Transcriptome-based Phylogeny of the Semi-aquatic Bugs (Hemiptera: Heteroptera: Gerromorpha) Reveals Patterns of Lineage Expansion in a Series of New Adaptive Zones.

Key innovations enable access to new adaptive zones and are often linked to increased species diversification. As such, innovations have attracted much attention, yet their concrete consequences on the subsequent evolutionary trajectory and diversification of the bearing lineages remain unclear. Water striders and relatives (Hemiptera: Heteroptera: Gerromorpha) represent a monophyletic lineage of insects that transitioned to live on the water-air interface and that diversified to occupy ponds, puddles, streams, mangroves and even oceans. This lineage offers an excellent model to study the patterns and processes underlying species diversification following the conquest of new adaptive zones. However, such studies require a reliable and comprehensive phylogeny of the infraorder. Based on whole transcriptomic datasets of 97 species and fossil records, we reconstructed a new phylogeny of the Gerromorpha that resolved inconsistencies and uncovered strong support for previously unknown relationships between some important taxa. We then used this phylogeny to reconstruct the ancestral state of a set of adaptations associated with water surface invasion (fluid locomotion, dispersal and transition to saline waters) and sexual dimorphism. Our results uncovered important patterns and dynamics of phenotypic evolution, revealing how the initial event of water surface invasion enabled multiple subsequent transitions to new adaptive zones on the water surfaces. This phylogeny and the associated transcriptomic datasets constitute highly valuable resources, making Gerromorpha an attractive model lineage to study phenotypic evolution.

Two new species of Rhagovelia (Hemiptera: Heteroptera: Veliidae) from Costa Rica, with a key and new records from the country.

Rhagovelia danpolhemi sp. nov., from the Caribbean Slope of Costa Rica and R. springerae sp. nov., from the northern portion of the country, are described, illustrated, compared with similar species, and included in a key to species recorded from the country. Rhagovelia calopa Drake & Harris, R. spinosa Gould, and R. tantilla Drake & Harris are recorded for the first time from Costa Rica. New provincial records are provided for R. acuminata Bacon, R. angustipes Uhler, R. armata (Burmeister), R. bisignata Bacon, R. crassipes Champion, R. elegans Uhler, R. femoralis Champion, R. solida Bacon, R. spinigera Champion, R. tenuipes Champion, and R. uncinata Champion. Additional distributional information is given for these species and for R. formosa Bacon and R. scabra Bacon.

New species and notes on Microveliinae from northern South America (Hemiptera: Heteroptera: Veliidae).

Euvelia mazzucconiae sp. nov., from northern Colombia is described, illustrated, and included in an updated identification key to the species of the genus. A map with the known geographical distribution of the species of Euvelia is presented. Additionally, two species from Colombia previously placed in the genus Paravelia are transferred to Microvelia and a species of the latter genus is synonymized, such that Paravelia acantha Padilla-Gil, 2013 = Microvelia acantha (Padilla-Gil, 2013) comb. nov., Paravelia fanera Padilla-Gil, 2013 = Microvelia fanera (Padilla-Gil, 2013) comb. nov., and Microvelia amrishi Makhan 2014 = Microvelia mimula White 1879 syn. nov.

A new Rhagovelia (Hemiptera: Heteroptera: Veliidae) from the Brazilian Amazon, with a key to species of the robusta group known from the country.

Rhagovelia zecai sp. nov., from the Brazilian Amazon, is described, illustrated, compared with similar species, and included in a key to species of the robusta group recorded from the country.

A synopsis of the genus Cylindrostethus Fieber 1861 (Insecta: Hemiptera: Gerridae).

Cylindrostethus Fieber, 1861 is one of the most striking genera of water striders (Insecta: Hemiptera: Gerridae) and has Pantropical distribution. Members of this group can be recognized by the very long, cylindrical body; the short antennomere IV; the short labium not reaching the mesosternum; and by characteristics of the abdomen of males and females. Although Neotropical representatives of the genus have been revised, there are pending taxonomic issues related to this fauna, and that of the Eastern Hemisphere has been barely studied in recent years. Here, we present a short note about the authorship of Cylindrostethus, an updated key to all species of the genus, a new synonymy, and the description of a previously unknown macropterous male of C. hungerfordi Drake and Harris.

Description of a New Species and New Records of Naucoridae (Hemiptera: Heteroptera: Nepomorpha) from Eastern Brazil.

The aquatic bug family Naucoridae (Hemiptera: Heteroptera: Nepomorpha) is currently represented in Brazil by 68 species. Although the diversity of the family has been the target of several recent studies, large areas of the country are still unexplored and several species that have been deposited in entomological collections are waiting for a formal description. Aiming to fill these knowledge gaps, a series of expeditions were carried out in six states of eastern Brazil between 2018 and 2023: Alagoas, Bahia, Ceará, Espírito Santo, Pernambuco, and Sergipe. The fieldwork targeted protected areas, but surrounding regions were also explored. The material obtained, in addition to specimens previously deposited in a national entomological collection, revealed the existence of Australambrysus margaritifer Jordão, Santos and Moreira, a new species herein described, and new records for other 11 species and two subspecies belonging to the genera Carvalhoiella De Carlo, 1963, Limnocoris Stål, 1876, Maculambrysus Reynoso-Velasco and Sites 2021, and Pelocoris Stål, 1876.

Checklist, taxonomy and distribution of the Rhagovelia Mayr, 1865 (Hemiptera: Heteroptera: Veliidae) of the Americas.

The genus Rhagovelia Mayr, 1865 is distributed worldwide, especially in the Tropics, and contains 184 species in the Americas, which are listed and included in complexes or grades, and in 18 species groups. Geographical distributions and altitudinal ranges are presented for each species. A new synonym is proposed, and some biogeographical aspects of the genus are analyzed, such as its distinct tropical distribution (97% of the known American species), and the narrow altitudinal ranges of the salina, tayloriella and cali groups. South America is determined to be the geographical area with the highest diversity of species (77% of the species richness of the Americas), and Brazil as the most biodiverse country.

A new Hydrometra ( Hemiptera: Heteroptera: Hydrometridae) from northeastern Brazil, with a key to the species recorded from the country.

Hydrometra sapiranga sp. nov. is described, illustrated, and compared with similar species. An identification key to the species of Hydrometra recorded from Brazil is also presented.

Two new species of Microvelia Westwood, 1834 (Hemiptera: Heteroptera: Veliidae) from Colombia, with a key to Colombian species.

Only six species of Microvelia have been recorded from Colombia up to the present, namely M. ancona, M. hinei, M. leucothea, M. longipes, M. panamensis, and M. pulchella. Microvelia inguapi sp. n. and M. piedrancha sp. n. are herein described and compared with similar species. An identification key to the Colombian species of Microvelia is presented. 

Gerromorpha (Hemiptera: Heteroptera) of eastern Mato Grosso State, Brazil: checklist, new records, and species distribution modeling.

The infraorder Gerromorpha comprises semiaquatic bugs, most of which spend much of their lifetime on the water surface, between floating plants, or on the margins of water bodies. Based on literature and collections made on streams and lakes on municipalities of eastern Mato Grosso, Brazil, a list has been elaborated with 52 species, including several new records. Out of the recorded species, 26 belong to the family Veliidae, 20 to Gerridae, three to Hydrometridae, two to Mesoveliidae, and one to Hebridae. The modeling of the potential geographical distribution is also presented for the 20 species that have been recorded for the first time from the state.

Revision of Potamobates Champion, 1898 (Hemiptera: Heteroptera: Gerridae) and description of a new genus for P. thomasi Hungerford, 1937.

Potamobates Champion, 1898 (Hemiptera: Heteroptera: Gerridae) heretofore included 18 species distributed from southern Mexico to Peru. They display a distinct morphology, especially regarding the projections of abdominal segment VIII. Specific identification and delimitation are difficult, and the genus lacks a thorough revision and evaluation of inter- and intraspecific variation. Here, we revise Potamobates, redescribe and/or illustrate known species, and describe P. molanoi Floriano and Moreira, sp. nov. and Brailovskybates Floriano and Moreira, gen. nov. The new genus is erected for P. thomasi Hungerford, 1937 and is characterized by the following features: (1) abdomen elongated, longer than the mesothorax; (2) abdominal spiracles positioned at the center of the segments; (3) male abdominal segment VIII without projections; (4) male pygophore and proctiger not rotated in relation to the longitudinal axis of the body; (5) female abdominal tergum VIII subequal in length and width; (6) and posterior margin of female abdominal sternum VII not produced medially, with a pair of lateral projections.

New species, new records and key to the species of the Rhagoveliaitatiaiana group (Hemiptera, Heteroptera, Veliidae) from Brazil.

Background: Rhagovelia Mayr, 1865 (Hemiptera, Heteroptera, Veliidae), known as riffle bugs, includes more than 400 species and is commonly found in tropical lotic environments, including coastal marine habitats, such as mangroves and estuaries. Due to the elevated number of species, the fauna from the Americas has been divided into several groups, which facilitates taxonomic studies. Amongst them, the itatiana group currently includes two species from the Greater Antilles and five from south-eastern and southern Brazil. Despite the many taxonomic studies developed during the past few decades, new species of Rhagovelia are still being discovered in several areas of the continent, including the Atlantic Forest of eastern Brazil. New information: Rhagoveliabispoi sp. n. is described, illustrated and compared with similar congeners. The new species belongs to the itatiaiana group and can be diagnosed by the uniformly black mesonotum, the presence of a tuft of setae medially on male abdominal sternum VII, the armature of the male hind femur and the distinctive shape of the paramere. In addition, we present new records of R.trepida Bacon, 1948 from the States of Paraná and Santa Catarina and a key to the species of the itatiaiana group recorded from Brazil.

A new species and updates on the Rhagovelia angustipes complex (Hemiptera, Heteroptera, Veliidae) in Colombia.

Rhagovelia Mayr, 1865 (Hemiptera, Heteroptera, Veliidae) is a diverse genus of small to medium-sized true bugs that live on the surface of the water, preferentially in lotic environments with moderate to strong current. The Rhagovelia angustipes species complex is particularly speciose in Colombia, and has recently been the subject of a revision. Nonetheless, new species of the complex are still being discovered in the country. We present here the description of Rhagovelia andradei sp. nov., collected on the eastern Colombian Andes, new records for three other species, R. calceola, R. gastrotricha and R. molanoi, an updated key, and a summary of the distribution of the complex in the country.

Description of a new species and new records of Rhagovelia Mayr, 1865 (Hemiptera: Heteroptera: Veliidae) from northern and northeastern Brazil.

Rhagovelia Mayr, 1865 (Hemiptera: Heteroptera: Veliidae) is a species-rich and widespread genus of semiaquatic bugs, found both in freshwater and coastal marine environments. Despite the considerable number of species recorded from Brazil, the northern and northeastern regions of the country remain poorly explored. We present here the description of a new species of the angustipes complex, Rhagovelia leilae Paiva, Rodrigues & Moreira, sp. nov., and new records for the following species: R. brunae Magalhães & Moreira, 2016; R. evidis Bacon, 1948; R. hambletoni Drake & Harris, 1933; R. humboldti Polhemus, 1997; R. tenuipes Champion, 1898; and R. whitei (Breddin, 1898). These include the first records of species of Rhagovelia from the states of Pernambuco and Tocantins, and also increase the number of known species from the states of Alagoas, Bahia, and Maranhão to six, five and six, respectively.

Descriptions of new species and new records of water bugs (Hemiptera: Heteroptera: Gerromorpha & Nepomorpha) from southeastern Brazil.

Although most of the diversity of true bugs (Hemiptera: Heteroptera) is terrestrial, over 550 species of water bugs (Heteroptera: Gerromorpha, Leptopodomorpha & Nepomorpha) have been recorded from Brazil alone. Southeastern Brazil, composed of the states of Esprito Santo, Minas Gerais, Rio de Janeiro and So Paulo, is the best studied region of the country, but there are still knowledge gaps in the area. Here, two new species are described from Esprito Santo: Hydrometra ruschii Cordeiro, Rodrigues & Moreira, sp. nov. and H. tuberculata Cordeiro, Rodrigues & Moreira, sp. nov. (Gerromorpha: Hydrometridae). Furthermore, new records from southeastern Brazil are provided for 78 species of water bugs, of which 19 are firstly recorded from Esprito Santo, four from Minas Gerais, eight from Rio de Janeiro, and seven from So Paulo.

New Species, New Records, and Updated Key to the Paravelia (Hemiptera: Heteroptera: Veliidae) from Brazil.

The broad-shouldered water-strider genus Paravelia Breddin, 1898 (Hemiptera: Heteroptera: Veliidae: Veliinae) is currently represented in Brazil by 38 species. Although the diversity of the genus in the country is relatively well known, eight states remain with no records of any species: Acre, Alagoas, Ceará (CE), Paraíba, Paraná, Pernambuco (PE), Piauí (PI), and Tocantins. Aiming to fill these gaps, several expeditions were carried out at conservation areas of the Caatinga biome between 2018 and 2021: Aiuaba Ecological Station (CE), Catimbau National Park (PE), and Serra das Confusões National Park (PI). Paravelia luisi sp. nov., a new species from PE, is described and illustrated. In addition, new records of P. bilobata Rodrigues, Moreira, Nieser, Chen & Melo, 2014, P. digitata Rodrigues & Moreira, 2016, and P. nieseri Moreira & Barbosa, 2012, and an updated key to the Brazilian species of Paravelia are provided. This study increases the number of species of Paravelia known in Brazil to 39 and provides the first records of the genus from three states: PE, with two species, and CE and PI, with one species each.

New species and notes on Paravelia Breddin, 1898 (Heteroptera: Veliidae) from South America.

The new species Paravelia ameliae (Heteroptera: Veliidae) is described based on macropterous specimens from the Department of Putumayo, in the Amazonian region of Colombia. The new species can be distinguished from all congeners mainly by the bicolored pronotum (dark-brown on the anterior two-thirds and light-brown posteriorly); the absence of distinct pruinosity or silvery patches on the anterior lobe of the pronotum; the basal macula of the forewing small and roughly ovate; the grasping comb of the male fore tibia occupying more than half of its length; the male hind femur with a row of 15 spines on the basal two-thirds; and the male paramere notched basally on its dorsal surface. Furthermore, this species displays sexual dimorphism in body shape and in hind tibial length, with males having a slightly constricted mid-abdominal region and hind tibia distinctly longer than in females. Also, in order to describe external morphological characteristics not mentioned in previous studies, supplemental descriptions are provided for P. albotrimaculata (Kirkaldy, 1899), P. loutoni Polhemus, 2014, P. nieseri Moreira Barbosa, 2012, and P. rotundanotata (Hungerford, 1930). Illustrations and a distribution map of all species treated here are presented.

New species, synonymies and records in the genus Rhagovelia Mayr, 1865 (Hemiptera: Heteroptera: Veliidae) from Colombia.

Rhagovelia medinae sp. nov., of the hambletoni group (angustipes complex), and R. utria sp. nov., of the hirtipes group (robusta complex), are described, illustrated, and compared with similar congeners. Based on the examination of type specimens, six new synonymies are proposed: R. elegans Uhler, 1894 = R. pediformis Padilla-Gil, 2010, syn. nov.; R. cauca Polhemus, 1997 = R. azulita Padilla-Gil, 2009, syn. nov., R. huila Padilla-Gil, 2009, syn. nov., R. oporapa Padilla-Gil, 2009, syn. nov, R. quilichaensis Padilla-Gil, 2011, syn. nov.; and R. gaigei, Drake Hussey, 1947 = R. victoria Padilla-Gil, 2012 syn. nov. The first record from Colombia is presented for R. trailii (White, 1879), and the distributions of the following species are extended in the country: R. cali Polhemus, 1997, R. castanea Gould, 1931, R. cauca Polhemus, 1997, R. gaigei Drake Hussey, 1957, R. elegans Uhler, 1894, R. femoralis Champion, 1898, R. malkini Polhemus, 1997, R. perija Polhemus, 1997, R. sinuata Gould, 1931, R. venezuelana Polhemus, 1997, R. williamsi Gould, 1931, and R. zeteki Drake, 1953.

New species and new records of semiaquatic bugs (Arthropoda, Insecta, Hemiptera, Heteroptera, Gerromorpha) from French Guiana.

Semiaquatic bugs (Hemiptera: Heteroptera: Gerromorpha) are predatory insects that occupy a wide range of freshwater and marine habitats, with some secondary transitions to terrestrial life. They currently represent more than 2100 species distributed through all continents, except for Antarctica, and are especially rich in the Neotropical and Oriental regions. Although the fauna from the former region is relatively well known, some areas remain almost unexplored. Such is the case of French Guiana, where only a few species have been previously recorded, several of which based on collections made in the 19th and early 20th centuries. As a result of material recently collected in the territory, the descriptions of Rhagoveliadepressa Rodrigues, Khila & Moreira, sp. nov., R.tantilloides Rodrigues, Khila & Moreira, sp. nov. and Steinoveliavittata Rodrigues, Khila & Moreira, sp. nov. (Veliidae) are presented here. New records for 28 species are also provided, of which Cylindrostethushungerfordi Drake & Harris, 1934, Neogerrismagnus (Kuitert, 1942), Rheumatobatesmangrovensis (China, 1943), R.trinitatis (China, 1943), Ovatametraobesa Kenaga, 1942, Telmatometrafusca Kenaga, 1941, T.parva Kenaga, 1941 (Gerridae), Mesoveliaamoena Uhler, 1894 (Mesoveliidae), Rhagoveliabrunae Magalhães & Moreira, 2016, R.elegans Uhler, 1894, R.ephydros (Drake & Van Doesburg, 1966), R.equatoria D. Polhemus, 1997, R.evidis Bacon, 1948, R.guianana D. Polhemus, 1997, R.tenuipes Champion, 1898, Oioveliacunucunumana (Drake & Maldonado-Capriles, 1952), Striduliveliaalia (Drake, 1957), S.stridulata (Hungerford, 1929), and S.tersa (Drake & Harris, 1941) (Veliidae) are reported from French Guiana for the first time.

Symbiotic Microorganisms and Their Different Association Types in Aquatic and Semiaquatic Bugs.

True bugs (Hemiptera, suborder Heteroptera) constitute the largest suborder of nonholometabolous insects and occupy a wide range of habitats various from terrestrial to semiaquatic to aquatic niches. The transition and occupation of these diverse habitats impose various challenges to true bugs, including access to oxygen for the aquatic species and plant defense for the terrestrial phytophagans. Although numerous studies have demonstrated that microorganisms can provide multiple benefits to terrestrial host insects, a systematic study with comprehensive higher taxa sampling that represents aquatic and semiaquatic habitats is still lacking. To explore the role of symbiotic microorganisms in true bug adaptations, 204 samples belonging to all seven infraorders of Heteroptera were investigated, representing approximately 85% of its superfamilies and almost all known habitats. The symbiotic microbial communities of these insects were analyzed based on the full-length amplicons of the bacterial 16S rRNA gene and fungal ITS region. Bacterial communities varied among hosts inhabiting terrestrial, semiaquatic, and aquatic habitats, while fungal communities were more related to the geographical distribution of the hosts. Interestingly, co-occurrence networks showed that species inhabiting similar habitats shared symbiotic microorganism association types. Moreover, functional prediction analyses showed that the symbiotic bacterial community of aquatic species displayed richer amino acid and lipid metabolism pathways, while plant-feeding true bugs benefited more from the symbiont-provided xenobiotics biodegradation pathway. These results deepened the recognition that symbiotic microorganisms were likely to help heteropterans occupy diverse ecological habitats and provided a reference framework for further studies on how microorganisms affect host insects living in various habitats. IMPORTANCE Symbiotic bacteria and fungi generally colonize insects and provide various benefits for hosts. Although numerous studies have investigated symbionts in terrestrial plant-feeding insects, explorations of symbiotic bacterial and fungal communities in aquatic and semiaquatic insects are rare. In this study, the symbiotic microorganisms of 204 aquatic, semiaquatic, and terrestrial true bugs were explored. This comprehensive taxon sampling covers ~85% of the superfamilies of true bugs and most insect habitats. Analyses of the diversity of symbionts demonstrated that the symbiotic microbial diversities of true bugs were mainly affected by host habitats. Co-occurrence networks showed that true bugs inhabiting similar habitats shared symbiotic microbial association types. These correlations between symbionts and hosts together with the functions of bacterial communities indicated that symbiotic microbial communities may help true bugs adapt to (semi)aquatic habitats.