Bessierus riobranco, Cruz & Gonçalves & Mariano & Hamada, 2020

Cruz, Paulo Vilela, Gonçalves, Inês C., Mariano, Rodolfo & Hamada, Neusa, 2020, One less monotypic genus in Leptophlebiidae (Ephemeroptera): A new species of Bessierus Thomas & Orth and new record from Brazil, Zootaxa 4820 (1), pp. 195-200 : 197

Bessierus riobranco sp. n.

( Figure 3 )

Material examined. Holotype, 1 male imago in alcohol, wings on slide; Brazil; Amapá; Oiapoque; Balneario Rio Pantanahy (Pantanari); 3 m alt.; 03º47’54.3”N / 51º48’05.5”W; 08.viii.2011; A. Pes, P. V. Cruz, A. Fernandes and N. Hamada cols; light trap; INPA.

Diagnosis. Male imago can be separated from B. doloris by the following combination of characters: (1) penis lobes closer to each other, almost touching ( Figs 3d and 3e ); (2) base of each penis lobe, on outer margin, expanded ( Fig. 3e ); (3) telopenis slender ( Fig. 3e ); (4) inner margin of basal 1/3 of forceps segment I straight ( Fig. 3d ).

Description. Male imago. Length of body 4.3 mm, forewing length 4.0 mm, cerci broken and missing. General coloration: yellowish brown. Head ( Figs 3b and 3c ): light brown, tinged with orange between ocelli; upper portion of eyes orangish, lower portion black; ocelli white, surrounded with black. Antennae light yellow brown. Thorax ( Figs 3b and 3c ) orange-brown, sutures darker. Wings ( Fig. 3a ): membrane of fore wings hyaline, veins C, Sc and R1 tinged with yellowish, remainder of veins yellowish, lighter rearward. Legs broken off and missing. Abdomen ( Figs 3b and 3c ): terga yellowish-brown, terga I light brown, terga II–VIII shaded with light brown, terga with light V-shaped area medially and laterally on anterior margin. Sterna grayish-white. Genitalia ( Figs 3 d–3f): styliger plate yellowish-brown, forceps yellowish-brown, lighter towards apex; inner margin of basal 1/3 of forceps segment I straight. Penis yellowish-orange, close to each other, almost touching; base of each penis lobe, on outer margin, expanded; telopenis slender. Caudal filaments broken and missing.

Female imago and nymph. Unknown

Etymology. In honor of Barão do Rio Branco, a Brazilian diplomat, lawyer, historian, geographer, journalist, politician, and professor. Due to his diplomatic efforts, he managed to peacefully resolve several territorial disputes, consolidating the borders of modern Brazil. One of his accomplishments was the addition of the territory of Amapá State, which became a part of Brazil in 1900, after a diplomatic dispute with the government of France. Name in apposition.

Figures

FIGURE 3. Male imago of Bessierus riobranco sp. n. a. forewing; b. body, dorsal view; c. body, lateral view; d. genitalia, ventral view; e. penes, ventral view; f. genitalia, lateral view.