Tortopus Needham & Murphy

Molineri, Carlos, 2010, A cladistic revision of Tor top us Needham & Murphy with description of the new genus Tortopsis (Ephemeroptera: Polymitarcyidae), Zootaxa 2481, pp. 1-36 : 9-11

Tortopus Needham & Murphy

Tortopus Needham & Murphy (in part), 1924: 23; Ulmer (in part), 1933: 197; Traver (in part), 1950: 596. Type-species: Tortopus igaranus Needham & Murphy , original designation.

Species composition: T. igaranus , T. circumfluus , T. harrisi , T. zottai , T. bellus , T. arenales sp. nov.

Adult: fore legs of male normal, remaining legs of male and all legs of female distorted and non-functional. Mesosternum: furcasternal protuberances approximating each other anteriorly (Fig. 4) so furcasternal longitudinal impression narrow basally and progressively wider posteriorly. Female pronotum with thin anterior portion (or ring), about 1/6 of the total length of pronotum in dorsal view. Wings sexually dimorphic, all veins of female thickened; posterior margin of hind wings of female with a reticulated pattern of veinlets. Female fore wing with veins R3 and short intercalary before it present (Fig. 8). Abdomen. Female abdominal sternum VIII with relatively small and deep sockets (forceps receptors), with its openings directed anteriorly, and with well marked longitudinal furrows on sternum associated to them ( Figs. 70–71 ). Male genitalia: abdominal sternum IX divided by a mediolongitudinal membranous furrow (Fig. 2); parastyli short, straight and pointed, less than 3 times the length of their bases; penes bladelike with their basal 1/5–1/4 fused (Fig. 2); lateral margin of penes narrowly sclerotized, apex not forming a hooked spine. Penial arms formed by a single transverse bar which is articulated to the posterior corners of tergum IX. Forceps two-segmented, basal segment short and small, with a ventral knob (Figs. 2); distal segment long, slender and clublike.

Nymph (only the nymph of T. harrisi is known, for a complete characterization see Molineri et al. 2010): head with fronto-clypeal region expanded, straight and not surpassing ventrally the mandibular tusks ( Fig. 95 ); mandibular tusks long with two large tubercles (submedian and subapical) on inner margin; maxilla with a basal finger like gill. Large filtering setae present on mouthparts and fore legs. Apex of tibia-tarsus in fore legs not strongly expanded (dorsal projection 2/5 of total length of claw). Abdomen with vestigial unilamellate gill on segment I.

Eggs. Hemispherical, bowl-shaped ( Figs. 67–69, 72 ). Length, 325–400 µm; width, 260–345 µm. No polar caps or attachment structures. Chorion with microsculptures consisting of slightly elevated pentagonal and hexagonal cells, or shallow subcircular grooves.

FIGURES 2–9. Tortopus igaranus . 2, male genitalia, ventral view (f1 and f2 = forceps segment 1 and 2, k = knob, mf = median furrow, pe = penes, ps = parastilus, sIX = ninth abdominal sternum); 3, same, lateral view; 4, mesofurcasternal plates (female paratype, fsi = furcasternal impression, fsp = furcasternal plates); 5, head (female paratype); 6, sockets on abdominal sternum VIII (female paratype, da = depressed area, s = socket, so = sockets´openning); 7, same (holotype); 8, fore wing (female paratype, R2, R3 and R4+5 = main veins of radial sector, IR = radial intercalary, iv = intercalary vein); 9, hind wing (female paratype).

Discussion and diagnosis. The adults of Tortopus can be separated from those of its sister genus Tortopsis by: 1) mesofurcasternal plates approximating each other only basally, with inner margins diverging posteriorly from their basal 1/3 or less (Fig. 4); 2) male abdominal sternum IX longitudinally divided by a median furrow (Fig. 2); 3) parastyli short, less than 3 times the length of their bases (pedestals); 4) penes bladelike and basally fused, at least on basal 1/5; 5) female fore wing with veins R3 and short intercalary present (Fig. 8) (veins IRSa and RSa 2 in Kluge 2004); 6) sockets on female abdominal sternum VIII relatively small and submedian in position ( Fig. 70 ), openings towards fore margin of sternum. The characters useful to separate Tortopus and Tortopsis from the other genera of the family are listed in the phylogenetic section (apomorphies of node c). The coupling apparatus of Tortopus s.s. apparently involves male forceps (not parastyli, poorly developed) and female sockets. Male forceps are not large enough to embrace female abdomen, but they seem to fit in the submedian sockets. Parastyli are so poorly developed that they could not reach female sockets during copula. In contrast, the coupling apparatus of Tortopsis (described in McCafferty & Bloodgood, 1989, for a species now moved to Tortopsis , see below) involves the strongly developed male parastyli and female sockets.

Figures

FIGURES 67 – 72. SEM photographs. Tortopus igaranus: 67, egg, general view; 68, egg, detail of convex side; 69, egg, detail of concave side. Tortopus arenales: 70, female abdominal sternum VIII; 71, same, detail of sockets; 72, eggs.

FIGURES 93 – 96. Polymitarcyidae, nymphal head: 93, Asthenopus sp.; 94, Campsurus near violaceus; 95, Tortopus harrisi; 96, Tortopsis obscuripennis.