Hydromastodon sallesi Polegatto & Batista, 2007

Salles, Frederico F., Dominguez, Eduardo, Mariano, Rodolfo & Paresque, Roberta, 2016, The imagos of some enigmatic members of the Hermanella complex (Ephemeroptera, Leptophlebiidae), ZooKeys 625, pp. 45-66 : 50-51

Taxon classification Animalia Ephemeroptera Leptophlebiidae

Hydromastodon sallesi Polegatto & Batista, 2007 Figures 3, 4, 7a, b

Diagnosis.

This is the only species of the genus known from a male imago. Therefore, it is impossible to ascertain at this time the characteristics that will distinguish it from its congeners.

Description of male imago

(in alcohol). Lengths: body, 4.6-5.6 mm; fore wings: 4.8-5.6 mm; hind wings: 0.8-0.9 mm. General coloration: light brown.

Head (Fig. 3a, b): yellowish-white, tinged with orange between ocelli; upper portion of eyes orangeish, lower portion black; ocelli white, surrounded with black and orange. Antennae light yellow-brown.

Thorax (Fig. 3a, b): yellowish-brown, sutures lighter. Wings (Fig. 4a, b, c): membranes of fore wing hyaline, base washed with light brown, veins C, Sc and R1 tinged with orange, remainder of veins yellowish. Hind wing hyaline. Fore leg yellowish, washed with brown; mid and hind legs yellowish-white.

Abdomen (Fig. 3a): Terga I–V almost completely washed with black, segments II–V with sublateral circular mark less pigmented; segments VI–X yellowish-brown. Terga II–IX washed with black as in Fig. 3a, II–VI hyaline, VII–X yellowish. Sterna yellowish-brown, with pleura washed with black. Genitalia: styliger plate yellowish, washed with brown; forceps yellowish, washed with brown, but whitish distomedially. Penis yellowish; spines orangeish. Caudal filaments broken off and lost.

Material examined.

One reared ♂ imago: Brazil, Roraima, Boa Vista, Rio Cauamé, 2°52'5.30"N / 60°44'25.40"W, 76 m asl, 21.v.2014, R. Boldrini col. (CZNC); one ♂ imago (partially molted) and two ♂ subimagos, same data as previous, except 03.ii.2007, J. Falcão col. (CZNC); 16 nymphs, same data as previous, except for 20.iii.2014, F.F. Salles, E. Domínguez, R. Boldrini, J. Gama-Neto col. (11 nymphs CZNC and 5 nymphs IBN); ten ♂ imagos: Brazil, Rondônia, Nova Londrina, Rio Urupá, 11°02'05"N / 62°08'34"W, 182 m asl, 02.ix.2012, N. Hamada leg. (5 INPA, 3 CZNC, 2 IBN).

Comments.

Imagos of Hydromastodon sallesi are readily distinguished from all members of the complex, except for Hydrosmilodon plagatus , by the shape of the forceps and by the presence of a strong and dorsally curved, medial projection at the styliger plate. Body color pattern (compare Fig. 3a herein to figs 2-4 of Lima et al. 2012), body length (around 5 mm in Hydromastodon sallesi , but around 10 mm in Hydrosmilodon plagatus ) and details of penis morphology are enough to separate these two taxa. Geographic distribution may also prove helpful with identification, as Hydrosmilodon plagatus is a typical Atlantic Forest species that seems to be restricted to the Brazilian coast, while Hydromastodon sallesi is found in western and northern Brazil in transitional areas between the Amazon forest and Brazilian savannah.

Hydromastodon sallesi was described based on a few nymphs from Mato Grosso (Rio Pindaíba, Nova Xavantina) and Roraima (Bem Querer falls, Rio Branco, Caracaraí). The material examined in the present paper was collected from the states of Roraima and Rondônia, the latter of which extends the known distribution of the genus and species to the east.

In Roraima, nymphs were predominantly captured on a small stream leading to Rio Branco, at the Bem Querer falls, and in Boa Vista, at the Cauamé River (Fig. 8). In the Cauamé River, nymphs (Fig. 7a, b) of this species were found under rocks, close to the river margins, and they were much less abundant than the nymphs of Leentvaaria palpalis (see immediately below).