Oecetis pseudoamazonica, new species

Fig. 11

Oecetis pseudoamazonica n. sp. is closely related to O. amazonica (Banks 1924) . The male genitalia of the 2 species are almost identical, and there are only small differences in some genital characters and wing venation. There are differences in the anterior margins of segment IX, which are reinforced by a conspicuous antecosta in both species. In O. amazonica this antecosta is continuous and it is not interrupted by its acrotergite (Fig. 1 C), whereas, in the new species, this antecosta is discontinuous at the acrotergite. In the genitalia, the posteroventral margin of segment IX is rounded in O. amazonica in ventral view (Fig. 1 D), but clearly produced into a median process which is rounded at the tip in the new species (Fig. 11 D). The phallic apparatus shows a subtle difference in the length of the ventral process, which is longer in O. amazonica . In O. amazonica, the crossveins r–m and m–cu are almost in line, but, in the new species, they are clearly staggered. The difference in size is important, the length of a forewing of O. amazonica is 10 mm (n = 16) while it is 6.1 mm (n = 5) in O. pseudoamazonica n. sp. The coloration pattern of wings is sharper and darker in O. amazonica, paler in the new species. The apex of each forewing in O. amazonica is obtuse, whereas it is acute in O. pseudoamazonica n. sp. Fork I in of O. amazonica is petiolate, but sessile in O. pseudoamazonica n. sp.

Specific diagnosis. Oecetis pseudoamazonica n. sp. can be distinguished from other species by the fact that in each forewing, R2+3 is branched and without a petiole, the apex of each forewing is acute, the acrotergite of segment IX is not separated from the rest of dorsum IX by antecosta, the posteroventral margin of segment IX has a median process that is rounded at the apex, and the forewings are relatively short.

Adult. Length of each forewings: 6.1 mm. Forewings each with R2+3 branched at midpoint of stigma and without petiole. Hind wings each with R2+3 and M branched near margin of wing; Cu1 branched more deeply (Fig. 11 A).

Male genitalia. Segment IX annular with 2 dorsal knobs; anterolateral margins almost straight, posterior margin slightly angulate (Fig. 11 B). Posterior margin of segment IX reinforced with well developed antecosta, except with antecosta poorly developed, bent, and partially bordering acrotergite in dorsal view (Fig. 11 C). Posteroventral margin of segment IX produced into median rounded process in ventral view (Fig. 11 D). Preanal appendages rounded with broad bases in lateral view (Fig. 11 B); fused almost completely on midline with U–shaped median excision in dorsal view (Fig. 11 C). Tergum X membranous, digitate and slightly upcurved in lateral view (Fig. 11 B); broad at base and slightly narrowed at tip in dorsal view (Fig. 11 C). Inferior appendages broad, each with ventral margin curved with apex thin and rounded in lateral view (Fig. 11 B); base broad with curved external margin gradually narrowing distally, abruptly narrowed at tip in ventral view (Fig. 11 D). Phallic apparatus rounded, with sinuous paramere spine, C-shaped phallotremal sclerite, and acute ventral process in lateral view (Figs. 11 E– F).

Holotype male. BOLIVIA: Río Mocovi, near Trinidad, 14°44'27''S, 64°54'24''W, 12.11.2001, (IML).

Paratypes. 2 males, same as holotype, (IML). Río Itenez, Versalles, 12°39'42''S, 63°22'21''W, 04.v.2006, (CBF-UMSA) ― 1 male; Lake San Gregorio, near Reyes, (IML) ― 1 male; Lake Granja, Bella Vista, 13°15'50''S, 63°42'33''W, 06.v.2006, (IML) ― 1 male.

Etymology. This species is named O. pseudoamazonica because of its close relationship and appearance with O. amazonica .