Morfologia externa da larva de Megadytes giganteus (Laporte, 1834) (Insecta: Coleoptera: Dytiscidae), com evidências sobre a condição monofilética da tribo Cybisterini

Abstract

The larval instar of the predaceous diving beetles Megadytes giganteus were studied based mainly on material collected in a sand dune swamp and temporary ponds located in Maricá, Rio de Janeiro States, Brazil (22°56'S, 42º50'W). The external morphology of the three instars larva is described. The larvae of third instar is illustrated. Many of the characters found in larva this species have different states represented in separate groups of Cybisterini or correlatives, contributing to the establishment of monofiletic groups. So, the unique ternimal larval characters of species of Cybisterini (fore margin of fronto-clypeous trilobed; subconic tegumentary process; antenna 9-segmented; dorsal pubescense of mandible; basal position of the posterior orifice of mandible; maxillary palpi 9-segmented; labial palpi 4-segmented; dense row of small spiniform setae in basal third on ventral margin on tarsi 1; row of branched spiniform setae in apical two-thirds on ventral margin on tarsi 1; urotergites reduced to a small retangular plate on segments 1 to 6; anus subapical) were taken as synapomorphies of the tribe.