The last instar larva and pupa of Ora depressa (Coleoptera: Scirtidae), a marsh beetle with underwater pupation
Libonatti Maria L., Jorge Gabrielle, Archangelsky Miguel, Michat Mariano C.
Acta Entomologica Musei Nationalis Pragae 58(2): 441-455, 2018
Published online: 24th October 2018
Published in print: 31st December 2018
Views: 1420
Abstract: In this contribution we describe and illustrate for the first time, detailed
morphology and chaetotaxy of the last instar larva and the pupa of Ora depressa
(Fabricius, 1801), and provide diagnostic characters and information on its
biology. The last instar larva of O. depressa exhibits the characters
traditionally recognized as diagnostic of the genus, i.e. the tip of the
mandible obtuse, and the fourth maxillary palpomere long, almost as long as
third palpomere. Ora depressa is characterized by a broadly elliptical body,
which is widest at the metanotum, being brownish testaceous in color with
several brown spots, having the dorsal surface mostly covered with numerous
grooved scale-like setae and also several ungrooved scale-like setae, hair-like
setae, club-like setae and pore-like sensilla distributed in a specific pattern,
and the femur and tibiotarsus bearing a row of natatorial setae. The last instar
larva of Ora depressa can be distinguished from those of the other known species
of the genus by lobes of clypeolabrum being as long as wide and socket bristles
with 2–6 inner teeth. The pupa of O. depressa differs from those of the other
known species of the genus in the absence of pronotal horns and by the place
where pupation occurs. Ora depressa pupates underwater, hanging from
water’s surface with the aid of the laterally expanded pronotum which bears
hydrophobic setation along the lateral margins.
Key words: Coleoptera, Scirtidae, marsh beetles, larva, pupa, morphology, chaetotaxy, Neotropical Region