CSL
Osteolaemus tetraspis (COPE, 1861)


NAMES | DISTRIBUTION | HABITAT | STATUS | APPEARANCE | IMAGES | DIET | BREEDING | CONSERVATION

FAMILY:
ALLIGATORIDAE

A. mississippiensis
A. sinensis
C. crocodilus
C. c. apaporiensis
C. c. fuscus
C. latirostris
C. yacare
M. niger
P. palpebrosus
P. trigonatus

FAMILY:
CROCODYLIDAE

C. acutus
C. intermedius
C. johnstoni
C. mindorensis
C. moreletii
C. niloticus
C. novaeguineae
C. palustris
C. porosus
C. rhombifer
C. siamensis
M. cataphractus
O. tetraspis
T. schlegelii

FAMILY:
GAVIALIDAE

G. gangeticus

DICHOTOMOUS KEY
[German]

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STATUS OF INFORMATION:
This information was most-recently updated January 2009 and is considered up-to-date. Please contact me directly regarding updates or corrections.

COMMON NAMES:
(West) African dwarf crocodile, Broad-snouted crocodile, Black crocodile, African caiman, Bony crocodile, African broad-nosed crocodile, Cocodrilo chico africano, Crocodile (à nuque) cuirassé, Crocodile nain (africain), Rough-backed crocodile, Crocodile à front (large), Stumpf krokodil, Bamba fiman

NAME ETYMOLOGY:
> Osteolaemus means "bony throat", derived from osteon (Greek for "bone") + laimos (Greek for "throat"), referring to the extensive osteoderms (bony plates) found in the neck and belly scales
> tetraspis means "four shields", derived from tetra (Greek for "four") + aspis (Greek for "shield"), referring to the cluster of four bony plates (nuchal scales) on the back of the neck
> osborni (one of the two recognised subspecies) means "of Osborn"

SUBSPECIES:
There are two recognised subspecies:
   O. t. tetraspis - West African Dwarf Crocodile
   O. t. osborni - Congo (or Osborn's) Dwarf Crocodile, formerly Osteoblepharon osborni
The taxonomic status of this species is still in doubt, with recent evidence suggesting that the above subspecies may be separate species, or a complex of several species.

DISTRIBUTION:
[CLICK ON MAP FOR DETAILED RANGE]
Distribution map Much overlap with Crocodylus cataphractus.
West and West-central Africa: Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Congo, Côte d'Ivoire, Democratic Republic of Congo, Equatorial Guinea, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Nigeria, Senegal, Sierre Leone, Togo

O. t. tetraspis found in more westerly areas
O. t. osborni found in Democratic Republic of Congo (formerly Zaire)

HABITAT:
Primarily found in permanent pools in swamps and areas of slow-moving freshwater in rain forests. Occasional reports of individuals in isolated savannah pools, where burrows are occupied during the dry season. Nocturnal. Spends most of the day in burrows which are constructed by the crocodile. These burrows are sometimes partially submerged, with the entrance under the water surface. Crocodiles emerge usually at night and forage either close to the water or extensively on the land, particularly in covered and forested areas. In some areas, individuals stay in isolated pools, hiding under tree roots during the day. The ecology of this species is similar to the New World Paleosuchus dwarf caimans.

STATUS:
     CITES: Appendix I
     IUCN Red List: VU A2cd (VULNERABLE)
     Estimated wild population: 25,000 to 100,000
Summary: Populations heavily exploited in some areas, and survey data very poor, but wide distribution lends some security

APPEARANCE:
[click on image for enlargement]
Head drawing Heavily armoured (neck, back, tail) with pronounced, ossified ventral scales. Nuchal scale pattern: 3 transverse series (1: two large scales; 2: two large scales; 3: two very small scales). Adult colouration uniformly dark on the back and sides, with lighter brown banding on body and tail of juveniles, and yellow patterning on head. Belly colour is yellowish with numerous black patches. Maximum recorded size 1.9m (6.3 feet). Short, blunt snout (snout length = basal width), more similar in fact to a caiman - this may be due to the fact that Osteolaemus has a similar ecology the dwarf caimans. O. t. tetraspis is lighter in colour, with more pointed, upturned snout. Heavy dorsal scale armour on back has led to the name 'rough-backed' dwarf crocodile. O. t. osborni is poorly known. Down-turned snout and less dorsal armour.

Dentition codeDENTITION:
4 pre-maxillary; 12-13 maxillary; 14-15 mandibular
Total no. of teeth = 60-64

IMAGES:
[click on image for enlargement]

Click Adult O. t. tetraspis Click Head of adult crocodile Click Dorsal view of O. t. tetraspis
Click Adult O. t. tetraspis Click Juvenile O. tetraspis being held Click Adult head in water

DIET:
Fish, amphibians, crustaceans, possibly other terrestrial prey. Populations studied in the Congo show a change in diet over the course of the year - fish during the wet season, when river flooding brings fish into the marshy habitat occupied by the dwarf crocodile. During the dry season, when the fish are not available, the crocodiles survive primarily on crustaceans, and their dietary intake is generally reduced.

BREEDING:
Individuals are generally solitary except during the breeding season. The nesting period starts at the beginning of the wet season (May-June), when mound nests are constructed. Only a small number of eggs are laid (usually around 10, but in rare instances as many as 20). Incubation period last between 85 to 105 days, and the hatchlings measure a mean total length of 28cm when they emerge from the eggs. The female guards the nest and subsequently protects the young for an unknown period of time in the water.

CONSERVATION:
This species was originally classified under CITES Appendix I, where it remains to this day (except for a limited downgrading to Appendix II for the Congo population in the late 1980s). However, most reports indicate that the species is in no immediate danger throughout most of its range because it is widely distributed in several countries, some of which have high numbers of crocodiles. In one or two areas (particularly Gambia and Liberia), the local population is thought to be severely depleted and in danger of local extirpation.

The main problem with this species is still lack of reliable and widespread survey data. Without such information, the overall status of the species cannot be determined, and thus the CITES Appendix I classification will remain. Although the Crocodile Specialist Group lists the species as LOW RISK (under the IUCN classifications) because of its distribution and healthy population sizes in some areas, the IUCN Red Data List for 1996 gives a category of VULNERABLE to reflect the uncertainly of its status in the wild. Lack of survey data are due to the difficulty in accessing available habitat. The implementation of national parks has been slow in western Africa, and the skin of Osteolaemus has little value - and therefore the incentives for management and thus monitoring are low.

The skin of this species is considered to be very poor quality, and therefore management programs based around this are unlikely to be viable. In areas where the species is used by local people, the skin is used for low-grade products. Meat through subsistence hunting is the main reason this species is taken in the wild, and although some reports indicate that this is likely to have an impact in some areas (e.g. Congo), habitat destruction is a far bigger threat to a species which otherwise has little value to the people who control what happens to the forest. An increasing local awareness is necessary for the future of Osteolaemus where it is threatened in the wild.

MORE INFORMATION:
For more information on distribution and conservation issues for this species,see the CSG
Action Plan resource.

SIGNIFICANT REFERENCES:

  • Inger, RF (1948). The systematic status of the crocodile Osteoblepharon osborni. Copeia 1948: 15-19
  • Kofron, P & Steiner, C (1994). Observations on the African dwarf crocodile, Osteolaemus tetraspis. Copeia 1994(2): 533-535
  • Schmidt, KP (1919). Contributions to the herpetology of the Belgian Congo based on the collection of the American Museum Congo Expedition, 1909-1915. Part I. Turtles, crocodiles, lizards and chameleons. Bull. Amer. Mus. Nat. Hist. 39: 385-624
  • Villiers, A (1956). Un crocodile nouveau pour le Sénégal, Osteolaemus tetraspis. Notes Afrique 70: 80-81
  • Waitkuwait, WE (1989). Present knowledge on the west African slender-snouted crocodile, Crocodylus cataphractus Cuvier 1824, and the west African dwarf crocodile, Osteolaemus tetraspis Cope 1861. In: Crocodiles. Their Ecology, Management and Conservation. A Special Publication of the IUCN/SSC Crocodile Specialist Group. IUCN, Gland, Switzerland. pp.259-275
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