Polycentropus silex Hamilton and Holzenthal, new species

Fig. 4

This new Ecuadorian species is placed in the bartolus group based on the occurrence of a single large spine in the phallic membrane (Fig. 4 E). The new species is very similar to P. ceciliae and P. f a s t h i in the shape of the inferior appendage (Fig. 4 A, C & D) and phallus (Fig. 4 E & F), but the presence of a nearly asetose, “thumb­like” lobe ventral to the setose body of the preanal appendage (Fig. 4 A) distinguishes the new species from P. ceciliae and P. f a s t h i and from all other bartolus group species.

Adult. Length of forewing: male 6.0 mm (n=1, possibly teneral). Body stramineous, legs stramineous, dorsum of head and thorax pale brown, clothed with long stramineous setae; general vestiture of forewing with fine, light brown to brown setae, with many small, scattered areas of golden setae, base of forewing with long, erect setae.

Male. Genitalia as in Fig. 4. Sternum IX in lateral view subtriangular, dorsolaterally with distinct triangular patch of minute spicules, in ventral view quadrate; anterior margin shallowly concave, posterior margin slightly concave. Tergum IX and X membranous, slightly sclerotized basally. Intermediate appendage slightly curved, upturned, short, exceeding preanal appendage by 1/2 its length; basal region complex, slightly expanded; apex acuminate, with preapical setae, in membranous sheathes. Preanal appendage short, bilobed, with setose thumb­like dorsal lobe and more digitate, asetose ventral lobe, broad basally; mesoventral process narrowly triangular, directed ventrad, apex hook­like. Inferior appendage densely setose, short, oval, dorsoventral height greater than length; dorsolateral flange broadly rounded; ventrally with dorsally­directed caudomesal point, exposed in lateral view; in ventral view, inferior appendage subtriangular, caudomesal point prominent, acute; in caudal view, inferior appendage suboval, caudomesal point broadly triangular, with more basal patch of heavy, erect setae. Phallobase very short; apicoventral projection long, narrow, with single point; phallic membranes with single, long spine; phallic sclerite oval (difficult to discern, especially apically). Subphallic sclerite U­shaped in caudal view.

Holotype male: ECUADOR: Pichincha: ca. 84 km SW Quito, Chiriboga Rd., el. 1400 m, 7 Sept. 1990, O.S. Flint, Jr. (NMNH).

Etymology. Silex is Latin for flint, a pure form of microcrystalline quartz (silicate) commonly found in limestone rock. We name this species “ silex ” to honor Dr. Oliver S. Flint, Jr. of the U.S. National Museum of Natural History, Washington, DC, for his many contributions to world trichopterology.