Insect life stages are known imperfectly in many cases, and classifications are based often on only one or a few semaphoronts of a species. This is unfortunate as information in alternative life stages often is useful for scientific study. Although recent examples of DNA in taxonomy have emphasized the identification of indistinguishable species, such sequence data facilitate the association of life history stages and hold considerable promise in phylogenetic analysis, evolutionary studies, diagnostics, etc. These concepts are discussed here and an example is provided from diving beetles (Dytiscidae: Coleoptera). Three unknown larval specimens of an apparent species of Laccophilinae collected in Namibia were associated with the species Philodytes umbrinus (Motschulsky) using DNA sequence data. An 806-bp portion of the gene cytochrome oxidase I was sequenced from the unknown larvae. Several identified adult specimens of species of Laccophilinae from Namibia were also sequenced, including two P. umbrinus specimens and specimens from four Laccophilus Leach species. Additional species of Laccophilus from other areas of the world also were sequenced, as were specimens of Agabetes acuductus (Harris), Australphilus saltus Watts, Neptosternus boukali Hendrich & Balke and a species of Laccodytes Re´gimbart. Parsimony analysis resulted in two most parsimonious trees with the unknown larva unambiguously resolved in a group with both adult specimens of P. umbrinus (bootstrap value ¼ 100%). The average pairwise p-distance between the unknown larva and adult P. umbrinus specimens averaged 0.09% (0-0.14%), compared with an average divergence between other conspecifics in the analysis of 0.24% (0-0.82%) and an overall average divergence between species of 13.49% (1.90-19.86%). Based on this, the unknown larvae were assigned to P. umbrinus. The larvae are diagnosed and described and their relationship with other Laccophilinae is discussed.
Laccornellus, new genus, is proposed for two austral South American species previously assigned to Laccornis Gozis (L. lugubris (Aube, 1838), the type species, known from Argentina and Uruguay, and L. copelatoides (Sharp, 1882), known from Chile). The valvifer is absent in the adult stage of females of these species and the males have a greatly enlarged internal sac on the aedeagus; these characters exclude them from Laccornis. The most similar and possibly most closely related genus to Laccornellus is the African genus Canthyporus Zimmermann, although no conclusive synapotypy was found. Relationships of extant, plesiotypic hydroporines remain problematic; however, divergence of Laccornellus and Canthyporus probably began about 120 million years ago when Africa and South America separated. The vicariant event preceding divergence of L. copelatoides and L. lugubris probably was the uplift of the Andes Mountains which began in the late Oligocene – early Miocene.
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