Description of the Second and Third Instars ofLaccornellus lugubris(Aubé) (Coleoptera: Dytiscidae: Hydroporinae)

Abstract

The second and third instars of Laccornellus lugubris (Aubé) are described and illustrated for the first time, including detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment, and urogomphi. Laccornellus Roughley and Wolfe shares with Canthyporus Zimmermann a similar shape and secondary setation of the last abdominal segment, the absence of secondary spine-like setae on the lateral margins of the parietal, and the presence of well-developed spinular pectens on the ventral surface of the femora (this last character also is shared with Laccornis Gozis). On the other hand, larvae of Laccornellus differ from those of Canthyporus, Laccornis, and Hydrovatus Motschulsky in the presence of secondary pores on the ventral surface of the prementum and of secondary setae on the tibia, metatarsus, and anterodorsal surface of femur. The known distributional range of L. lugubris is considerably expanded.

Larval morphology ofAllodessusGuignot (Coleoptera: Dytiscidae)

“…Within Bidessini, Allodessus belongs to the group of genera in which the larvae bear a short last abdominal segment and long urogomphi (Amarodytes, Glareadessus, Hypodessus, Liodessus, Neoclypeodytes) (Perkins 1980;Alarie and Wewalka 2001;Alarie 2006, 2008;Alarie et al 2007). These characters distinguish the genus from Uvarus (Matta 1983) and Anodocheilus (Michat and Torres 2006). On the other hand, the lack of a colour pattern on the head and abdomen distinguishes Allodessus from Neoclypeodytes (Perkins 1980).…”

“…Despite the fact that Bidessini represent one of the most significant radiations of diving beetles, with about 40 genera and 600 species (Nilsson 2001(Nilsson , 2003(Nilsson , 2004Nilsson and Fery 2006), larval morphology of members of this tribe remains very imperfectly known. So far, the larvae of only 13 genera are known (Meuche 1937;Watts 1963;Bertrand 1972;Perkins 1980;Richoux 1982;Matta 1983;Nilsson 1985;Alarie and Wewalka 2001;Alarie 2006, 2008;Michat and Torres 2006;Alarie, Michat, Archangelsky and Barber-James 2007), some of them very superficially, and the larvae of about 2/3 of the genera are unknown. Regarding Allodessus, only a very brief description of the mature larva is available (Watts 1963).…”