Stibasoma bicolor Bigot

Stibasoma bicolor Bigot

(Figs. 13–18)

Stibasoma bicolor Bigot, 1892: 636 (description); Knab, 1913: 408, 411 (key, citation); Lutz, 1915: 112 –113 (translation of the original description); Kröber, 1932: 242, 254–255 (citation, diagnosis); Fairchild, 1967: 95 (citation); Fairchild, 1971: 75 (catalog); Fairchild & Burger, 1994: 112 (catalog).

Tabanus tristis Wiedemann, 1828: 164 (description; previously occupied by T. tristis Fabricius, 1798): Fairchild, 1961: 230 (citation).

Stibasoma triste; Knab, 1913: 408, 411 (key, citation); Lutz, 1915: 112 (translation of the original description and designation as junior synonym of S. bicolor); Kröber, 1932: 244, 253–254 (key, redescription).

Stibasoma semiflavum Lutz, 1915: 115 (description); Kröber, 1932: 243, 245, 259 (citation, key, redescription); Fairchild, 1961: 230 (as junior synonym of S. bicolor).

Diagnosis. Predominantly dark brown to black, with lateral sides of proximal part of the abdomen yellow.

Redescription. Female (Itatiaya, 6.xii.1925). Head. Frons dark brown; gray pollinosity laterally to midcallus, best seen in dorsal view. Frontal callus as wide as frons, dark brown. Subcallus dark brown, shiny; base of the antenna with yellow pollinosity. Antenna dark brown; scape and pedicel with black hairs; pedicel with a dorsal projection; flagellum with golden pollinosity; basal flagellomere with dorsal spine reaching the second flagellomere; basal flagellomere with a slight angle ventrally. Face and parafacia dark brown with gray pollinosity, best seen in dorsal view. Gena and postgena dark brown, with gray pollinosity and dark brown hairs. Palpus dark brown with black hairs.

Thorax. Scutum and scutelum dark brown to black, with gray pollinosity and black hairs. Postpronotal lobe brown, lighter than the scutum, with white hairs proximally and black hairs distally. Notopleura, proepisternum and proepimeron dark brown to black with black hairs. Anepisternum and anepimeron dark brown to black, with sparse silver pollinosity and black hairs. Katepisternum dark brown to black, with dense silver pollinosity and few black hairs. Katepimeron dark brown to black with dense silver pollinosity. Coxa dark brown to black with gray pollinosity and black hairs. The remaining parts of the leg dark brown with black hairs, except for reddish hairs on ventral side of the tarsus. Wing yellow, with venation and pterostigma yellow. Halter yellow, apex whitish.

Abdomen. Tergites 1 and 2 with lateral margins yellow with yellow hairs and dark brown with dark brown hairs in middle. Tergite 3 entirely dark brown with yellow hairs laterally and dark brown hairs in middle. The other tergites entirely dark brown with dark brown hairs. Sternites 1 to 3 dark brown with distal margin yellow and yellow hairs. The other sternites entirely dark brown with dark brown hairs.

Measurements. (n = 1, Itatiaya, 6.xii.1925) Body length: 11.28mm. Wing length: 10.57mm. Frontal index: 4,59. Divergence index: 1,45.

Redescription. Male (holotype S. semiflavum). Head. Dorsal part of the eye reddish-brown, with large ommatidia; ventral part dark brown, with small ommatidia. Subcallus dark brown, with silver gray pollinosity; base of antenna with golden pollinosity. Antenna dark brown, scape and pedicel with black hairs and silver pollinosity ventrally; basal flagellomere with dorsal spine reaching first flagellomere. Face and parafacia dark brown with silver pollinosity and dark brown hairs. Palpus dark brown with black hairs.

Thorax. Scutum and scutellum dark brown to black with gray pollinosity and black hairs. Postpronotal lobe lighter than the scutum, with few black and white hairs. Notopleuron, proepisternum and proepimeron dark brown to black, with black hairs. Anepisternum, anepimeron, katatergite and katepisternum dark brown with black hairs; katepimeron dark brown with silver pollinosity. Coxa dark brown to black with gray pollinosity and black hairs. The rest of the leg dark brown with black hairs, except for reddish hairs on the ventral side of the tarsus. Wing yellow, venation yellow. Pterostigma yellow and halter yellow with whitish apex.

Abdomen. Tergites 1 to 3 entirely yellow with yellow hairs; the other tergites dark brown with dark brown hairs. Sternites 1 to 3 yellow with yellow hairs; the other sternites dark brown with dark brown hairs.

Measurements. (n = 1, holotype S. semiflavum) Body length: 15mm. Wing length: 12.25mm.

Type-locality. Brazil.

Distribution. Brazil (Espírito Santo to Santa Catarina, Minas Gerais).

Type material examined. Stibasoma bicolor: “Co-type” “ Brazil, ex coll. J. Bigot;\ ex. coll. G.H.Verrall.\ B.M.1914-500.” “ SYNTYPE \ Stibasoma \ bicolor Bigot\ det. J.E.CHAINEY 1978” “ BMNH (E)#\ 240354 (Syntype, female, BMNH). Stibasoma semiflavum: “Joinville\ Schmalz ded.\ Jan. 1914 ” “Nº T626\ Inst. O. Cruz\ Coleção A. Lutz” “ Stibasoma \ semiflavum Lutz \ HOLOTYPE ” (Holotype, male, IOC).

Additional material examined. BRAZIL. Paraná: 2 females, Morretes, x.1984, J.A. Rafael, (INPA); Rio de Janeiro: female, Itatiaya, 6.xii.1925, without collector, (MNRJ); female, Petrópolis, 15.xi.1919, J. G. Foetterle, (IOC).