At blacklight: Berosus sp.? - Berosus

Moved

… Matthew Pintar, 17 May, 2023 - 10:27am

Moved

… margarethe brummermann, 11 April, 2010 - 12:18pm

B. fraternus vs. B. infuscatus.

I have narrowed it down to these two based on:

1) lack of spines on elytral apices
2) last abdominal sternite with two small teeth in apical margin (see here for a good example).
3) mesosternal protuberance low, not crest-like or falcate.
4) pronotum testaceous with dark central markings.

Separating Bf and Bi is best done as follows:

Bf: elytra and pronotum of male and elytra of female without evidence of microreticulation, appearing shiny and more deeply-impressed elytral striae
Bi: elytra and pronotum of female and pronotum of male with microreticulation and not shining; less-impressed elytral striae.

I am leaning towards B. fraternus, although with the glare it's hard to tell if the specimen is shining or just the light reflection.

By the way, I had the wrong author. It was by van Tassell, not Vaurie, and the complete citation is: van Tassell, E. R. 1963. A new Berosus from Arizona, with a key to the Arizona species (Coleoptera: Hydrophilidae). Coleopterists Bulletin. 17(1): 1-5.

… Blaine Mathison, 10 April, 2010 - 6:08pm

Thank you so much

for the detailed info. I will check for shininess. To the naked eye they are shiny all over

… margarethe brummermann, 10 April, 2010 - 8:14pm

if you can narrow it down...

both candidates are new species for BugGuide, so we win, either way! :)

… Blaine Mathison, 10 April, 2010 - 8:28pm

Shiny.

I've checked three more specimens. Small punctures are there, though. would be nice to compare both spp.
Abdominal teeth are definitely present.

… margarethe brummermann, 11 April, 2010 - 12:12pm

Berosus yes

But would need shots of the underside, especially of the mesothorax and last abdmominal sternites for a species-level ID. Vaurie made a key to the AZ Berosus spp. I dont remember the exact citation, but it was in Coleopterists Bulletin, in the 60's or 70's. I have the key at home.

… Blaine Mathison, 9 April, 2010 - 12:24pm

I'll get some

shots of the underside

… margarethe brummermann, 9 April, 2010 - 12:58pm

when you do...

please try and get as close as you can with regards to the terminal abdominal sternites. The presence (or absence) of a pair of tiny teeth is an important diagnostic feature.

… Blaine Mathison, 9 April, 2010 - 1:52pm

This is as close asI can get it

I think I see two teeth

… margarethe brummermann, 9 April, 2010 - 10:41pm