Leucotrichia rhomba Thomson & Holzenthal

Thomson, Robin E. & Holzenthal, Ralph W., 2015, A revision of the Neotropical caddisfly genus Leucotrichia Mosely, 1934 (Hydroptilidae, Leucotrichiinae), ZooKeys 499, pp. 1-100 : 35-36

Taxon classification Animalia Trichoptera Hydroptilidae

Leucotrichia rhomba Thomson & Holzenthal sp. n. Fig. 37

Diagnosis.

Leucotrichia rhomba sp. n., is known only from the male holotype. This species is most similar to Leucotrichia brochophora , Leucotrichia lerma , and Leucotrichia padera . These species share a similar form in the apex of the phallus, sternum VIII, and segment IX, as discussed under Leucotrichia brochophora . Leucotrichia rhomba can be separated from the other 3 species by the size and shape of the mesoventral process of sternum VII (Fig. 37B, D). The apex of the process is enlarged and, in ventral view, rhomboid and rugose. The posterior margin of sternum VIII is also much more deeply concave in Leucotrichia rhomba than in any of the other 3 species.

Description.

Male. Length of forewing 2.4 mm (n=1). Head unmodified, with 3 ocelli; antennae unmodified. Dorsum of head brown with yellow and dark brown setae; thorax brown with light brown setae dorsally, brown ventrally; leg segments with brown setae. Forewings covered with fine brown setae with light yellow patch extending from basal 3/4 along the length of outer edge. Genitalia. Abdominal sternum VII with elongate mesoventral process with apex enlarged; in ventral view apex rhomboid, rugose. Sternum VIII in ventral view with posterior margin deeply concave. Segment IX anterolateral margin produced mesally, posterolateral margin irregular; in dorsal view anterior margin concave, posterior margin concave. Tergum × with dorsal sclerite continuous with ventral sclerite; ventral sclerite with rounded projection on posterior margin; membranous apex subtriangular. Subgenital plate fused with ventral sclerite of tergum X; with dorsal arm not apparent; ventral arm digitate with basal projection, in ventral view oblong. Inferior appendage broadest mesally, apex hooked dorsally, bearing single dorsal spine; in ventral view entirely fused, oval, basally enlarged, apex with shallow emargination. Phallus apex not well expanded, bearing pair of internal apodemes.

Holotype male: COSTA RICA: Puntarenas: Río Jaba at rock quarry, 1.4 km (air) W Las Cruces, 8.79°N, 82.97°W, 9.viii.1990, el. 1150 m, Holzenthal, Blahnik, and Muñoz, 1 male (UMSP000201350) (UMSP).

Etymology.

Rhombus, Latin for “rhomboid”, a quadrilateral of which only the opposite sides and angles are equal, referring to the shape of the enlarged apex of the mesoventral process of sternum VII.