Americabaetis labiosus Lugo-Ortiz & McCafferty, 1996

Salles, F. F., Raimundi, E. A., Boldrini, R. & Souza-Franco, G. M., 2010, The genus Americabaetis Kluge (Ephemeroptera: Baetidae) in Brazil: new species, stage description, and key to nymphs, Zootaxa 2560 (1), pp. 16-28 : 23

Americabaetis labiosus Lugo-Ortiz & McCafferty, 1996

( Figs. 1c , 14–17 , 18, 21, 25 , 29 )

Americabaetis labiosus Lugo-Ortiz & McCafferty, 1996: 164 ; Francischetti et al., 2003: 69; Domínguez et al., 2006: 70; Salles et al., 2010: 302 .

Diagnoses. Nymphs: 1) Frontal keel absent; 2) lingua broadly pointed apically; 3) glossa 0.6x length of paraglossa, 4) apex of paraglossa with rows of pectinate setae; 5) segment II of labial palp with a small distomedial projection; 6) posterior margin of abdominal terga with rounded spines.

Male imago: 1) turbinate eyes anteriorly divergent and widely separated from each other, upper surface ellipsoidal ( Fig. 14 ); 2) terga light whitish brown, lateral margins darker ( Figs. 14, 15 ); 3) forceps with first segment constricted medioapically ( Fig. 17 ); 4) posterior margin of subgenital plate with a small rounded projection ( Fig. 17 ); 5) length of body relatively small (4.0 mm).

Description (Male imago). Measurements. Body 4.0 mm; forewing 4.0– 4.3 mm; antenna 0.7 mm; tibia I: 1.31 mm; tibia II: 0.88 mm; tibia III: 0.89 mm.

Head ( Figs. 14–15 ). Coloration light brown with V shaped brown mark between compound eyes. Turbinate portion of compound eyes orangish; basal half of stalk brown, paler toward apex. Antenna light brown. Dorsal portion of turbinate eyes ellipsoidal; length 1.5x width; stalk height 0.5x width of dorsal portion; inner margins widely separated, divergent anteriorly.

Thorax ( Figs. 14–15 ). Pro, meso and metanotum brown; submedioscutum light brown; scutellum dark brown. Sternum brown. Anteronotal protuberance rounded. Metascutellar protuberance pointed dorsally. Legs whitish. Leg I: tibia 1.7x length of femur; tarsi 1.6x length of femur; and with 4 segments decreasing on length apically. Leg II and III: tibia 1.4x length of femur; tarsi 0.4x length of femur. Forewing ( Figs. 16 ) hyaline, posterior region of costal and subcostal veins grayish; veins Costal and subcostal light brown; stigmatic area with 6 cross veins not touching subcostal vein; marginal intercalary paired, except single between veins ICu1 and A; length of intercalary vein between IMA and IMA2 1.7x distance between adjacent longitudinal veins; length of forewing about 2.4x width.

Abdomen ( Figs. 14–15 ). Terga light whitish brown, lateral margins darker; tracheation blackish. Sterna light whitish brown. Genitalia ( Figs. 17 ) segment I whitish washed with brown, segments II and III whitish. Forceps segment I distinctly constricted medioapically; 0,5x length of segment II; distance between base of forceps 0,2x distance between lateral margins of forceps. Forceps segment II narrow submedially. Forceps segment III elongate, 2.7x as long as wide; 0.17x length of segment II. Posterior margin of subgenital plate with a small rounded projection.

Comments. In Brazil A. labiosus is apparently restricted to the southern area of the country. Their nymphs, as those of A. titthion and A. mecistognathus , sp. nov., inhabit shallow areas with moderate to fast current ( Fig. 29 ). However, unlike these species, they are often associated with dead leaves above rocks. The altitudinal range of this species varies from 700 to 1900 m.a.s.l.

Distribution. PARAGUAY, URUGUAY, BRAZIL: Rio Grande do Sul, Paraná, Santa Catarina; Rio de Janeiro, Espírito Santo, São Paulo. NEW RECORDS: Minas Gerais ( Fig. 1b ).

Material examined. MINAS GERAIS, Chácara , Cachoeira Menezes, 16/i/2000, CNF & R. F. Rocha ; ESPÍRITO SANTO, Santa Teresa , Nova Lombardia , Sítio Capitel de Santo Antônio, Córrego Grande, S 19°52’31.0” / W 40°31’49.1”, 768 m. a.s.l., 19-20/i/2008, 20/ii/2009, FFS col. ( CEUNES). One male imago (reared), Brazil , ESPÍRITO SANTO, Alfredo Chaves Country , Nova Estrela, waterfall Petralonga, 20°39'76.6"S/ 40°50'72.6"W, 23.v.2008, RB col. One male imago and one male subimago (reared), Brazil , ESPÍRITO SANTO, Alfredo Chaves Country , Nova Estrela, waterfall Petralonga, 20°39'76.6"S/ 40°50'72.6"W, 20.ii.2009, RB col .

Figures

FIGURE 1. Distribution of the species of Americabaetis in Brazil. Fig. 1b, map of Brazil; Figs. 1a, c–e, partial map of Brazil. a) A. mecistognathus, sp. nov.; b) A. alphus; c) A. labiosus; d) A. longetron; e) A. titthion. (Question mark indicates that a species is reported to a state, but the exact location is unknown; grey mark indicates record based on literature, white mark indicates new record. AL, Alagoas; BA, Bahia; ES, Espírito Santo; GO, Goiás; MG, Minas Gerais; MT, Mato Grosso; PR, Paraná; RJ, Rio de Janeiro; RS, Rio Grande do Sul; SC, Santa Catarina; SE, Sergipe; SP, São Paulo).

FIGURES 14–17. Americabaetis labiosus. Male imago. 14. Lateral view; 15. Dorsal view; 16. Forewing; 17. Genitalia.

FIGURES 18–26. Americabaetis spp. Nymph. 18. Head of A. labiosus (frontal view); 19. Head of A. longetron (f.v.); 20. Labial palp of A. alphus; 21. Labial palp of A. labiosus; 22. Abdomen in dorsal view of A. longetron; 23. Abdomen in dorsal view of A. alphus (male); 24. Abdomen in dorsal view of A. alphus (female); 25. Posterior margin of terga IV of A. labiosus; 26. Posterior margin of terga IV of A. longetron.

FIGURES 27–30. General aspect of Americabaetis nymphs’ habitat. 27. A. mecistognathus, sp. nov.; 28. A. alphus and A. longetron; 29. A. labiosus; 30. A. titthion.