Notacanthurus Tshernova, 1974

Braasch, Dietrich & Boonsoong, Boonsatien, 2009, A new Notacanthurus Tshernova, 1974 and a new Rhithrogena Eaton, 1881 (subgenus Tumungula Zhou & Peters, 2004) from Thailand (Heptageniidae, Ephemeroptera), Zootaxa 2166, pp. 33-44 : 34

Genus Notacanthurus Tshernova, 1974

(Type species: Notacanthurus zhiltzovae [ Ecdyonurus ] Tshernova, 1972)

The outlines of genus Notacanthurus described herin are comprehended in the sense of Braasch (1986) and Kluge (2004). The main characters of the males are: anterior part of head strongly extended; ventrally with infolded lapels (Braasch 1986: p. 120, Figs. 1, 2); eyes contiguous; forewings with shadened crossveins between C, Sc and R1. Penis lobes fused and bulging to somewhat bilobed, with exclusion of apex being incised (Braasch 1986: p. 120, Figs. 4, 8, 7); dorsal penis with small triangular or subquadrangular apicolateral sclerites, ventrally incompletely sclerotized.

Larvae of Notacanthurus are characterized by head broadened laterally (HI = 1.3 – 1.4); abdominal terga I – IX with longitudinal dorsal ridge, (in most species having shape of spines posteriorly; except N. edentatus Braasch,1986 which has a median dorsal ridge only) (Braasch 1986). Pattern of terga mainly consists of pairs of conspicuous oblique stripes directed inwards distally; posterior margin of terga with densely positioned tiny bristles producing look of chagrination; on femur of mature larvae a striking middle cross band as in imagines of many Electrogena Zurwerra & Tomka, 1985 , for instance in mature larva of E. affinis (Eaton, 1885) , a femur band is visible but not consistent in alcohol); claws of legs presumably in all known northern hemisphere Notacanthurus species without denticulation; gill I banana-like, gills II – VI ellipsoid-elongated to rounded-triangular plate, gill VII obliquely lanceolate, tufts of filaments moderately evolved; hypopharynx with compact supralinguae shortly reversed, lingua widened at its base; mandibles (Braasch 1986: p. 121, Figs. 18.1 – 18.4) with long shafts and slender incisors, inner margin completely covered by numerous, apically rounded toothlets; labium with stocky, short-stalked glossae, apically rounded; maxillae with scattered bristles on dorsal surface, crown of maxillae with 21 – 24 comb-like bristles. Caudal filaments with whorls of small spines. Notacanthurus was placed together with Electrogena in tribus Notacanthurini ( Wang and McCafferty 2004). Kluge (2004) stated the autapomorphy of larvae of Notacanthurus as having terga median longitudinal ridge with ‘spines posteriorly.’ Recently, Webb and McCafferty (2007) have made evident such a median dorsal ridge in larva of the new genus Darthus ( D. vadorus Webb & McCafferty, 2007 ) from Borneo, too.