Description
Caecilia occidentalis is a poorly-known caecilian with a total length range of 547 - 1035 mm (Taylor 1969, Fernández-Roldán and Lynch 2022). The head is equal to or wider than the body and is tapered with the snout extending about 2.0 to 2.3 mm beyond the mouth (Taylor 1969, Lynch 2009). The narial plugs within the mouth are elevated (Taylor 1969). Caecilians also have paired sensory tentacles located anterior and lateral to the snout and close to the nostril than the eye (Taylor 1969, Lynch 2009). There are 8 - 13 premaxillary-maxillary teeth, 9 - 12 prevomeropalatine teeth, 11 - 12 dentary teeth, and 3 - 5 splenial teeth (Taylor 1969). There are two collars, but they may not be clearly separated on the dorsal surface and the second may be fused with the first dorsal fold. There are 186 - 221 primary grooves, of which 4 - 20 are complete, and 0 - 12 secondary grooves (Taylor 1969, Fernández-Roldán and Lynch 2022). The transverse dorsal grooves are either only slightly visible or completely absent. Scales can be found in the grooves of over two thirds of the body. These subdermal scales are incredibly small and only reach 0.2 mm in diameter at most (Taylor 1696).

DIAGNOSIS:

Caecilians can be diagnosed via the following characteristics: location of the tentacle relative to the nostrils and eyes, presence of primary, secondary, and tertiary grooves, shape of the cloaca, the presence of a tail, and coloration (Lynch 2009). Caecilians in the Caeciliidae family lack true tails, have grooves, rounded ends to their bodies (Wilkinson and Nussbaum 2006), imperforate stapes, inner mandibular teeth, eyes that are surrounded or covered by the maxillopalatine, and only monocusped teeth (Wilkinson et al. 2011). Caecilia occidentalis resembles Caecilia subterminalis; however, C. occidentalis has more primary grooves than C. subterminalis (Lynch 2009). Caecilia occidentalis can be differentiated from C. goweri as the latter has more secondary grooves that may fully encircle the body (Fernández-Roldán and Lynch 2022).

COLORATION:

In life, C. occidentalis appears black or blue (Lynch 2009, Fernández-Roldán and Lynch 2022). In preservative, C. occidentalis also has a cream or yellow colored lateral stripe that is best defined anteriorly and posteriorly and becomes reduced to a broken line or completely absent in the middle (Taylor 1969). Preserved specimens have also been recorded to have cream or yellow spots located on the head (Taylor 1969).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Colombia

View distribution map in BerkeleyMapper.

Caecilia occidentalis is found in Colombia (IUNC 2019), specifically, it occurs in the Cordillera Central in Antioquina Department, Cordillera Occidental, in Purace, Cauca Department, and in an isolated record in the southwestern Cali in Valle del Cauca Department (Acostas-Galvis 2000, Ramirez-Chaves et al. 2010). Its elevational range is 1,500 - 2,200 meters above sea level. The estimated extent of occurrence is 24,229 km². Caecilia occidentalis is a terrestrial species that can be found under the ground of cloud forests and lower montane forests (IUNC 2019). However, it has also been recorded within the city limits of Popayán, which suggests it may be able to endure disturbances to its habitat (Ramirez-Chaves et al. 2010).

Life History, Abundance, Activity, and Special Behaviors
Caecilia occidentalis is fossorial, and rarely observed or encountered, making them difficult to sample. Additionally, there is no widely known sampling technique used for caecilians (Gower and Wilkinson 2005). As a result, information on the population status of C. occidentalis is lacking (IUNC 2019).

The growth of C. occidentalis predominantly involves increasing the length of the body while the head and body width only increases little in proportion to the degree of the body lengthening (Taylor 1969).

It is believed that C. occidentalis is oviparous (Wake and Case 1975).

Trends and Threats
Caeceilia occidentalis was assessed for the IUCN Red List of Threatened Species in 2019 and identified as “Near Threatened” according to criteria B1ab(iii) - the species is believed to occur in about 10 forest habitat locations in Colombia that have been threat-defined. These habitats continue to decline in availability and quality due to deforestation. The species is threatened by commercial and residential development - specifically in the development of housing and urban areas, aquaculture and agriculture - specifically the growing of annual and perennial non-timber crops, and small-holder farming. Some populations have been recorded in the Parque Nacional Naturales Farallones de Cali, which is protected (IUNC 2019).

Relation to Humans
As of 2022, there are no known records of Caecilia occidentalis being used by humans or being traded (IUCN 2019).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Urbanization

Comments

PHYLOGENETIC RELATIONSHIPS:

Caecilian taxonomy is unstable due to small sample sizes; some species only have one specimen. Consequently, attempts to understand caecilian taxonomy rely on a handful of morphological characters and there is an incomplete understanding of variation (Gower and Wilkinson 2005).

As of 2011, the family Caeciliidae is compose of the genera, Caecilia, and Oscaecilia, with the next more closely related family being Typhlonectidae (Wilkinson et al. 2011)

References
Acosta-Galvis, A.R. (2000). Ranas, Salamandras y Caecilias (Tetrapoda: Amphibia) de Colombia. Biota Colombiana, 1(3), 289-319. [link]

Fernández-Roldán, J.D., and Lynch, J.D. (2022). On the geographic distribution of the caecilians Caecilia goweri and Caecilia occidentalis. Herpetological Bulletin, 162, 30-31. [link]

Gower, D.J. and Wilkinson, M. (2005). Conservation biology of caecilian amphibians. Conservation Biology, 19(1), 45-55. [link]

IUCN SSC Amphibian Specialist Group. (2019). Caecilia occidentalis. The IUCN Red List of Threatened Species 2019: e.T59522A49354812. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T59522A49354812.en. Accessed in May 2022

Lynch, J. D. (1999). Una aproximación a las culebras ciegas de Colombia (Amphibia: Gymnophiona). Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 23, 317–337. [link]

Ramírez-Chaves, H.E., Pérez, W.A., Mejía-Egas, O., Tobar-Tosse, H.F., Muñoz, A. and Trujillo Lozada, A. (2010). Biodiversidad en el campus de la Universidad del Cauca, Popayán, Colombia. Biotecnología en el Sector Agropecuario y Agroindustrial, 8(2), 104-117. [link]

Taylor, E.H. (1969). On the status of Caecilia occidentalis Taylor. The University of Kansas Science Bulletin, 48, 785–790. [link]

Wake, M.H. and Case, S. M. (1975). The Chromosomes of Caecilians (Amphibia: Gymnophiona). Copeia, 1975(3), 510–516. [link]

Wilkinson, M., and Nussbaum R.A. (2006) Caecilian Phylogeny and Classification. In J.-M. Exbrayat (Ed.) Reproductive Biology and Phylogeny of Gymnophiona: Caecilians Volume 5 (pp. 39–78). Science Publishers [link]

Wilkinson, M., San Mauro, D., Sherratt, E., and Gower, D. J. 2011. A nine-family classification of caecilians (Amphibia: Gymnophiona). Zootaxa 2874: 41-64. [link]

Species Account Citation: AmphibiaWeb 2023 Caecilia occidentalis: Cauca Caecilian <https://amphibiaweb.org/species/1864> University of California, Berkeley, CA, USA. Accessed Apr 20, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 20 Apr 2024.

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