Miradessus gen. nov. from South America described for two species previously in Amarodytes Régimbart, 1900 and two new species (Arthropoda, Insecta, Coleoptera, Adephaga, Dytiscidae, Hydroporinae, Bidessini).

Miradessusgen. nov. is described for two previously described species, Amarodytespulchellus Guignot, 1955 from Colombia, with new records from Venezuela, and A.plaumanni Gschwendtner, 1935, from Brazil, and two previously unknown species, Miradessusbenisp. nov., from Bolivia and Peru, and Miradessusrikaesp. nov. from Ecuador. The genus is characterized by 1) occipital line absent; 2) basal pronotal striae present; 3) basal elytral stria absent; 4) sutural elytral stria absent; 5) transverse carina on elytral epipleuron at humeral angle absent; 6) distinct marginal bead on anterior clypeal margin absent; and 7) male median lobe deeply multilobed with a dorsal portion separate from a unilobed or bilobed ventral portion.

ResumenSe describe a Miradessusgen. nov. para dos especies previamente descriptas, Amarodytespulchellus Guignot, 1955 de Colombia, con nuevos registros de Venezuela, y A.plaumanni Gschwendtner, 1935, de Brasil, y dos especies previamente desconocidas, Miradessusbeni, sp. nov., de Bolivia y Perú, y Miradessusrikae, sp. nov., de Ecuador. El género se caracteriza por 1) línea occipital ausente; 2) estría pronotal basal presente; 3) estría elitral basal ausente; 4) estría elitral sutural ausente; 5) carena transversa en el ángulo humeral del epipleuron elitral ausente; 6) reborde marcado en el margen anterior del clípeo ausente; y 7) lóbulo medio del macho profundamente multilobado con una porción dorsal separada de una porción ventral unilobada o bilobada.

Hydraena bahiana sp. n., a new minute moss beetle (Coleoptera, Hydraenidae) from highlands of Northeast Brazil.

Hydraena (Hydraenopsis) bahiana sp. nov. is described from Bahia State, Northeast Brazil, based on three specimens collected in pools at the headwater of a stream, 1,705 m. asl. The new species belongs to the Hydraena scintillabella subgroup of the leechi group. Description and diagnostic characters are offered; habitus photographs and line drawings of both male and female genitalia are provided. Habitat and distributional data of the new species are also included.

Larval morphology of the Neotropical diving beetle genus Hemibidessus Zimmermann, 1921 (Coleoptera: Dytiscidae: Bidessini).

We describe for the first time the larva of the diving-beetle genus Hemibidessus Zimmermann, 1921, based on instars II and III of H. conicus (Zimmermann, 1921). We include detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi in order to discover useful characters for distinguishing Hemibidessus larvae from those of other known Bidessini. Hemibidessus larvae characteristically have elongate legs armed with natatory setae and elongate urogomphi that bear numerous secondary setae, features commonly associated with an increased swimming ability. These characters are shared with Brachyvatus Zimmermann, 1921, suggesting a close phylogenetic relationship between these two genera. The primary seta UR8 is inserted apically on urogomphomere 2 in Hemibidessus larvae, a feature so far only shared with the mature larva of Yola Gozis, 1886. Other characters that combined with those previously mentioned are useful to distinguish Hemibidessus from other bidessines are the absence of a ventroapical spinula on antennomere 3 and the presence of secondary dorsal setae on protarsus.

Annotated checklist of Hydraenidae (Coleoptera, Polyphaga) of Brazil.

A checklist of known species of the water beetle Hydraenidae (minute moss beetles) recorded from Brazil is assembled, rendering a total of 34 species distributed in four genera: Adelphydraena Perkins, 1989 (one species), Hydraena Kugelann, 1794 (19 species), Parhydraenida J. Balfour-Browne, 1975 (11 species) and Ochthebius Leach, 1815 (three species). For each taxon a complete account of its nomenclature, including synonyms and historical name combinations are included. The habitats (when known) and geographical distribution of each species organized by Brazilian states are also provided.

Description and chaetotaxic analysis of the larval instars of Hydrocanthus debilis Sharp, 1882 (Coleoptera: Noteridae).

All larval instars of the burrowing water beetle species Hydrocanthus debilis Sharp, 1882 are described and illustrated, including morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment, and urogomphus. Larvae of this species have many small dark dorsal maculae on the body, which easily distinguishes it from other known species of the genus except H. socius Sahlberg, 1884. Larvae of H. debilis can easily be separated from those of H. socius by their smaller size, the length of parietal seta PA13 relative to seta PA14, and the relative distance between egg bursters.

Morphological remarks on Adelphydraena amazonica Perkins amp; Ribera, 2020 and new records of two other Hydraenidae from Brazil (Coleoptera).

Undescribed morphological features of Adelphydraena amazonica Perkins Ribera, 2020 are provided based on material collected in the type locality (Amazonas State, northern Brazil). Aedeagus, male sternite X, last female abdominal segments and spermatheca are illustrated and described for the first time. Habitat information on the type locality is also included. New records on two Brazilian Hydraenidae species are provided.

Hydaticus aequalis sp. n. and a new record of H. devexus Trémouilles, 1996 from Brazil (Coleoptera, Dytiscidae, Hydaticini).

Hydaticus aequalis sp. n. is described from Brazil, where it was recently discovered in the central lowlands region of the Amazon forest. The new species differs from all other Neotropical congeners by its uniformly brown dorsal surface and the shape of medial lobe. The dorsal habitus and male genitalia are illustrated, and a distribution map is provided. The habitat, a small stream and associated forest pool, is illustrated and described. In addition, a new record of H. devexus Trémouilles, 1996, previously known from a single specimen, is reported from the highlands of northeastern Brazil, and a modified key to Neotropical species of the genus is provided.

Suphisellus grossoi sp. n., a new burrowing water beetle from South America, and notes on S. flavolineatus (Régimbart, 1889) and S. grammicus (Sharp, 1882) (Coleoptera: Noteridae).

Suphisellus grossoi sp. n. is described from the Reserva Natural del Bosque de Mbaracayú, Canindeyú department, Paraguay. Diagnostic characters are described and illustrated in detail. New records are provided for S. flavolineatus (Régimbart, 1889) and S. grammicus (Sharp, 1882), which are also briefly diagnosed. Suphisellus melzeri Zimmermann, 1925 is proposed as a junior subjective synonym of S. flavolineatus (syn. n.), and lectotypes are designated for both taxa.

Rediscovery of the Neotropical water scavenger beetle Protistolophus spangleri Short with notes on its habitat and behavior (Coleoptera: Hydrophilidae: Hydrophilinae).

The water scavenger beetle genus Protistolophus Short contains a single species, P. spangleri Short, 2010, known from southern Venezuela. The genus was hitherto known only from a single partly-incomplete male specimen, making it one of the rarest and most poorly known aquatic hydrophilid genera in the world. Only one other New World aquatic hydrophilid genus, the Ecuadorian cave endemic Troglochares Spangler, is known from a single specimen or locality. In a phylogenetic analysis of the Hydrophilini based on adult morphology, the genus Protistolophus was resolved as the sister taxon to the remaining genera of the tribe, implying it is an ancient and possibly relict lineage-it possesses a very unusual combination of characters, including a very weakly developed mesoventral keel. It was the only genus not included in a recent molecular phylogeny of the Hydrophilini as no suitable material was available for DNA (Toussaint et al. 2017).

Characterization and mapping of sensilla on the head appendages of noterid larvae (Coleoptera: Noteridae), and development of a preliminary biometric method for taxa delimitation.

Larvae of the burrowing water beetle family Noteridae are distributed worldwide and are often abundant in a broad range of aquatic habitats, playing an important role in structuring freshwater communities, yet they have remained among the most poorly studied groups of aquatic beetles. Studies on sensillar equipment of aquatic insect larvae are largely lacking, despite their potential use in phylogeny and biometric identification methods. In this article, the external morphology and distribution of sensilla on the head appendages of first instar larvae of selected genera of Noteridae were examined using scanning electron microscopy. Seven main types were distinguished based on their morphological structure: basiconica (3 subtypes), campaniformia (2 subtypes), chaetica (7 subtypes), coeloconica (6 subtypes), coniform complex (2 subtypes), placodea, and styloconica (3 subtypes). The apex of the labial palpus was found to be the most variable and informative region in regard to the number, relative position, and topology of sensilla. Fingerprint models were, therefore, generated for this region in each of the studied genera, allowing their identification.

Hydrodessus ducke sp. n. and new records of other species of the genus (Coleoptera, Dytiscidae, Bidessini).

Hydrodessus ducke sp. n. is described and illustrated based on specimens collected in Amazonas State (northern Brazil), bringing the total number of Hydrodessus species to 33. The new species can be distinguished from other species in the genus by body size and shape, coloration, and characteristics of the elytral carina, prosternal process, metaventral carina, and male genitalia. The male of H. latotibialis Miller, 2016 is described and illustrated for the first time from specimens collected in Pará State, northern Brazil. New records for 17 species from Brazil, French Guiana and Suriname are provided, and the newest existing key to species is updated to accommodate the new taxon.

Two new species of Hydraena Kugelann, 1794 from Brazil (Coleoptera: Hydraenidae).

Hydraena (Hydraenopsis) josefinae sp. nov. and H. (H.) pernambucana sp. nov. are described respectively from Amapá and Pernambuco States, Brazil. Hydraena (H.) josefinae sp. nov. is a member of the scintillabella subgroup of the leechi group, while H. (H.) pernambucana sp. nov. belongs to the orcula complex in the marginicollis subgroup of the marginicollis group. Descriptions and diagnostic characters for both new species are offered; habitus photographs and line drawings of male genitalia of the two new species, as well as drawings of female genitalia of H. josefinae sp. n., are provided. Male genitalia of H. alterra Perkins, 1980 is illustrated and compared with that of the closely related H. josefinae sp. nov. Habitat and distributional data of the two new species are also included.

Larval morphology and analysis of primary chaetotaxy in the genus Suphis Aubé, 1836 (Coleoptera: Noteridae).

The three larval instars of Suphis cimicoides Aubé, 1837 are described and illustrated, including morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphus. A preliminary ground plan of primary chaetotaxy for noterid larvae is presented for the first time, based on the species described herein and examination of larvae of the genera Hydrocanthus Say, 1823 and Suphisellus Crotch, 1873. This ground plan is compared with previous systems proposed for other adephagan families. Larvae of Noteridae can be distinguished from those of other families of Hydradephaga by the following combination of characters: (1) antennomere 3 with a rugged area on distal portion; (2) abdominal segment VIII with a U-shaped wavy membranous area ventrally; (3) absence of pore FRd; and (4) presence of seta AB16. Several sensilla present in noterid larvae (notably setae TR2 and TA1 and pores PAl, PAm, COd, TRb and FEb) are absent in larvae of Meruidae. On the contrary, parietal seta PA5 is present in Meruidae but absent in Noteridae. The presence of pore COc in Noteridae may indicate that this family has retained the ancestral condition found only in Carabidae. On the other hand, the absence of setae FE7, FE8, FE9 and FE10 in Noteridae is similar to the condition found in Carabidae, Gyrinidae and Meruidae.

Hamadiana chapadensis, a new genus and species of diving beetle from Brazil (Coleoptera, Dytiscidae, Laccophilinae, Laccophilini).

Hamadiana chapadensis gen. n. and sp. n. is described based on a single male specimen collected in Central Brazil. The new species belongs to the diving beetle tribe Laccophilini but could not be assigned to any existing genera, therefore a new genus is described to accommodate it. Hamadiana gen. n. is unique among Laccophilini in having the hind margin of the metacoxal process deeply incised and medially slightly protruded backwards. In addition, it differs from other genera of the tribe by having the antennomeres simple, not expanded, the metacoxal lines not straight, and the metatibiae with two simple apical spurs. The habitus, male genitalia, and diagnostic features are illustrated, and a distribution map is provided. A recently published key to Laccophilini is modified to include the new genus.

Description of the second- and third instar larvae of Platynectes (s. str.) decemnotatus (Aubé, 1838) (Coleoptera: Dytiscidae: Agabinae: Platynectini).

The second- and third instar larvae of Platynectes (s. str.) decemnotatus (Aubé, 1838) are described and illustrated in detail for the first time, with special emphasis on morphometry and chaetotaxy. Larvae of P. decemnotatus can be distinguished from most other Agabinae by having secondary setae on the urogomphus and share with the other known species described in detail the presence of a ventroapical spinula on antennomere 3 and the absence of an occipital suture, natatory dorsal setae on tibia and tarsus and natatory setae on urogomphus. Platynectes decemnotatus larvae differ from larvae of Agabus Leach, 1817, Hydrotrupes Sharp, 1882 (currently in Hydrotrupini), Ilybiosoma Crotch, 1873, Ilybius Erichson, 1832 and the previously described Platynectes species in having a one-segmented urogomphus, a character previously observed only in larvae of Agabinus Crotch, 1873. The second- and third instar larvae of P. decemnotatus differ from those of P. (Agametrus) curtulus (Régimbart, 1899) in having the apical lateroventral process of antennomere 3 protruding (not protruding in P. curtulus). The third-instar larva of P. decemnotatus can also be distinguished from that of P. (Gueorguievtes) decempunctatus (Fabricius, 1775) by the absence of secondary dorsal setae on the tibia.