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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.

Information on even the most basic biological aspects is often missing for many species and even higher taxa of caecilians. As in other amphibians, development is plesiomorphically biphasic and aquatic larvae are present in Rhinatrematidae, Ichthyophiidae, and some Indotyphlidae. However, only very little information on larval morphology and ecology is available. Here I describe a series of Epicrionops bicolor larvae and metamorphs from Peru and provide details on the development of the annulation pattern, colouration, external gills, lateral line system, and other morphological characters and discuss the taxonomic value of lateral line characters. Specimens were collected at two different times of the year, allowing inferences of a few key demographic characteristics. Hatching probably occurs around August and September at a size of approximately 55 to 65 mm. Larval development takes about 1 year to complete and metamorphosis occurs at around 180–190 mm total length.

Amazops gen. nov. {urn:lsid:zoobank.org:act:D9F1C39D-4B47-46CF-AB9D-51896D4C619C} 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., Published as part of Wilkinson, Mark, Reynolds, Robert P. & Jacobs, Jeremy F., 2021, A new genus and species of rhinatrematid caecilian (Amphibia: Gymnophiona: Rhinatrematidae) from Ecuador, pp. 27-34 in Herpetological Journal 31 (1) on page 28, DOI: 10.33256/31.1.2734, http://zenodo.org/record/5838883

Caecilians (order Gymnophiona) are elongate, limbless, snake-like amphibians that are the sister-group (closest relatives) of all other recent amphibians (frogs and salamanders). Little is known of their cardiovascular anatomy and physiology, but one nearly century old study suggests that Hypogeophis (family Indotyphlidae), commonly relied upon as a representative caecilian species, has atrial septation in the frontal plane and more than one septum. In contrast, in other vertebrates there generally is one atrial septum in the sagittal plane. We studied the adult heart of Idiocranium (also Indotyphlidae) using immunohistochemistry and confirm that the interatrial septum is close to the frontal plane. Additionally, a parallel right atrial septum divides three-fourths of the right atrial cavity of this species. Idiocranium embryos in the Hill collection reveal that atrial septation initiates in the sagittal plane as in other tetrapods. Late developmental stages, however, see a left-ward shift of visceral organs and a concordant rotation of the atria that reorients the atrial septa towards the frontal plane. The gross anatomies of species from six other caecilian families reveal that (i) the right atrial septum developed early in caecilian evolution (only absent in Rhinatrematidae) and that (ii) rotation of the atria evolved later and its degree varies between families. In most vertebrates a prominent atrial trabeculation associates with the sinuatrial valve, the so-called septum spurium, and the right atrial septum seems homologous to this trabeculation but much more developed. The right atrial septum does not appear to be a consequence of body elongation because it is absent in some caecilians and in snakes. The interatrial septum of caecilians shares multiple characters with the atrial septum of lungfishes, salamanders and the embryonic septum primum of amniotes. In conclusion, atrial septation in caecilians is based on evolutionarily conserved structures but possibly exhibits greater variation than in any other vertebrate order.

Epicrionops parkeri (Dunn, 1942): Figure 7C Rhinatrema parkeri Dunn 1942: 458. Epicrionops parkeri — Taylor 1968: 216. Material examined. Table 1. A bicolored caecilian with well-developed tail; lateral stripe yellow, cream or white from head or second collar onto tail; stripe ending at posterior level of vent; subcaudal region dark lilac to blackish (Taylor 1968). Epicrionops parkeri differs from E. bicolor (a species with similar coloration pattern distributed in Colombia) by having a larger body length and 198 primary annuli (in contrast to 117–135 primary annuli in E. bicolor)., Published as part of Restrepo, Adriana, Molina-Zuluaga, Claudia, Hurtado, Juan P., Marín, Carlos M. & Daza, Juan M., 2017, Amphibians and reptiles from two localities in the northern Andes of Colombia, pp. 203-237 in Check List 13 (4) on page 217, DOI: 10.15560/13.4.203, {"references":["Dunn ER (1942) The American caecilians. Bulletin of the Museum of Comparative Zoology, Harvard University 91: 439 - 540.","Taylor EH (1968) The Caecilians of the World: A Taxonomic Review. University of Kansas Press, Lawrence, 848 pp."]}