Eastern Colombian Páramo Liodessus Guignot, 1939 diving beetles are genetically structured, but show signs of hybridization, with description of new species and subspecies (Coleoptera, Dytiscidae).

We studied Liodessus diving beetles from six eastern Colombian Páramo areas, as well as from the Altiplano. We discovered a highly characteristic new species, based on male genital morphology, Liodessussantarositasp. nov., in the Páramo de Guantiva-Rusia. Specimens from the Altiplano around Bogotá, and the Páramos of Almorzadero, Chingaza, Matarredonda, Rabanal y Rio Bogotá and Sumapaz form one clade of genetically similar populations based on mitochondrial Cox1 sequence data. The individuals of this clade are sub-structured according to their geographic distribution. The populations differ from each other mainly in terms of body size and coloration and, at most, subtly in their genital morphology. In two cases, we find putative hybrid populations between Altiplano and Páramo areas. We suggest that the different Páramo populations are in an early phase of speciation, and perhaps already genetically isolated in some cases. They are here assigned subspecies status to highlight these ongoing processes pending more comprehensive geographic sampling and use of genomic data. We refer to this clade as the Liodessusbogotensis complex, containing Liodessusb.bogotensis Guignot, 1953; Liodessusb.almorzaderossp. nov.; Liodessusb.chingazassp. nov.; Liodessusb.lacunaviridis Balke et al., 2021, stat. nov.; Liodessusb.matarredondassp. nov., and Liodessusb.sumapazssp. nov.

A new Colombian species of Liodessus diving beetles from the Páramo de Sumapaz (Coleoptera, Dytiscidae, Bidessini).

Liodessuspicinus sp. nov. is described from the Páramo de Sumapaz near Bogota D.C. at 3,500 m above sea level. The species can be distinguished from the other Colombian Liodessus species by its dark coloration, discontinuous habitus, shiny surface of the pronotum and elytron, presence of a distinct occipital line, distinct basal pronotal striae, short or even faint basal elytral striae, as well as by its distinct geographic distribution and cox1 signature.

New Liodessus species from the high Andes of Peru (Coleoptera: Dytiscidae, Bidessini).

We describe four new species of the diving beetle genus Liodessus Guignot from the high Andean regions of Peru: Liodessus alpinus sp. nov. from Junín, L. hauthi sp. nov. from Huánuco and Churubamba, L. rhigos sp. nov. from Junín, and L. thespesios sp. nov. from Cusco. We delineate the species using morphological structures and provide a 5' mitochondrial cytochrome c oxidase 1 database on the Barcode of Life Data System (BOLD). We also provide taxonomic notes on Liodessus acollensis Guignot, 1955 and L. andinus Guignot, 1957, described from the high Andes of Peru and Bolivia. These species occur at higher altitudes above 3,400 m and up to 4,900 m, and were collected in shallow, exposed peatland pools and puddles, mostly in steppes and high Andean Puna. The known distribution and habitat preferences of each species are outlined briefly.

Hydaticus (Prodaticus) hauthi sp. nov., a new diving beetle from the cloud forest in the Cordillera El Sira, Peru (Coleoptera: Dytiscidae).

A new species of the genus Hydaticus Leach, 1817, subgenus Prodaticus Sharp, 1882 (Coleoptera: Dytiscidae) has been discovered in the mountains of Cerros del Sira, Peru. It is here described as Hydaticus (Prodaticus) hauthi sp. nov.. It is morphologically similar to the Peruvian H. panguana Megna, Balke, Apenborn Hendrich, 2019. The new species differs from H. panguana by its almost complete black dorsal surface and the shape of the median lobe. Diagnostic characters of both species, including illustrations of male genitalia and habitus, are presented, and a modified key for the 12 Neotropical species is provided.

The return of the Duke-locality data for Megadytes ducalis Sharp, 1882, br />the world's largest diving beetle, with notes on related species (Coleoptera: Dytiscidae).

Megadytes (Bifurcitus) ducalis Sharp, 1882 is the largest diving beetle in the world and has been considered a candidate for the world's rarest insect (Jones 2010). It was described from "Brazil", is only known from the male holotype in the Natural History Museum (London), and typically thought to be extinct. Here we report the finding of 10 additional specimens, all collected at the end of the 19th century, which were discovered incidentally in different historical collections, including drawers with unsorted diving beetle accessions of the Muséum National d'Histoire Naturelle (Paris). These specimens, whilst old, reveal exact locality data for the first time, enabling focused field campaigns to attempt to rediscover this giant alive. Locality labels all indicate Santo Antônio da Barra (present name Condeúba), in the southern part of Bahia, Brazil, suggesting that the species may have a restricted distribution in wetter parts of the Brazilian savanna or cerrado. We also describe the female of M. ducalis for the first time and present new records of the putatively closely related species Megadytes magnus Trémouilles Bachmann, 1980 and M. lherminieri (Guérin-Méneville, 1829), the latter being recorded for the first time from Ecuador. These three morphologically similar species together form the subgenus Bifurcitus Brinck, 1945 and we provide photographs of their habitus, median lobes and other morphological details.

A review of Peruvian diving beetles of the genus Hydaticus Leach, 1817, with description of Hydaticus (Prodaticus) panguana sp. nov. and notes on other Neotropical species (Coleoptera: Dytiscidae).

We review the Peruvian Hydaticus Leach, 1817 (Coleoptera: Dytiscidae) and describe Hydaticus panguana sp. nov. from Huánuco Department. In the context of this work, we also provide new country records for several species: Hydaticus lateralis Laporte, 1835 (for Peru, Guyana, Venezuela, Suriname); H. xanthomelas (Brullé, 1837) (for Peru); H. subfasciatus Laporte, 1835 (for Colombia); H. fractivittis Guignot, 1951 (for Paraguay). Hydaticus riehli Wehncke, 1876 and H. verecundus Clark, 1864, described from "Cuba" and "South America", respectively, were probably mislabelled specimens, and do not belong to the Neotropical fauna. Diagnostic characters, including illustrations of male genitalia and habitus, are presented for seven of the 11 Neotropical species, and a modified key is provided. Altogether four species of Hydaticus are now known from Peru.

Tepuidessus grulai sp. nov. from Acopán Tepui in Venezuela (Coleoptera: Dytiscidae: Hydroporinae: Bidessini).

We report the discovery of the second Bidessini diving beetle species from a Venezuelan table-top mountain (also referred to as "tepui"). Tepuidessus grulai sp. nov. from Acopán Tepui can easily be separated from Tepuidessus breweri Spangler, 1981, described from Roraima Tepui, about 140 km apart from Acopán Tepui, by its much broader habitus with distinct outline discontinuity between pronotum and elytra, well developed, long and deep basal striae on pronotum and elytra and by the unbordered apical abdominal ventrite.

A new species of Agaporomorphus Zimmermann, 1921 from Peru (Coleoptera, Dytiscidae, Copelatinae).

Agaporomorphusjulianeae sp. n. is described from the Biological Field Station Panguana, in Huànuco province of central Peru. The new species belongs to the Agaporomorphusknischi-group sensu Miller 2005. Together with Agaporomorphusknischi Zimmermann, 1921 and Agaporomorphuscolberti Miller & Wheeler, 2008 this is the third species of the genus with broadly enlarged male antennomeres. The new species can be separated from Agaporomorphuscolberti and Agaporomorphusknischi by the smaller please expanded male antennomere VIII, and the form of the median lobe. Important species characters (median lobe, male antennae, metafemur, colour pattern) of the new species and Agaporomorphusknischi are figured, and the habitat, a temporary blackwater forest pond, and its species rich water beetle coenosis are illustrated and described in detail. The Brazilian Agaporomorphusmecolobus Miller, 2001, only known from the type material from Sao Paulo, is here recorded for Minas Gerais. Habitus photos of four additional Agaporomorphus species and Hydrodytesopalinus (Zimmermann, 1921) are provided. Altogether ten species of Agaporomorphus are now known.

Ancient associations of aquatic beetles and tank bromeliads in the Neotropical forest canopy

Water reservoirs formed by the leaf axils of bromeliads are a highly derived system for nutrient and water capture that also house a diverse fauna of invertebrate specialists. Here we investigate the origin and specificity of bromeliad-associated insects using Copelatinae diving beetles (Dytiscidae). This group is widely distributed in small water bodies throughout tropical forests, but a subset of species encountered in bromeliad tanks is strictly specialized to this habitat. An extensive molecular phylogenetic analysis of Neotropical Copelatinae places these bromeliadicolous species in at least three clades nested within other Copelatus. One lineage is morphologically distinct, and its origin was estimated to reach back to 12-23 million years ago, comparable to the age of the tank habitat itself. Species of this clade in the Atlantic rainforest of southern Brazil and mountain ranges of northern Venezuela and Trinidad show marked phylogeographical structure with up to 8% mtDNA divergence, possibly indicating allopatric speciation. The other two invasions of bromeliad water tanks are more recent, and haplotype distributions within species are best explained by recent expansion into newly formed habitat. Hence, bromeliad tanks create a second stratum of aquatic freshwater habitat independent of that on the ground but affected by parallel processes of species and population diversification at various temporal scales, possibly reflecting the paleoclimatic history of neotropical forests.