Alainites lingulatus

General appearance
Body size small medium up to about 5mm long (excluding antennae & cerci)
Body cylinderical & elongated

Head
Frontal ridge on head between antennae (absent in other Baetis spp.)

Thorax
Hindwing pads well developed
No villiopore on femora
Legs pale without dark marking: a large whitish mark on femora dorsally in mature larvae, but might be unnoticeable in early instars
Dorsal surface of femora, tibiae and tarsi densely covered with trapezoidal scales

Abdomen
7 pairs of gills I - VII, single, tracheated but poorly seen
Posterior margins of terga II - X with triangular spines
Paraprocts with a tongue-like prolongation
Cerci length is slightly longer than half of body length; central filament is about third quarter of cerci length

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 Sam A Shui Tsuen (Lantau Island), Pak Ngau Shek, Chuen Lung, Hok Tau, Tai Mong Tsai (Sai Kung) and Tai Shui Hang (Ma On Shan).

Reference:
Tong, X. & Dudgeon, D. (2000) Two new species of Alainites (Ephemeroptera: Baetidae) from Hong Kong, China. Pan-Pacific Entomologist 76: 115-120.

Remarks:
Larvae of Alainites lingulatus Tong & Dudgeon resembles A. clivosus Chang & Yang from Taiwan. Both of species are having 7 pairs of gills and triangular spines on posterior marginal of abdominal terga II - X. However, A. lingulatus could be distinguished by paraprocts that possess long tongue-like prolongation and presence of a row of 8 - 11 denticles on tarsal claws (cf. 11 -13 denticles in A. clivosus).