Epeorus aculeatus Braasch

Webb, J. M. & Mccafferty, W. P., 2006, First description of the adult male of Epeorus aculeatus Braasch (Ephemeroptera: Heptageniidae), Zootaxa 1277, pp. 65-68 : 65-67

Epeorus aculeatus Braasch

Epeorus aculeatus Braasch, 1990:7 ; Nguyen and Bae, 2004: 19

Adult description (in alcohol)

Body length 10.6 mm; forewing 10.4 mm; caudal filaments 27.0 mm. Eyes grayblack, contiguous dorsally. Ocelli black basally, white apically. Frons pale brown. Thorax brown; mesonotal transverse suture absent; medial depression of mesothoracic furcasternum convergent anteriorly; mesosternum with dark transverse band ( Fig. 3 ). Forefemur pale brown with dark brown spot medially, dark apically; tibia and tarsus brown; ratio of foreleg segments (F:Ti:Ta1:Ta2:Ta3:Ta4:Ta5) 5.5:6.6:2.4:2.3:2.0:1.3:0.7; foreclaws dissimilar. Midleg light brown, femur with dark spot medially. Hindlegs missing. Wings with veins brown. Abdominal terga 2–7 yellowish brown with brown markings ( Fig. 1 ); terga 8–10 brown with dark markings; sterna ( Fig. 2 ) yellowish brown, slightly darker medially. Genitalia ( Figs. 4 and 5 ) brown; base of forceps with small median flange; subgenital plate slightly excavated medially; penes fused basally, widely divergent apically and with titillators present. Caudal filaments brown.

Diagnosis and discussion

Because no other Epeorus from southeast Asia are known from the adult stage, we cannot know how E. aculeatus differs from the other species. Based on larval characteristics, Kluge (2004) indicated that E. aculeatus is closely related to the southern European E. torrentium Eaton , the type species of Epeorus . The penes of E. aculeatus are similar to those of E. torrentium and closely related species in that they are fused basally and divergent apically, but the penis lobes are much more slender. It also differs in having titillators and dissimilar foretarsal claws. We do not feel it is prudent at this time to speculate on the phylogenetic position of E. aculeatus .

Material examined

THAILAND, Chiengmai Province, small stream and waterfalls, Doi Sutep, W of Chiengmai, 1450 ft, 19­XI­1964, WL & JG Peters, 2 reared male imagos with associated exuviae (penes missing from one specimen).

Figures

FIGURES 1 – 5. 1, dorsal view of male; 2, ventral view of male abdomen; 3, thoracic sternum of male; 4, dorsal view of penes; 5, ventral view of penes.