Molecular phylogeny of the H ydroscaphidae ( C oleoptera: M yxophaga) with description of a remarkable new lineage from the G uiana S hield

The phylogeny of the aquatic beetle family H ydroscaphidae is inferred from one mitochondrial ( COI ) and five nuclear ( 18S , 28S , wingless , arginine kinase and CAD ) genes. Bayesian, maximum likelihood and maximum parsimony analyses were conducted on a combined dataset that included representatives from all three described hydroscaphid genera, three new species of the family of uncertain placement, and representatives from the myxophagan families S phaeriusidae, T orridincolidae and L epiceridae. All analyses strongly supported a set of nearly identical trees in which (i) the monophyly of H ydroscaphidae and all its constituent genera is affirmed, (ii) the nearly cosmopolitan genus Hydroscapha is sister to the remaining and exclusively N eotropical genera, and (iii) the new, morphologically aberrant taxa from the G uiana S hield form a monophylum separate from any described genus. Here, we review each genus of the family including the description of Confossa S hort, J oly, G arcía & M addison gen.n. to accommodate three new species: C. sculptura sp.n. , C. falcata sp.n. and C. minima sp.n. The new genus possesses a remarkable perforated abdominal surface that we hypothesize serves as a respiratory plastron. We also present a key to the genera and a catalogue of species of the family.