Some species of the diving beetle tribe Hygrotini (subfamily Hydroporinae) are among the few insects able to tolerate saline concentrations more than twice that of seawater. However, the phylogenetic relationships of the species of Hygrotini, and the origin and evolution of tolerance to salinity in this lineage, are unknown. In this work, we aim to reconstruct how many times salinity tolerance did evolve in Hygrotini, whether this evolution was gradual or if tolerance to hypersalinity could evolve directly from strictly freshwater (FW) species, and to estimate the probabilities of transition between habitats. We build a phylogeny with ca. 45% of the 137 species of Hygrotini, including all major lineages and almost all of the known halophile or tolerant species. We used sequence data of four mitochondrial (COI-5′, COI-3′, 16S + tRNA and NADH1) and three nuclear (28S, 18S and H3) gene fragments, plus ecological data to reconstruct the history of the salinity tolerance using Bayesian inference. Our results demonstrate multiple origins of the tolerance to salinity, although most saline and hypersaline species were concentrated in two lineages. The evolution of salinity was gradual, with no direct transitions from FW to hypersaline habitats, but with some reversals from tolerant to FW species. The oldest transition to saline tolerance, at the base of the clade with the highest number of saline species, was dated in the late Eocene-early Oligocene, a period with decreasing temperature and precipitation. This temporal coincidence suggests a link between increased aridity and the development of tolerance to saline waters, in agreement with recent research in other groups of aquatic Coleoptera.

Paroster baylyi sp. n. and P. ursulae sp. n. are described from south-western Australia, and compared with the similar P. michaelseni Régimbart, 1908. Their median lobes, parameres, gonocoxae, gonocoxosterna and habitus are illustrated, and details about their unique habitats and water beetle coenoses are given. The two new species are the first dytiscids to be known breeding solely in temporarily water filled rock-holes—so-called “pan-gnammas”—in the Mallee zone of south-western Australia. The total number of described species in the genus Paroster Sharp, 1882 is now 11. Eight aquatic Coleoptera of the families Dytiscidae and Hydrophilidae are recorded from 13 pan-gnammas on four granite outcrops in south-western Australia.

Fery, H. & Nilsson, A. N.: A revision of the Agabus chalconatus- and erichsoni-groups (Coleoptera: Dytiscidae), with a proposed phylogeny. Ent. scand. 24: 79-108. Copenhagen, Denmark. April 1993. ISSN 0013-8711. The Holarctic chalconatus- and erichsoni-groups, with 19 and three species respectively, are revised. The following seven new species are described: Agabus balkei from Siberia, Agabus jaechi from Turkey, Agabus larsoni from Canada, Agabus lenkoranensis from Azerbaijan, Agabus pederzanii from Italy, Agabus samokovi from Bulgaria, and Agabus wewalkai from Turkey. Lectotypes are designated for the following nominal species: Dytiscus chalconatus Panzer, 1796, Dytiscus nigroaeneus Marsham, 1802, Colymbetes montanus Stephens, 1828, Agabus neglectus Erichson, 1837, Agabus subtilis Erichson, 1837, Agabus gagates Aubé, 1838, Agabus altaicus Gebler, 1848, Agabus erichsoni Gemminger & Harold, 1868, Gaurodytes lutosus Crotch, 1873, Agabus fuscoaenescens Régimbart, 1877, Agabus aenescens Poppius, 1905, Agabus satunini Zaitzev, 1913, and Agabus melanocornis Zimmermann, 1915. The following new synonyms are established: Agabus altaicus Gebler, 1848 = Agabus subtilis Erichson, 1837; Agabus melanocornis Zimmermann, 1915 = Colymbetes montanus Stephens, 1828; Gaurodytes bulgaricus Csiki, 1943 = Dytiscus conspersus Marsham, 1802; Agabus skiathos Hinterseher, 1981 = Agabus pseudoneglectus Franciscolo, 1972; and Agabus maestroae Fresneda & Hernando, 1987 = Agabus albarracinensis Fery, 1986. Agabus aenescens Poppius, 1905, and A. satunini Zaitzev, 1913, are recognized as valid species (sp. rev.). The chalconatus-group is divided into four subgroups and the phylogeny of the group is reconstructed. The relationships of the chalconatus- and erichsoni-groups with other Agabus species-groups and with Ilybius Erichson are discussed.

The tribe Hygrotini Portevin, 1929 is currently composed of four genera, Heroceras Guignot, 1950, Herophydrus Sharp, 1880, Hygrotus Stephens, 1828 (with two subgenera, Coelambus Thomson, 1860, and Hygrotus s. str.), and Hyphoporus Sharp, 1880. A recent molecular phylogeny of the tribe with ca. 45% of the 137 described species of Hygrotini, including the type species of all genus-level taxa, revealed extended para- or polyphyly of the current genera and subgenera (Villastrigo et al., Zoologica Scripta, in press), for which reason a new classification of the tribe Hygrotini is proposed. Within Hygrotini only two genera are recognised: Clemnius n. gen. (with two subgenera: Clemnius s. str. with type species Hyphydrus decoratus Gyllenhal, 1810, and Cyclopius n. subgen. with type species Hydroporus acaroides LeConte, 1855) and Hygrotus (with four subgenera: Coelambus, Hygrotus s. str., Hyphoporus n. stat. and Leptolambus n. subgen. with type species Dytiscus impressopunctatus Schaller, 1783). Two genera are synonymised under Hygrotus s. str., Herophydrus n. syn. and Heroceras n. syn. The following 67 new combinations, for species thus far treated under the genera Heroceras, Herophydrus, Hygrotus and Hyphoporus, result from the new classification: Clemnius (s. str.) berneri (Young & Wolfe, 1984) n. comb., Clemnius (s. str.) decoratus (Gyllenhal, 1810) n. comb., Clemnius (s. str.) hydropicus (LeConte, 1852) n. comb., Clemnius (s. str.) laccophilinus (LeConte, 1878) n. comb., Clemnius (s. str.) sylvanus (Fall, 1917) n. comb., Clemnius (Cyclopius) acaroides (LeConte, 1855) n. comb., Clemnius (Cyclopius) farctus (LeConte, 1855) n. comb., Clemnius (Cyclopius) marginipennis (Blatchley, 1912) n. comb., Hygrotus (s. str.) assimilis (Régimbart, 1895) n. comb., H. (s. str.) bilardoi (Biström & Nilsson, 2002) n. comb., H. (s. str.) capensis (Régimbart, 1895) n. comb., H. (s. str.) confusus (Régimbart, 1895) n. comb., H. (s. str.) descarpentriesi (Peschet, 1923) n. comb., H. (s. str.) discrepatus (Guignot, 1954) n. comb., H. (s. str.) endroedyi (Biström & Nilsson, 2002) n. comb., H. (s. str.) gigantoides (Biström & Nilsson, 2002) n. comb., H. (s. str.) gigas (Régimbart, 1895) n. comb., H. (s. str.) goldschmidti (Pederzani & Rocchi, 2009) n. comb., H. (s. str.) gschwendtneri (Omer-Cooper, 1957) n. comb., H. (s. str.) hyphoporoides (Régimbart, 1895) n. comb., H. (s. str.) ignoratus (Gschwendtner, 1933) n. comb., H. (s. str.) inquinatus (Boheman, 1848) n. comb., H. (s. str.) janssensi (Guignot, 1952) n. comb., H. (s. str.) kalaharii (Gschwendtner, 1935) n. comb., H. (s. str.) morandi (Guignot, 1952) n. comb., H. (s. str.) muticus (Sharp, 1882) n. comb., H. (s. str.) natator (Biström & Nilsson, 2002) n. comb., H. (s. str.) nigrescens (Biström & Nilsson, 2002) n. comb., H. (s. str.) nodieri (Régimbart, 1895) n. comb., H. (s. str.) obscurus (Sharp, 1882) n. comb., H. (s. str.) obsoletus (Régimbart, 1895) n. comb., H. (s. str.) ovalis (Gschwendtner, 1932) n. comb., H. (s. str.) pallidus (Omer-Cooper, 1931) n. comb., H. (s. str.) pauliani (Guignot, 1950) n. comb., H. (s. str.) quadrilineatus (Régimbart, 1895) n. comb., H. (s. str.) reticulatus (Pederzani & Rocchi, 2009) n. comb., H. (s. str.) ritsemae (Régimbart, 1889) n. comb., H. (s. str.) rohani (Peschet, 1924) n. comb., H. (s. str.) rufus (Clark, 1863) n. comb., H. (s. str.) sjostedti (Régimbart, 1908) n. comb., H. (s. str.) spadiceus (Sharp, 1882) n. comb., H. (s. str.) sudanensis (Guignot, 1952) n. comb., H. (s. str.) travniceki (Šťastný, 2012) n. comb., H. (s. str.) tribolus (Guignot, 1953) n. comb., H. (s. str.) variabilis secundus (Régimbart, 1906) n. comb., H. (s. str.) variabilis variabilis (Guignot, 1954) n. comb., H. (s. str.) verticalis (Sharp, 1882) n. comb., H. (s. str.) vittatus (Régimbart, 1895) n. comb., H. (s. str.) wewalkai (Biström & Nilsson, 2002) n. comb., Hygrotus (Hyphoporus) anitae (Vazirani, 1969) n. comb., H. (Hyphoporus) aper (Sharp, 1882) n. comb., H. (Hyphoporus) bengalensis (Severin, 1890) n. comb., H. (Hyphoporus) bertrandi (Vazirani, 1969) n. comb., H. (Hyphoporus) caliginosus (Régimbart, 1899) n. comb., H. (Hyphoporus) dehraduni (Vazirani, 1969) n. comb., H. (Hyphoporus) elevatus (Sharp, 1882) n. comb., H. (Hyphoporus) geetae (Vazirani, 1969) n. comb., H. (Hyphoporus) josephi (Vazirani, 1969) n. comb., H. (Hyphoporus) kempi (Gschwendtner, 1936) n. comb., H. (Hyphoporus) montanus (Régimbart, 1899) n. comb., H. (Hyphoporus) nilghiricus (Régimbart, 1903) n. comb., H. (Hyphoporus) oudomxai (Brancucci & Biström, 2013) n. comb., H. (Hyphoporus) pacistanus (Guignot, 1959) n. comb., H. (Hyphoporus) pugnator (Sharp, 1890) n. comb., H. (Hyphoporus) severini (Régimbart, 1892) n. comb., H. (Hyphoporus) subaequalis (Vazirani, 1969) n. comb., H. (Hyphoporus) tonkinensis (Régimbart, 1899) n. comb.

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.