(Panephemeroptera Euephemeroptera Euplectoptera Anteritorna Bidentiseta Branchitergaliae
Heptagennota Pentamerotarsata Radulapalpata 
Stenonema/fg1 - Stenonema/fg2)

Nomen hierarchicum: Stenonema/fg2 [f:2004; g:1933] (sine Stenacron, Macdunnoa)

In circumscription fits:

— subgen. Stenonema: Kluge 1983b: 16 (unpublished)

— gen. Stenonema: Jensen 1974: 225

— Stenonema/fg2: Kluge 2004: 174

References. Edmunds & Jensen & Berner 1976: * *; – Lewis 1978a: *; – Bednarik & McCafferty 1979: * *; – Kluge 2004: * * * *.

Character of Stenonema/fg2 of unclear phylogenetic status.

(1) Tergalii I–VI are not pointed (unlike Stenacron), apically obliquely truncate or rounded, with anal margin the longest [that is connected with development of anal rib – see Stenonema/fg1 (2)] (Edmunds & al. 1976: Fig.126–127).

Plesiomorphies of Stenonema/fg2. Unlike Macdunnoa, tergalii VII [thin and lacking fibrillose portion – see Stenonema/fg1 (3)] are not shortened.

Variable characters of Stenonema/fg2. In selected species of Stenonema/fg2 on maxilla the apical-ventral row of pectinate setae [see Radulapalpata (3)] is vestigial; this character was erroneously regarded as an apomorphy of the whole taxon Stenonema/fg2; actually in some species up to 9 normally developed pectinate setae can be present (Bednarik & McCafferty 1979: 6).

Size. Fore wing length 6–16 mm.

Distribution. North and Central America (dominate in Eastern Nearctic).

The taxon Stenonema/fg2 is divided into:

1. Stenonema/fg3

2. Maccaffertium