Asthenopus crenulatus, Molineri, Carlos, Cruz, Paulo Vilela & Emmerich, Daniel, 2011

Molineri, Carlos, Cruz, Paulo Vilela & Emmerich, Daniel, 2011, A new species of Asthenopus (Ephemeroptera: Polymitarcyidae: Asthenopodinae) from Brazil and Colombia, Zootaxa 2750, pp. 33-38 : 34-37

Asthenopus crenulatus sp. nov.

Male imago ( Figs. 1–7 ). Length (mm): body, 7.0–7.8; fore wing, 7.5–8.6; hind wing, 3.1–3.7; fore leg (from coxa to apex of claw), 6.2–6.9; cerci, 21.6. General coloration yellowish white. Head ( Figs. 1–2 ) brownish dorsally except small pale median mark on hind margin, tinged black at base of antennae and on a triangle between ocelli; ventrally much paler, with blackish markings. Antennae yellowish shaded slightly with gray on apex of scape and pedicel, flagellum hyaline; scape and pedicel long and slender, scape (0.23 mm) slightly longer than pedicel (0.18 mm), flagellum long, reaching hind margin of pronotum. Thorax ( Figs. 1–2 ). Pronotum and propleurae translucent yellowish completely shaded with brown, darker on anterior ring, and lateral and hind margins of posterior ring; a narrow pale sinuous strip separates anterior and posterior rings; presternum pale. Mesonotum yellowish shaded gray on sutures mainly between posteroscutal protuberances; mesopleurae and sternum slightly paler with gray shading on anterior half. Metanotum yellowish shaded gray medially, pleurae and sternum paler, translucent. Legs. Forelegs similar in length to body, 0.7–0.9 times the length of the forewing; coxa, trochanter and femur yellowish brown, rest translucent yellowish, shaded gray almost completely but lighter apically. Length (mm) of foreleg segments (mean of two males): femur (0.79), tibia (1.59), tarsite 1 (0.1), tarsite 2 (1.22), tarsite 3 (0.92), tarsite 4 (0.81), tarsite 5 (0.66), longer claw (0.38), shorter claw (0.22). Middle and hind legs with long coxae and trochanters; femora, tibiae and tarsi very reduced and membranous; both legs yellowish, shaded with gray mainly on a basal spot of hind coxa and distal mark on hind femur. Wings ( Figs. 3–4 ). Membrane hyaline except on costal and subcostal sector of fore and hind wings, grayish, sometimes whitish apical half; all veins yellowish brown; short marginal intercalaries (mi in Fig. 3 ) attached along entire hind margin of both wings. Three to four crossveins between R and M sectors basally to R stem (arrows in Fig. 3 ). Ratio Rs length from fork to margin (B in Fig. 3 )/ stem length (A in Fig. 3 ) = 4. Ratio MA length from fork to margin/stem length, range 9 to 11. Abdomen ( Figs. 1– 2 ) whitish translucent shaded very slightly with brownish gray on dorsum, sterna paler; tergum X shaded stronger on three longitudinal marks (one median, two sublateral) and margins. Genitalia ( Figs. 5–7 ): forceps whitish translucent, penes yellowish; pedestals (p in Fig. 5 ) relatively short, well separated from each other by a subrectangular median plate (mp in Fig. 5 ); forceps relatively long and slender, with setae on inner margin increasing in number distally, apex curved medially ( Fig. 5 ); base of penes well developed, penean arms cylindrical, curved medially, and with many spines subapically on outer margin ( Figs. 6–7 ). Cerci whitish; terminal filament very reduced, straight, with 6 thin annuli.

Female subimago ( Figs. 8–13 ). Length (mm): body, 10.2–10.8; fore wing, 11.1; hind wing, 4.3. General coloration yellowish light brown. Head ( Figs. 8–9 ) dorsally blackish except on median zone, paler; venter of head yellowish white. Antennae light yellowish, shaded gray on apex of scape and pedicel. Thorax ( Figs. 8–9 ) yellowish brown with blackish membranes, shaded with brownish gray on pronotum and with black on posteromedian marks on meso- and metanotum. Legs whitish yellow shaded brownish on dorsum. Wings ( Figs. 10–11 ), membrane slightly tinged with light brown, veins brownish; costal and subcostal sector of fore and hind wings, grayish, sometimes apical half of costal and subcostal sector of forewing whitish; forewing with four longitudinal intercalary veins between R2 and R3. Abdomen ( Figs. 8–9 ). Terga yellowish shaded with brownish gray; sterna whitish yellow with anteromedial longitudinal brownish line and two reddish brown spots medially; sternum VIII ( Fig. 12 ) with paired anteromedian sockets, sockets small, shallow and contiguous (so in Fig. 13 ). Terminal filament whitish, shorter than tergum VIII, with 6 thin annuli; cerci yellowish brown paler apically, 0.5–0.6 times the length of the abdomen.

Eggs. Length, 221–266 μm; width, 143–152μm. Slightly oval; yellow with two polar caps on apices, each formed by a long coiled filament; no chorion microsculptures visible at 100X.

Nymphs. Unknown.

Remarks. The differences between male imago and subimago are limited to length of forelegs, forceps and cerci. The penes of imago and subimago are similar, allowing the identification in both stages.

Etymology. From Latin crenulatus meaning "minutely crenated", because of the remarkable penile structure ( Figs. 5–7 ).

Diagnosis and discussion. Asthenopus crenulatus sp. nov. can be distinguished from the other species of the genus by the following combination of characters: 1) male foreleg with large and apically widening tibia, first tarsite partially fused to second tarsite, foreleg length 0.7–0.9 times the length of forewing; 2) marginal intercalary veins present on the entire margin of fore and hind wings ( Figs. 3–4 , 10–11 ), generally shorter than distance between longitudinal veins in male ( Figs. 3–4 ), but longer and anastomosed in female ( Figs. 10–11 ); 3) basal relation of forewing veins IMP-MP1 variable (IMP joined to MP1, or basally free); 4) forewing with 3 to 4 crossveins between Rs and MA basal to Rs fork; 5) ratio total length/basal width of forceps 8.5–9.0 (tl/bw in Fig. 5 ); 6) penes long and slender, outer apical margin with many small spines ( Figs. 6–7 ).

Asthenopus crenulatus is more closely related with A. picteti (Hubbard) than to other species of the genus. The characters shared by both species include the relatively slender forceps and penes and the relatively long male forelegs. Both species can be easily distinguished by the larger size (forewing length, 12 mm), and absence of subapical penile spines in A. picteti . Furthermore, the extremely specialized foretibial-tarsal joint and apically enlarged foretarsal claws of A. picteti ( Traver 1956) are absent in the new species, that shows the common states for these characters (tarsite 1 not fused with tibia, and claws widening slightly on the apex).

Female adults are only known for A. curtus ( Berner 1978) and an undetermined species from Uruguay (" Asthenopodes sp." in Traver 1956) but sockets on the VIII sternum were not known to occur in the genus until now. These structures were studied by McCafferty and Bloodgood (1989) in a species of Tortopsis and recently described for females of Tortopus ( Molineri 2010) . They are supposed to function as part of the coupling apparatus during copula.

Material. Holotype male from BRAZIL: AM 240, Ramal Paulo Freire, Sitio os Pioneiros, Km-05, Presidente Figueiredo, Amazonas, 94 m, 24.iv.2008, S 2° 4' 5" – W 59° 54'28.8", light trap, N. Hamada col.. Paratypes: 1 male imago and 3 male subimagos same data as holotype; 1 male imago (wings and genitalia on slide), 9 male subimagos, and 4 female subimagos from BRAZIL: AM 240 - Km 21: Sitio da Corredeira Santo Amaro, Presidente Figueiredo, Amazonas, 112 m, 21.iv.2008, S 2° 2' 21.4" – W 59° 50' 43.9", light trap, N. Hamada col.; and 1 male imago (wings and legs on slide) from COLOMBIA-BRAZIL: Reserva Natural Palmarí, río Yavarí, Muelle Centro Administrativo, 120 m, 29.v.2002, S 4° 17' 10" – W 70° 17' 49", light trap, M. C. Zúñiga, D. Emmerich, R. Zúñiga and A. Zúñiga col. The paratype male imago from river Yavarí is deposited in MUSENUV, one male imago and one female subimago (paratypes) from Brazil are deposited in IML, the remaining material (holotype and paratypes) in INPA.

Figures

FIGURES 1 – 7. Asthenopus crenulatus sp. nov. Male imago. 1, body, d. v. (= dorsal view); 2, body, v. v. (= ventral view); 3, forewing; 4, hind wing; 5, genitalia, v. v.; 6, penes; 7, detail of penes. Abbreviations: bw = basal width; mi = marginal intercalaries; mp = median plate of styliger; p = pedestal; s IX = sternum IX; tl = total length.

FIGURES 8 – 13. Asthenopus crenulatus sp. nov. Female subimago. 8, body, d. v. (= dorsal view); 9, body, v. v. (= ventral view); 10, forewing; 11, hind wing; 12, abdominal sterna VIII – IX; 13, detail of sockets. Abbreviations: so = sockets; s VIII, s IX = sterna VIII and IX. d. v.