AMPHIBIAWEB
Phrynobatrachus chukuchuku
family: Phrynobatrachidae
 
Species Description: Zimkus BM 2009 Biogeographical analysis of Cameroonian puddle frogs and description of a new species of Phrynobatrachus (Anura: Phrynobatrachidae) endemic to Mount Oku, Cameroon. Zool J Linn Soc 157:795-813

Country distribution from AmphibiaWeb's database: Cameroon

View distribution map using BerkeleyMapper.


Conservation Status (definitions)
IUCN (Red List) Status
CITES
Other International Status None
National Status None
Regional Status None

   

From the Encyclopedia of Life account:

Summary

Phrynobatrachus chukuchuku is a miniature (snout–vent length < 20 mm) species of puddle frog. Members of this genus are identified by the presence of a midtarsal tubercle, elongate inner metatarsal tubercle, and outer metatarsal tubercle. Chevron shaped glands are present on the dorsum of this species, although these glands may be difficult to discern in this species because of dark brown dorsal coloration. The tympanum is either indistinct or only scarcely visible and a supratympanic fold is present. Pedal webbing is absent or extremely rudimentary. Males of this species have unique ventral coloration characterized by a black throat, dark brown to black pectoral and abdominal regions, and a light or white area on the proximal hind limbs. Minute spines cover the venter in males, often appearing as white asperities.


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Etymology

This species name is derived from Cameroonian pidgin English phrase ‘chuku-chuku’ meaning ‘spiny’ or ‘thorny’ and refers to the minute spinules visible in males.


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Distribution

Phrynobatrachus chukuchuku is known only from Mt Oku, Cameroon.


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Morphology

This species has an oval, compact body shape and slender limbs. The head is slightly longer than wide. Canthus rostralis is rounded but distinct; loreal region is straight to slightly concave. Distance from naris to rostral tip is less than half that from naris to the anterior portion of the eye. Internarial distance is approximately equal to interorbital distance. Tympanum is indistinct and much smaller than the diameter of eye. A supratympanic fold is present. Premaxillary and maxillary teeth are present, as well as a conical median papilla on the tongue. Relative length of fingers are as follows: III > IV ³ II > I. Large and oval palmar and thenar tubercles are present on the hand, and round subarticular tubercles are present on the fingers. Manual webbing is absent. Finger tips are not expanded or only slightly bulbous. Tibiofibula is slightly longer than femur. The relative length of toes are as follows: IV > III > V > II > I. A midtarsal tubercle, a conspicuous and elongate inner metatarsal tubercle, and smaller outer metatarsal tubercle are present. Pedal webbing is absent or rudimentary, present only on toe bases. Expansion of pes digit tips varies from bulbous to slightly expanded into small discs; circum-marginal grooves are variably present. Dorsal skin is smooth with chevron-shaped glands forming an ‘X’ or “W” pattern present in the scapular region. Small, white asperities are found on the flanks extending from above the eye and supratympanic fold to anterior of the hind limb; often these spots may be present on the upper lip from the rostrum to the insertion of the forelimb. The venter (gular, pectoral, and abdominal regions) in males may be partially or completely covered with small spines or asperities that appear whitish in the pectoral and abdominal regions; ventral asperities are not present in females. The gular skin in males is slightly thickened, causing multiple lateral folds, and the asperities in this region are black (Zimkus, 2009).

Colour (in ethanol) varies from medium to dark brown with some darker, brown spots. A thin, cream, vertebral line may be present as in the holotype. A paler triangle is often present on the snout. Dorsal sides of hind limbs are barred; ventral sides vary in pigmentation with regions appearing cream or mottled. Chevron-shaped scapular glands are often outlined in darker brown but may difficult to detect because of dark dorsal coloration. A light coloured area is present on the proximal hind limbs anterior to the cloaca, and other portions of the limbs in close proximity to the elbows and knees are often light coloured in males, whereas the remaining portions are brown. The lower jaw is often lined with lighter brown or even white. Males have a black throat, as well as dark brown to black pectoral and abdominal regions. The venter of females is immaculately white or cream, and the lower jaw is normally lined with the brown dorsal colour (Zimkus, 2009).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Size

All specimens within the type series had snout–vent lengths less than 20 mm; females were significantly larger than males (t-test: P = 0.0089; Zimkus, 2009).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Diagnostic Description

Phrynobatrachus chukuchuku is readily distinguished from all other Phrynobatrachus because males have a unique ventral coloration, including a black throat, dark brown to black pectoral and abdominal regions that extend just anterior to the hind limbs, and a light or white area on the proximal hind limbs in close proximity to the cloaca. The venter may be partially or completely covered with small spines or asperities. Females are lighter than males on the ventral side; their venters appear completely white or cream in color and generally lack any conspicuous markings. Small, white spots or asperities extend from above the eye to the insertion of the hind limbs and may be present in either sex.


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Comparisons

Phrynobatrachus chukuchuku is morphologically most similar to other small Cameroonian species, such as P. latifrons, P. calcaratus, P. cornutus, P. hylaios, P. manengoubensis, and P. werneri. Phrynobatrachus latifrons has distinct webbing and males exhibit a yellow throat, whereas P. chukuchuku generally lacks webbing and males possess a black throat. Phrynobatrachus chukuchuku can be easily differentiated from P. calcaratus and P. cornutus because it does not have an eyelid cornicle. Phrynobatrachus werneri and P. hylaios differ from P. chukuchuku by much darker coloration, both on the dorsum and venter (not including the dark or black gular region found in males), as well as the presence of ventral spines in males. This species differs from large-bodied Cameroonian Phrynobatrachus (P. africanus, P. auritus, P. batesii, P. cricogaster, P. natalensis, P. plicatus, and P. steindachneri) by absence of pes webbing (Zimkus, 2009).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Habitat and Ecology

Phrynobatrachus chukuchuku is known only from high altiude grasslands of Mt Oku (2800 m), Cameroon. Such grasslands do not occur in other highland areas of the Cameroon Volcanic Line, such as Mt Kupe (summit 2064 m), Mt Nlonako (summit 1825 m), Mt Manengouba (summit 2411 m), Tchabal Mbabo (highest elevation approximately 2380 m), or Obudu Plateau (highest elevation approximately 1700 m).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Phylogenetics

Phrynobatrachus chukuchuku differs from 12 Cameroonian species of Phrynobatrachus by mitochondrial (12S rRNA, valine-tRNA, and 16S rRNA) sequence divergence of 4.94–18.69%. No sequence divergence was detected amongst the three P. chukuchuku sequences. Of the miniaturized Cameroonian species examined, Phrynobatrachus chukuchuku is genetically closest to P. werneri and P. manengoubensis with a 4.94–5.54% difference in the mtDNA fragment examined (Zimkus, 2009).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

IUCN Red List Category and Justification of Conservation Status

Phrynobatrachus chukuchuku is not currently included in the IUCN's Red List assessment of amphibian species. Following the IUCN (2001) criteria, this species would be recognized as Critically Endangered because its extent of occurrence is less than 10 km2, its area of occupancy is less than 10 km2, all individuals are known from a single location in the high elevation grasslands near the summit of Mt. Oku, and there is continuing decline in the extent and quality of its habitat on Mt. Oku.


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Threats

This species is threatened by habit loss occurring near the summit of Mt Oku related to overgrazing by cattle, goats, and horses owned by local people. Fire is also a potential threat to the habitat of the species.


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Conservation Actions and Management

Few portions of highlands of western Cameroon are under formal protected status at the national level (Bergl et al., 2007). Some highland habitats, such as forests on Mt Oku, are delineated well and have some protection from local traditional rulers, but people often ignore local laws. Zimkus (2009) reports that if conservation of unique taxa with smaller ranges is a priority, then the mid-highlands, including Mt Manengouba, the Bamenda-Banso Highlands, and specifically Mt Oku, should be the focus of conservation efforts.


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/