The last instar larva and pupa of Ora depressa (Coleoptera: Scirtidae), a marsh beetle with underwater pupation

LIBONATTI, M. L.; JORGE, GABRIELLE; ARCHANGELSKY, M.; MICHAT, M.C.

ACTA ENTOMOLOGICA MUSEI NATIONALIS PRAGAE

NARODNI MUZEUM - PRIRODOVEDECKE MUZEUM

Lugar: Buenos Aires; Año: 2018 vol. 58 p. 441 - 455

0374-1036

In thiscontribution we describe and illustrate for the fi rst time, detailedmorphology and chaetotaxy of the last instar larva and the pupa of Oradepressa (Fabricius,1801), and provide diagnostic characters and information on its biology. Thelast instar larva of O. depressaexhibitsthe characters traditionally recognized as diagnostic of the genus, i.e. the tipof the mandible obtuse, and the fourth maxillary palpomere long, almost as longas third palpomere. Ora depressa ischaracterized by a broadly elliptical body, which is widest at the metanotum,being brownish testaceous in color with several brown spots, having the dorsal surfacemostly covered with numerous grooved scale-like setae and also severalungrooved scale-like setae, hair-like setae, club-like setae and pore-like sensilladistributed in a specific pattern, and the femur and tibiotarsus bearing a rowof natatorial setae. The last instar larva of Oradepressa can bedistinguished from those of the other known species of the genus by lobes of clypeolabrumbeing as long as wide and socket bristles with 2?6 inner teeth. The pupa of O.depressa differsfrom those of the other known species of the genus in the absence of pronotalhorns and by the place where pupation occurs. Oradepressa pupatesunderwater, hanging from water?s surface with the aid of the laterally expandedpronotum which bears hydrophobic setation along the lateral margins.