erhaia norbui sp. nov. from the type locality, district Haa, Uesu, Naychu, ca. 2700 m a. s. l. 3 holotype, NBCB 1239 (H = 2.3 mm) and paratypes used for DNA analyses (4 UGSB 25956, H = 1.5 mm 5 UGSB 25957, H = 1.8 mm). Scale bar: 1 mm.