Labiobaetis atrebatinus

Body cylinderical & elongated, frontal ridge on head between antennae

Antennal scape with a distinct lobe at distolateral margin
Terminal segment of maxillary palpus with a distinct concave near apex

Hindwing pads present
No villiopore on femora
Legs pale without marking

7 pairs of gills I - VII, single, tracheated but poorly seen
Abdominal terga II - IX with a pair of submeidal oblique dashes & a pair of small dots in midregion

Terminal filament is not reduced -- 3 caudal filaments are shown clearly
Cerci length is slightly longer than half of body length

The following specimen was mounted in slide. Just for reference.

Legs

 

Its mouthparts of labrum, mandibles, maxillae and labium are illustrated as follow (hypopharynx is excluded).

Labrum

Maxillae

Mandibles

Labium

 

Distribution:
In Hong Kong, specimens are recorded from Lam Tsuen River, Ha Wun Yiu, Pat Ngau Shek, Chuen Lung, Tan Shan River, Nam Chung River, Tan Chuk Han, Tai Po Kau Forest Stream, Ho Chung, Tai Mong Tsai, Sha Kok Mei (Sai Kung).

Reference:
Shi, W. & Tong, X. (2014) The genus Labiobaetis (Ephemeroptera: Baetidae) in China, with description of a new species Zootaxa 3815(3): 397-408.