A new genus and species of subterranean diving beetle from Laos (Coleoptera, Dytiscidae, Hydroporinae, Hydroporini)

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The first stygobiontic diving beetle known from Laos, Laodytes lapiei n. gen., n. sp., is described from a cave located in the Vientiane province. Its morphological characters lead to its placement, among Hydroporinae, in Hydroporini. Inside these, the new species could not be assigned to an existing genus. As a result, a new genus has been defined without it being possible, at the present stage, to assign it to one of the currently recognized subtribes. Résumé.-Nouveaux genre et espèce de Coléoptère aquatique souterrain du Laos (Coleoptera, Dytiscidae, Hydroporinae, Hydroporini). Le premier Dytiscidae stygobie connu du Laos, Laodytes lapiei n. gen., n. sp., est décrit d'une grotte de la province de Vientiane. Ses caractères morphologiques conduisent à le placer, parmi les Hydroporinae, dans les Hydroporini. À l'intérieur de ceux-ci, la nouvelle espèce n'a pu trouver place dans aucun genre existant. En conséquence, un nouveau genre a été défini, sans qu'il soit possible, à ce stade, de le rattacher à l'une des sous-tribus actuellement reconnues.

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We describe a new subterranean species of the genus Exocelina Broun, 1886 (Coleoptera: Dytiscidae) from the Malay Peninsula. Almost all of the 196 species of that genus are epigean and distributed mainly in New Guinea, Australia, Oceania and New Caledonia. One epigean species is, however, known from China. The discovery of a species on the Malay Peninsula fills that distribution gap to some degree.
The subtribe Deronectina Galewski, 1994 (Dytiscidae, Hydroporinae, Hydroporini) is distributed in the Nearctic, in the north of the Neotropical region, and in the Palaearctic and Afrotropical regions. It is currently composed of 194 species and 13 subspecies in eight genera: Amurodytes Fery & Petrov, 2013, Boreonectes Angus, 2010, Deronectes Sharp, 1882, Nebrioporus Régimbart, 1906, Oreodytes Seidlitz, 1887, Scarodytes Gozis, 1914, Stictotarsus Zimmermann, 1919, and Trichonectes Guignot, 1941. We present a morphological and a molecular phylogeny of the species of the subtribe, and a revision of their taxonomy to accommodate our phylogenetic results. The morphological phylogeny is based on the study of 54 characters of the adults of 189 species and 2 subspecies, of which 114 species and the 2 subspecies were coded in the morphological matrix. For the molecular phylogeny we investigated 115 species and 11 subspecies, using a combination of fragments of four mitochondrial (COI, 16S rRNA, tRNA-Leu and NAD1) and two nuclear genes (18S rRNA and H3), analysed with maximum likelihood and Bayesian methods. For both datasets we included the type species of all genus-group taxa. The morphological, molecular and combined phylogenies mostly agree with the current classification of the group, but in some cases our results are in contradiction with established genera. Most remarkable are the polyphyly of Stictotarsus and Nebrioporus, the low support for the monophyly and internal phylogeny of Oreodytes, and the low support for the monophyly of Deronectina with molecular data. Thus, we introduce some taxonomic changes in the current classification to accommodate the generic concepts to our phylogenetic results. Nine new genera are established: Clarkhydrus n. gen. (type species Hydroporus roffii Clark, 1862), Hornectes n. gen. (type species Hydroporus quadrimaculatus Horn, 1883), Iberonectes n. gen. (type species Deronectes bertrandi Legros, 1956), Larsonectes n. gen. (type species Potamonectes minipi Larson, 1991), Leconectes n. gen. (type species Hydroporus striatellus LeConte, 1852), Mystonectes n. gen. (type species Deronectes neomexicanus Zimmerman & Smith, 1975), Nectoboreus n. gen. (type species Hydroporus aequinoctialis Clark, 1862), Nectomimus n. gen. (type species Oreodytes okulovi Lafer, 1988), and Zaitzevhydrus n. gen. (type species Hydroporus formaster Zaitzev, 1908). Three genera are reinstated as valid: Deuteronectes Guignot, 1945 (stat. rest.) (type species Hydroporus picturatus Horn, 1883), Nectoporus Guignot, 1950 (stat. rest.) (type species Hydroporus abbreviatus Fall, 1923), and Neonectes J. Balfour-Browne, 1940 (stat. rest.) (type species Hydroporus natrix Sharp, 1884). Thirty-six new combinations for species and subspecies thus far treated in the genera Boreonectes, Nebrioporus, Oreodytes and Stictotarsus result from the new classification: Clarkhydrus corvinus (Sharp, 1887) n. comb., C. decemsignatus (Clark, 1862) n. comb., C. deceptus (Fall, 1932) n. comb., C. eximius (Motschulsky, 1859) n. comb., C. falli (Nilsson, 2001) n. comb., C. interjectus (Sharp, 1882) n. comb., C. minax (Zimmerman, 1982) n. comb., C. opaculus (Sharp, 1882) n. comb., C. roffii (Clark, 1862) n. comb., C. spectabilis (Zimmerman, 1982) n. comb., Deuteronectes angustior (Hatch, 1928) n. comb., Hornectes quadrimaculatus (Horn, 1883) n. comb., Iberonectes bertrandi (Legros, 1956) n. comb., Larsonectes minipi (Larson, 1991) n. comb., Leconectes striatellus (LeConte, 1852) n. comb., Mystonectes coelamboides (Fall, 1923) n. comb., M. grammicus (Sharp, 1887) n. comb., M. neomexicanus (Zimmerman & Smith, 1975) n. comb., M. panaminti (Fall, 1923) n. comb., M. titulus (Leech, 1945) n. comb., Nectoboreus aequinoctialis (Clark, 1862) n. comb., N. dolerosus (Leech, 1945) n. comb., N. funereus (Crotch, 1873) n. comb., Nectomimus okulovi (Lafer, 1988) n. comb., Nectoporus angelinii (Fery, 2015) n. comb., N. congruus (LeConte, 1878) n. comb., N. crassulus (Fall, 1923) n. comb., N. obesus obesus (LeConte, 1866) n. comb., N. obesus cordillerensis (Larson, 1990) n. comb., N. rhyacophilus (Zimmerman, 1985) n. comb., N. sanmarkii sanmarkii (C.R. Sahlberg, 1826) n. comb., N. sanmarkii alienus (Sharp, 1873) n. comb., N. sierrae (Zimmerman, 1985) n. comb., N. subrotundus (Fall, 1923) n. comb., Zaitzevhydrus formaster formaster (Zaitzev, 1908) n. comb., and Z. formaster ulanulana (C.-K. Yang, 1996) n. comb.
Among the hundreds of thousands of species of beetles, there is one family, containing some 4,300 species, that stands out as one of the most diverse and important groups of aquatic predatory insects. This is the Dytiscidae, whose species are commonly known as diving beetles. No comprehensive treatment of this group has been compiled in over 130 years, a period during which a great many changes in classification and a near quadrupling of known species has occurred. In Diving Beetles of the World, Kelly B. Miller and Johannes Bergsten provide the only full treatments of all 186 Dytiscid genera ever assembled. Entomologists, systematists, limnologists, ecologists, and others with an interest in aquatic systems or insect diversity will find these extensively illustrated keys and taxon accounts immensely helpful. The keys make it possible to identify all taxa from subfamily to genera, and each key and taxon treatment is accompanied by both photographs and detailed pen-and-ink drawings of diagnostic features. Every genus account covers body length, diagnostic characters, classification, species diversity, a review of known natural history, and world distribution. Each account is also accompanied by a range map and at least one high-resolution habitus image of a specimen. Diving beetles are fast becoming important models for aquatic ecology, world biogeography, population ecology, and animal sexual evolution and, with this book, the diversity of the group is finally accessible.
Four new species and three new genera of stygobiontic beetles are described: Dytiscidae: Siamoporus deharvengi, new genus, new species from Thailand; Sinodytes hubbardi, new genus, new species, hom China; Noteridae: Speonotenus bedosae, new genus, new species, from Indonesia; Elmidae: Neoelmis sketi, new species, from Ecuador. All of the taxa were collected from aquatic habitats in caves and bring the total known stygobiontic beetles to 23 species, 1 subspecies, and 20 genera, in 5 families. A list of the described stygobiontic beetles is included. Line drawings and/or micrographs illustrate the taxa and a map shows the type localities.
  • P J Spangler
sPangLer P. J., 1996. -Four new stygobiontic beetles (Coleoptera: Dytiscidae; Noteridae;