New records of semiaquatic bugs (Hemiptera, Heteroptera, Gerromorpha) from the Caatinga biome, Brazil

. Semiaquatic bugs (Hemiptera, Heteroptera, Gerromorpha) are small to mid-sized insects, currently represented by more than 2,100 known species distributed on all continents, except Antarctica. So far, 244 species have been recorded from Brazil, but only 63 from the Northeast Region of the country. The relatively small number of species in this region is related to the virtual lack of knowledge on the fauna of the Caatinga, a biome that is distributed essentially throughout this region. We present here new records for 28 species based on material collected in four federal conservation units of the Caatinga biome: Aiuaba Ecological Station (Ceará state), Chapada Diamantina National Park (Bahia state), Catimbau National Park (Pernambuco state), and Serra das Confusões National Park (Piauí state). Moreover, several species are recorded for the first time from at least one of these states: 11 from Bahia, 10 from Ceará, two from Pernambuco, and eight from Piauí.


Introduction
Semiaquatic bugs (Hemiptera, Heteroptera, Gerromorpha) are currently represented by eight families, approximately 160 genera, and more than 2100 species distributed on all continents, except Antarctica (Polhemus and Polhemus 2008;Moreira 2015). They are small to mid-sized insects, and most of them are adapted for walking or rowing on the surface of water (Crumière et al. 2016;Armisén et al. 2022). Gerromorphans can be commonly found on the surface or along the margins of freshwaters, but some taxa inhabit marine or terrestrial habitats (Andersen 1982;Schuh and Slater 1995;Dias-Silva et al. 2013;Moreira et al. 2018). So far, 244 species have been recorded from Brazil, but only 63 from the Northeast Region of the country (Moreira 2023a(Moreira , 2023b(Moreira , 2023c(Moreira , 2023d. Furthermore, many of these were recorded for the first time from the region very recently (Franco et al. 2020(Franco et al. , 2021Rodrigues et al. 2021a; Rodrigues and Moreira 2022).
The relatively small number of species known from the Northeast Region is related to the virtual lack of knowledge on the fauna of the Caatinga, a biome that is largely distributed throughout this region, apart from a small portion in northeastern Minas Gerais state (IBGE 2004). Currently, the number of species recorded from each state in the region is as follows: 32 from Alagoas, 20 from Bahia, seven from Ceará, 30 from Maranhão, three from Paraíba, 10 from Pernambuco, 11 from Piauí, four from Rio Grande do Norte, and 29 from Sergipe (Moreira 2023a(Moreira , 2023b(Moreira , 2023c(Moreira , 2023d. We present here new records for 28 species based on material collected in four federal conservation units of the Caatinga biome in the states of Bahia, Ceará, Pernambuco and Piauí, northeastern Brazil.

Study Area
The Northeast Region occupies 18.25% of the Brazilian territory, with 1,554,291 km², and includes nine states and four biomes (percentage of the region in parenthesis): Caatinga (65%), Atlantic Forest (17%), Cerrado (14%), and Amazon (4%) (IBGE 2004(IBGE , 2018. The Caatinga is an exclusively Brazilian biome that occupies 10.3% (862,745 km 2 ) of the country and has a semiarid climate. This reflects on the hydrological regime of the rivers and on a specialized vegetation, which is the most diverse in the world among those with this type of climate (MMA 2011;Rodrigues et al. 2021a;IBGE 2022a).
Aiuaba Ecological Station ( Fig. 2) was created in February 2001, occupies an area of 11,525 hectares, and is located in Aiuaba municipality, Ceará state (BRASIL 2001). Although EEA represents only 0.07% of the territorial area of the state (14,889,444 ha), it is important in the hydrological cycle of the Alto Jaguaribe hydrographic sub-basin due to its dense vegetation cover (MMA 2006;IBGE 2022b). This ecological station is located in one of the most isolated areas of Ceará, the Sertão dos Inhamuns microregion, with elevations ranging from 400 to 700 m a.s.l., annual rainfall values between 590 and 684 mm, with rainy periods concentrated in the months of December to June; the station displays typical arboreal Caatinga vegetation (MMA 2006(MMA , 2017. Chapada Diamantina National Park (Fig. 3) was created in September 1985, occupies an area of 152,132 ha, and is distributed among six municipalities of Bahia state: Andaraí, Ibicoara, Itaetê, Lençóis, Mucugê, and Palmeiras (BRASIL 1985;ICMBio 2007). This UC represents 0.27% of the territorial area of the state and a watershed between the Middle São Francisco and the Itaperuçu-Paraguaçu sub-basins. Furthermore, two of the largest rivers in Bahia, the Contas and the Paraguaçu, are formed within the UC (MMA 2017;IBGE 2022c). The vegetation of PNCD is a mosaic that includes xerophytic formations at elevations of approximately 500-900 m a.s.l., typical of the Caatinga biome; grassland formations, from forest formations to those devoid of trees with intense grass cover, normally associated with the Cerrado biome; formations with deciduous, semideciduous or even evergreen characteristics, associated with the Atlantic Forest biome; and rupestrian formations on exposed rock or lithosols, generally above 1000 m a.s.l., known as rupestrian fields (Velloso et al. 2002). Elevations generally range from 500 to 1000 m a.s.l., with several peaks reaching between 1600 and 1800 m a.s.l., and some points above 2000 m a.s.l. Rainfall in the park area is high and mainly of orographic origin, with greater intensity in its eastern portion (MMA 2017).
Serra das Confusões National Park (Fig. 4) Santa Luz, andTamboril do Piauí (BRASIL 1998, 2010;IBGE 2022d). Its relief is relatively flat, with an average elevation of 600 m a.s.l. and with emphasis on the sandstone plateaus and adjacent depressions of the Parnaíba basin. The average annual rainfall is 650 mm, and large trees predominate in the vegetation at lower elevations, some reaching 20 m in height. At higher elevations, trees are mediumsized, up to 6 m in height. In the wetter valleys, undergrowth associated with bromeliads and pteridophytes predominates, with giant trees punctuating the environment (MMA 2017).
Catimbau National Park (Fig. 5)  paintings estimated to be up to 6000 years old. The predominant climate in the region is the semi-arid of the transition zone between the agreste and the hinterland of Pernambuco, with average annual temperatures of 23 °C and about 60-75% of the rainfall occurring from March to July. The least rainy period is from September to January, with October being the driest month. The local Caatinga vegetation has endemic species, especially cacti and bromeliads (MMA 2017).

Methods
Aiming to cover different areas based on climate, alti-  tude, and vegetation, we performed collections at the four UCs during eight expeditions between 2018 and 2021. These collections were part of the project "Diversidade e Conservação de Hemiptera (Insecta) da Caatinga" (Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPq, grant number 421.413/2017-4). We conducted the collections with permits from the National System of Biodiversity Authorization and Information (SISBIO; permits #62159-1, #62159-2, #62159-3, #62159-4, and #62159-5). We collected specimens by active search with the aid of aquatic nets, and with light traps (white sheet). Specimens are deposited in the Coleção Entomológica do Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil (CEIOC).
We took photographs of the specimens using a Leica M205 C stereomicroscope coupled with a digital camera, using the Leica LAS imaging system. We obtained geographic coordinates of the collecting localities with a GPS receiver and produced maps using ArcGIS v. 10.5 (ESRI Inc., Redlands, CA, USA). The distribution presented for each species is according to Moreira   2023a, 2023b, 2023c, 2023d, 2023e), and abbreviations of Brazilian states are according to the official standard (IBGE 2022f). First state records are highlighted by asterisks (*).
Paraguay, Peru, Suriname, Trinidad and Tobago, Venezuela.   I longer than the head width, including the eyes; the abdominal segment VIII of the males without an apical projection on the ventral surface; and the posterior projection of the last abdominal laterotergite of the females weakly developed (Nieser and Melo 1997 Identification. Our male specimens were identified based on the presence of a rounded gibbosity on the venter of abdominal segment VIII, in addition to a posterior curved spine-like projection. Additionally, both males and females have the mesopleuron brown with a lighter stripe of variable size (Nieser and Melo 1997).   Identification. Our specimens can be distinguished from other South American species of the genus by the body shorter than 5 mm; the pronotum of the apterous form longer than wide, with the posterior lobe covering the mesonotum entirely or almost entirely; the shape of the last abdominal laterotergite of females in lateral view; and the abdominal segment VIII of the male, in dorsal view, with subequal length and width (Nieser 1994;Nieser and Melo 1997 Identification. Our specimens were identified based on the male fore femur without a basal tubercle, but instead with a fringe of setae on this area; and the posterior projection of the female last abdominal laterotergite long, distinctly surpassing the posterior margin of abdominal sternum VII, which is almost straight, without projections (Nieser 1970 Identification. Microvelia ayacuchana can be grouped with those species of Microvelia with a very short pronotum in the apterous form. Our specimens were identified based on the abdominal sternum VII of the males longer than the preceding two together, with a large central U-shaped notch at the posterior margin; and the venter of abdominal segment VIII centrally depressed, with a long posterior projection (Moreira 2012). The females were identified by association with males from the same localities, but also because of their strongly produced last abdominal laterotergite (Drake and Maldonado-Capriles 1952     Identification. Microvelia nelsoni can be grouped with those species of Microvelia in which the pronotum of apterous form covers most of the dorsum of thorax, leaving only the posterolateral metathoracic triangles exposed. Our male specimen was identified by the generally black body coloration, with an orangered mark on the pronotum, and areas of silvery pubescence along the mesal eye margin, the base of head, the sides of abdominal mediotergites I and IV, the center of mediotergites V-VII, and on laterotergites adjacent to mediotergites III-VI. The pattern of silvery pubescence on the abdomen described above differs a little from that on the original description of the species ), but we consider this to be just an intraspecific variation.

Distribution in
General distribution. Brazil. Identification. Microvelia quieta can be grouped with those species of Microvelia with the pronotum of the apterous form covering the mesonotum, but not the metanotum. Our specimens were identified based on the terminalia of the male, which has a pair of short, rounded, lateral projections on the proctiger (Moreira 2012).

Distribution in
General distribution. Brazil.

Distribution in Brazil.
AL, BA*, MG, MT, PI*, SE. Figure 8D New records. BRAZIL -Bahia • Mucugê, PNCD, Identification. Microvelia venustatis can be grouped with those species of Microvelia with the pronotum extended posteriorly, covering the mesonotum almost entirely, except for short lateral lobes. Our specimens were further identified based on the body short, mainly black, with an orange mark on the pronotum; the antennomere IV fusiform, 4.5 times or longer than the largest width, thicker than antennomeres I-III; and the male terminalia small and strongly inserted into the abdomen (Moreira 2012 Identification. Our males were identified based on the relatively uniform dorsolateral row of setae on antennomere IV; the incrassate hind trochanter, connected beyond the base of the hind femur, without a long spur or a fringe of long setae ventrally on the basal lobe; and the hind femur bare at base, without an anteriorly directed dense tuft of bristles in this area (Hungerford 1954). Females from the same localities were associated with the males based on the size and color.

Microvelia venustatis Drake & Harris, 1933
General distribution. Brazil. Identification. Our specimens were identified based on the mesonotum with longitudinal black marks; the male abdominal sternum VIII without a ventral projection; and the female abdominal laterotergites slightly elevated, not reflected over the mediotergites (Nieser and Melo 1999).  Identification. Our specimens of L. lacuniferus were identified mainly based on the shape of the male paramere, which was figured by Drake and Chapman (1958: 320). Identification. Our specimens of M. hebroides were identified mainly based on the shape of the male paramere, which was figured by Drake and Chapman (1958: 320  Identification. Our specimens can be distinguished from its congeners in having the body shorter than 5 mm, antennomere II distinctly shorter than the antennomere III, a prominent vertical process centrally on the pronotum lacking, and the male paramere slender and elongate (Polhemus 2021 Identification. Our specimens of S. quadrispinosa were identified based on the following characteristics: body length 4.70-5.40 mm; hind femur incrassate, more than 2× wider than middle femur, with a spine on distal 2/3 of the posterior margin distinctly larger than the others; stridulatory structure on lateral margin of abdominal laterotergites formed by a row of fine vertical ridges; and apex of male paramere rounded (Floriano et al. 2017).

Discussion
We collected individuals of 28 species, 17 genera, and five families of Gerromorpha in the UCs studied. The richest UC is the PNCD, with 23 species and 12 genera, followed by the EEA, with 15 species and 11 genera, the PNSC with 14 species and nine genera, and the PNCA with five species and three genera. Additional species of the genera Paravelia Breddin, 1898 and Rhagovelia Mayr, 1865 (Veliidae) from the study area are treated separately in two works: Rodrigues and Moreira (2022) and Paiva et al. (in prep.).
The following eight species are herein reported from Piauí for the first time, increasing the number of species in the state to 19: Brachymetra albinervus, Lim. aduncus aduncus, Lim. profugus, Mi. longipes, Mi. mimula, Mi. quieta (Gerridae), Hydrometra argentina (Hydrometridae), and Mesoveli. amoena (Mesoveliidae). Despite the fair amount of first state records, no species are recorded here exclusively from the PNSC. Only the following pair of semiaquatic bugs were previously reported from the PNSC: T. adamsoni (Gerridae) (Rodrigues et al. 2012) and Pa. nieseri Moreira & Barbosa, 2012 (Veliidae) (Rodrigues and Moreira 2022). Both were found in our samples in this UC, and the former is recorded here, while the latter was reported elsewhere (Rodrigues and Moreira 2022).
Finally, two species are herein recorded from Pernambuco for the first time, increasing the number of species in the state to 12: Mi. longipes (Gerridae) and Mesoveli. amoena (Mesoveliidae). In addition to the small amount of first state records, no species are reported exclusively from the PNCA in this work. Only two species of Gerromorpha were previously recorded from the PNCA, namely Pa. luisi Rodrigues & Moreira, 2022 and Pa. digitata Rodrigues & Moreira, 2016 (Veliidae), both of which were collected during our surveys and reported elsewhere (Rodrigues and Moreira 2022).