Oecetis iguazu Flint 1983

Oecetis iguazu

This species, O. punctipennis (Ulmer), and O. connata Flint form a closely related complex of species. Oecetis connata is easily distinguished by the almost complete fusion of the cerci and tenth tergum and elongate, slender claspers. From its closest relative, O. punctipennis, O. iguazu is to be distinguished by its almost parallel-sided clasper with a large basomesal lobe. The forewings lack the white marks along the apex which are so conspicuous in O. punctipennis.

ADULT.—Length of forewing, 8 mm. Color pale yellowish brown; forewing with tufts of dark hair at the forks of veins, at junctions with crossveins and longitudinal veins, and along wing margin where veins end. Forewing with R2+3 branched at about a third of distance to margin beyond s; hindwing with R2+3, M, and Cu1, all with small marginal forks, anal area reduced.

Male Genitalia: Ninth segment annular. Cercus about twice as long as broad. Tenth tergum with apicodorsal margin drawn out into a small point. Clasper elongate, almost parallel-sided, apex broadly rounded; with a distinct basomesal lobe. Aedeagus short, shaped like a bird's head, apicoventral margin produced.

MATERIAL.—Holotype (male): ARGENTINA, PCIA. MISIONES, Río Iguazú, Camp Nañdu, 25 Nov 1973, O.S. Flint, Jr., USNM Type 100542.

Paratypes: PARAGUAY, DEPTO. SAN PEDRO, Arroyo Tapiracuay, San Estanislao, 27 Nov 1973, O.S. Flint, Jr., 1. DEPTO. ITAPUA, Pirapó, Jan 1972, L.E. Peña G., 1. BRAZIL, EDO. SANTA CATARINA, Nova Teutonia, 15 Sep 1963, F. Plaumann, 2; same, but 27 Sep 1964, 1; same, but Sep 1963, 1; same, but Oct 1964, 1; same, but 31 Oct 1931, 1 (MCZ); same, but 29 Oct 1934, 1 (MCZ). EDO. RIO DE JANEIRO, Mun. Rio Claro, Rio Pirai, 8 Apr 1977, C.M. and O.S. Flint, Jr., 1, 3. EDO. ESPÍRITO SANTO, Fazenda Santa Clara, 15 km SE Santa Teresa, 22 Apr 1977, C.M. and O.S. Flint, Jr., 2, 3 (USP).

This genus, which is distributed from Canada southward through North, Central, and South America including the Greater Antilles and the Chilean Subregion, is placed in the tribe Nectopsychini of the Leptocerinae. The adults are brightly colored, and the color patterns are very necessary for classification; therefore, they should be kept dry and preserved on pins.

In many cases I find the recognition and definition of species in this genus very confusing. In general, the male genitalia are very similar throughout the genus and much given to small differences both within and between populations. The wing coloration seems to be rather stable, at least within populations, but sometimes does vary between populations. I have decided to recognize species in this genus based primarily on what seems to me to be distinctive differences in color pattern as well as major differences in male genitalia. Thus I will recognize groups of species, each group with very similar, but not specifically differentiated, male genitalia. The species in these groups will be distinguished by coloration. I realize that this splitting will occasionally result in the division of a true species if there is extreme variation, especially of a clinal nature, but I believe this to be of a less serious nature than the confounding of several species under one name. Hopefully, further study of the male genitalia will reveal which parts are of greatest stability and use in defining the species and which are of little use. At this time I note that setae and setae-bearing lobes and processes are extremely variable, often differing on the two sides of the same specimen.

The larvae of a number of North American species have been described (Ross, 1944; Haddock, 1977; Wiggins, 1977). All construct basically tubular cases in a great number of forms. Some are nearly cylindrical sand cases, others are of mixed sand and long plant pieces, and a few cases are of leaf fragments. They inhabit many sites from small mountain brooks to large rivers, marshes and lakes. They are apparently detritivores.