Smicridea (Rhyacophylax) salta Flint 1974

Smicridea (R.) salta

This and S. radula are the smallest species of the genus found in the region of this study. The species may be immediately recognized by the combination of very small size and uniform grayish brown color with a pale subapical band on the forewing. It is clearly a member of the signata group on the basis of genitalia and is closest to S. arizonensis, new species. In the male sex it is distinguished by the presence of a small spur ventrolaterally and narrower, more elongate apices of the tenth tergite, plus small differences in the tip of the aedeagus.

The female internal plate is very slender and “wishbone” shaped, quite unlike that of S. arizonensis.

ADULT.—Length of forewing 3.5 mm. Color grayish brown; forewing uniformly grayish brown with a pale subterminal band, wing of male darker than in female (Figure 33). Fifth sternum with anterolateral process slightly longer than length of sternum in male, about half length of sternum in female. Male genitalia: Ninth segment produced into a pointed, upturned lobe anterolaterally. Tenth tergite in lateral aspect with tip upturned and pointed, ventral margin with a sharp spur at midlength; in dorsal aspect with apex produced into a long, rounded lobe. Clasper with basal segment long, slightly enlarged beyond midlength; apical segment with tip pointed in dorsal aspect. Aedeagus tubular, with basal and apical sections meeting at an angle of about 110°; apex with a narrow, ventral tonguelike process, in dorsal aspect with apicolateral dark marks, internally with a long, thin, eversible structure. Female genitalia: Ninth segment blunt apically, with anterolateral margin produced and angled at about 90°. Internal plate with posterior arms narrow, with a small narrow anteromesal process. Vagina with anterior bar bearing short, posteriorly directed processes laterally, posteriorly with a pair of elongate, lightly sclerotized plates.

IMMATURE STAGES.—Unknown.

MATERIAL.—Holotype, male: MEXICO, SAN LUIS POTOSI, El Salto (26 miles W of Antiguo Morelos), 8 August 1966, O. S. Flint, Jr. USNM Type 72707. Paratypes: Same data, 150 ; same, but 3 June 1967, 5 250 ; same, but 23–24 June 1965, 25 75 ; same, but 11–14 July 1963, Duckworth and Davis, 100 ; same, but 8 May 1964, Blanton, et al., 2 3 . Palitla, 5 June 1966, O. S. Flint, Jr., l 2 . TAMAULIPAS: 6 miles S of Ciudad Victoria, 1050′, 6 August 1963, Duckworth and Davis, 1 . 4 miles SW of Ciudad Victoria, 1100′, 10 July 1965, Duckworth and Davis, 3 .

BIOLOGY.—The adults of this species are attracted to lights, often in great numbers. Although the larvae have not been taken, they probably may be found in the streams adjacent to the adult collection sites. A few adults have been taken near small, shallow streams a meter or two in width with shallow riffles. The one site, El Salto, where this species has been consistently collected in abundance, is quite different. Here, just below a large waterfall, the river is 10–20 meters wide, with boulders and deep pools, overflowing travertine rims.