Pelocoris Stl, 1876 of northeastern Brazil (Hemiptera: Heteroptera: Naucoridae): first records and a key to the species.

Naucoridae is a family of aquatic bugs, distributed in tropical and subtropical regions of the world, and comprises 437 species, 47 genera, and eight subfamilies. Five subfamilies, 10 genera and 68 species have been recorded from Brazil. Pelocoris Stl is a genus exclusive to the New World, with 14 species described; eight species and two subspecies have been recorded from Brazil. For the northeastern region, there are no records of occurrence for any species in this genus. The objective of this work was to survey the fauna of Pelocoris in the northeastern region and map the distribution of the species. We examined 180 specimens belonging to six species: Pelocoris binotulatus nigriculus Berg, 1879, P. bipunctulus (Herrich-Schffer, 1853), P. magister Montandon, 1898, P. poeyi (Gurin-Mneville, 1835), P. politus Montandon, 1897, and P. subflavus Montandon, 1898. This work contributes directly to reducing the Wallacean and Linnean gaps in Naucoridae diversity for northeastern Brazil and highlights the diversity in the region, which is still poorly studied and poorly known.

An enigmatic new species of Belostoma Latreille from central-western Brazil (Heteroptera: Belostomatidae: Belostomatini).

The new species Belostoma inusitatum is described and illustrated based on specimens from the west side of the Araguaia-Tocantins basin, in Mato Grosso state in central-western Brazil. This new species is assigned to the B. triangulum species group and compared with its congeners. A key and distribution map for the species of this group are included. The three-articulated antenna without lateral projections of B. inusitatum n. sp. is documented for the first time in Belostoma. Also, the uncommon shape of the prosternal keel, the distinct reduction of the hemelytral membrane, and the diverticulum of the phallosoma sharply incised at the posterior margin are reported for this new species. A discussion about the reduction in the number of antennal articles and the size of the hemelytral membrane in Belostoma and Abedus is presented.

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.

The new Belostoma fittkaui species group with supplemental descriptions of B. fittkaui De Carlo and B. sayagoi De Carlo.

The giant water bug fauna from tropical South America remains poorly known. Three species of Belostoma Latreille (Belostoma fittkaui De Carlo, B. sayagoi De Carlo and B. hirsutum Roback Nieser) have been cited only a few times in the literature. These three species are remarkable since they represent an extreme variation for the genus, with article II of the labium distinctly shorter than article III. Here, the synonymy of B. hirsutum with B. sayagoi is proposed based on examination of type material and additional specimens. Further, B. fittkaui and B. sayagoi are redescribed, including discussion about comparative morphology with congeners. A new species group is proposed for these species and a key to the Belostoma species groups is provided. Distribution records 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.