Chasmogenus

Chasmogenus is a Neotropical genus of water scavenger beetles belonging to the family Hydrophilidae.^[1]

Chasmogenus
Dorsal view of Chasmogenus lineatus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Suborder:	Polyphaga
Infraorder:	Staphyliniformia
Family:	Hydrophilidae
Subfamily:	Acidocerinae
Genus:	Chasmogenus Sharp, 1882
Type species
Chasmogenus fragilis Sharp, 1882
Diversity
36 species described to 2021
Synonyms
Dieroxenus Spangler, 1979

Taxonomy

The genus Chasmogenus was described for the first time by David Sharp in 1882 for species from Guatemala and Panama.^[2]

Since 1919 the genus Crephelochares (from the Old World) was considered a synonym of Chasmogenus,^[3] but thanks to the results of a phylogenetic analysis involving molecular data,^[4] both taxa are now considered distinct genera on their own right.^[1]

Currently, a total of 36 species is identified and documented, most of them recorded from the Guiana Shield Region.

Description

Small size (2.5–5.0 mm), bearing a clearly visible sutural stria; long maxillary palps; metafemora usually densely covered by hydrofuge pubescence. The external morphology in Chasmogenus is very uniform across species, so that most species can only be identified by the shape of the male genitalia.

By the presence of the sutural stria, in the Neotropical region, Chasmogenus can only be confused with some members of the genus Primocerus.^[1]

Habitat

According to Girón and Short:^[1]

The vast majority of Chasmogenus are known from forested habitats, including the margins of streams and forest pools. A few species are known from open marsh habitats (e.g., Chasmogenus australis García and Chasmogenus sapucay Fernández). They can be found among the vegetation and submerged leaf litter. They are also attracted to lights, though usually not in large numbers. Only one species [Chasmogenus cremobates (Spangler)] has been collected in seepages.

— Girón and Short, The Acidocerinae (Coleoptera, Hydrophilidae): taxonomy, classification, and catalog of species

Species

1. Chasmogenus acuminatus Smith and Short, 2020 ^[5]
2. Chasmogenus amplius Smith and Short, 2020 ^[5]
3. Chasmogenus australis García, 2000 ^[6]
4. Chasmogenus bariorum García, 2000 ^[6]
5. Chasmogenus barrae Short, 2005 ^[7]
6. Chasmogenus berbicensis Smith and Short, 2020 ^[5]
7. Chasmogenus brownsbergensis Smith and Short, 2020 ^[5]
8. Chasmogenus cajuina Alves, Clarkson and Lima, 2020 ^[8]
9. Chasmogenus castaneus Smith and Short, 2020 ^[5]
10. Chasmogenus clavijoi Smith and Short, 2020 ^[5]
11. Chasmogenus clinatus Glynn and Short, 2021 ^[9]
12. Chasmogenus cremnobates (Spangler, 1979) ^[10]
13. Chasmogenus cuspifer Smith and Short, 2020 ^[5]
14. Chasmogenus flavomarginatus Smith and Short, 2020 ^[5]
15. Chasmogenus fluminensis Clarkson and Ferreira-Jr, 2014 ^[8]
16. Chasmogenus fragilis Sharp, 1882 ^[2]
17. Chasmogenus gato Smith and Short, 2020 ^[5]
18. Chasmogenus gironae Glynn and Short, 2021 ^[9]
19. Chasmogenus guianensis Smith and Short, 2020 ^[5]
20. Chasmogenus ignotus Smith and Short, 2020 ^[5]
21. Chasmogenus inpa Glynn and Short, 2021 ^[9]
22. Chasmogenus itatiaia Clarkson and Ferreira-Jr, 2014 ^[8]
23. Chasmogenus ligulatus Smith and Short, 2020 ^[5]
24. Chasmogenus lilianae Clarkson and Ferreira-Jr, 2014 ^[8]
25. Chasmogenus lineatus Smith and Short, 2020 ^[5]
26. Chasmogenus lorenzo Short, 2005 ^[7]
27. Chasmogenus pandus Smith and Short, 2020 ^[5]
28. Chasmogenus rufinasus (Knisch, 1924) ^[11]
29. Chasmogenus ruidus Short, 2005 ^[7]
30. Chasmogenus sapucay Fernández, 1986 ^[12]
31. Chasmogenus schmits Smith and Short, 2020 ^[5]
32. Chasmogenus schoedli Short, 2005 ^[7]
33. Chasmogenus sinnamarensis Smith and Short, 2020 ^[5]
34. Chasmogenus tafelbergensis Smith and Short, 2020 ^[5]
35. Chasmogenus ubatuba Clarkson and Ferreira-Jr, 2014 ^[8]
36. Chasmogenus undulatus Smith and Short, 2020 ^[5]