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

Abstract 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.


Introduction
Veliidae (Hemiptera, Heteroptera, Gerromorpha) is a worldwide distributed group of semiaquatic bugs that is especially rich in the Neotropics (Polhemus and Polhemus 2008). The most speciose genus in the region is Rhagovelia Mayr, 1865, (Veliidae, Rhagoveliinae), containing almost 200 described American species and being commonly found in lotic environments, sometimes in groups of hundreds of individuals (Padilla-Gil and Moreira 2013, Moreira 2015).
American Rhagovelia are distributed into 18 species groups, which are further organised into one grade (non-monophyletic) and five complexes (monophyletic) (Polhemus 1997, Moreira et al. 2012, Padilla-Gil and Moreira 2013. Although not a monophyletic lineage, the abrupta grade can be diagnosed by the pronotum of the apterous forms longer than the dorsal length of the eye, but shorter than three times the exposed portion of the mesonotum and with the posterior margin convex (Polhemus 1997).
Five species groups are currently recognised within the abrupta grade, namely cali, itatiaiana, lucida, secluda and torquata. Amongst them, the itatiaiana group is recognised by the general blackish colouration with distinctively contrasting orange markings on the pronotum and abdominal laterotergites; the forewing with four closed cells, of which the distalmost two extend into the distal half of the wing (Matsuda 1956, fig . 7); the macropterous females with the dorsal abdominal carinae not evident on mediotergites II and III; and the ventral abdominal sutures simple and unmodified (Polhemus 1997).
There are seven known species in the itatiaiana group, namely R. accedens Drake, 1957, R. itatiaiana Drake, 1953, R. macta Drake & Carvalho, 1955, R. trepida Bacon, 1956, R. trianguloides Nieser & Melo, 1997, R. mira Drake & Harris, 1938and R. vegana Drake & Maldonado-Capriles, 1956. The last two species are endemic to the Greater Antilles (Cuba and Dominican Republic), while the other five are restricted to south-eastern and southern Brazil (Polhemus 1997, Padilla-Gil and Moreira 2013, Moreira 2023. Additionally, Padilla-Gil 2012 and Padilla-Gil 2019 described the two Colombian species R. candelilla Padilla-Gil, 2012 and R. mallama Padilla-Gil, 2019, but considering the general distribution of the group and the issues related to species described by the author in question (see Galindo-Malagón et al. (2021), Galindo-Malagón et al. (2022) for details), this assignment and even the validity of such species need to be verified.
Based on material collected in south-eastern and southern Brazil during the past decade, we present here the description of a new species of the itatiaiana group, new records from the States of Paraná and Santa Catarina and a key to the species occurring in the country.

Materials and methods
The material examined is deposited in the following institutions: Coleção Entomológica do Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil (CEIOC); Laboratório de Biologia Aquática, Universidade Estadual Paulista Júlio de Mesquita Filho, Assis, Brazil (LABIA); Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil (MNRJ, entomological collection destroyed in 2018); Museu de Zoologia, Universidade de São Paulo, São Paulo, Brazil (MZUSP); and National Museum of Natural History, Smithsonian Institution, Washington D.C., USA (NMNH). Methods and terminology follow the standards set in the latest revision of the genus (Polhemus 1997) and subsequent species descriptions. All measurements are given in millimetres.
Digital photographs of the specimens deposited in the CEIOC were obtained using a Leica M205 C stereomicroscope coupled with a Leica DFC450 C digital camera, using the software Leica LAS 4.8.0 for capturing and stacking images. Specimens deposited in the NMNH were photographed with a Cannon EOS 5D digital camera and combined into multifocal images using Visionary Digital Software. Maps were produced using the software Qgis 2.6.1.

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ZooBank 090D3712-A5EB-4E20-A8A9-035805C091CE Apterous male (Figs 1, 3a, 4b). General colour black. Head with shiny impressed midline and a pair of shiny oblique indentations at base. Antenniferous tubercle brown. Proximal portion of antennomere I yellow; rest of antenna brown. Eye dark reddishbrown. Clypeus, buccula and jugum yellow to yellowish-brown. Labium yellowishbrown, dark-brown at apex. Pronotum black, with transverse yellow band adjacent to head; band at mid-line about 1/3 as long as pronotum, extending over propleuron laterally. Meso-and metanota black (Fig. 1a, c). Meso-and metapleura black, with a small brown mark ventrally on mesopleuron and a larger brown mark dorsally on metapleuron. Proepisternum and proacetabulum light-yellow. Pro-, meso-and metasterna black. Meso-and metacetabula yellow. All coxae yellow. Fore and hind trochanters light-yellow; fore trochanter with a small brown mark distally; middle trochanter yellow to brown proximally, dark-brown to black distally. Fore femur with proximal 1/2 yellow, distal 1/2 dark-brown to black. Middle femur dark-brown to black, darker dorsally. Hind femur dark-brown to black; dorsum with a yellowish-brown mark at base and posterior surface; venter with a large mark, yellow proximally, becoming narrower and brownish distally. All tibiae and tarsi brown to dark-brown. Abdominal mediotergites I-VII brownish-black; V-VII with shiny black spot centrally. Abdominal laterotergites black mesally, yellow laterally. Abdominal sterna II-VI mostly black, orange-brown laterally; VII black, with two yellow spots submesally. Abdominal segment VIII brown, lighter ventrally; pygophore and proctiger brown.  Head short, velvety, with a few long setae anteriorly and adjacent to mesal eye margin. Antennae covered by short brown setae; antennomeres I-II also with a few thicker, longer setae. Antennomeres I-III cylindrical; I curved laterally; IV fusiform. Labium wide, reaching base of mesosternum. Jugum and adjacent portion of proepisternum without black denticles. Pro-, meso-and metanota densely covered by short setae, with longer setae laterally. Pronotum longer than dorsal eye length, shorter than three times exposed portion of mesonotum, with posterior margin convex. Pro-, meso-and metapleura with a few long setae. Legs covered by brown setae, more densely on trochanters, femora and tibiae; femora and tibiae also with rows of longer, thicker, black setae. Fore tibia slightly widened distally, weakly concave near apex. Trochanters a b c d e f  without spines. Hind femur with row of 10-11 short spines on proximal third, the last one sometimes slightly longer than the others; distal 2/3 with two parallel rows of spines, dorsalmost row with 11-12 spines, the first and tenth or eleventh larger than the others, ventralmost row with 5 short spines (Figs 1d, 3a). Hind tibia arched, with two parallel rows of about 12-15 subequal short spines, a longer subapical spine and a straight apical spur (Fig. 1d). Dorsum of abdomen densely covered by setae, longer and more numerous on posterior segments. Abdominal sterna with faint longitudinal median carina; II-VI with long golden setae medially; sternum VII with a tuft of setae medially on anterior region (Fig. 1e). Terminalia covered by long setae. Proctiger with rounded apex and lateral projections near middle. Parameres symmetrical, shape as in Fig. 4b.
Apterous female (Fig. 2). Similar to apterous male in colour and structure, except for: hind femur much narrower (Table 1), with smaller yellowish marks; proximal half without spines, distal half with a decreasing row of about 7 spines (Fig. 2a, b). Hind tibia straight, without spines throughout length, with apical spur (Fig. 2a, b). Abdominal laterotergites more elevated than in males; last segment with a tuft of setae posteriorly (Fig. 2a). Abdominal sterna without median carina; sternum VII yellowish-brown, with a pair of longitudinal light marks, one on each side of mid-line, without tuft of setae medially on anterior region (Fig. 2b).
Variation. Fore tibia, hind femur and hind tibia less robust in some males (Table 1). Concavity near apex of male fore tibia may be incipient. Larger pre-apical spine of male hind tibia may be underdeveloped.

Diagnosis
Within the itatiaiana group, Rhagovelia bispoi sp. n. is more similar to R. itaiaiana Drake, 1953, R. macta Drake & Carvalho, 1955and R. trepida Bacon, 1948, with which it shares the presence of a medial tuft of setae on the anterior portion of male abdominal sternum VII. However, males of the new species have the main row of spines on the hind femur with two large spines separated by nine or ten smaller spines (Figs 1d, 3a), whereas in R. itatiaiana and R. trepida, the row consists of a large spine followed by spines gradually decreasing in length towards the apex (as in Fig. 3b). The condition of the row of spines is similar in the new species and R. macta; however, they can be distinguished by the mesonotum entirely black in the former (Fig. 1a), but yellowish in the latter (Fig. 5c) and by the shapes of the parameres (compare Fig. 4b, d).

Etymology
The new species is named in honour of Dr. Pitágoras da Conceição Bispo, who collected the specimens and also advised CFBF during her doctoral studies.

Distribution
This species is endemic to the Brazilian Atlantic Forest and is distributed from the coastal areas of the States of Rio de Janeiro and São Paulo to the northern portion of the State of Rio Grande do Sul. It has been seldom collected and reported in only three previous studies (Bacon 1948, Polhemus 1997, Moreira and Barbosa 2011. Above, we present new records of this species from the States of Paraná and Santa Catarina, in southern Brazil (Fig. 6b).

Key to the Rhagovelia itatiaiana group from Brazil
Modified from Polhemus (1997); apterous males are required or recommended for several steps. -Main row of spines on male hind femur with one large spine followed by spines gradually decreasing in length (as in Fig. 3b); male paramere as in Fig. 4c Rhagovelia itatiaiana (Figs 4c,5b,6a) 4 Main row of spines on male hind femur with one large spine followed by spines gradually decreasing in length (Fig. 3b); male paramere as in Fig. 4e Rhagovelia trepida (Figs 3b , 4e, 5d, 6b) -Main row of spines on male hind femur with two large spines separated by nine or ten smaller spines (Figs 1d, 3a); male paramere as in Fig. 4b Rhagovelia bispoi sp. n. (Figs 1, 2