CLADOENDESIS OF EPHEMEROPTERA
Heptagennota Pentamerotarsata Radulapalpata Rhithrogena/fg1
Epeorus/fg1 - Epeorus/fg2)
Nomen hierarchicum: Epeorus/fg2 [f:2004; g:1881] (sine Bleptus; incl. Ironodes)
In circumscription fits:
gen. Epeorus: Edmunds & Traver 1954
Epeorus/g2: Kluge 2004: 202.
References. Tshernova 1974: *; 1976: *; Kluge 1988: * *; 1993: * *; 2004: * * *
Autapomorphies of Epeorus/fg2.
(1) Tergalius I is more or less widened anteriad of costal rib, thus the costal rib passes at a distance from margin (unlike Bleptus, where all tergalii ribs are marginal).
(2) On tergalii IIVII strongly developed costal rib (which, unlike tergalius I, retains its position on costal margin) is covered by dense short stout curved pointed spine-like setae (Kluge 2004: Fig.64:J). Probably, this helps larva to couple with stone, on which larva sits in a stream: tergalii are immovably spread by sides and pressed by their costal margins to the substrate. Such specialization of tergalii appeared to be possible, because tergalii are unable to respiratory movements [see Rhithrogena/fg1 (6)].
(3) Dorsal side of larval body bears stripes of dense thin hairs: anterior margin of head shield [see Heptagennota (1)] is widened and bears a stripe of very dense thin hairs directed anteriorly or dorsally; dorsal side of each tibia bears a longitudinal stripe of dense thin hairs directed dorsally.
Similar stripes of dorsally directed hairs on various parts of body (legs, head, caudalii, abdomen) evolved in various mayfly groups where larvae are specialized for inhabitancy in rapid streams. Probably these hairs have some hydrodynamic importance. In other Radulapalpata such hairs are not developed or weakly developed. Judging by uniform structure and position of hairs on head and tibiae of Epeorus/fg2, in this taxon these hairs have common origin (i.e. represent an autapomorphy of Epeorus/fg2). Besides this, dorsal stripes of hairs on other parts of body (cerci, abdomen) evolved independently in selected groups of Epeorus/fg3.
Size. Fore wing length 720 mm.
Distribution. Holarctic and Oriental Region.
|The taxon Epeorus/fg2 is divided into:|
2.3.1. plesiomorphon Albertiron
2.4.1. plesiomorphon Iron/g2