Freshwater Macroinvertebrates in Hong Kong

Baetiella trispinata

General appearance
Body size medium-small up to about 5mm long (excluding antennae & cerci)
Body color yellow brown; thoracic nota with some brown markings and tubercules
Body shape dorso-ventral flattened

Head
The details for mouthparts illustrated in the following pictures

Thorax
Pro- and mesonotum with numerous small tubercules dorsally; metanotum with a single large tubercule medially
Mesonotum with two longitudinal narrow pale stripes next to midline (shown in mature larvae only)
Hindwing pads reduced
Femora with long dense bristles dorsally; a single row of setae on hind femora and tibiae dorsally (cf. two rows in Labiobaetis vera)
The details for each leg illustrated in the following pictures

Abdomen
Gills I - VII single without serrate margins and untracheated
Posterior margins of terga I - III with single median dorsal tubercle, but paired dorsal tubercules on terga IV - IX
Central filament is greatly reduced to give a two-tailed impression; cerci length longer than body length by 1.3 times.

Legs

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

Labrum

Mandibles

Maxillae

Labium

Distribution:
Widespread in Hong Kong, specimens are recorded from Tai Po Kau Forest Stream, Lam Tsuen River, Ng Tung Chai, Shing Mun, Pui O and Shek Mun Lap (Lantau Island).