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

is described for two previously described species, Guignot, 1955 from Colombia, with new records from Venezuela, and Gschwendtner, 1935, from Brazil, and two previously unknown species, , from Bolivia and Peru, and 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.

New species and new distributional records of the hygropetric water scavenger beetle genus Oocyclus Sharp (Coleoptera: Hydrophilidae) from the Guiana Shield.

The species of the water scavenger beetle genus Oocyclus Sharp are reviewed for the Guiana Shield region of South America. Seven species are recorded, including one here described as new: Oocyclus paraiso sp. n.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

Hydraena (Hydraenopsis) josefinae sp. nov. and H.

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.

Description of the immature stages of the Neotropical whirligig beetle Gyrinus (Neogyrinus) rozei Ochs, 1953 (Coleoptera: Gyrinidae) and first report of the parasitoid wasp Melanosmicra sp. (Hymenoptera: Chalcididae) on a Gyrinus species.

In most species of Gyrinidae, the immature stages are unknown, especially due to the difficulty in collecting the juveniles and assigning them to a particular species. Molecular association is a feasible technique that may solve this problem. Recent studies have used DNA sequence data, specifically the gene cytochrome oxidase subunit I (COI), to associate immature and adult stages, thus enabling the description of the former.

On the genus Berosus Leach (Coleoptera: Hydrophilidae) in the State of Roraima, Brazil: description of three new species and new records.

As a contribution to knowledge of the aquatic beetles of the Neotropical Region, the genus Berosus Leach is recorded for the first time from Roraima State in northern Brazil. Three new species are described and illustrated: Berosus illuviosus sp. n.

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

Hamadiana chapadensis gen. n. and sp.

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.

Gyrinus rhyssonotum sp. n., a new species of Gyrinidae (Coleoptera: Adephaga) from northern Brazil.

Gyrinus rhyssonotum sp. n. is described and illustrated based on adult males and females collected in Barcelos County, Amazonas state, Brazil.

Description of the mature larva and pupa of Ora semibrunnea Pic (Coleoptera: Scirtidae) with notes on its biology.

In this paper we describe and illustrate for the first time the immature forms (larva and pupa) of Ora semibrunnea Pic, 1922, including biological information and behavior observed in the laboratory. This is the first record of the occurrence of this species in the Brazilian Amazon region. Larvae and pupae were found in natural lakes associated with macrophyte banks.

Gyretes Brullé (Coleoptera: Gyrinidae) from Brazil: Morphology of eggs and early instars.

Taxonomic information regarding Gyrinidae is mostly based on adults, especially due to the difficulty in collecting immatures and assigning them to a particular species. Association between immatures and adults is sometimes difficult because closely related species can be found in the same habitat. To solve this problem a feasible technique is rearing under laboratory conditions.

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.

Three new species of Reichardt & Vanin, 1976 (Coleoptera, Torridincolidae) from Brazil.

The monotypic Neotropical genus Claudiella Reichardt & Vanin, 1976 is currently known only from Brazil (C. ingens Reichardt & Vanin, 1976). We describe here three new species from Brazil, C.

A Checklist of the Gyrinidae (Coleoptera: Adephaga) of Brazil.

A checklist of all known species of the water beetle family Gyrinidae (whirligig beetles) recorded from Brazil is assembled. This checklist is based on literature published prior to 2012. A total of 206 species and subspecies are cited for Brazil, distributed among three genera (Enhydrus Laporte, 1834, Gyrinus Geoffroy, 1762 and Gyretes Brullé, 1835).