Description

DESCRIPTION:

Juveniles resemble adults. Their eyes are not visible, and their tentacles are positioned closer to the nostril than the eye. They have 116 - 119 primary annuli, which have clear demarcations. Small scales are present in the annular folds. The outer teeth of the lower jaw in the young have multicusped teeth, some of which are long and recurved (Kouete et al. 2012).

DIAGNOSIS:

Herpele are the only African caecilians with both secondary annular grooves and bone-covered eyes (Kouete et al. 2012). They are the only caecilians with a perforate stapes, no separate septomaxillae or prefrontal bones, and multiple small antotic foramina on each side of the skull. Within the genus H. squalostoma is identified on the basis of having fewer than 135 primary annuli. The only other species in the genus, H. multiplicata, has more than 150 annuli (Wilkinson et al. 2003).

COLORATION:

In life, these caecilians are grey and purplish (Kouete et al. 2012). In preservative, they are dark olive and marked with merging yellow spots. (Stutchbury 1834).

VARIATION:

There is some variation in the number of primary annuli, as well as in the coloration in living specimens (Kouete et al. 2012).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Cameroon, Central African Republic, Congo, Congo, the Democratic Republic of the, Equatorial Guinea, Gabon, Nigeria

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (11 records).

Herpele squalostoma is found in Africa, specifically in the countries of Cameroon, Central African Republic, Congo, The Democratic Republic of the Congo, Equatorial Guinea, Gabon, and Nigeria. It is found at elevations from sea level to 800 meters (IUCN 2018). The species generally lives in subtropical or tropical lowland forests. It is terrestrial and fossorial, and nonmigratory. It possibly lives in fruit tree plantations and rural gardens (Kouete et al. 2012).

Life History, Abundance, Activity, and Special Behaviors
Because of a largely tropical distribution and subterranean habitats, caecilians in general are rarely encountered in routine herpetological surveys (Gower and Wilkinson 2005). This has contributed to a lack of information regarding abundance.

The right lung of H. squalostoma is elongate and spans about 30% of total body length, whereas the left lung is essentially rudimentary; it is less than 5% of the length of the right lung. Unlike other caecilians, which have shorter systemic arches, H. squalostoma has longer arches with an extra-coelomic passage that is unique among tetrapods (Wilkinson 1992).

Larva
Herpele squalostoma is presumed to be oviparous with direct development. Its oviductal eggs, combined with a conspicuous lack of embryos or fetuses within caught specimens, supports the proposal that this species is oviparous. Its young lack larval features, which supports the proposal that it has direct development. The species is not dependent on water bodies for reproduction (Kouete et al. 2012).

Herpele squalostoma is a caecilian species that engages in maternal dermotophagy. The young have deciduous, multicuspid, and polystichous teeth. They also have proportionally large jaw muscles, like other dermatophagic caecilians. Young were found with stratum corneum tissue within the gut, which presumably was ingested from the mother. The same clutch, under care of the mother, gained weight without any added food (Kouete et al. 2012).

Trends and Threats

The species is listed as “Least Concern” due to its “relatively wide distribution and presumed large population.” However, the exact population abundance of H. squalostoma is unknown. The species is presumed to be in decline (IUCN 2018), and thus more research and monitoring are required to have a better grasp on their trends or threats (Gower and Wilkinson 2005).

While explicit consideration of African caecilians has yet to be undertaken, general forest decline is still a concern for caecilian populations (Gower and Wilkinson 2005). In Gabon, for example, the logging and oil industries are a threat to amphibian wildlife including caecilians (Burger et al 2006). Caecilian abundance in general is also reported to be in decline, but a causal relationship has yet to be proven (Gower and Wilkinson 2005).

Herpele squalostoma specimens have tested positive for Batrachochytrium dendrobatidis suggesting chytridiomycosis infection is a potential threat. Another caecilian species, the geographically nearby and closely related Geotrypetes seraphini, has had both wild-caught and commercial individuals mortally infected with chytridiomycosis. However, exact infectiousness and lethality has not been measured for H. squalostoma or other caecilians (Gower et al. 2013).

A “small” number of H. squalostoma can be found in the international pet trade. It’s unknown if a sustainable practice (Gower and Wilkinson 2005).

The species has not been recorded from the Cabinda Enclave of Angola, but it presumably occurs there (IUCN 2018). The species occurs in many protected areas including Moukalaba-Doudou National Park in Gabon (Burger et al. 2006).

Relation to Humans
A “small” number of H. squalostoma appear in the international pet trade, but exact numbers are unknown. Similarly, whether it is a sustainable practice or exact details of this commercial use are unknown (Gower and Wilkinson 2005).

Possible reasons for amphibian decline

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

Comments

PHYLOGENETIC RELATIONSHIPS:

As of 2021, there were only two species in the Herpele genus: H. squalostoma and H. multiplicata. According to the molecular phylogeny by Frost et al. (2006), and consistent with the phylogenetic claims of Wilkinson et al. (2011), the genus Herpele is most closely related to Boulengerula, which together comprise the family Herpelidae. Herpelidae shares the most recent common ancestor with Caeciliidae, Typhlonectidae, Indotyphlidae, Siphonopidae, and Dermophiidae (Wilkinson et al. 2011).

ETYMOLOGY: n/a OTHER INTERESTING INFORMATION:

When first described, H. squalostoma was called Caecilia squalostoma (Stutchbury 1834).

This species was featured in News of the Week on 31 July 2023:

Previous studies on frogs and salamanders suggest a limited correlation between parental care and the transmission of microbiome from parent directly to the offspring, or vertical microbiome transmission. However, caecilians— among the most poorly known of terrestrial vertebrates and the most elusive amphibians— have not been investigated in this context. The oviparous, direct-developing caecilians present a unique opportunity for studying parent-offspring interactions because they exhibit elaborate forms of parental care. Juveniles both feed on the skin of the mother and, at least in some species, imbibe a fluid from her cloaca, both quite likely leading to vertical bacterial transmission. Kouete et al. (2023) studied the microbiomes of Herpele squalostoma, an oviparous, direct developing caecilian from Central Africa that engages in parental care through skin-feeding. Using 16S rRNA metabarcoding. they found that juveniles shared an important proportion of their skin and gut microbiome with the skin and gut of mothers, including high similarities with the mothers' skin. In addition, nitrogen stable isotope (15N) values of juvenile skin were approximately three times higher than that of the mothers, indicating a higher trophic position for juveniles due to skin-feeding. (Marcel Kouete)

References

Burger, M., Pauwels, O., Branch, W., Tobi, E., Yoga, J., Mikolo, E. (2006) “An assessment of the amphibian fauna of the Gamba Complex of Protected Areas, Gabon.” Gabon: Biodiversity of an equatorial African rainforest. Bulletin of the Biological Society of Washington, 12, 297-307. [link]

Frost, D. R., Grant, T., Faivovich, J., Bain, R. H., Haas, A., Haddad, C. F. B., de Sá, R. O., Channing, A., Wilkinson, M., Donnellan, S. C., Raxworthy, C. J., Campbell, J. A., Blotto, B. L., Moler, P., Drewes, R. C., Nussbaum, R. A., Lynch, J. D., Green D. M., Wheeler, W. C. (2006). "The amphibian tree of life." Bulletin of the American Museum of Natural History, 297, 1-370. [link]

Gower, D. J., Thomas, D., Loader, S. P., Wilkinson, M., Kouete, M. T., Tapley, B., Orton, F., Daniel, O. Z., Wynne, F., Flach, E., Müller, H., Menegon, M., Stephen, I., Browne, R. K., Fisher, M. C., Cunningham, A. A., Garner, T. W. J. (2013) “Batrachochytrium dendrobatidis infection and lethal chytridiomycosis in caecilian amphibians (Gymnophiona).” EcoHealth 10, 173–183. [link]

Gower, D. J., and Wilkinson, M. (2005). ''Conservation biology of caecilian amphibians.'' Conservation Biology, 19(1), 44-45.

IUCN SSC Amphibian Specialist Group (2018). "Herpele squalostoma." The IUCN Red List of Threatened Species 2018: e.T59565A16958011. https://dx.doi.org/10.2305/IUCN.UK.2018-1.RLTS.T59565A16958011.en. Downloaded on 13 April 2020.

Kouete, M., Wilkinson, M., Gower, D. (2012) “First reproductive observations for Herpele Peters, 1880 (Amphibia: Gymnophiona: Herpelidae): Evidence of extended parental care and maternal dermatophagy in H. squalostoma (Stutchbury, 1836).” ISRN Zoology, 2012, 1-7. [link]

Stutchbury, I. (1836) “Description of a new species of the genus Chamaeleon.” Transactions of the Linnaean Society of London 1(17), 362. [link]

Wilkinson, M. (1992) “Novel modification of the tetrapod cardiovascular system in the West African caecilian Herpele squalostoma (Amphibia: Gymnophiona: Caeciliaidae).” Journal of Zoology 228:2, 277-286. [link]

Wilkinson, M., Müller, H., Gower, D. J. (2003) “On Herpele multiplicata (Amphibia: Gymnophiona: Caeciliidae).” African Journal of Herpetology 52:2, 119-122. [link]

Wilkinson, M., San Mauro, D., Sherratt, E., Gower, D.J. (2011). "A nine-family classification of caeclians (Amphibia: Gymnophiona)." Zootaxa, 2874(1), 41-64. [link]

Species Account Citation: AmphibiaWeb 2023 Herpele squalostoma: Congo Caecilian <https://amphibiaweb.org/species/1899> University of California, Berkeley, CA, USA. Accessed Nov 22, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Nov 2024.

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