SummaryAcquisition of new ecological opportunities is a major driver of adaptation and species diversification [1, 2, 3, 4]. However, how groups of organisms expand their habitat range is often unclear [3]. We study the Gerromorpha, a monophyletic group of heteropteran insects that occupy a large variety of water surface-associated niches, from small puddles to open oceans [5, 6]. Due to constraints related to fluid dynamics [7, 8, 9] and exposure to predation [5, 10], we hypothesize that selection will favor high speed of locomotion in the Gerromorpha that occupy water-air interface niches relative to the ancestral terrestrial life style. Through biomechanical assays and phylogenetic reconstruction, we show that only species that occupy water surface niches can generate high maximum speeds. Basally branching lineages with ancestral mode of locomotion, consisting of tripod gait, achieved increased speed on the water through increasing midleg length, stroke amplitude, and stroke frequency. Derived lineages evolved rowing as a novel mode of locomotion through simultaneous sculling motion almost exclusively of the midlegs. We demonstrate that this change in locomotory behavior significantly reduced the requirement for high stroke frequency and energy expenditure. Furthermore, we show how the evolution of rowing, by reducing stroke frequency, may have eliminated the constraint on body size, which may explain the evolution of larger Gerromorpha. This correlation between the diversity in locomotion behaviors and niche specialization suggests that changes in morphology and behavior may facilitate the invasion and diversification in novel environments.

Eight new species of Paravelia Breddin, 1898 from Brazil are described and illustrated: P. amapaensis sp. nov. from Amapá State, P. bipunctata sp. nov. from Minas Gerais, Mato Grosso and Mato Grosso do Sul States, P. bilobata sp. nov. and P. polhemusi sp. nov. from Mato Grosso State, P. bahiana sp. nov. from Bahia State, P. lacrymosa sp. nov. from Minas Gerais State, P. micromaculata sp. nov. from Maranhão State, and P. ornata sp. nov. from Amazonas State. The genus is redescribed, with photos of the dorsal view for nineteen species: P. basalis (Spinola), P. biae Spangler, P. boliviana Breddin, P. bullialata Polhemus & Polhemus, P. capillata (Drake& Harris), P. capixaba Moreira, Nessimian & Rúdio, P. conata (Hungerford), P. dilatata Polhemus & Polhemus, P. foveata Polhemus & Polhemus, P. itatiayana (Drake), P. lanemeloi Moreira & Barbosa, P. manausana Polhemus & Polhemus, P. nieseri Moreira & Barbosa, P. platensis (Berg), P. recens (Drake & Harris), P. rotundanotata (Hungerford), P. spinifera Polhemus & Polhemus, P. splendoris (Drake & Harris) and P. williamsi (Hungerford). Three of these species are recorded for the first time from Brazil: P. platensis, P. spinifera and P. williamsi. Also, the macropterous forms of P. capixaba and P. dilatata are described. Lastly, an identification key to the 36 species of Paravelia recorded from Brazil and a checklist of described species are presented.

RESUMOUma nova espécie críptica de Triatoma é descrita dentro do subcomplexo T. rubrovaria. As diferenças entre T. pintodiasi sp. nov. e T. circummaculata incluem, entre outras, o padrão cromático e diferenças morfológicas nas estruturas fálicas, como nos parâmeros, suporte do falosoma, processo do endosoma e vesica. Análises bioquímicas realizadas na hemolinfa e a comparação morfométrica da cabeça também registraram diferenças entre as duas espécies e outras do subcomplexo T. rubrovaria. Palavras

The phylogenetic relationships among selected species and genera of Mesoveliidae (Insecta: Hemiptera: Heteroptera: Gerromorpha) were investigated in a parsimony analysis of 2858 bp of DNA sequence data from the genes encoding COI + II, 16S rRNA and 28S rRNA. The resulting phylogeny showed that

ABSTRACT. Triatoma pintodiasi has been described and recently grouped in the Rubrovaria subcomplex. T. pintodiasi was initially compared to T. carcavalloi by staining and subsequently identified as T. circummaculata. However, after thorough examination, it was observed to be a cryptic species of T. circummaculata, and was described based on morphological features, morphometric data, and biochemical patterns of hemolymph. Thus, this paper aims to describe the karyotype of, and spermatogenesis in, T. pintodiasi, in order to elucidate the reproductive biology and taxonomy of the species. Sex chromosomes of T. pintodiasi formed a heteropyknotic chromocenter, and compaction of chromatin was observed during prophase. However, in contrast to observations in T. carcavalloi and T. circummaculata, in T. pintodiasi it was observed individualization of the sex chromosomes. The diploid chromosome set of the species 2n = 22 (20A + XY) is described through analysis of metaphases I and II. Initial cytogenetic characteristics of T. pintodiasi are described and the observed differences in the chromocenter

The phylogenetic relationships among selected species and genera of Gerrinae (Heteroptera: Gerridae) were investigated in a parsimony analysis of 2268 bp o f D N A sequence data from the genes encoding C O I + I1, 16S rRNA and 28S rRNA. The taxa represented 12 of 15 recognized genera of Gerrinae and with outgroup taxa from all other subfamilies of Gerridae, including three of five recognized genera of Eotrechinae, which is considered the sister-group of Gerrinae. The resulting phylogeny shows that Gerrinae is not monophyletic, since a clade comprising Gerris, Aquarius, Limnoporus, Tachygerris, Eurygerris and Gigantometra is more closely related to representatives of the subfamily Eotrechinae than to a clade comprising Limnogonus, Neogerris, Limnometra, Tenagogerris and Tenagogonus. The two currendy recognized gerrine tribes, Tachygerrini and Gerrini, were also paraphyletic, since Eurygerris was sister-group to Gigantometra, while Tachygerris was sister-group to Limnoporus + Aquarius + Gerris. Limnogonus and Neogerris were found to be strongly supported sister-taxa, and their sister-group was a clade comprising Limnometra, Tenagogerris and Tenagogonus, none o f which were monophyletic. Finally, Aquarius chilensis (Berg, 1881) was sister-group to a clade comprising Aquarius amplus (Drake & Harris, 1938), A. remigis (Say, 1832) and A. remigoides (Gallant & Fairbaim, 1993), recognized as the A. remigis species group, and the entire clade was sister-group to Gerris. Based on the phylogenetic reconstruction, we oudine possible diagnostic character combinations for a future revision o f the Gerrinae and discuss the fossil record. While some of the relationships reinstate earlier ideas, e.g., Limnogonus and Neogerris being sister groups, many others are poorly supported and poorly diagnosed, and therefore, we retain from drawing taxonomic conclusions until data is available from the remaining genera, which can support a future generic revision of the Gerrinae. The updated checklist o f species assigned to the subfamily is there fore based on the established taxonomy.

Naturalists have been fascinated for centuries by animal colors and color patterns. While widely studied at the adult stage, we know little about color patterns in the embryo. Here, we study a trait consisting of coloration that is specific to the embryo and absent from postembryonic stages in water striders (Gerromorpha). By combining developmental genetics with chemical and phylogenetic analyses across a broad sample of species, we uncovered the mechanisms underlying the emergence and diversification of embryonic colors in this group of insects. We show that the pteridine biosynthesis pathway, which ancestrally produces red pigment in the eyes, has been recruited during embryogenesis in various extraocular tissues including antennae and legs. In addition, we discovered that this cooption is common to all water striders and initially resulted in the production of yellow extraocular color. Subsequently, 6 lineages evolved bright red color and 2 lineages lost the color independently. Despite the high diversity in colors and color patterns, we show that the underlying biosynthesis pathway remained stable throughout the 200 million years of Gerromorpha evolutionary time. Finally, we identified erythropterin and xanthopterin as the pigments responsible for these colors in the embryo of various species. These findings demonstrate how traits can emerge through the activation of a biosynthesis pathway in new developmental contexts.

Four new species of Paravelia Breddin (Hemiptera: Veliidae) from Brazil are described and illustrated: Paravelia bachmanninew species and P. bromelicolanew species from the states of São Paulo and Santa Catarina; P. luederwaldtinew species from the state of São Paulo; and P. digitatanew species from the states of Bahia and Rio Grande do Norte; totalling 61 valid species for the genus. Two of the new species (P. bachmanni and P. bromelicola) are bromeliad inhabitants, and a key to the eight bromeliadicolus species of the genus is provided. In addition, based on type material, P. amoena (Drake), P. kahli (Drake and Harris), P. nexa (Drake and Harris), and P. parilis (Drake and Harris) are re-described and illustrated. Lastly, taxonomic and distributional notes for the following species are also presented: P. basalis (Spinola), P. boliviana Breddin, P. capillata (Drake and Harris), P. cognata (Drake and Harris), P. dilatata Polhemus and Polhemus, P. foveata Polhemus and Polhemus, P. itatiayana (Drake), P. nieseri Moreira and Barbosa, P. manausana Polhemus and Polhemus, P. platensis (Berg), P. recens (Drake and Harris), and P. splendoris (Drake and Harris).