Miguel Archangelsky

Phylogeny of Hydrophiloidea (Coleoptera: Staphyliniformia) using characters from adult and preimaginal stages

A phylogenetic analysis using characters from egg cases, larvae, pupae and adults was conducted; the outgroups included the beetle families Silphidae, Hydraenidae and Histeridae. Characters from the immature stages were obtained mostly from material reared in the laboratory, those from the adults were obtained from Hansens generic revision for the superfamily. The results support the position of Hydraenidae within the Staphylinoidea, and not as part of Hydrophiloidea; Histeroidea is proposed as the sister group of Hydrophiloidea. At family level two clades are distinguished; the relationships within the first clade are ((Georissidae Epimetopidae) Helophoridae), those within the second are ((Hydrophilidae Spercheidae) Hydrochidae). Larval characters were most informative at the base of the tree, especially those associated with the spiracular atrium; adult characters were most informative at the apex of the tree.

DESCRIPTIONS OF LARVAE OF DESMOPACHRIA BABINGTON (COLEOPTERA: DYTISCIDAE: HYDROPORINAE): THE D. VICINA SHARP SPECIES GROUP

Abstract Larval morphology of the Desmopachria vicina Sharp species group is investigated. For this purpose, the three larval instars of Desmopachria concolor Sharp and Desmopachria punctatissima Zimmermann are described and illustrated for the first time, with an emphasis on the morphometry and chaetotaxy. Both species have the setae LA3, LA4 and LA5 inserted proximally on the prementum and the seta LA10 inserted distally on the second labial palpomere, the two larval autapomorphies that define the genus Desmopachria Babington. They are also characterized by the presence of secondary setae on the ventral surface of the siphon of third-instar larva; this character state is a synapomorphy of Desmopachria + Hyphydrus Illiger. Desmopachria concolor and D. punctatissima are very similar morphologically, suggesting that they could be closely related phylogenetically. Larvae of the D. vicina species group differ from those of the Desmopachria convexa (Aubé) species group in the presence of one additional seta on the dorsal surface of the prementum, the more distal insertion of the seta LA2 on the prementum, and the absence of one of the distal pores (LAb or LAd) on the first labial palpomere.

Phylogenetic relationships of Leuronectes Sharp (Coleoptera: Dytiscidae: Agabinae) based on larval morphology and chaetotaxy

The phylogenetic relationships of the diving beetle (Dytiscidae) genus Leuronectes Sharp are revised based on a cladistic analysis of seven Agabinae genera and 54 morphological and chaetotaxic characters from larvae. For this purpose, larvae of L. curtulus Regimbart are described and illustrated in detail for the first time, with particular emphasis on morphometry and chaetotaxy. The results show that Leuronectes is well placed within Agabinae based on the absence of natatory setae on tibia and tarsus in instars II and III, the urogomphus composed of two urogomphomeres, and the absence of secondary setae on urogomphus. Leuronectes is resolved as part of a basal polytomy along with Platynectes Regimbart and a clade formed by the remaining agabine genera. Leuronectes shares with Platynectes the setae UR2, UR3 and UR4 not inserted contiguously, with Platambus Thomson the anterolateral lobes of frontoclypeus not projected beyond anterior margin, with Hydrotrupes Sharp the seta AB9 inserted dorsolaterally, and with Ilybius Erichson the seta LA10 inserted submedially. Leuronectes is unique within Agabinae in having the apical lateroventral process of the third antennomere not protruding and additional ventroapical pores on third antennomere, and is unique within the dytiscid genera studied in having the seta LA12 inserted submedially and one additional spine-like seta inserted on the lateral margin of abdominal segment VIII.

Description of the preimaginal stages of Dibolocelus ovatus (Gemminger and Harold, 1868) (Coleoptera, Hydrophilidae: Hydrophilinae)

The larva, pupa and egg case of Dibolocelus ovatus are described and illustrated with line drawings. Biological observations, based on material reared in laboratory, are included.

Description of New Neotropical Berosini Larvae: Derallus paranensis and Hemiosus dejeanii (Coleoptera: Hydrophilidae)

Abstract The larval stages of the Neotropical species Derallus paranensis Oliva, 1981 and Hemiosus dejeanii (Solier, 1849) are described and figured for the first time. Notes on the bionomics of these two species are included. Larvae of D. paranensis and H. dejeanii are compared to those of other Derallus Sharp and Hemiosus Sharp species. Comparative notes to differentiate larvae of two genera related to Derallus, Allocotocerus Kraatz and Regimbartia Zaitzev are provided.

Description of the preimaginal stages of Dactylosternum cacti (Coleoptera: Hydrophilidae, Sphaeridiinae)

The immature stages of Dactylosternum cacti (LeConte, 1855) are described, and information on the biology of this species is included. The larva of this species is compared to a larva associated with adults of Dactylosternum subrotundum (Fabricius, 1792) from Brazil; differences between both larvae raise questions about their congenerity.

Description of the Preimaginal stages of Derallus angustus sharp, 1882 (Coleoptera: Hydrophilidae, Berosinae)

The third instar larva, pupa, egg case and eggs of Derallus angustus are described and illustrated with line drawings. Biological and behavioral observations, based on material reared in laboratory, are included. The larvae of D. angustus and D. rudis are compared. The immatures of Derallus and Berosus are also compared from a morphological and biological point of view.

Description of the preimaginal stages and biology of Phaenonotum (Hydroglobus) puncticolle bruch (Coleoptera: Hydrophilidae)

The larvae and egg case of Phaenonotum (Hydroglobus) puncticolle Bruch, 1915 are described, based on material collected in the field and reared in the laboratory. Behavioral and populational data are included and discussed. The larvae and egg cases are compared to those of Phaenonotum (Phaenonotum) exstriatum (Say, 1835).

Immature Stages of Neotropical Enochrus (Coleoptera: Hydrophilidae): E. (Methydrus) lampros Knisch, 1924 and E. (Hugoscottia) tremolerasi Knisch, 1922

The preimaginal stages of the Neotropical species E. (M.) lampros Knisch, and Enochrus (H.) tremolerasi Knisch, are described and illustrated for the first time. They are compared to the immatures of the Neotropical species E. (M.) vulgaris (Steinheil) and E. (Hugoscottia) scutellaris (Bruch), the Nearctic E. (M.) fimbriatus (Melsheimer) and E. (M.) pygmaeus nebulosus Say, and the Australian E. (M.) maculiceps (MacLeay). Bionomical notes on the two species are included.

Description of the Larva of Macrelmis Isis (Hinton, 1946), With Distributional Notes of the Species (Coleoptera, Elmidae)

beetles. From the Neotropical region some 35 genera and 300 species have been described. Of these, 23 genera are endemic, two are shared with the Australian region, and the remaining ten with the Nearctic region. Despite being common in lotic habitats, the knowledge of this family is poor in many parts of South America. Argentina is probably one of the most neglected areas regarding the knowledge of the elmid fauna, only seven species have been reported for this country (Hinton 1946a, 1951 and 1970; Spangler & Brown 1981). In contrast, several neighbouring countries of Argentina such as Brazil and Bolivia harbour many species, suggesting that the number of argentine species should be larger (Tremouilles et al. 1995). It is also expected that further studies on argentine elmids will result in description of new species since this is a large country, rich in biogeographical regions that range from subtropical to subantarctic areas. Macrelmis Motschulsky, 1859, has 39 species, three of them Nearctic (Southern United States), the remaining ones are Neotropical; nearly all of them were previously assigned to a different genus, Elsianus Sharp 1882. Hinton (1946b) described 12 new Brazilian species within the genus Elsianus Sharp, including Elsianus isus. Almost 40 years later Brown (1984), after examining the type of Macrelmis, M. dentata Motschulsky, 1859, discovered that it is the same as the genus Elsianus Sharp, 1882, this resulted in the transfer of all species previously ascribed to Elsianus to the genus Macrelmis, by Brown (1984). Macrelmis isis (Hinton, 1946), reported here, is the first record of this genus for Argentina. Despite being common and easily associated with adults, preimaginal stages of Elmidae are poorly known for the Neotropical region. For the genus Macrelmis only two species, both of them from Mexico, have been described by Hinton (1940): M. granigera (Sharp, 1882) and M. striata (Sharp, 1882). The larvae of two other species are described by Hinton (1940) in the same paper (as Elsianus sp. ?), they were not assigned to any species at the time, but one of them belongs to the genus Huleechius Brown, 1981. Bertrand (1956, 1972) summarizes all that is known on larval stages of this genus; based mostly on Hinton’s work, Bertrand recognizes two larval groups he names granigera-type and striata-type. Finally, one Peruvian larva within this genus (also identified as Elsianus sp.) was described by Spangler (1966), but was not assigned to any known species. In this paper, besides presenting a detailed description of the mature larvae of M. isis, we also illustrate some adult characters that we consider important in order to differentiate male and female specimens; they complement Hinton’s original description of M. isis.