Unidentified snake, Quintana Roo, Mexico

Punta Laguna, Quintana Roo, Mexico. May 12, 2017.

comments (6)

Ferdy Christant

Lion

I've asked John Sullivan to look at this one. Posted 7 years ago
1. Thibaud Aronson
  
  Lion
  
  Thanks! On Inaturalist I saw very similar photo,s taken in the same area, that were identified as Mastigodryas melanolomus, which was common in the reserve. But this one looks very different from the standard morph, which I saw a lot, so I would appreciate an expert's input. Posted 7 years ago

John Sullivan

Lion

That's definitely an interesting one. I can imagine it being Mastigodryas melanolomus. It has the looks of a diurnal racer-type snake (very big eyes, general proportions). I've never seen pictures of M. melanolomus that are such a bright red/orange though. Thibaud, were the similar photos you saw on iNaturalist this same color? I failed to find them in a quick search.

A species found in this area that's a good color match is Stenorrhina freminvillei. However, they are not particularly fast (and thus not so long and thin), and have proportionally much smaller eyes.

No other clear candidates popped out at me from riffling through Snakes of Mexico. I'm currently inclined to think it's an unusually colored M. melanolomus, but I am by no means confident. Posted 7 years ago
1. Thibaud Aronson
  
  Lion
  
  Thanks for the input John! I'd also considered S. freminvillei but I agree that beyond the color it's not a good match.
  Here are the photos I was referring to on Inaturalist:
  https://www.inaturalist.org/observations/6456124
  https://www.inaturalist.org/observations/2884320
  
  These look pretty small, as was mine. Could it be this color morph is restricted to young individuals of M. melanolomus? Posted 7 years ago
2. 1. John Sullivan
    
    Lion
    
    Juvenile Masticophis melanolomus typically look quite different from adults. However, normally adults are of uniform color and juveniles have some sort of banded pattern. So if this is a juvenile-only color pattern, it is a particularly unusual one. Also, the M. melanolomus on the Yucatán Peninsula typically have thin dark edges on their dorsal scales (origin of the name "melanolomus"), which are not present here.
    
    I see that the first iNaturalist specimen that you linked was identified by some people as Masticophis/Coluber mentovarius. If that were correct, the individual would definitely be a juvenile, because adults of that species are much more obviously robust. Juveniles of that species are of uniform color, but typically have a thin light dorsolateral line on the front of the body, which is not present in any of the snakes we're discussing here. Also, I have found no mention of that species being such a bright orange color either.
    
    Julian Lee's Amphibians and Reptiles of the Yucatán Peninsula mentions a third species that is similar to those two, but significantly smaller: Symphimus mayae. It looks like a decent match for yours in general body and head shape, but I also haven't found any mention of it being this color. Also, the eyes on yours look a little larger than the eyes of S. mayae to me, but I could be wrong. Also, it is supposed to always have indistinct dark vertebral and lateral lines, and I see no sign of those here.
    
    Still mysterious! Posted 7 years ago
  2. 1. Thibaud Aronson
      
      Lion
      
      Well I certainly appreciate your looking into this, John! In a way I am also glad that this is a head-scratcher. Even in places so well-trodden by naturalists as Yucatan, there are still mysteries to be found!
      As I'm not competent to decide in favor of one species or another, I'll leave it as unidentified. Posted 7 years ago

No species identified

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By Thibaud Aronson

Uploaded Nov 22, 2017. Captured May 12, 2017 14:55 in Quintana Roo Nuevo Durango - Coba, Quintana Roo, Mexico.

Explore Mexico 1,017 653 0

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