Carnivorous diving beetles of the genus Desmopachria (Coleoptera: Dytiscidae) from Brazil: New species, new records, and a checklist

Abstract Eight new species of DesmopachriaBabington, 1841 are described and illustrated from Brazil: D. dicrophallica sp. nov. , D. disticta sp. nov. , D. grammosticta sp. nov. , D . grandinigra sp. nov. , D. itamontensis sp. nov. , D. leptophallica sp. nov. , D. stethothrix sp. nov. , and D. ukuki sp. nov. The species D. amyaeMiller, 2001 , D. cheiMiller, 1999 , D. margarita Young, 1990, and D. volatidiscaMiller, 2001 are recorded for the first time from Brazil. From species of the Desmopachria reported in Brazil, D. aldessaYoung, 1980 has a new record from Pará state and D. fossulataZimmermann, 1928, D. granoidesYoung, 1986 , and D. laevis Sharp, 1882 have new records from Rio de Janeiro State. A checklist of all Desmopachria recorded from Brazil is presented with notes about some of the localities. Resumo Oito espécies novas de DesmopachriaBabington, 1841 são descritas e ilustradas para o Brasil, D. dicrophallica sp. nov. , D. disticta sp. nov. , D. grammosticta sp. nov. , D . grandinigra sp. nov., D. itamontensis sp. nov., D. leptophallica sp. nov., D. stethothrix sp. nov. e D. ukuki sp. nov. As espécies D. amyaeMiller, 2001, D. cheiMiller, 1999 , D. margarita Young, 1990 e D. volatidiscaMiller, 2001 são registradas pela primeira vez para o Brasil. Das espécies de Desmopachria registradas para o Brasil D. aldessaYoung, 1980 tem um novo registro para o estado do Pará e D. fossulataZimmermann, 1928 , D. granoidesYoung, 1986 e D. laevis Sharp, 1882 têm novos registros para o estado do Rio de Janeiro. Uma listagem de todos os Desmopachria registrados para o Brasil é apresentada, com notas acerca de algumas localidades.


Introduction
The genus Desmopachria  is one of the largest Dytiscidae groups around the world, with 111 valid species at the present (Braga and Ferreira-Jr 2011;Makhan 2012;Megnar and Sánchez-Fernández 2014), 58 of which are recorded from Brazil. These species are common in Neotropic and southern Nearctic freshwater areas and occur in a variety of lentic habitats, including ponds, streams, forest pools, bromeliads, and tree hole pools (Miller 2005).
Desmopachria can be collected in large numbers using black lights and mercury vapor lamps (Miller 2005). Due to the small size of the insects, manual collections or collections using sieves rarely obtain these species. However, because not all species are attracted to light traps, the most appropriate way to manually collect these small predaceous diving beetles is to use samplers with mesh of 1 mm in diameter or less. However, care must be taken during collection because these samplers tend to get coated with sediment very quickly. A very effective method is to place the sampler over a plastic tray immediately after scraping. The water drained through the mesh usually contains small aquatic beetles, which are easily seen in the bottom of the tray. The compression of the sediment and of the vegetation from the banks of aquatic environments allowing water runoff to a plastic tray usually brings along some small aquatic beetles. Despite difficulties of collection, new species of the Desmopachria are regularly encountered, and it seems likely that the true number of species is significantly higher than currently known.
Desmopachria are small (1.00-2.50 mm in length), rounded beetles with colors varying from light brown to black, and they may have spots or streaks. The beetles are usually without sexual dimorphism.  listed a series of diagnostic characters of this genus, such as reduction of the metacoxal lobes, reduction of the anterior metatarsal claw, antennomeres 1-2 wider than following articles, antennomeres 5-10 short and slightly expanded in apical half, labial palpus with apical pair of sensilla widely separated, maxillary palpus with an apical sensillum, pronotum with posterolateral angles produced backward, metacoxae fused to visible abdominal sternite one, and metatibia with apical transverse row of spines discontinuous medially.
In our study, eight new species of Desmopachria from Brazil are described and illustrated in this article, and new records for D. amyae , D. chei Miller, 2001 D. volatidisca Miller, 2001 from Brazil are presented. From species of the Desmopachria reported in Brazil, D. aldessa Young, 1980 has a new record from Pará State and D. fossulata , D. granoides Young, 1986, and D. laevis Sharp, 1882 have new records from Rio de Janeiro State. A checklist of all Desmopachria recorded from Brazil is presented with notes about some localities.

Materials and Methods
The specimens were examined under a stereoscopic microscope with up to 150 times magnification. The measurements were obtained with the aid of a grid ocular with accuracy of 0.01 mm onto a stereomicroscope, and specimens were preserved in tubes with ethyl alcohol 92%. The genitalia were mounted in slides and coverslips with glycerin gel to drawings and stored in microvials within the specimen tube. Because the species of this genera usually lack external sexual dimorphism, the only way of determinate the sex of specimens is examining the genitalia, therefore only the sex of the holotype was determined. The terminology used in the descriptions follows that of Young ( , 1995 and Miller ( , 2005. The specimens were deposited in Coleção Entomológica Prof. José Alfredo Pinheiro Dutra, Departamento de Zoologia, Universidade Federal do Rio de Janeiro, Brazil (DZRJ)  In the descriptions of new species, the collection were the specimens were deposited is given first, the geographic coordinates are listed second, and the labels accompanying the specimens are listed third, each between quotation marks and separated by bars. When the geographic coordinates of a collection place were unknown, the central point of the municipality is presented. A checklist of all Desmopachria reported from Brazil is presented, with the locations and their authors in parentheses. In the list, we denote new records by (*). Notes explaining common location changes are presented before the list, and explanations for specific cases within the list are below the referred species.

Nomenclature
This publication and the nomenclature it contains have been registered in Zoobank. The LSID number is: urn:lsid:zoobank.org:pub:4EF7A35B-0535-4FC8-AB3B-BC1E3A88AF0B It can be found online by inserting the LSID number after www.zoobank.org/.
Desmopachria dicrophallica sp. nov. (Figures 1-3) Description. Holotype male: total length 2.30 mm; maximum width 1.50 mm; elytral length 1.60 mm; maximum width of the pronotum 1.10 mm. Head, pronotum, and ventral surface light brown; elytron dark brown ( Figure 1). Body rounded. Head inconspicuously punctate; clypeus lightly truncate and beaded; antennomeres 6-10 slightly expanded in apical half. Pronotum short and wide, very fine and inconspicuously punctuate except for the posterior margin, where the punctures are coarse, without basal striae, and lateral bead wide. Prosternal process apically strongly forked, area between rami forming a deep pit; metasternum, metacoxae, and ventrites without punctures. Elytron with coarse punctures. Aedeagus strongly margined, with base wide narrowing to apex and subtly widening in the apical third. Paramere thin and broad with a narrowing in the apex, apex rounded and surrounded with dense rows of setae in both sides (Figures 2-3).
Taxonomic notes. This new species belongs to the D. portmanni group sensu  in having the prosternal process sexually dimorphic, male process apically strongly forked, area between rami forming a deep pit, female process not as in male. The shape of genitalia this species is unique. The dilatation in third apical, the jagged and surrounded with rows of setae in both sides are unprecedented features in this genus.

Desmopachria disticta sp. nov. (Figures 4-6)
Description. Holotype male: total length 2.13 mm; maximum width 1.45 mm; elytral length 1.40 mm; maximum width of the pronotum 1.25 mm. Head, pronotum, and ventral surface light brown; elytron dark brown ( Figure 4). Body rounded. Head inconspicuously punctate; clypeus inconspicuously truncate and not beaded; antennomeres 8-10 slightly expanded in apical half. Pronotum short and wide, very fine and inconspicuously punctuate except for center of base, where punctures are coarse, without basal striae, and lateral bead wide; prosternal process apically strongly forked, area between rami forming a deep pit; metasternum, metacoxae, and abdomen with printed lines short and irregular, without punctures. Elytron with two types of punctures, a very fine and inconspicuous and others coarse. Aedeagus margined with forked base, laterally expanding into center apex; apex acute. Paramere broad, narrowing subtly near apex, with rows of setae in outer margin; apical area flattened, in dorsal view ( Figures 5-6).
Intraspecific variation. Body measurements vary in total length from 2.10 to 2.20 mm; maximum width 1.45-1.48 mm; elytral length 1.38-1.50 mm; maximum width of pronotum 1.13-1.25 mm. Etymology. The specific epithet is the Greek prefix di meaning "two," and the Greek adjective stiktos, meaning "punctured," referring to double punctures on the dorsal surfaces of the pronotum and elytra.
Taxonomic notes. This new species belongs to the D. portmanni group sensu  in having the prosternal process sexually dimorphic, male process apically strongly forked, area between rami forming a deep pit, female process not as in male. Different types of punctures on pronotum also are present in Desmopachria bryanstonii Clark, 1862, D. decorosa Young, 1995, D. dispar Sharp, 1882 laevis, but in none of these species is it so abrupt and conspicuous. The genitalia of D. disticta sp. nov. is not typical of the D. portmanni group, with lateral expansions of aedeagus and parameres wide with a row of setae on the outer margin instead of the inner.

Geographic distribution. So far known only from the Amazonas State in Brazil.
Desmopachria grammosticta sp. nov. (Figures 7-9) Description. Holotype male: total length 2.52 mm; maximum width 1.80 mm; elytral length 1.65 mm; maximum width of the pronotum 1.29 mm. Dorsal and ventral surface dark brown (Figure 7). Body rounded. Head inconspicuously punctate; clypeus indistinctly beaded; antennomeres 6-10 slightly expanded in apical half. Pronotum short and wide, with two types of punctures, a very fine and others coarse, without basal striae and lateral bead; prosternal process apically strongly forked, area between rami forming a deep pit. Metasternum, metacoxae, and abdomen with coarse punctures. Elytron with two types of punctures, a scattered very fine and others dark and very coarse forming rows. Aedeagus with half of length of paramere, margined with base wide narrowing to apex; apex rounded. Paramere thin, distal third with internal edge flattened, and internal margin with rows of setae (Figures 7-9). Etymology. The specific epithet is the Greek prefix gramme, meaning "line," and the Greek adjetive stiktos, meaning "punctured," referring to the linear rows formed by coarse punctures on the elytral surface.
Taxonomic notes. This new species belongs to the D. portmanni group sensu  in having the prosternal process sexually dimorphic, male process apically strongly forked, area between rami forming a deep pit, female process not as in male, and the characteristic genitalia with paramere curved, with a row of bristles on the internal edge. The coarse dark punctures forming rows in the elytron occurs in D. goias Young, 1995 andD. variegata Sharp, 1882, however both species are much smaller in size and the length of aedeagus is bigger. The genitalia are only comparable to D. aurea , but the aedeagus base of this species is thinner than D. grammosticta sp. nov., and D. aurea is smaller in sizeand with a different colour pattern.
Geographic distribution: So far known only from the Amazonas State in Brazil.
Body rounded, very fine, and inconspicuously punctate. Clypeus indistinctly beaded; antennae with rounded scape, pedicel narrower and longer than flagellomeres, antennomeres 5-9 slightly expanded in apical half. Pronotum short and wide; basal striae and lateral beads absent. Pro-and mesotarsum with ventral adhesive setae; prosternal process apically strongly forked, area between rami forming a deep pit. Ventral surface of metatibia covered with short and wide spines. Aedeagus with wave margin; base bifurcates and apex rounded. Paramere thin, with wave margin and row of setae in internal margin before apex ( Figures  11-12).
Intraspecific variation. Body measurements vary in total length from 2.16 to 2.25 mm; maximum width 1.38-1.47 mm; elytral length 1.44-1.59 mm; maximum width of pronotum 1.14-1.20 mm. Etymology. The specific epithet is the Latin adjective grandis, meaning "big" or "large," and the Latin adjective niger, referring to the species Desmopachria nigra Zimmermann, 1923, which is very similar in black color but smaller in size.
Taxonomic notes. This new species belongs to the D. portmanni group sensu  in having the prosternal process sexually dimorphic, male process apically strongly forked, area between rami forming a deep pit, female process not as in male, and the characteristic genitalia with paramere curved, with a row of bristles on the internal edge. This is a bromelicolous species and has a black vitreous color characteristic of the two other bromelicolous species, D. nigra and D. laesslei Young, 1981. However, compared to the types of D. nigra and the bibliography of D. laesslei, the new species proved to be bigger. Demopachria laesslei belongs to D. convexa group and has a different type of genitalia, with subapical articulable process in lateral lobes, and the type of D. nigra has no more genitalia, therefore not allowing comparison between the two species, but the species only reaches 2.00 mm in size.

Geographic distribution: So far known only from the Minas Gerais and Rio de Janeiro States in Brazil
Desmopachria itamontensis sp. nov. (Figures 13-15) Description. Holotype male: total length 2.70 mm; maximum width 1.80 mm; elytral length 1.80 mm; maximum width of the pronotum 1.40 mm. Dorsal and ventral surface dark brown. (Figure 13) Body rounded. Head inconspicuously punctate; lightly truncate and beaded; antennomeres 6-10 slightly expanded in apical half. Pronotum short and wide, with course punctures except for an area in each side of the disc; without basal striae and lateral bead; prosternal process apically strongly forked, area between rami forming a deep pit; metasternum, metacoxae, and ventrites with coarse punctures except for the area around the coxal line. Elytron with course scattered punctures. Aedeagus a little more than half the length of paramere; margined with base wide and narrowing to apex; apex truncated. Paramere thin, distal third with inner edge flattened and with a dense row of setae (Figures 14-15). Etymology. The specific epithet itamontensis is the gentilic to natives from Itamonte municipality, the place of origin of the type material.

Intraspecific variation.
Taxonomic notes. This new species belongs to the D. portmanni group sensu  in having the prosternal process sexually dimorphic, male process apically strongly forked, area between rami forming a deep pit, female process not as in male, and the characteristic genitalia, with paramere curved and with a row of bristles. This species is very similar in the shape of the body and the genitalia to D. grammosticta sp. nov., but the pronotum has a pair of areas without punctures in each side of disc, and the punctures of elytra do not form rows. The genitalia are almost identical, except that the aedeagus reaches a little over half of parameres, while in D. grammosticta sp. nov. it reaches halfway; D. itamontensis sp. nov. has the most dense rows of setae.
Body rounded. Head fine, shallow, and very sparsely punctuate; clypeus with very fine margin, slightly truncated; antennomeres 5-9 slightly expanded in apical half. Pronotum short and wide, shallow and densely punctuate, without basal striae and lateral bead. Metasternum and metacoxae with fine, shallow, and very sparse punctures. Elytron coarse, shallow, and densely punctuate. Ventrites finely and sparsely punctuate; last ventrite transversely impressed. Aedeagus with basal half broad and apex half strict, narrowing abruptly in the middle followed by a slight swelling, apex with a long incision in the center get up close to the swelling. Paramere with the apical half di-vided two lobes; dorsal lobe straight, with few long setae on inner margin near the apex; ventral lobe rounded, with few setae and a row of short setae on the outer margin (Figures 17-18).
Intraspecific variation. Body measurements can vary in total length from 1.03 to 1.06 mm; maximum width 0.64-0.74 mm; elytral length 0.65-0.68 mm; maximum width of the pronotum 0.54-0.56 mm. Etymology. The specific epithet is the Greek adjective leptos, meaning "thin," and the Greek noun phallos, meaning "aedeagus," referring to thin apex of the aedeagus.

Type
Taxonomic notes. This species belongs to the Desmopachria nitida group sensu  because of the lateral lobes deeply bifid with apex divided into two long rami. This new species is similar to D. margarita Young and D. psarammo Miller, 1999, however, it differs from D. margarita by the lack of rounded area in aedeagus and the general shape of paramere in position of bristles in lobes, and from D. psarammo by the absence of pattern of maculae in the elytra, the smaller size, and the general shape of aedeagus.

Geographic distribution: So far known only from the Rio de Janeiro State in Brazil
Desmopachria stethothrix sp. nov. (Figures 19-25) Description. Holotype male: total length 2.28 mm; maximum width 1.50 mm; elytral length 1.38 mm; maximum width of the pronotum 1.05 mm. Head yellow. Pronotum yellow with pair of basal dark brown spots. Elytron yellow with brown maculae; a large, irregular brown macula on the disc reaching the base with four expansions along the length, a brown subhumeral macula stretched longitudinally from the base, four brown maculae along the lateral, the first, third, and fourth short stretch along the side (Figure 19). Ventral surface yellow.
Body rounded. Head inconspicuously punctate; clypeus not truncate and beaded; antennomeres 7-9 slightly expanded in apical half. Pronotum short and wide, very fine and inconspicuously punctate, basal striae long and undulated, and lateral beads absent; prosternal process setiform, skirted by a row of long setae ( Figure 20); metasternum, metacoxae, and abdomen with scattered fine punctures. Elytron with very fine and obscure punctures. Aedeagus with basal half wide and apical half lined, apex truncate with a straight truncated apical expansion. Paramere wide with undulating edges, in ventral view apex bilobated with rows of setae, in dorsal view only the largest lobe is visible (Figures 21-22).

Intraspecific variation.
The elytra pattern of colors can vary in the extent depending on the melanism in each specimen (Figures 23-24). The females do not have the rows of bristles in prosternal process (Figure 25). Body measurements variable in male, the total length 2.23-2.38 mm; maximum width 1.50-1.55 mm; elytral length 1.45-1.50 mm; maximum width of pronotum 1.30-1.33 mm and in female the total length 2.05-2.15 mm; maximum width 1.38-1.50 mm; elytral length 1.25-1.50 mm; maximum width of pronotum 1.13-1.25 mm. Etymology. The specific epithet is the Greek noun stethos, meaning "chest," and the Greek adjective thrix, meaning "hairy" or "shaggy," referring to the prominent pubescence on the prosternal process surface of male.

Type-material
Taxonomic notes. This new species belongs to the D. glabricula group sensu  in having median and lateral lobes very strongly robust and heavily sclerotized. The only species with colored elytra in this group is D. volvata Young, 1981, but the pattern of maculae do not have all characteristic expansions of D. stethothrix sp. nov. The prosternal process and genitalia in this new species are unique and distinctive.

Geographic distribution: So far known only from the Amazonas State in Brazil
Desmopachria ukuki sp. nov. (Figures 26-28) Description. Holotype male: total length 2.03 mm; maximum width 1.50 mm; elytral length 1.38 mm; maximum width of the pronotum 1.05 mm. Head and pronotum light brown. Elytron light brown with dark maculae for transparency ( Figure 26). Ventral surface light brown.
Body rounded. Head inconspicuously punctate; clypeus indistinctly beaded; antennomeres 7-9 slightly expanded in apical half. Pronotum short and wide, very fine and inconspicuously punctate, without basal striae and lateral bead; prosternal process apically strongly forked, area between rami forming a deep pit. Metasternum, metacoxae, and abdomen with scattered fine punctures. Elytron with fine and obscure punctures. Last ventrite with an undulated suture. Aedeagus with broad base, apical half narrowed and margined, apex truncated. Paramere wide almost thin, inner margin with a tuft of setae in distal third. ( Etymology. The specific epithet is an apposition noun that refers to the Ukuki community, the place of origin of the type material.
Taxonomic notes. This new species belongs to the D. portmanni group sensu  in having the prosternal process sexually dimorphic, male process apically strongly forked, area between rami forming a deep pit, female process not as in male, and the characteristic genitalia, with paramere curved and with a row of bristles on the internal edge. This species is only comparable with D. speculum Sharp, 1887, which has a shape of body and genitals very similar, but can be separated by the large body size of D. ukuki sp. nov.

Checklist of Desmopachria species known from Brazil
Notes: (1) In 1975, Mato Grosso State was divided into Mato Grosso and Mato Grosso do Sul States. In old articles, like , the area currently occupied by Mato Grosso do Sul state is known as Mato Grosso.
(2) The material record from Brazil with the specific location of "Santa Rita" weas collected by the Finnish R. F. Sahlberg in August 1850.  mentions "Santa Rita [da Floresta]," now district of Cantagalo Municipality, Rio de Janeiro States. Although in August 1850 Sahlberg explored the district of Cantagalo for three months (Papavero 1973), the villa of Santa Rita da Floresta was only founded in 1876 by Portuguese immigrant Captain Bernardo de Souza and his cousins. Second Papavero (1973), Sahlberg visited the golden mines in Minas Gerais and must have collected in this state from Chapéu d'Uvas to Diamantina (the ancient Tejuco), and Santa Rita would be in this itinerary. In this case, Santa Rita corresponds to Santa Rita Durão District, Mariana Municipality, Minas Gerais State.