Erhaia norbui, Gittenberger & Gyeltshen & Stelbrink, 2022

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

Erhaia norbui sp. nov.

Figs 2 , 3-5 , 6

Material examined.

Holotype. (Fig. 4 ) Bhutan • District Haa, Uesu, Naychu , ca. 2700 m a.s.l.; 27°22'33"N 89°17'15"E; Sangay Norbu leg. 2020 (NBCB 1239).

Paratypes. (Figs 5 - 6 ) 3 shells (NBCB 1240), 2 shells (RMNH.MOL.511432).

Diagnosis.

Shell pale greyish, large for the genus (H> 2 mm), with a globular body whorl and a roundish aperture.

Description.

Shell obliquely ovoid, with 3½-3¾ regularly convex whorls that are separated by a deep suture; clearly higher than broad; pale greyish with fine irregular growth lines and some blackish-brown periostracal ridges, one of which runs from the apertural columellar border into the umbilicus. Aperture nearly circular in fully grown specimens, with a continuous, free peristome that is thickened, not reflected; with a minute umbilicus. Protoconch encrusted in all specimens; teleoconch without spiral sculpture.

Measurements of shells with thickened apertural border (n = 6): H 2.3-2.6 mm, B 1.6-1.8 mm. Holotype 2.3 × 1.7 mm.

Shells of E. jannei , which are most similar in shape, are yellowish-brown and a little narrower, with the aperture slightly compressed laterally. The other Bhutanese Erhaia species known, i.e., Erhaia pelkiae and E. wangchucki Gittenberger, Sherub & Stelbrink, 2017, are smaller, i.e. H <2 mm and H <2.2 mm, respectively; their shells are less pale, of an elongated ovoid shape and with an elliptical aperture in E. pelkiae , or conical shape with a piriform aperture in E. wangchucki .

Ecology

(Fig. 2 ). The species was found in spring water among abundant watercress. The annual temperature of the water is 9-12 °C, with pH of 7-8.5 and 6.5 mg/l oxygen.

Molecular data

(Fig. 7 ). Both of the individuals (paratypes) that we analyzed genetically shared an identical haplotype for both COI (GenBank acc. no.: OM135616) and 16S rRNA (GenBank acc. no.: OM135244). The uncorrected genetic p-distances between E. norbui sp. nov. vs. E. jannei and E. wangchuki were 3.97% and 5.19%, respectively, for COI, and 1.42% and 1.22%, respectively, for 16S rRNA.

Notes.

The three Erhaia species from Bhutan form a highly supported clade, with Erhaia sp. from China as the sister-group. Interestingly, the species called E. jianouensis , from China, and Akiyoshia kobayashii , from Japan, form the highly supported sister-group of the remaining Erhaia species (see foregoing notes for Erhaia ). For additional notes regarding the truncatelloidean gastropods of N. India, Nepal, Bhutan, and S. China, in particular the species of Erhaia , see also Gittenberger et al. (2020).

Etymology.

The epithet norbui refers to Mr. Sangay Norbu, who discovered this species.

Figures

Figure 2. Habitat of E. norbui sp. nov. at the type locality. Photo by Mr. Sangay Norbu.

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.