Choroterpes (Dilatognathus) nigella (Kang & Yang 1994)

Kluge, Nikita J., 2014, Indonesian species of Dilatognathus Kluge 2012 (Ephemeroptera, Leptophlebiidae, Choroterpes s. l.) and species-specific sexual dimorphism in development of maxilla, Zootaxa 3786 (1) : -

Choroterpes (Dilatognathus) nigella (Kang & Yang 1994)

= Choroterpides nigella Kang & Yang 1994 = Dilatognathus/g(1) sp.3: Kluge 2012

Material. THAILAND: province Mae Hong Son, river Namlang near Lot Cave, 12.I.1998, coll. V. Ivanov: 17 larvae; province Muang Pai, river Pai, 11.I.1998, coll. V. Ivanov: 7 larvae; SW Chiang Mai, Doi-Ithanon, river Klang, 17.I.1998, coll. Grigorenko: 1 larva; national park Kaeng Krachan, river Pchetchabun, 26.II.2006, coll. M. Chertoprud: 4 larvae. CHINA, HAINAN, Miao-Li, 19.XII.1957, coll. N. Andrianova: 2 larvae (one of them with developing cuticle of next instar).

Additional characteristics. Larva. Described by Kang & Yang (1994). Differs from all other species of Dilatognathus by shape of labrum, whose median incision is deep, semicircular and bordered by sharp semicircular impression on dorsal surface (Kang & Yang 1994: Fig. 3A). Structure of maxillary apex in penultimolarva is the same as in ultimolarva: with long tusk bearing 3 vestiges of ventral pectinate setae, without ventro-apical flange and without dentiseta.

Imago. Unknown.

Egg. Described by Kang & Yang (1994).

Dimension. Length of ultimolarva 6–10 mm.

Distribution. Indochina Peninsula ( Thailand), Hainan and Taiwan Islands.

Discussion. Kang & Yang (1994) described Choroterpides nigella based on larvae and eggs. They did not compare Ch. nigella with Ch. minor . As characters distinguishing Ch. nigella from Ch. major , only two ones are named: (1) transversal curved row of long setae on labrum and (2) tooth-like maxillary tusk with three comb-like setae at its base. Actually, both characters are present in all Dilatognathus, including Ch. (D.) major (Ulmer 1939: Figs 262, 265).