Description
Scolecomorphus kirkii is the largest species of Scolecomorphus, a caecilian genus. Adults have a total length ranging from 163 - 234 mm for males and 288 - 485 mm for females (Nussbaum 1985; Channing 2001; Nussbaum 2003). Farooq and Conradie (2015) noted a specimen with a snout-vent length of roughly 250 mm, however, this specimen might be a different species. From a dorsal view, the head is sub-triangular with a very prominent, rounded snout. The head width is roughly 1 - 3 mm shorter than the head length. The snout projects roughly 1.4 mm beyond the mouth. The small nares have valves that are distinct and visible in the external nares (Boulenger 1883; Nussbaum 1985). The tentacular apertures (not visible from a dorsal view) are about 1 mm long, located below and just behind the nostril, and fitting into the sockets (Nussbaum 1985; Channing 2001). The tentacular aperture to narial distance is smaller than the internarial distance (Nussbaum 1985). The eyes, located at the base of the tentacle, can be projected outside their skull (Nussbaum 2003). The teeth are described as elongate, small, subequal, conical, monocuspid, and curved posteriorly (Boulenger 1883; Nussbaum 1985). In all types of teeth, the teeth on the anterior ends are larger; but in the dentary teeth, they are only slightly larger on the anterior end. The palatine teeth begin where maxillary teeth end. In southern Malawi, premaxillary-maxillary teeth of the caecilian range from 15 - 23, prevomeropalatine teeth range from 13 - 24, and dentary teeth range from 18 - 34; in the Uluguru Mountains of Tanzania, premaxillary-maxillary teeth range from 14 - 16, prevomeropalatine teeth range from 9 - 14, and dentary teeth range from 16 - 24; in the south-central highlands of Tanzania, premaxillary-maxillary teeth range from 18 - 20, prevomeropalatine teeth range from 10 - 13, and dentary teeth range from 19 - 20. There are no splenial teeth (Nussbaum 1985).

The body of S. kirkii is slender, with a diameter ranging from 7 - 20 mm (Boulenger 1883; Loveridge 1953; Channing 2001). Body width ranges from 6 - 8 mm for males and 7 - 11 mm for females in Southern Malawi and the Uluguru Mountains of Tanzania; in the south-central highlands of Tanzania, body width ranges from 9 - 14 mm for females. Regarding the collar region, the first nuchal groove is indistinct such that the first collar is fused with the head. The third nuchal groove is only distinct dorsally, with a ventral fusion of the second collar and the first annulus. A short, transverse, dorsal groove is on both collars (Nussbaum 1985). The first few rings are complete, while the rest are fused dorsally and ventrally, interrupted on the dorsal and ventral lines (Boulenger 1883; Nussbaum 1985). Body annuli vary from 130 - 142 in males and 140 - 154 in females (Nussbaum 1985). A specimen, which may be a different species, of unknown sex from Mount Namuli of Mozambique was recorded to have 156 annuli (Farooq and Conradie 2015). Kirk’s Caecilian has a blunted and rounded posterior end (Boulenger 1883; Channing 2001). The vent is a longitudinal ventral slit near the posterior end, with an oval impression around the vent on the underside of the terminal shield (Nussbaum 1985; Channing 2001). The terminal shield is roughly 4.5 mm in length (Nussbaum 1985).

Juveniles are transversely convex on the ventral side of the rostrum. Their tentacles are visible dorsally and a little protruded. The premaxillary-maxillary teeth are relatively large, bicuspid, and straight; the labial cusp is small and near the apex. A few teeth are on the lateral region of the paraoral processes, point laterally, posterolaterally, or dorsolaterally, and show signs of wear; teeth on the ventral surface of the rostrum and in a more lateral position also show signs of wear. The teeth of the lower jaw are erupted; lancet-shaped “foetal” teeth are anterior and in three to four rows, with four rows in the symphyseal region. The largest row is the innermost, the latter successively smaller. Outer rows show more wear. Teeth near the jaw articulation are large, monocuspid, and in a singular row. The posterior of the gut has a yolk-like, white, amorphous mass (Müller et al. 2009).

DIAGNOSIS:

Kirk’s Caecilian may be the only species of Scolecomorphus found south of the 10°S latitude in Africa, however, the specimen recovered in this area may be a different species (Farooq and Conradie 2015). Coloration can differentiate S. kirkii from Boulengerula changamwensis, as B. changamwensis is more of a flesh-pink while S. kirkii is bicolared, with more of a olive, lavender-gray above and pinkish below (Loveridge 1932; Boulenger 1883). Scolecomorphus kirkii is also relatively larger than S. uluguruensis, which has a total length ranging from 140 - 360 mm, and S. vittatus, which has a total length ranging from 140 - 376 mm. The number of annuli can further separate S. kirkii from S. uluguruensis, which has roughly 124 - 149, and S. vittatus, which has roughly 120 - 148 (Loader et al. 2003).

COLORATION:

In life, S. kirkii is described as bicolored, with dark olive-brown, lavender-gray or black on the upper three-fourths of its body and a flesh or cream-colored venter (including chin, throat, and underside of terminal shield) (Boulenger 1883; Loveridge 1953; Nussbaum 2003). The sides are generally brownish (Loveridge 1953; Channing and Rödel 2019). Anteriorly and ventrally, the coloration is more white; towards the midbody, pink speckles appear, concentrated posteriorly to create a pink appearance (Loveridge 1953; Channing and Rödel 2019). The border of dorsal and ventral coloration can be diffuse (Nussbaum 1985). A light area can be seen along the tract of the tentacular aperture (Nussbaum 2003). Small, darkly pigmented eyespots are at the base of the tentacle and only visible in young specimens (Loveridge 1953; Channing 2001; Farooq and Conradie 2015; Channing and Rödel 2019). In preservation, S. kirkii is still dark, olive-brown above but yellowish-olive below (Boulenger 1883; Nussbaum 1985; Conradie et al. 2016).

Juveniles have a well-developed band of dark coloration, covering the dorsal and dorsolateral regions of the body and stretching from the snout tip to body terminus. Around the nostrils, tentacular aperture bases, and paraoral processes lack pigmentation (Müller et al. 2009).

VARIATION:

Younger specimens have more restricted dorsal coloration. Adults from southern Malawi have more extended dorsal coloration that can encircle the body just anterior to the vent. Adults from the Uluguru Mountains do not show any dorsal coloration on the venter (Nussbaum 1985). The adults from the south-central highlands of Tanzania that Nussbaum (1985) observed were too badly dried to determine coloration details but they were still bicolored.

Females have a larger maximum size than males and have more primary annuli. Specimens from the Uluguru Mountains of Tanzania also have more primary annuli and fewer teeth on all series than specimens from southern Malawi. The smallest known mature male had a total length of 163 mm, while the smallest known mature female had a total length of 288 mm (Nussbaum 1985).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Malawi, Mozambique, Tanzania, United Republic of

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (6 records).

Scolecomorphus kirkii is endemic to regions of Mozambique, Malawi, and Tanzania, at an elevation range of about 500 - 2000 m (Nussbaum 1985; IUCN 2016; Channing and Rödel 2019). In northern Mozambique, S. kirkii can be found in Mount Mabu of the Zambezia Province, Mount Namuli of the Nampula Province, and the Serra Mecula of the Niassa Province (Farooq and Conradie 2015; Conradie et al. 2016; IUCN 2016). In southern Malawi, Kirk’s Caecilian can be found in the relatively high elevation (above 1400 m) mountains east of the Shire Valley, especially in the Cholo Mountains (Loveridge 1953; Nussbaum 1985; Channing 2001; Channing and Rödel 2019). In Tanzania, S. kirkii can be found in the Masisiwe area of the Udzungwa Mountains, the Nguru, Rubeho, Uluguru, and Mahenge Mountains, and the Ubena Highlands (Channing 2001; Gower 2004; IUCN 2016; Channing and Rödel 2019). These caecilians inhabit tropical rainforests and agricultural areas (Nussbaum 2003).

Life History, Abundance, Activity, and Special Behaviors
Scolecomorphus kirkii is an efficient burrower, whose diet mainly consists of arthropods and earthworms; mineral soil can also be found in the guts (Loveridge 1953; Channing 2001; Nussbaum 2003).

They may be seen emerging from soil after heavy rain to feed on earthworms, found under vegetation, or in soil (Loveridge 1953; Channing 2001; Nussbaum 2003; Conradie et al. 2016).

Gower et al. (2004) found a specimen of a partially digested S. kirkii in the gut of the snake Atractaspis aterrima. It is theorized that the bright coloration of Kirk’s Caecilian may aposematic, but A. aterrima was not deterred.

The species is viviparous and offspring may engage in post-hatching skin feeding or engage in intra-oviductal feeding (Nussbaum 2003; Müller et al. 2009)

The premaxillary-maxillary arcade undergoes a series of developmental changes overtime, first forming a broad arc oriented at a large angle to the sagittal axis in the fetal stage; the dental lamina of premaxilla and out-turned maxillary arcade is thus nearly transverse in orientation. From fetal to juvenile stage, the angle to the sagittal axis decreases gradually, and thus the difference in orientation of the premaxillary-maxillary arcade between fetus and juvenile is relatively small. Juvenile and adult stages, however, show a stark gap of orientation, but it is unclear if the transition from juvenile to adult is gradual or more or sudden (Müller et al. 2009).

Müller et al. (2009) theorized that neonate Scolecomorphus engage in postparitive feeding by feeding on maternal skin, with strong ventral cephalic and nuchal concavity in the juvenile stage as adaptation to this feeding method. This theory is due to a lack of hypertrophied oviduct lining, juveniles of S. kirkii and S. vittatus found with amorphous, flaky, white substances in their hindgut, as opposed to usual invertebrate prey that adults would feed on, and fetuses of S. kirkii have premaxillary–maxillary and dentary teeth crowns covered by epidermis, thus likely nonfunctional, as opposed to juveniles with erupted teeth with signs of wear.

Larva
Fetuses have a broad head dorsally and a wedge-shaped head laterally, with blunt and laterally projecting paraoral processes. Their tentacles are slightly visible dorsally and positioned laterally on an imaginary line running from the upper corner of the mouth to nares. The underside of the rostrum is nearly flat and triangular, with a line of roughly eight knob-like projections that are about 0.5 mm from and parallel to the margin of the mouth. One to two more protuberances are posterolateral on the paraoral process on each side. The tip of a tooth may be seen through the epidermis of a protuberance at high magnification. The upper margins of the mouth and the lower jaw are very rounded; the lower jaw has epidermis-covered dentary teeth anteriorly arranged in three rows around the symphysis and two more rows laterally. Three long gills are behind the head laterally, the second is the longest followed by first and third, and all have gill filaments. No lateral line organs, spiracular openings, labial folds, or tail fin are present. No yolk is visible externally, however, enlarged intestines are visible through the venter and possibly full of yolk (Müller et al. 2009).

A weak band of dark pigmentation runs from the tip of the snout to body terminus, covering the dorsal and dorsolateral sides, excluding the nostrils, tentacles, and paraoral processes (Müller et al. 2009). It is unclear if this description is in life or preservation.

It is debated if the fetal teeth are for intra-oviductal feeding before birth or for postpartum maternal skin feeding (Müller et al. 2009).

Trends and Threats

Scolecomorphus kirkii is threatened by annual and perennial non-timber crops, logging and wood harvesting, and agricultural and forestry effluents (such as herbicides and pesticides). The soil moisture and temperature suitable for this caecilian is reliant upon vegetation, which may be affected by habitat disturbance and conversion as a result of deforestation and agriculture (IUCN 2016).

Kirk’s Caecilian resides in the Uluguru Nature Reserve, Mahenge Forest Reserve, Udzungwa National Park and Forest Reserves, and Rubeho Forest Reserve of Tanzania, although it is not endemic to protected areas of the Southern Highlands. In Malawi, it occurs in some protected areas of the highlands (IUCN 2016).

Relation to Humans

Scolecomorphus kirkii may be involved in the pet trade but is rarely traded (IUCN 2016).

Possible reasons for amphibian decline

Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Local pesticides, fertilizers, and pollutants

Comments

Using Maximum Likelihood and Bayesian Inference on the whole mitochondrial genome, at a family level, Scolecomorphidae is sister to the Chikilidae family (San Mauro et al. 2014).

Indigenous Nyanja people of Mulanje call S. kirkii “Nianta” while people of the indigenous Mang’anja tribe of Cholo call the species “Nyongolozi,” which may mean earthworm (Loveridge 1953).

OTHER INTERESTING INFORMATION:

Lake Tanganyika retains its name from the time of the species description, but the Tanganyika Territory itself, as noted in Boulenger 1883 and Loveridge 1953, has become the United Republic of Tanzania after combination with the former protectorate of Zanzibar (Tanganyika 2024).

Laurent (1974) and Nussbaum (1985) both discuss how Taylor (1968) had issues describing particular African caecilians. In particular, Nussbaum (1985) remarked how Taylor (1968) used a desiccated specimen of S. kirkii to incorrectly designate it as the holotype of S. convexus, which has since been synonymized.

The eyes can be projected outside their skull (Nussbaum 2003).

References

Boulenger, G. A. (1883). "Description of a new genus of Coeciliae." Annals and Magazine of Natural History, 11(48). [link]

Channing, A. (2001). Amphibians of Central and Southern Africa. Cornell University Press, Ithaca, NY.

Channing, A., Rödel, M.-O. (2019). Field Guide to the Frogs and Other Amphibians of Africa. Penguin Random House South Africa, Cape Town, South Africa.

Conradie, W., Bittencourt-Silva, G., Engelbrecht, H. M., Loader, S. P., Menegon, M., Nanvonamuquitxo, C., Scott, M., Tolley, K. A. (2016). "Exploration into the hidden world of Mozambique’s sky island forests: new discoveries of reptiles and amphibians." Zoosystematics and Evolution, 92(2), 163-180. [link]

Frank, N. and Ramus, E. (1995). A Complete Guide to Scientific and Common Names of Reptiles and Amphibians of the World. NG Publishing Inc., Pottsville, Pennsylvania.

Gower, D.J., Rasmussen, J. B., Loader, S. P., Wilkinson, M. (2004). "The caecilian amphibian Scolecomorphus kirkii Boulenger as prey of the burrowing asp Atractaspis aterrima Günther: Trophic relationships of fossorial vertebrates." African Journal of Ecology, 42(2), 83-87. [link]

H.O.M. Farooq and W. Conradie (2015). ''A second record of Scolecomorphus kirkii Boulenger, 1883 (Gymnophiona: Scolecomorphidae) for Mozambique.'' Herpetology Notes, 8, 59-62.

IUCN SSC Amphibian Specialist Group. 2016. Scolecomorphus kirkii. The IUCN Red List of Threatened Species 2016: e.T59651A16944395. https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T59651A16944395.en. Accessed on 10 June 2024.

Laurent, R.F. (1974). "Caecilians from Central Africa: Additions and Corrections to Taylor’s Treatise." Copeia, 1974(3), 787-788. [link]

Loader, S.P., Wilkinson, M., Gower, D.J. and Msuya, C. (2003). ''A remarkable young Scolecomorphus vittatus (Amphibia: Gymnophiona) from the Pare Mountains, Tanzania. .'' Journal of Zoology, 259, 93-101.

Loveridge, A. (1953). "Zoological results of a fifth expedition to east Africa. IV. Amphibians from Nyasaland and Tete." Museum of Comparative Zoology at Harvard College, 110(4), 325-406. [link]

Müller, H., Wilkinson, M., Loader, S. P., Wirkner, C. S., Gower, D. J. (2009). "Morphology and function of the head in foetal and juvenile Scolecomorphus kirkii (Amphibia: Gymnophiona: Scolecomorphidae)." Biological Journal of the Linnean Society, 96(3), 491-504. [link]

Nussbaum, R. A. (1985). ''Systematics of caecilians (Amphibia: Gymnophiona) of the family Scolecomorphidae.'' Occasional Papers of the Museum of Zoology University of Michigan, (713), 1-49.

Nussbaum, R. A. (2003). ''Kirk's caecilian, Scolecomorphus kirkii.'' Grzimek's Animal Life Encyclopedia, Volume 6, Amphibians. 2nd edition. M. Hutchins, W. E. Duellman, and N. Schlager, eds., Gale Group, Farmington Hills, Michigan.

San Mauro, D., Gower, D.J., Müller, H., Loader, S.P., Zardoya, R., Nussbaum, R.A., Wilkinson, M (2014). "Life-history evolution and mitogenomic phylogeny of caecilian amphibians." Molecular Phylogenetics and Evolution , 73, 177-189. [link]

Taylor, E.H. (1968). The Caecilians of the World. A Taxonomic Review. University of Kansas Press, Lawrence, Kansas.

“Tanganyika Trusteeship Documents.” United Nations: Dag Hammarskjöld Library. https://research.un.org/en/docs/tc/tanganyika. Accessed on 10 June 2024.

Species Account Citation: AmphibiaWeb 2024 Scolecomorphus kirkii: Kirk's Caecilian; Lake Tanganyika Caecilian; Nianta; Nyongolotzi <https://amphibiaweb.org/species/2022> University of California, Berkeley, CA, USA. Accessed Jan 17, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 17 Jan 2025.

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