The first stygobiont species of Coleoptera from Portugal, with a molecular phylogeny of the Siettitia group of genera (Dytiscidae, Hydroporinae, Hydroporini, Siettitiina)

Iberoporusplutosp. n., the first stygobiont beetle from Portugal (Dytiscidae, Hydroporinae), is described from a single female from the cave Soprador do Carvalho (Coimbra). The species is highly troglomorphic, depigmented, blind, and with elongated appendages not adapted for swimming. A molecular phylogeny based on a combination of three mitochondrial and two nuclear genes showed the new species to be sister toI.cermeniusCastro & Delgado, 2001 from Córdoba (south of Spain), within the subtribe Siettitiina of the tribe Hydroporini. Both species are included in a clade withSiettitiaavenionensisGuignot, 1925 (south of France) andRhithrodytesagnusFoster, 1992 andR.argaensisFery & Bilton, 1996 (north of Portugal), in turn sister to the rest of species of genusRhithrodytesBameul, 1989, in what is here considered theSiettitiagroup of genera. We resolve the paraphyly ofRhithrodytesby transferring the two Portuguese species toIberoporusCastro & Delgado, 2001,I.agnus(Foster, 1992),comb. n.andI.argaensis(Fery & Bilton, 1996),comb. n.