Polyplectropus trilobatus Flint 1981

Polyplectropus trilobatus

Together with P. recurvatus (Yamamoto) and P. deltoides (Yamamoto) this species forms a distinctive group that is characterized by the long curved dorsomesal process of the cerci and by the basic shape of the lateral lobes of the cerci and claspers. P. trilobatus may be recognized from the other species by the shape of the lateral lobes of the cerci which are united ventrally and bear a small bifid ventromesal process, as well as the very large ventral lobe of the clasper.

ADULT.—Length of forewing, 4 mm. Specimen in alcohol, denuded; forewing membrane slightly darker along anterior half. Anterolateral angles of fifth sternum of abdomen with a filmentous process which is as long as sternum and annulate apically. Male genitalia: Ninth sternum broad ventrally, tapering to a narrow rounded dorsal margin. Tenth tergum membranous. Cercus with a slender, filamentous dorsal process directed anteriad at base then curving dorsad and posteriad; with lateral, platelike lobes, united midventrally, each with a rounded dorsolateral hump, a small ventrolateral process, and a small bifurcate midventral process from the posterior margin. Clasper with a rounded dorsolateral lobe and a slightly smaller posteroventral lobe, each having a number of peglike setae mesally. Aedeagus with a larger basal portion, and a longer, narrower apical tubelike portion whose apicoventral margin is produced into a trilobate plate; internally with a curved platelike sclerite.

MATERIAL.—Holotype, male: VENEZUELA, ARAGUA, Maracay, Río Limón, Estacion Piscicultura, 23 Apr 1975, F.H. Weibezhan. USNM Type 76614.

The genus is known in the New World from the southwestern United States to Argentina, including the West Indian islands. There are closely related genera in the Tropics of the African and Asian continents. The adults are seldom taken at lights, but appear to be generally diurnal, displaying on leaves in the full sun. It is quite probable that other species occur in Venezuela.

The larvae construct long, slender, silken tubes over the substrate. Often these tubes are most common on boulders above the water line, where they are kept wet by spray from adjacent falls or seepage. The larvae of a number of North American and West Indian species have been described (Edwards, 1961; Flint, 1964; Wiggins, 1977).