Smicridea (Rhyacophylax) atrobasis Flint 1983

Smicridea (Rhyacophylax) atrobasis

In coloration, this species at first sight appears to be the same as S. (R.) appendiculata Flint; however, the dark marks on the forewings are more extensive in S. atrobasis. The genitalia of the two species are totally different, and S. atrobasis shows its closest relationship to species of the S. brasiliana group. From all known species in this group, S. atrobasis is easily distinguished on the basis of color and presence of apicolateral lobes on the aedeagus.

ADULT.—Length of forewing, 5 mm. Eye of male very large, middorsally width of eye 1 times that of interocular distance. Color stramineous; head and thorax dorsally dark purplish black; forewing dark purplish black in basal quarter and in 2 transverse bands apicad, otherwise covered with golden hair. Anterolateral process of fifth sternum of male about as long as sternum; without internal sacs.

Male Genitalia: Ninth segment with anterior margin produced into a long, narrowly rounded lobe. Tenth tergum divided apicomesally; tergite in lateral and dorsal aspects with tip produced and rounded. Clasper with basal segment long and parallel-sided; apical segment bluntly pointed. Aedeagus with base enlarged, angled to axis of stem, which is long and slightly upturned apically; apex with a long, slender internal sclerite, and apicolateral lobes that progressively become directed basad as the internal sclerite is exserted.

MATERIAL.—Holotype (male): ARGENTINA, PCIA. ENTRE RÍos, Salto Grande, Río Uruguay, 16 Nov 1973, O.S. Flint, Jr., USNM Type 100535.

Paratypes: Same data as holotype, 7, 13. PROV. MISIONES, Camp Nañdu, Río Iguazú, 25 Nov 1973, O.S. Flint, Jr., 52, 2. BRAZIL, EDO. SANTA CATARINA, Nova Teutonia, Nov 1963, F. Plaumann, 3, 1; same, but Jan 1964, 2; same, but Oct 1964, 4, 51. URUGUAY, DPTO. ARTIGAS, San Gregorio, 29 Nov 1959, Carbonell, Mesa, and San Martin, 1; Río Uruguay, Barra Arroyo Guaviyú, 28 Dec 1954, C.S. Carbonell, 1. DPTO PAYSANDÚ, Puerto Pepe-Ají, 8 Nov 1955, C.S. Carbonnell, 25 (FHCU). DPTO. SALTO, Salto Grande, 10 Nov 1955, C.S. Carbonell, 52, 72 (FHCU).