Yellow beetle with black markings, Montezuma, Colombia

Found on our outside table, attracted to light. Quite large, but not as large as a rhinoceros beetle.

comments (5)

Pudding4brains

Lion

Hi Ferdy, it's an Ancognatha. There are 22 species in the genus, with some fairly newly described ones. Most recent data I could find would place 10 species in Colombia:
Ancognatha atacazo Kirsch, 1885
Ancognatha castanea Erichson, 1847
Ancognatha horrida Endrödi, 1967
Ancognatha humeralis Burmeister, 1847
Ancognatha lutea Erichson, 1847
Ancognatha matilei Dechambre, 2000
Ancognatha scarabaeoides Erichson, 1847
Ancognatha ustulata Burmeister, 1847
Ancognatha veliae Pardo-Locarno et al., 2006
Ancognatha vulgaris Arrow, 1911.

There is a nice page with images of many species here:
http://unmondeencouleurs.piwigo.com/index?/category/5246-ancognatha_erichson_1847
If you click through to the various species pages you'll see that these can be quite variable in their markings and there are some that in their variability could probably resemble your beetle, but except for vulgaris and humeralis these are not in the list of known species from Colombia (yet?).
The page at piwigo is missing images for two species from the Colombian list : matilei and veliae - both recently described as new species. These should be similar to each other and both should only have a small humeral spot and no other markings, according to the key fragment on this page:
http://treatment.plazi.org/id/03B387D0525CFFFF2A37FD80FA8BCD7D
Here is one of the two:
https://zenodo.org/record/172035#.WjsuG62Eq00
I'd say we can rule those out.
That leaves us with only humeralis and vulgaris as a (very) good fit _and_ previously recorded from Colombia.
In the original description of vexans from Panama that species is set off against the similar looking humeralis and vulgaris and here it is mentioned that females of humeralis are lacking the conspicuously widened elytral margin about half way down the side.:
http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1078&context=entomologypapers
Your beetle has this (and hence is a female), so it could be vulgaris or vexans, but vexans is not (yet) recorded from Colombia.
So as long as I'm not missing any new country records or new descriptions it would seem that it may be fair to assume it must be the very common Ancognatha vulgaris ... Posted 7 years ago, modified 7 years ago
1. Pudding4brains
  
  Lion
  
  Hmmmpffff ... the image of a female humeralis linked below _does_ have the expanded elytral margins, so either that image is misidentified or the analysis by Ratcliffe was off.
  http://unmondeencouleurs.piwigo.com/_datas/l/y/k/lyk4d12exs/i/uploads/l/y/k/lyk4d12exs//2014/07/14/20140714213752-614b4561-la.jpg
  
  P.S. This more recent article by Ratcliffe keys out female humeralis/vulgaris much the same:
  https://www.researchgate.net/publication/299355779_A_New_Species_of_Ancognatha_Erichson_Coleoptera_Scarabaeidae_Dynastinae_Cyclocephalini_from_Peru_with_Distributions_of_Peruvian_Ancognatha_Species
  
  But meantime I've found another image of a female "humeralis" that _does_ show the "Female epipleuron strongly thick-
  ened into elongate knob." also on the supposed humeralis:
  http://projects.biodiversity.be/openup/rbins/3125.jpg
  Interesting discrepancy ... but to be solved some other day ... Posted 7 years ago, modified 7 years ago
2. Ferdy Christant
  
  Lion
  
  Wow Arp, wasn't expecting this to get identified. Wonderful surprise and impressive research, thanks! Posted 7 years ago
3. 1. Pudding4brains
    
    Lion
    
    I had written an email to professor Ratcliffe about the discrepancy and he kindly (and quickly) responded, He states about your image:
    "Considering that the specimen does have the knob (flange), it could be A. vulgaris, a common species in Colombia".
    Cheers, Arp Posted 7 years ago, modified 7 years ago
  2. 1. Ferdy Christant
      
      Lion
      
      Well that just settles it then. Thanks Arp and professor! Posted 7 years ago

The Ancognatha vulgaris

Ancognatha vulgaris is a relatively small Scarab Beetle (Scarabaeidae) from the New World. Taxonomy of Scarabs is in constant flux, or under discussion if you will, but many workers will classify Ancognatha under the Dynastinae.

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Similar species: Beetles

Species identified by Pudding4brains