Alainites acutulus

General appearance
Body size medium-small up to about 5mm long (excluding antennae & cerci)
Body cylinderical and elongated; frontal ridge on head between antennae

Head
The details for mouthparts illustrated in the following pictures

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
6 pairs of gills II - VII, single, tracheated but poorly seen
Posterior margins of terga I - VII without spines
Paraprocts with a pointed prolongation
Cerci length is slightly longer than half of body 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 Tai Po Kau Forest Stream, Shing Mun and Ng Tung Chai.

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 acutulus Tong & Dudgeon resembles A. yehi Chang & Yang from Taiwan. Both of species are having 6 pairs of gills and abdominal terga I - VII without posterior marginal spines. However, A. acutulus could be distinguished by paraprocts that possess short acute prolongation and by presence of a row of long robust setae on dorsal margin of femora.