A take on Quadriops

If there is one thing clear to me now regarding Neotropical acidocerines is that, for the most part, genera are fairly easy to recognize by their external morphology, but when it comes to species the challenge can get a lot harder.

Here I am, starting a new revision (a third one, with the previous ones in standby for different reasons) this time Quadriops, which is an exclusively Neotropical genus described in 1999 by Hansen. It has six described species:

Quadriops amazonensis García, 2000: 59 (Venezuela: Amazonas)

Quadriops dentatus Hansen, 1999: 134 (Venezuela: Bolívar)

Quadriops depressus Hansen, 1999: 136 (Perú: Loreto; Ecuador: Napo)

Quadriops politus Hansen, 1999: 135 (Perú: Loreto)

Quadriops reticulatus Hansen, 1999: 135 (Costa Rica: Puntarenas; Panama: Chiriquí)

Quadriops similaris Hansen, 1999: 136 (British Guiana: Ikuribisi; Venezuela: Bolívar)

Hansen offers a key to his species (translated to Spanish by García 2000). There is one species (Q. dentatus) in which the elytral punctures are not aligned in striae, all the others have aligned punctures (see image below).

The characters used by Hansen to separate the species with aligned punctures are mostly related to the presence or absence of shallow reticulation of the frons, clypeus and pronotum.

For me at this point, with the specimens I have seen, I would dare to say that all of the species with aligned punctures might be only one widespread species, given that:

- The species described so far are based on only a few specimens (usually one or two; seven at most)

- The males are known for four of the species and the differences on the illustrations for three of them are only slight.

Of course more observations are needed, also because I think differences on the shallow reticulations could be attributed to development for example, and not necessarily reflect interspecific differences.

References

• García, M. (2000). Una nueva especie de Quadriops Hansen, 1999 (Coleoptera: Hydrophilidae: Hydrophilinae) de Venezuela. Boletín del Centro de Investigaciones Biológicas, 34(1).

• Hansen, M. (1999). Fifteen new genera of Hydrophilidae (Coleoptera), with remarks on the generic classification of the family. Insect Systematics & Evolution, 30(2), 121-172.