Erhaia wangchuki, Gittenberger, Edmund, Sherub, Sherub & Stelbrink, Bjoern, 2017

Gittenberger, Edmund, Sherub, Sherub & Stelbrink, Bjoern, 2017, Erhaia Davis & Kuo (Gastropoda, Rissooidea, Amnicolidae) also in Bhutan, ZooKeys 679, pp. 21-28 : 22-23

Erhaia wangchuki sp. n. Figs 1, 2

Material.

District Wangdue Phodrang, Gangchhu (Figs 5, 6), 2883 m alt.; 27°26'N 90°11'E; Jigme Wangchuk leg. 21.iii.2015. National Biodiversity Centre, Serbithang, Thimphu [holotype NBCB1013, paratypes NBCB1014/2].

Shell.

Conical, broader than high, with a flat apex because the initial ¾ -1 whorl is planispiral; 3¼ whorls in total. Body whorl large, the height of the aperture exceeds that of the spire. Aperture with a broadly rounded outer lip and a nearly straight parietal side, so that a columellar border is hardly recognizable. Growthlines moderately strong, with a more prominent periostracal ridge at more or less regular distances. Teleoconch whorls broadly shouldered and separated by a deeply incised suture. Aperture oblique ovoid, smooth inside; apertural edge not touching the penultimate whorl. Umbilicus widely open. The holotype is the largest shell and measures 2.15 × 1.77 mm.

The shell differs from the shells of the three ' Erhaia ' species reported from Nepal by Nesemann et al. (2007) by the large body whorl, the relative height of the aperture, and by being broader than high. The other species that are referred to as Erhaia in the literature, from areas that are further apart than Bhutan and Nepal, also have different combinations of character states.

Notes.

This species is known from the source of the Gangzetem brooklet, emerging from an underground spring aquifer surrounded by blue pine ( Pinus wallichina ) and a small open meadow (Figs 5, 6). The stream bed substrate, viz. pebbles, small rocks and parts of plants, is covered with dark-green algae, housing an abundant diversity of aquatic invertebrates. Alongside the brooklet are rhododendrons ( Rhododendron thomsonii , R. arboretum , R. kesangae ), berries ( Berberies asiatica , Rosa sericea ), betula ( Betula utilis ), larch ( Larix griffithii ), daphne (Daphne bholua) and remnants of dead dwarf bamboo ( Yushania microphyllus ).

A farm road to the villages of Gangphel and Zizi crosses over the stream. The source is very close (~50m) to that road. The stream also spins a chhukhor, i.e. a water powered prayer wheel. At the very outlet of the stream is a water tank, which supplies drinking water to Damchu Lhakhang. The brooklet meanders into the Phobji main stream, and measures about 1100 meters. During the pre-monsoon (21.03.2015) and post-monsoon (29.11.2015), physiochemical properties of the stream were measured. The water is almost neutral (pH 7.06, 7.58) and has a nearly stable temperature (6.76, 6.20 ºC).

Etymology.

wangchuki , after Jigme Wangchuk, who discovered these minute snails.