Mortogenesia Lestage, 1923: 110

Soldán, Tomáš & Godunko, Roman J., 2013, Description of larva, redescription of adults and biology of Mortogenesia mesopotamica (Morton, 1921) (Ephemeroptera: Palingeniidae), Zootaxa 3741 (2), pp. 265-278 : 266

Mortogenesia Lestage, 1923: 110

Type species: Palingenia mesopotamica Morton, 1921 , original designation

Mortogenesia Lestage : Ulmer, 1933: 196; Buldovsky, 1935a: 833; Buldovsky, 1935b: 153; Demoulin, 1952: 4; Edmunds & Traver, 1954: 240; Demoulin, 1958: 6; Demoulin, 1965: 312; McCafferty, 1991: 354 Mortogenesia /g(1): Kluge, 2004: 255

Adult. Large mayflies, with body length about 21–26 mm and length of forewings 17–28 mm. Head about twice as broad as long with obtuse epicranial suture angle. Frontal ocellus smaller by 1/2 than lateral ones. Distance between eyes approximately as long as the eye width.

Pronotum about three times broader than long. Forewings longer by 1/4 than abdomen. Wings with rich transversal venation, longitudinal veins not paired. Vein CuA of forewings simple; veins MP1 and iMP are not brought together. Bifurcation of MA more distally that bifurcation of Rs. Forelegs distinctly longer than hind legs. All tarsi five-segmented. In males, all legs with two claws; fore claws paddle-like; those of middle and hind legs more slender, pointed apically. In females, legs strongly reduced; tarsal segments of all legs fused together, with completely eliminated segmentation; all claws simple.

Forceps base widely arc-shaped. Forceps with 6–7 segments. Penis lobes roughly triangular, rounded at apex, divergent (approximately at the right angle), reaching to about 1/3 of the length of forceps segment 1. Cerci well developed, paracercus reduced, with 6–8 segments, membranous without any bristles.

Larva. Head with two pairs of clypeal spines of irregular shape and two pairs of genal pointed spines. Mandibular tusks with 7 heavily sclerotized, large and stout teeth on outer margin; lack of apical spine-like seta on these teeth. Maxillary palps two-segmented. Labial palps two-segmented; apical segment strongly asymmetric, spoon-shaped; basal segment oval, with conspicuous basal group of very long and strong bristles situated medially. Foretibia stout with conspicuous outer sclerotized spines. Fore claws roughly triangular, with broad basis, about twice as long as wide, without denticles.

Gill 1 leaf-like, simple, with distinct simple trachea. Gills 2–6 with blunted apically posterior branches. Gill 7 with pointed and narrow posterior branch, as long as the anterior one. Gills 2–7 with distinct branched central trachea in both anterior and posterior parts.

Differential diagnosis. In both adult and larval stage, the genus Mortogenesia is most related to the genus Palingenia . In adults, there is primitive wing venation with not geminated longitudinal veins and vein CuA of forewing is simple, without bifurcation (CuA bifurcated and geminated longitudinal veins in Anagenesia , Plethogenesia and Cheirogenesia ); forewing veins MP1 and iMP are not brought together (in contrast to Cheirogenesia ); forceps with 4–7 segments (usually two-segmented in the other genera, exceptionally foursegmented in some Anagenesia ). In larvae, integral denticles are present on mandibular tusks (present in Cheirogenesia ; in other genera articulated spine-like setae only) and outer margin of foretibia are provided with conspicuous sclerotized spines (other genera with spine-like setae only). However these characters are evidently plesiomorphic, they single the genera Palingenia and Mortogenesia out from other Palingeniidae showing evident apomorphies: reduced number of forceps segments and reduced of wing venation tending to geminated longitudinal veins.

Mortogenesia can be distinguished from Palingenia according to the following characters: In adults, (i) distance between eyes approximately as long as the eye width (smaller than the eye width or eyes nearly contiguous in Palingenia ), (ii) each claw of a pair similar in male (dissimilar in Palingenia ), (iii) tarsi of hind legs five-segmented (four-segmented in Palingenia ), (iv) penis lobes roughly triangular, rounded, divergent (long and slender, slightly or moderately divergent in Palingenia ). In larvae, (i) distance between eyes like in adults, (ii) maxillary palps two-segmented (three-segmented in Palingenia ), (iii) distal segment of labial palps asymmetric, bulbous (nearly symmetric, cylindrical or rounded in Palingenia ), (iv) basal segment of labial palps with conspicuous group of bristles near the base on inner margin (no conspicuous group of bristles apparent in Palingenia ), (v) claws of forelegs short, triangular, at bases as wide as tarsus (claws longer, at bases as wide as one half of tarsus width in Palingenia ), (vi) gill 1 simple, leaf-like (bilobate, roughly V-shaped in Palingenia ), (vii) gills 2–6 with blunt apex of posterior branches and with distinct branched central trachea in both anterior and posterior parts (rounded apex of posterior branches and not branched central trachea in Palingenia ).