Americabaetis alphus 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 : 22

Americabaetis alphus Lugo-Ortiz & McCafferty, 1996

( Figs. 1b , 20, 23, 24 , 28 )

Americabaetis alphus Lugo-Ortiz & McCafferty, 1996: 163 ; Francischetti et al., 2003: 69; Salles et al., 2004: 2; Domínguez et al., 2006: 69; Salles et al., 2010: 302 .

Diagnoses. Nymphs: 1) frontal keel present; 2) lingua pointed apically; 3) glossa 0.8x length of paraglossa; 4) apex of paraglossa with rows of simple setae; 5) segment II of labial palp with a strong distomedial projection; 6) posterior margin of abdominal terga with pointed spines.

Male imago: 1) turbinate eyes uniformly and widely separated from each other, upper surface ellipsoidal; 2) forceps with first segment not constricted medioapically; 3) posterior margin of subgenital plate without a small rounded projection; 4) length of body relatively small (less than 5.0 mm).

Distribution. ARGENTINA, BOLIVIA, CHILE, PARAGUAY, BRAZIL: Rio Grande do Sul, Santa Catarina, Paraná, Minas Gerais, São Paulo, Rio de Janeiro, Espírito Santo, Mato Grosso, Bahia. NEW RECORDS: Pernambuco, Sergipe, Goiás, Amazonas ( Fig. 1a ).

Comments. Americabaetis alphus is probably the species of Ephemeroptera with the widest distributional range in South America, as well as one of the most abundant, at least in Brazil. Their nymphs are found in several biomes and on small streams to large rivers, often associated with marginal vegetation and leaf litter in areas with slow to moderate current ( Fig. 28 ). The altitudinal range of this species is also highly variable, specimens were found from the sea level to 1900 m.a.s.l. They were also encountered in pristine to moderately impacted streams, demonstrating that the species is somewhat tolerant, what, in turn, would explain its wide distribution.

Material examined. ALAGOAS, Rio Largo, Afluente do Rio Mandaú , "Lajeiro", S 09°28.496' / W 35°52.303', Vegetação marginal, 15/iii/2004, CNF COL. ( UFVB) ; SERGIPE, Japaratuba, Rio da Prata , S 10°37.764' / W 36° 55.451', Vegetação marginal, 18/iii/2004, muitos, CNF COL. ( UFVB) ; GOIÁS, Corumbá de Goiás. Corredeira da Igreja Presbiteriana , acima da calheira, S 15°49’37.1’’ / W 48°46’34.8’’, 26/vi/2003, NH COL. ( INPA) ; BAHIA, Correntina. Rio do Mucambo , S 13°16’45.4’’ / W 44°33’52.0’’, pedras roladas em correnteza, 03/viii/2003, NH & FFS COL. ( DZRJ) ; AMAZONAS, Presidente Figueiredo, Ig . Santa Cruz, hidrófitas submersas em correnteza, 08/x/03, FFS ( CEUNES) ; AMAZONAS, Presidente Figueiredo, Ig. do Km 20, vegetação marginal em correnteza fraca, 07/x/03, F.F.Salles ( CEUNES) ; ESPÍRITO SANTO, Santa Teresa, Nova Lombardia, Sítio Capitel de Santo Antônio , S 19°52’16.0” / W 40°31’43.3”, 718 m. a.s.l., 19/i/ 2008, FFS col. ( CEUNES) ; 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., 20/i/2008, vegetação marginal, FFS col. ( CEUNES) ; ESPÍRITO SANTO, Caparaó , córrego na estrada, S 20°24’05,5’’ / W 41° 453.45,9’’, 1015 m.a.s.l., 21/iv/2008, vegetação marginal, FFS col. ( CEUNES) .

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 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.