Epeorus (Belovius) unicornutus Braasch, 2006

Boonsoong, Boonsatien & Braasch, Dietrich, 2013, Heptageniidae (Insecta, Ephemeroptera) of Thailand, ZooKeys 272, pp. 61-93 : 65-66

Epeorus (Belovius) unicornutus Braasch, 2006 Fig. 5F

Epeorus (Belovius) unicornutus Braasch, 2006: 80, 82, Figs 1-8. (orig.)

Larva.

Braasch 2006b: 80, 82, Figs 1-8.

Adult.

Unknown.

Eggs.

Unknown.

Distribution.

Nam Thob Ranger Station, Phu Luang Wildlife Sanctuary, Nam Thob stream (Loei province).

Diagnosis.

The larva of Epeorus unicornutus can be distinguished from that of other congeners by the combination of the following characters: abdominal terga 2-9 each with single, prominent, acute median spine and with a row of short spines on posterior margin, tergum 10 with short spines and hair-like setae on posterior margin.

Habitat and biology.

Larvae of Epeorus unicornutus are found in headwater streams shaded under tree canopies in mountainous areas (alt 330 m) where the streams are 10-12 m wide and 10-15 cm in depth. The water temperature ranges between 22-23°C, pH between 7.0-7.2, total dissolved solids range between 18-20 mg/L, and conductivity between 28-30 µS /cm. The larvae are found underneath stones in fast flowing reaches of the streams. The coarse mineral substrate consists of boulder (60%), cobble (30%), gravel and coarse sand (10%), and abundant fallen leaves. Epeorus unicornutus is found under minimally disturbed conditions of Nam Thob streams, Loei province.

Remarks.

Braasch (2006b) described this species based on larval specimens from River Indravati near Dalaghat 1,200 m, Nepal, Himalayas. In this study, this species were found from northern and northeastern parts of Thailand. This species is different from other known species of the genus Epeorus by abdominal terga 2-9 each with single, prominent, and acute median spine.