Rivudiva trichobasis Lugo-Ortiz & McCafferty
Creators: name: Cruz, Paulo Vilela
name: Boldrini, Rafael
name: Salles, Frederico Falcão
name: Hamada, Neusa
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Ephemeroptera
Baetidae
Rivudiva
Rivudiva trichobasis

description: Rivudiva trichobasis Lugo-Ortiz & McCafferty   
 Diagnosis. The male imago of Rivudiva trichobasis can be distinguished from the other species of the genus by the following combination of characteristics: 1) dorsal portion of turbinate eyes with inner margins not parallel, divergent anteriorly (Figs. 1, 2); 2) length of forewing about 3.7× width (Fig. 3); 3) hind wings absent; 4) segment III of abdomen with one large medially red mark near anterior margin (Figs. 4, 5); 5) forceps segment III oval, 2× as long as wide (Fig. 6); 6) posterior margin of subgenital plate with apex concave (Fig. 6).   
 Male imago (Figs. 1–6). Maximum length: body 3.4–3.5 mm; cerci: 4.9 mm; forewing: 4.4 mm; antenna: 0.7 mm; tibia I: 0.7 mm; tibia II: 0.5 mm; tibia III: 0.5 mm. (n=2).   
 Head. Coloration greenish brown. Ocelli whitish, base light brown. Turbinate portion of compound eye orange (Figs. 1, 2, 4, 5). Antenna with scape brown, pedicel and flagellum green washed with brown. Dorsal portion of turbinate eye oval (Figs. 4, 5); length 1.3× width; stalk height 1.8× width of dorsal portion; inner margins not parallel, divergent anteriorly, reaching or not reaching each other posteriorly.   
 Thorax (Figs.1, 2, 4, 5). Anteronotal protuberance black; mesoscutum green washed with brown; submesoscutum green; posterior scutal protuberance brown; scutellum green washed with brown; metanotum often with two reddish marks laterally (they may be absent sometimes) (green colour of all segments lost in alcohol). Anteronotal protuberance slightly rounded. Metascutellar protuberance dorsoposteriorly directed. Legs whitish. Leg I: tibia 1.2× length of femur; tarsi 1.2× length of femur; and with 4 segments decreasing in length apically. Legs II and III: tibia 1.0× length of femur; tarsi 0.4× length of femur. Wings. Forewing hyaline (Fig. 3); veins light brown; stigmatic area with three cross veins touching subcostal vein and one not touching; marginal intercalary veins paired, except between veins ICuA1 and ICuA2 (single), and between ICuA2 and A (absent); length of each intercalary vein 0.6× distance between adjacent longitudinal veins; length of forewing about 3.7× width. Hind wing absent.   
 Abdome (Figs. 1, 2, 4, 5). Terga with all segments green (colour lost in alcohol) with lateral margins black; segments I, II, IV, V and VI with two small medially red marks, sometimes without; segment III with one large medially red mark near anterior margin; segment VI with one medially red mark near anterior margin; segments VII and VIII with two red marks near anterior margin. Sterna segments I to VI translucent green washed with brown; segments VII to IX white washed with brown. Caudal filaments segments I to III brown, others white. Genitalia (Fig. 6). Forceps brown. Forceps segment I without small distomedial projection; 0.5× length of segment II; distance between base of forceps 0.4× distance between lateral margins of forceps. Forceps segment II basally broad. Forceps segment III oval, 2× as long as wide; 0.2× length of segment II. Posterior margin of subgenital plate with apex concave.   
 Material examined. Five male imagos, three reared, Brazil, Amazonas State, Presidente Figueiredo County, AM 240 Highway, Km 21, Igarapé Recanto da Pantera, sand, 12/xi/2009, Cruz, P.V. and Boldrini, R. col., two in INPA, others in UFES.   
 Remarks. Salles & Nascimento (2009) described for the first time the male imago of Rivudiva and proposed a generic diagnosis for the imagos of the genus. This diagnosis included, among other characteristics: hind wings present or absent, when present with two longitudinal veins and with costal projection pointed, placed in the basal fourth of anterior margin; forceps three-segmented, segment III long, about 2× as long as wide; distal margin of subgenital plate with small pointed projection, however, the latter characteristic was not observed in the adults of R. trichobasis. Additionaly, we propose the inclusion of the following characteristics to the original diagnosis of Salles & Nascimento (2009): 1) male imago with dorsal portion of turbinate eyes oval; 2) forewings with paired marginal intercalary veins; 3) anteronotal protuberance rounded; 4) metascutellar protuberance dorsoposteriorly directed; 5) posterior margin of subgenital plate concave or with distinct medial spine.
description: Published as part of Cruz, Paulo Vilela, Boldrini, Rafael, Salles, Frederico Falcão & Hamada, Neusa, 2011, The male imago of Rivudiva trichobasis Lugo-Ortiz & McCafferty from Amazonas state, Brazil, pp. 60-62 in Zootaxa 2907 on pages 60-62, DOI: 10.5281/zenodo.277777