Revision of the emBelostoma triangulum/em group (Insecta: Heteroptera: Belostomatidae).

The genus Belostoma comprises about 70 species classified in sixteen species groups. Here, the remarkable Belostoma triangulum group sensu Lauck, 1964, is revised. Belostoma bicavum Lauck, 1964 is proposed as a junior synonym of B. bachmanni De Carlo, 1957, which is added to this group. Thus, the rearranged group is now composed of two species: Belostoma bachmanni and B. triangulum Lauck, 1964. Redescriptions of these species are presented including a discussion about comparative morphology with other species of the genus. The geographic distributions of the species in the B. triangulum group are also updated.

Coevolution between male and female genitalia in Belostoma angustum Lauck, 1964 (Insecta, Heteroptera, Belostomatidae): disentangling size and shape.

Sexual and natural selection mechanisms might drive variation in the genitalia of male animals. All aforementioned mechanisms are known to predict the coevolution of male and female genital morphology. Belostoma angustum is known to have subtle variation in the male and female genitalia of its members. In this species, phallosoma with dorsal arms and ventral diverticulum are assumed to be intromittent male genital traits that interact with the female genital chamber. We thus evaluated the existence of variation after disentangling the size from the shape of male genitalia in B. angustum. Body and genitalia dimensions and photographs of phallosoma with dorsal arms, ventral diverticulum and lateral views of the right paramere (the non-intromittent part) were obtained. Semi-landmarks and landmarks were used to capture phenotypic variation, by eliminating all non-shape variation with a Procrustes superimposition. Male and female specimens collected from the same location or immediate vicinity were grouped, and 12 groups originating from 12 locations were used to conduct two block-Partial Least Squares analyses (PLS). Group structures were also taken into account by adopting a multilevel approach. The male and female genital traits had similarly shallow static allometry slopes, as well as the dispersion values around the mean (i.e. coefficient of variation) and the standard error of the estimate. The correlation between the pooled within-locality covariance matrix of the symmetric component of phallosoma with dorsal arms and the female genital chamber was significant (r-PLS=0.37), as well as that with male body dimensions (r-PLS=0.36), even after controlling for allometry. Specimens with lower PLS shape scores had narrower phallosoma with dorsal arms, with poorly curved outer margins of the dorsal arms, whereas specimens with higher PLS shape scores had slightly shorter dorsal arms, with strongly curved outer margins. Lower shape scores were associated with narrower and especially shorter and narrower female genital chambers. Similar shallow allometric curves among sexes and the correlation between intromittent male parts and the female genital chamber, as well as male dimensions, suggest the coevolution of these contact structures in size and in shape.

Revision of the Belostoma dentatum group sensu Nieser (Insecta, Heteroptera, Belostomatidae).

Species of Belostoma in the dentatum and subspinosum groups are large and closely related, and have been combined by some authors into a single group, the dentatum group, comprising 15 species. This group is recognized by the scutellum reaching the nodal line and the ventral diverticulum of the phallus with distinct dorsal caudal and ventroapical protuberances. Previously, each group included five and 10 species, respectively; members of the dentatum group ranged in length from 38.0 to 52.0 mm, whereas those of the subspinosum group ranged from 26.0 to 40.0 mm. The following species of the dentatum group, now reformulated, include: Belostoma anurum (Herrich-Schäffer), B. asiaticum (Mayr), B. bordoni De Carlo, B. cummingsi De Carlo, B. columbiae Lauck, B. dallasi De Carlo, B. dentatum (Mayr), B. elongatum Montandon, B. ellipticum Latreille, B. foveolatum (Mayr), B. guianae Lauck, B. harrisi Lauck, B. malkini Lauck, B. porteri De Carlo, B. pseudoguianae Roback & Nieser, B. subspinosum Palisot de Beauvois, and B. venezuelae Lauck. Belostoma bordoni is herein included in the dentatum group based on male genitalic morphology, and the subspecies B. subspinosum subpinosum (Palisot de Beauvois) and B. subspinosum cupreomicans (Stål) are synonymized as a single valid species, B. subspinosum. Belostoma peruvianum De Carlo is synonymized with B. dentatum. Based on the study of male genitalic characteristics, B. cachoeirinhensis Lanzer-de-Souza appears to be conspecific with B. cummingsi; however, because we could not borrow types of B. cachoeirinhensis, we do not synonymize it. Sketches of specimens identified either as B. boscii (Le Peletier de Saint-Fargeau & Serville) or B. anurum by A.L. Montandon from Muséum National d'Histoire Naturelle are provided with comments in order to show the variation of male genitalia through the B. subspinosum complex. Our findings suggest that the dorsal arms of the phallotheca curved apically to be diagnostic of this complex. No firm conclusion is possible because of the great variation in the male genitalia; however, the general aspect of the ventroapical protuberance together with the dorsal arms provide some definition of B. subspinosum. A key to these species is also given, deeply modified after D.R. Lauck and N. Nieser.

A New Approach to Chromosomal Evolution in the Giant Water Bug (Heteroptera: Belostomatidae).

The genus Belostoma, known colloquially as "giant water bugs," presents striking cytogenetic diversity and extensive chromosome variability. Notwithstanding, its karyotype evolution is not well understood. We analyzed 8 species of Belostoma (77 samples). The meiotic analysis revealed 2n = 14 + XY for Belostoma horvathi and Belostoma candidulum; 2n = 22 + XY for Belostoma cummings; 2n = 26 + X1X2Y for Belostoma dentatum, Belostoma elongatum, and Belostoma discretum; and 2n = 26 + X1X2X3Y for Belostoma testacopallidum and Belostoma dilatatum. All species showed holokinetic chromosomes. Based on heterochromatin distribution patterns and 18S rDNA, the species of the genus Belostoma were separated into four groups. The analysis of C0t-1 DNA showed that the repetitive DNA, partly composed of microsatellite DNA, was absent on the Y chromosome. Fluorescent in situ hybridization (FISH) using a microdissected X chromosome in species with simple sex system presents uniform hybridization in the nuclear region corresponding to the X chromosome. Species with multiple systems revealed discrete markings. The present data in conjunction with the existing literature led us to propose a new evolutionary hypothesis for the group, with an ancestral karyotype with a low diploid number, simple sex determination system, and nucleolus organizer regions (NORs) on the sex chromosomes. That karyotype would have originated other karyotypes through agmatoploidy, simploidy, heterochromatinization, and movement of the 18S rDNA.

Veliidae (Insecta, Heteroptera, Gerromorpha) from southeastern Brazil: three new species from Rio de Janeiro State, a new species group for Neotropical Rhagovelia Mayr, and notes on distribution and synonymy / Veliidae (Insecta, Heteroptera Gerromorpha) do Sudeste do Brasil: três novas espécies do Estado do Rio de Janeiro, um novo grupo para espécies neotropicais de Rhagovelia Mayr, e notas sinonímicas e de distribuição

Microvelia nelsoni sp. nov., M. takiyae sp. nov., and Rhagovelia mangaratiba sp. nov. are described. Rhagovelia scitula and R. whitei are transferred from the robusta group to the new whitei group. Rhagovelia denticulata is synonymized under R. scitula. Microvelia longipes, Oiovelia brasiliensis, Rhagovelia sooretama, R. trianguloides, R. vaniniae, and Stridulivelia quadrispinosa are recorded for the first time from Rio de Janeiro State. Additional new municipality records in Rio de Janeiro State are presented for Microvelia braziliensis, M. ioana, M. mimula, M. pulchella, Paravelia basalis, P. itatiayana, Rhagovelia accedens, R. agra, R. aiuruoca, R. elegans, R. hambletoni, R. henryi, R. itatiaiana, R. lucida, R. macta, R. modesta, R. novana, R. scitula, R. tenuipes, R. tijuca, R. triangula, and R. zela. Corrections are presented for the previously published distributions of Rhagovelia aiuruoca, R. lucida, R. macta, and R. triangula.

Microvelia nelsoni sp. nov., M. takiyae sp. nov. e Rhagovelia mangaratiba sp. nov. são descritas. Rhagovelia scitula e R. whitei são transferidas do grupo robusta para o novo grupo whitei. Rhagovelia denticulata é sinonimizada com R. scitula. Microvelia longipes, Oiovelia brasiliensis, Rhagovelia sooretama, R. trianguloides, R. vaniniae e Stridulivelia quadrispinosa são registradas pela primeira vez no Estado do Rio de Janeiro. Ocorrências adicionais novas no Estado do Rio de Janeiro são apresentadas para Microvelia braziliensis, M. ioana, M. mimula, M. pulchella, Paravelia basalis, P. itatiayana, Rhagovelia accedens, R. agra, R. aiuruoca, R. elegans, R. hambletoni, R. henryi, R. itatiaiana, R. lucida, R. macta, R. modesta, R. novana, R. scitula, R. tenuipes, R. tijuca, R. triangula e R. zela. Correções acerca das distribuições de Rhagovelia aiuruoca, R. lucida, R. macta e R. triangula são apresentadas.

A synopsis of the Hydrometra (Hemiptera, Heteroptera, Hydrometridae) from the Amazon River floodplain, Brazil, with redescription of Hydrometra argentina Berg / Sinopse de Hydrometra (Hemiptera, Heteroptera, Hydrometridae) da várzea do Rio Amazonas, Brasil, com a redescrição de Hydrometra argentina Berg

Hydrometra argentina Berg, 1879, H. caraiba Guérin-Méneville, 1857 and H. guianana Hungerford & Evans, 1934 are newly recorded in the Amazon River floodplain, Brazil. A redescription of H. argentina is also given, as the original description is incomplete. A key to the three known species occurring in this region is provided. Hydrometra argentina can be distinguished from H. caraiba and H. guianana by the body length smaller than 12.50 mm, anteoculus/postoculus ratio between 1.80 and 2.00, clypeus narrow and conical, metacetabulum with no circular pits, and projections on male abdominal sternite VI in the shape of simple spines. The other species can be distinguished mainly by the anteoculus/postoculus ratio and position of projections on male abdominal sternite VI.

Novos registros na várzea do Rio Amazonas, Brasil, são feitos para Hydrometra argentina Berg, 1879, H. caraiba Guérin-Méneville, 1857 e H. guianana Hungerford & Evans, 1934. Uma redescrição de H. argentina também é provida, já que a descrição original é incompleta. Uma chave de identificação para as três espécies do gênero ocorrentes na área é apresentada. Hydrometra argentina pode ser distinguida de H. caraiba e H. guianana pelo comprimento do corpo menor que 12,50 mm, proporção anteóculo/pós-óculo entre 1,80 e 2,00, clípeo estreito e cônico, metacetábulo sem pontuações, e projeções do esternito abdominal VI do macho na forma de espinhos simples. As demais espécies distinguem-se principalmente pela proporção anteóculo/pós-óculo e pela posição das projeções do esternito abdominal VI do macho.

A synopsis of the species of Mesovelia (Insecta: Heteroptera: Mesoveliidae) occurring in the floodplain of the Amazon River, Brazil, with redescriptions of Mesovelia mulsanti White and M. zeteki Harris & Drake / Sinopse das espécies de Mesovelia (Insecta: Heteroptera: Mesoveliidae) ocorrentes na várzea do Rio Amazonas, Brasil, com redescrições de Mesovelia mulsanti White e M. zeteki Harris & Drake

Mesovelia mulsanti White, 1879 and M. zeteki Harris & Drake, 1941 are newly recorded in the Amazon River floodplain, Brazil. A key to the three known species ocurring in this region is also provided. Mesovelia mulsanti can be distinguished from M. amoena and M. zeteki by the body length larger than 2.50 mm, the head without longitudinal brown stripes near midline, and the forefemur and midfemur of the male, which have ventral rows of spines. Mesovelia amoena differs from M. zeteki in aspects of body color and in number of spinules near posterior margin of abdominal sternite VI of male.

Mesovelia mulsanti White, 1879 e M. zetekiHarris & Drake, 1941 são registradas pela primeira vez na várzea do Rio Amazonas. Uma chave de identificação para essas espécies é fornecida. Os espécimes de M. mulsanti podem ser diferenciados dos das demais espécies pelo tamanho do corpo maior que 2,50 mm, pela ausência de faixas marrons longitudinais próximas à porção mediana da cabeça e pela presença de uma fileira ventral de espinhos nos fêmures anteriores e medianos dos machos. Mesovelia amoena diferencia-se de M. zeteki em termos de coloração do corpo e do número de espinhos próximos à margem posterior do sexto esternito abdominal dos machos.

Duas novas espécies de Belostoma Latreille, 1807 (Hemiptera: Heteroptera: Belostomatidae) do grupo plebejum sensu Nieser, 1975 / Two new species of Belostoma Latreille, 1807 (Hemiptera: Heteroptera: Belostomatidae) of plebejum group sensu Nieser, 1975

Representantes do grupo plebejum são encontrados de Honduras até o sul da América do Sul e compreendem sete espécies de pequeno porte. Como resultado de um estudo de revisão do grupo, são descritas duas espécies novas: Belostoma estevezae Ribeiro & Alecrim, sp. nov., do Estado do Mato Grosso, Brasil, similar a B. nicaeum Estévez & Polhemus, 2007, em termos de carena prosternal, e B. nessimiani Ribeiro & Alecrim, sp. nov., do Estado do Amazonas, Brasil, sendo bastante similar a B. parvum Estévez & Polhemus, 2007, em termos de genitália masculina. Uma chave de identificação para as espécies do grupo plebejum com as espécies novas incluídas é fornecida.

Species of plebejum group comprises seven extant small species of giant water bugs. This group is currently reported from Honduras to southern South America. Two new species are described as a result from a revisional study of this group: Belostoma estevezae Ribeiro & Alecrim, sp. nov., from Mato Grosso State, Brazil, and B. nessimiani Ribeiro & Alecrim, sp. nov., from Amazonas State, Brazil. The prosternal keel of B. estevezae, sp. nov., is similar to that of B. nicaeum Estévez & Polhemus, 2007, while the male genitalia structures of B. nessimiani, sp. nov., is similar to those of B. parvum Estévez & Polhemus, 2007. A key to the species of plebejum group with new species included is also provided.