Reclassification of Cybistrinae Sharp, 1880 in the Neotropical Region (Coleoptera, Adephaga, Dytiscidae), with description of new taxa.

The classification of the Neotropical Cybistrinae Sharp, 1880 (Coleoptera: Adephaga: Dytiscidae) is extensively revised based on a phylogenetic analysis of morphological features of the group. A new genus, Nilssondytesgen. nov. is described for a unique new species, Nilssondytesdiversussp. nov. from Venezuela. The New World genus, Megadytes Sharp, 1882, with several subgenera, was found to not be monophyletic. The type species of Megadytes, Dytiscuslatus Fabricius, 1801 and the species Cybisterparvus Trémouilles, 1984 were found to be monophyletic together, and phylogenetically more closely related to Cybister Curtis, 1827 than to other species assigned to Megadytes sensu stricto, which were found to also be monophyletic. The name Megadytes is here restricted to include only Megadyteslatus and Megadytesparvus. These two species assigned to this newly restricted genus concept are reviewed and diagnosed. A new genus, Metaxydytesgen. nov., is erected to include all the other species currently assigned to Megadytes sensu stricto. The current subgenus names assigned to Megadytes, Bifurcitus Brinck, 1945, Paramegadytes Trémouilles & Bachmann, 1980, and Trifurcitus Brinck, 1945, are elevated to genus rank since they are variously paraphyletic. The two species assigned to Cybister (Neocybister) Miller, Bergsten & Whiting, 2007, Cybister (Neocybister) festae Griffini, 1895, and Cybister (Neocybister) puncticollis (Brullé, 1837) re reviewed and diagnosed with the former redescribed and its type specimens considered for the first time since its description. Another evidently new species and possible new genus, Megadytes species, IR57 (Ribera et al. 2008), from Peru, is also characterized, but not formally treated because of lack of important data for the single, partial specimen. Diagnostic features are illustrated for the entire group.

ResumenLa clasificación de Cybistrinae Sharp, 1880 neotropicales (Coleoptera: Adephaga: Dytiscidae) se revisa ampliamente con base en un análisis filogenético de características morfológicas del grupo. Un nuevo género, Nilssondytesgen. nov. se describe para la única nueva especie Nilssondytesdiversussp. nov. de Venezuela. Se encontró que el género, Megadytes Sharp, 1882, del Nuevo Mundo y con varios subgéneros, no es monofilético. Se encontró que la especie tipo de Megadytes, Dytiscuslatus Fabricius, 1801 y la especie Cybisterparvus Trémouilles, 1984 forman un grupo monofilético y filogenéticamente más estrechamente relacionado con Cybister Curtis, 1827 que con otras especies asignadas a Megadytes sensu stricto, que se encontró que también forman un grupo monofilético. El nombre Megadytes se restringe aquí para incluir solo a Megadyteslatus y Megadytesparvus. Se revisan y diagnostican estas dos especies asignadas a este nuevo concepto restringido del género. Un nuevo nombre, Metaxydytesgen. nov., se erige para incluir a todas las demás especies actualmente asignadas a Megadytes sensu stricto. Los nombres subgenéricos actuales asignados a Megadytes, Bifurcitus Brinck, 1945, Paramegadytes Trémouilles y Bachmann, 1980 y Trifurcitus Brinck, 1945, se elevan al rango de género, nuevo estado, ya que son parafiléticos de diversas formas. Se revisan y diagnostican las dos especies asignadas a Cybister (Neocybister) Miller, Bergsten y Whiting, 2007, Cybister (Neocybister) festae Griffini, 1895 y Cybister (Neocybister) puncticollis, redescribiendo la primera y considerando sus especímenes tipo por primera vez desde su descripción. Otra especie evidentemente nueva y posible nuevo género, Megadytes, IR57 (Ribera et al. 2008), de Perú, también se caracteriza, pero no se trata formalmente debido a la falta de datos importantes para el único espécimen parcial. Las características diagnósticas se ilustran para todo el grupo.

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.

Larval morphology and new records of the iconic diving beetle Acilius sinensis Peschet, 1915 (Coleoptera: Dytiscidae: Dytiscinae)-a species well established in western Yunnan, China.

Adults and larvae of the very rare Chinese endemic species Acilius sinensis Peschet, 1915 are newly reported from three localities in western Yunnan, which indicates the presence of viable populations in this area. Based on the available data, the rarity of the species in collections is more caused by collecting bias than actual threat of its habitat loss. All larval instars of A. sinensis are for the first time described according to the now generalized larval descriptive format of Dytiscidae, which incorporates detailed chaetotaxic and morphometric analyses. Like other known Acilius Leach, 1817 larvae, A. sinensis is characterized by the typical Y-shaped median process of prementum. So far as the third instar larva is considered, A. sinensis shares with A. fraternus (Harris, 1828), A. kishii Nakane 1963, A. semisulcatus Aubé, 1838, and A. sulcatus (Linnaeus, 1758) the median process of prementum invaginated at nearly 75% of its length compared to less than 35% in A. abbreviatus Aubé, 1838, A. duvergeri Gobert, 1874, and A. canaliculatus (Nicolai, 1822). As far as chaetotaxy is concerned, A. sinensis is distinguished by the presence of the primary pore PAo located on the ventral face of the parietal. The habitat of the species is briefly commented. Acilius sinensis is here newly proposed for inclusion in the IUCN red list in the category Vulnerable.

The very rare Japanese endemic diving beetle Japanolaccophilus niponensis (Kamiya, 1939), (Coleoptera: Dytiscidae, Laccophilinae): larval morphology and phylogenetic comparison with other known Laccophilini.

The three larval instars of Japanolaccophilus niponensis (Kamiya, 1939) (Coleoptera: Adephaga, Laccophilinae) are described for the first time according to the now genevralized larval descriptive format of Dytiscidae (Coleoptera: Adephaga), which incorporates detailed chaetotaxic and morphometric analyses. A parsimony analysis based on larval characteristics of 14 Laccophilini species in seven genera was conducted using the program TNT. One of the main results is that Japanolaccophilus Satô, 1972, which so far was treated as being related to Neptosternus Sharp, 1882 now stands out as sister to Laccophilus Leach, 1815, and Philodytes J. Balfour-Browne, 1938 with strong support. Additionally, Laccomimus Toledo & Michat, 2015, and Africophilus Guignot, 1948 are resolved as monophyletic and sister to a clade which itself is subdivided into two well supported clades: Neptosternus + Australphilus Watts, 1978, and Japanolaccophilus + (Laccophilus, Philodytes). Philodytes is here newly accepted as junior synonym of Laccophilus.

Morphology of the larvae of Sandracottus femoralis Heller, 1934, and S. mixtus (Blanchard, 1843) and phylogenetic comparison with other known Aciliini (Coleoptera: Dytiscidae, Dytiscinae).

We describe the larvae of the diving-beetle genus Sandracottus Sharp, 1882 based on S. femoralis Heller, 1934 and S. mixtus (Blanchard, 1843). We include detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, terminal abdominal segment and urogomphi in order to discover useful characters for distinguishing Sandracottus larvae from those of other known Aciliini (Coleoptera: Dytiscidae, Dytiscinae). A provisional parsimony analysis based on larval characteristics of seven Aciliini species in four genera (Acilius Leach, 1817, Graphoderus Dejean, 1833, Sandracottus, Thermonectus Dejean, 1833) was conducted using the program TNT. A clade grouping Eretini and Aciliini stands out as the most strongly supported in this analysis. The tribe Aciliini finds itself monophyletic with also very good support. Our analysis, however, failed to depict any clear phylogenetic relationships within the Aciliini although each of the four genera studied emerged from our study as morphologically distinct.

Bunites distigma (Brull, 1837): discovery of the second- and third-instar larvae and phylogenetic relationships within the Colymbetinae (Coleoptera: Dytiscidae).

The second- and third-instar larvae of the diving beetle Bunites distigma (Brull, 1837) are described and illustrated for the first time, including detailed morphometric and chaetotaxic analyses of selected structures, and their phylogenetic relationships within the Colymbetinae are re-evaluated. The results support previous hypotheses on the position of this genus based on first-instar characters, as Bunites Spangler, 1972 shares a common origin with Meladema Laporte, 1835, Hoperius Fall, 1927 and Neoscutopterus J. Balfour-Browne, 1943, and within this clade, it is sister to Meladema. Instars II and III of Bunites differ from other colymbetine genera by the presence of a basal suture on the urogomphi combined with the presence of posteroventral secondary setae on the protarsus. Some information on the habitat of the species is also provided.

Redescription and neotype designation of Suphis fluviatilis Guignot, 1948 (Coleoptera: Dytiscoidea: Noteridae) and notes on other species of the genus.

Suphis fluviatilis Guignot, 1948 was described based on a single female specimen, and according to the author, the type was deposited in the Museum National dHistoire Naturelle (Paris, France). However, the diagnostic features of the specimen deposited under this name and provided with the respective labels deviate considerably from those given by Guignot in his original description. It is shown that this specimen belongs to Suphis notaticollis Zimmermann, 1921, confirming previous observations by Luis Grosso in 1980. Thus, a neotype of S. fluviatilis is designated to avoid instability of the nomenclature by the impending synonymy of S. fluviatilis with S. notaticollis. Suphis fluviatilis is redescribed in detail, including illustrations of the main diagnostic characters. The species is compared with other Neotropical Suphis species, in particular with S. notaticollis. Additionally, the male genitalia of Suphis intermedius Rgimbart, 1903 are described for the first time, and a first record from Paraguay is given.

Morphology of the larvae of Rhantaticus congestus (Klug, 1833) and phylogenetic comparison with other known Aciliini (Coleoptera: Dytiscidae: Dytiscinae).

We describe the second- and third instar larvae of the diving beetle Rhantaticus congestus (Klug, 1833), including detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, terminal abdominal segment and urogomphi in order to discover useful characters for distinguishing Rhantaticus Sharp, 1882 larvae from those of other known Aciliini (Coleoptera: Dytiscidae: Dytiscinae). A parsimony analysis based on 94 larval characteristics of nine Aciliini species in five genera (Acilius Leach, 1817, Graphoderus Dejean, 1833, Rhantaticus, Sandracottus Sharp, 1882, Thermonectus Dejean, 1833) was conducted using the program TNT. Rhantaticus shares with all these genera several larval character states which support its inclusion in the Aciliini. Whereas Rhantaticus larva stands out from other known genera by several unique character states, our parsimony analysis did not recover any clear phylogenetic position of this genus within the Aciliini.

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.

An outlook on larval morphology of Copelatinae diving beetles with phylogenetic considerations (Coleoptera: Adephaga, Dytiscidae).

The larvae of 12 species of Copelatinae, Copelatus alternatus Sharp, 1882, C. caelatipennis princeps Young, 1963, C. glyphicus (Say, 1823), C. japonicus Sharp, 1884, C. masculinus Rgimbart, 1899, C. nakamurai Guorguiev, 1970, C. oblitus Sharp, 1882, C. parallelus Zimmermann, 1920, C. tenebrosus Rgimbart, 1880, Exocelina australiae (Clark, 1863), E. ferruginea (Sharp, 1882), and Liopterus haemorrhoidalis (Fabricius, 1787) are described or redescribed, including for the first time a detailed chaetotaxy analysis of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi. A provisional parsimony analysis based on larval characteristics of 13 copelatine species was conducted using the program TNT, which reinforces the monophyletic origin of the Copelatinae. Copelatinae larvae stand out from the remaining Dytiscidae based on several synapomorphies, including the unusual shorter length of the mesothoracic legs. Legs and urogomphi morphology suggest that Copelatinae larvae studied evolved a creeping way of life. The provisional phylogenetic analysis presented in this study provides some arguments for the validity of the taxonomic status of the genera Liopterus Dejean, 1833 and Exocelina Broun, 1886.

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.

Larval morphology of the Madagascan endemic diving beetle genus Hovahydrus Biström, 1982 (Coleoptera: Dytiscidae) and phylogenetic comparison with other known Hyphydrini.

We describe for the first time the instar III larva of the diving beetle genus Hovahydrus Biström, 1982, based on H. praetextus (Guignot, 1951) and a new species yet to be described (identified here as Hovahydrus sp. near H. minutissimus (Régimbart, 1903)). 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 Hovahydrus larvae from those of other known Hyphydrini (Coleoptera: Dytiscidae, Hydroporinae). A provisional parsimony analysis based on larval characteristics of 11 Hyphydrini species in eight genera was conducted using the program TNT. Larval morphology supports a close relationship between Hovahydrus, Hyphydrus Illiger, 1802, and the endemic South Africa genera Andex Sharp, 1882, Coelhydrus Sharp, 1882, Darwinhydrus Sharp, 1882 and Primospes Sharp, 1882.

Description of the second- and third-instar larvae of Hydrovatus crassulus Sharp, 1882 (Coleoptera: Dytiscidae: Hydrovatini).

The second- and third-instar larvae of the diving-beetle species Hydrovatus crassulus Sharp, 1882 are described and illustrated, including detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi. Larvae of this species lack the parietal pore PAo, the premental seta LA3 and the urogomphal seta UR8, and have the sensillum MN2 shaped as a short hair-like seta and the ventral surface of the abdominal segments IIV sclerotized. All these characteristics are shared with the other species of Hydrovatus Motschulsky, 1853 known in detail (H. caraibus Sharp, 1882) and therefore are considered diagnostic for the genus. Hydrovatus crassulus also characterizes by the presence of a small galea, which reinforces the hypothesis that this structure is part of the ancestral condition of Hydrovatus. Larvae of H. crassulus differ from those of H. caraibus in having a smaller size, a smaller ratio U/LAS, and a larger ratio U1/U2, and also in the presence (in most cases) of a secondary seta on the anteroventral surface of femur.

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.

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.

Burmese amber reveals a new stem lineage of whirligig beetle (Coleoptera: Gyrinidae) based on the larval stage.

Burmese amber is well known for preserving unique extinct lineages of insects. Here, we describe a new fossil beetle in its larval stage from Burmese amber. Bayesian and parsimony phylogenetic analysis of 50 morphological characters support this fossil as being sister to both the tribes Dineutini and Orectochilini, representing an extinct stem lineage in Gyrininae. It is described here as a new genus and species of whirligig beetle, Chimerogyrus gigagalea gen. & sp. nov., a taxon that preserves remarkable intermediate features between the whirligig beetle tribe Gyrinini and the crown Orectochilini and Dineutini. This new taxon preserves key features for studying the evolution of characters within the larval stage of the Gyrinidae and highlights the importance of Burmese amber for preserving both stem and crown lineages present during the mid-Cretaceous, before the end-Cretaceous mass extinction event.

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. The objectives of this study were (1) to describe and illustrate the immature stages of Gyrinus (Neogyrinus) rozei Ochs, 1953 including morphometric, chaetotaxic and bionomic information, and (2) to assess the usefulness of the gene COI to associate immatures and adults of Gyrinus. The studied specimens were collected in Roraima state, northern Brazil. The association of immature and adult stages was done either by rearing adults under laboratory conditions or by using DNA sequence data (COI). Eggs were described based on scanning electron microscopy; they are distinguished mainly by several features of chorion, micropyle and reticulation. Larvae of G. (N.) rozei can be distinguished from those of other Neotropical Gyrinidae by a combination of several characters, including the stipes with five robust hook-like additional setae on the dorsointernal margin, and the lacinia roughly hook-shaped. The pupa is similar to that of G. argentinus Steinhel, 1869, except for the number of setae on the body. The first record of the parasitoid wasp Melanosmicra sp. (Hymenoptera: Chalcididae) on a Gyrinus species is also provided.

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.

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.