Oecetis knutsoni Flint 1981

Oecetis knutsoni Flint

Oecetis knutsoni Flint, 1981a:32.

This species was described from Venezuela and is here recorded from Colombia. In addition, I have seen examples from Bolivia. It appears to be rather common in the fast flowing rivers and streams of the Andes. It is quite possible that the larva ascribed to O. avara (Banks) by Correa is actually that of O. knutsoni which is much more common in the region.

MATERIAL.—COLOMBIA. DPTO. ANTIOQUIA: Quebrada La Mosca, 1 km W Guame, 7 Feb 1983, O.S. Flint, Jr., 5, 1; same, but 2 Mar 1984, C.M. & O.S. Flint, Jr., 17, 7. 10 km E Medellín [road to Guarne], 7 Feb 1983, O.S. Flint, Jr., 1. Quebrada La Agudelo, 2 km E El Retira, 8 Feb 1983, O.S. Flint, Jr., 2; same, but 25 Feb 1984, C.M. & O.S. Flint, Jr., l1, 1. Río Medellín, 5 km S Caldas, 16 Feb 1983, O.S. Flint, Jr., 7, 2; same, but 6 km S Caldas, 24 Feb 1984, C.M. & O.S. Flint, Jr., 3; same, but Estación Primavera above Caldas, 1600 m, 30 Aug 1983, U. Matthias, 3. Quebrada El Retira, 16 km NW Medellín [road to San Pedro], 20 Feb 1984, C.M. & O.S. Flint, Jr., 1, 1. Quebrada La Cebolla, El Retira (trap A), 21 May 1983, U. Matthias, 2; Feb 1984, 1. Quebrada La Ayurá, Envigado (trap B), 13 Oct 1983, U. Matthias, 1; 3 Nov 1983, 1.

Oecetis knutsoni

This species is closely related to O. punctata (Navas) described from Costa Rica. It is to be distinguished in the male by the structure of the genitalia, especially the claspers. In O. knutsoni, the clasper bears a large lobe from the posterolateral margin and another from the dorsomesal margin, and the tenth tergum is reduced to a very minuscule lobe.

ADULT.—Length of forewing, 8–9 mm (male), 6–8 mm (female). Color generally stramineous; forewing with 20 dark spots in membrane at forks and junctions of veins and along apex at ends of veins. Forewing venation with R2+3 forked at s; hindwing with R2+3, M, and Cu, all deeply forked. Male genitalia: Ninth segment annular, dorsally with a pair of small knobs from posterior. Cercus an elongate, ovoid lobe. Tenth tergum virtually lacking, consisting of a small point between cerci and a small flap above aedeagus. Clasper consisting of a lightly sclerotized lateral portion, which is slightly produced ventrally, bears an elongate, spinous lobe from posterolateral margin, ends dorsally in a series of slender seta-tipped processes, and a curved spinous lobe mesally; mesal portion heavily sclerotized and darker, in posterior aspect as broad as high, mesal margin vertical, dorsal margin with a small angular projection centrally. Aedeagus tubular, apex directed slightly ventrad, with a simple C-shaped internal sclerite. Female genitalia: Ninth sternum lightly sclerotized, not conspicuously darkened. Vagina with conspicuous lateral supports, roughly conical, with a central keyhole-like opening.

MATERIAL.—Holotype, male: VENEZUELA, ARAGUA, Ocumare [de la Costa], 17 Apr 1972, L.V. Knutson, USNM Type 76630.

Paratypes: Same data as holotype, 1. Rancho Grande, 1100 m, 11–15 Jan 1966, S.S. and W.D. Duckworth, 1. Maracay, Río Limón, Estacion Piscicultura, F.H. Weibezahn, 8–9 Oct 1974, 1; 19–20 Nov 1974, 4 1; 4–5 Dec 1974, 5; 3–4 Jan 1975, 1; 29–30 Jan 1975, 6 1; 12–13 Feb 1975, 1 1; 25–26 Feb 1975, 4 1; 11–12 Mar 1975, 9 2; 24–25 Mar 1975, 2; 7–8 Apr 1975, 7 3; 22–23 Apr 1975, 1; 6–7 May 1975, 1 1; 19–20 May 1975, 1; 3–4 Jun 1975, 1; 17–18 Jun 1975, 1; 1–2 Jul 1975, 1; 15–16 Jul 1975, 6 5; 11–12 Aug 1975, 2; 25–26 Sep 1975, 19 7; 3–6 Feb 1976, C.M. and O.S. Flint, Jr., 1. BARINAS: Barinitas, 22–23 Feb 1969, P. and P. Spangler, 1. Puente Parangula, 8 km S Barinitas, 18 Feb 1976, C.M. and O.S. Flint, Jr., 3.