Baetiella marginata Braasch 1983

Baetiella marginata Braasch, 1983

(Figs 48, 52)

Baetiella marginata: Braasch, 1983: 153

Diagnosis. Vertex of head and dorsal surface of thorax without tubercles or elevation (Fig. 52); abdominal terga without dorsal protuberance (Fig. 48), surface of terga and sides of sterna each with numerous pores. Hind wing pads minute; gills present on segments I–VII, oval and without tracheation, surface scattered with numerous pores, margin smooth with long fine setae. Paraproct with many pores and short fine setae medially, inner margin with 4– 6 blunt setae. Cerci longer than body length; inner margin of cerci with 1–6 swimming bristles successively increasing in number towards apex; median caudal filament with 3–4 segments.

Material examined. CHINA, Tibet: 1 nymph on slides and 3 nymphs in ethanol, Medog County, Lage Town (29.47°N, 94.99°E, alt. 3,520m), 26.ix.2010, leg. Xianfu Li.

Distribution. China (Tibet), Nepal.

Comments. The type material of Baetiella marginata Braasch, 1983 was not available for this study, but our specimens collected from Tibet exactly match with the illustrations and descriptions by Braasch (1983). Judging from the morphological characteristics and geographical range, we consider it as a newly recorded species for the Chinese mayfly fauna. B. marginata Braasch was originally collected in a mountainous stream (alt. 1,950m) near Dhunche of Nepal (Braasch 1983). Our specimens were also collected from a stream 3,520 meters above sea level in Tibet. The surfaces of abdominal sterna and gills of this species are covered with numerous pores which may be related to adaptation for hypoxic environment in high altitudes.