Wednesday, January 6, 2021

[Herpetology • 2021] Amazops amazops • A New Genus and Species of Rhinatrematid Caecilian (Gymnophiona: Rhinatrematidae) from Ecuador


Amazops amazops 
Wilkinson, Reynolds & Jacobs, 2021


Abstract
 A new genus and species of rhinatrematid caecilian, Amazops amazops gen. et sp. nov., is described based on a single specimen from Orellana, Ecuador collected in 1990. Among other features the new taxon differs from all other rhinatrematid caecilians in having less than four annular grooves interrupted in the region of the vent and in the squamosal contributing to the bony margin of the orbit. A consideration of its distinctive morphology suggests that it is plausible that the new taxon is the sister taxon of all other rhinatrematid caecilians. That the genus is known from a single specimen, and that this is the first new rhinatrematid species from the Andes described for more than 50 years, highlights the poor sampling (collecting) of rhinatrematid caecilians and limited knowledge of their diversity.

Keywords: Andes, biodiversity, computed tomography, morphology, South America, systematics, taxonomy

USNM 320729, holotype of Amazops amazops sp. nov. with head end (top), whole body (middle) and tail end (bottom). 
Scale bar gradations in mm. 
Photo by Harry Taylor (Natural History Museum, London).

CT scan of skull USNM 320729, holotype of Amazops amazops sp. nov.

The holotype of Amazops amazops sp. nov. in life [USNM 320729]. 
Photo by William W. Lamar.

Amazops gen. nov. 

Diagnosis. Rhinatrematid caecilians with the squamosal contributing to the margin of the orbit. 

Content: A single species Amazops amazops, sp. nov., the type by monotypy and by designation. 

Etymology: The name is a portmanteau word combining reference to the Amazonian provenance of the type and only known species and the distinctive topological relationships of its eye and orbit, particularly the contribution of the squamosal to the bony margin of the orbit, which is unknown in any other rhinatrematid. As mandated by the code, gender is masculine. 

Remarks: Three other features of the only known specimen of this genus are distinctive, known in no other rhinatrematids and might be diagnostic for the genus: lack of contact between the quadrate and maxillopalatine, contact between the squamosal and frontal and the small number of annular grooves that are interrupted by the vent. 

  
Amazops amazops sp. nov.
 
Etymology. As for the genus. For nomenclatural purposes the specific epithet is considered to be a genderless noun in apposition.

Remarks. That the species is known from a single specimen is sufficient reason to suggest that the IUCN conservation status of the species should be data deficient. Effort is needed to identify populations of this distinctive lineage as a precursor to any meaningful study of its natural history. Based on it being a rhinatrematid it is assumed that it will share the reproductive mode of the other rhinatrematids, as far as is known, in being oviparous with an aquatic larval stage (San Mauro et al., 2014, Müller, 2020) and thus being dependent on water bodies for its reproduction. 

 Map showing type locality (black star) of Amazops amazops sp. nov.


 Mark Wilkinson, Robert P. Reynolds and Jeremy F. Jacobs. 2021. A New Genus and Species of Rhinatrematid Caecilian (Amphibia: Gymnophiona: Rhinatrematidae) from Ecuador. Herpetological Journal. (31); 27-34. DOI: 10.33256/hj31.1.2734