CLADOENDESIS OF EPHEMEROPTERA

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Autapomorphies of Oligoneuriella/fg1. 

(1) Penis [see Geminovenata (6)] has peculiar structure (Kluge 2004: Fig.46:B-47:A,B). Paired penis lobes are completely separated and deeply inserted into segment IX; ventral wall of each penis lobe bears a sclerotized process directed medio-ventrally; this process is always completely hidden by sternite IX and styliger (unique apomorphy); shape of these processes differs in Oligoneuriella/g2 and Oligoneuriopsis. Distal part of each lobe (projected externally) consists of a lateral longitudinal sclerotized lobe and a median telescopic lobe with gonopore at its apex. Apices of lateral sclerotized lobes are more or less curved medially toward one another. Located between them median telescopic lobes are cylindrical, at rest have length subequal to the lateral lobes, and in everted condition can become several times longer. Inverted surface of the telescopic lobe is densely covered by microtrichia, which in everted condition are directed proximally, and in inverted condition – distally. Besides Oligoneuriella/g1, a pair of cylindrical telescopic lobes are present in Homoeoneuria/g2 (see below), but there penis structure is different, and paired lobes have a common unpaired base.

(2) In male imago middle and hind legs [non-functional – see Geminovenata (2)] before the last (claw-bearing) segment have 2 segments only (if not take into account the first segment, which is fused with tibia, shortened, and non-expressed), thus tarsus looks as 3-segmented. Non-unique apomorphy: the same in Elassoneuria/g2 (but not in Elassoneuria/g1-Madeconeuria).

Plesiomorphies of Oligoneuriella/fg1. On fore wing RSa+iRS is present (unlike Elassoneuria/g1 and Homoeoneuria/g2), not approximated to RA (unlike Lachlania and Oligoneuria/f5=g6); bifurcation of MA is situated near wing base (unlike Elassoneuria/g1) (Demoulin 1952b: Fig.1). Gonostylus is developed (unlike Homoeoneuria/g2 and Fittkauneuria), has not less than 2 distal segments [see Discoglossata (12)] (unlike Oligoneuria/f4=g5). Larval head shield has no keel (unlike Elassoneuria/g1), anterior margin of head shield with long setae directed anteriorly and medially [see Discoglossata (1)] (Kluge 2004: Fig.44:E-F).

Variable characters of Oligoneuriella/fg2. Variable characters of Oligoneuriella/g2. Paracercus is usually well-developed in mature larva and adult, being vestigial in young larva; in some species paracercus of mature larva is also vestigial – particularly in bicaudata [Oligoneuriella].