AMPHIBIAWEB
Phrynobatrachus irangi
family: Phrynobatrachidae

© 2004 Robert C. Drewes (1 of 2)
Conservation Status (definitions)
IUCN (Red List) Status Endangered (EN)
CITES
Other International Status None
National Status None
Regional Status None

Country distribution from AmphibiaWeb's database: Kenya

 

View distribution map using BerkeleyMapper.

   

From the Encyclopedia of Life account:

Summary

Phrynobatrachus irangi is a large species (SVL 36-51 mm) of puddle frog from the Central Mountains of Kenya. Members of this genus are identified by the presence of a midtarsal tubercle, elongate inner metatarsal tubercle, and outer metatarsal tubercle. Scapular glands in this species are distinct and x-shaped. P. irangi is characterized by its ovular tympanum, minute dorsal and lateral asperities, slight dilation of the digit tips, and only rudimentary to moderate webbing (3 phalanges free on toe IV). Tiny asperities are present on the central plantar surface of the foot in males and the majority of females. Males also exhibit one or two spines on the walking surface of the foot and several longitudinal, distensible vocal folds in the gular region.


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

Etymology

The name refers to the type locality in the Irangi Forest, Meru District, Kenya.


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

Distribution

This species is currently known from only two montane localities in Kenya: Irangi Forest on the south-eastern slopes of Mount Kenya; and Kimande on the south-eastern slopes of the Aberdare Mountains (Drewes et al., 2004).


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

Morphology

This is a robust frog with stout habitus. The snout protrudes but is rounded, not sharply angled. The diameter of the eye is slightly more than half the distance to tip of snout, nearly equal to interorbital space. Tympanum visible and ovalular in shape; its diameter approximately three-fourths that of eye and situated beneath a dermal fold that originates from mid-point of posterior margin of eye, curves ventrally around tympanum and terminates midway between angle of jaw and origin of forelimb. Tip of fingers and toes rounded, only slightly dilated. Tip of each toe in males with one or two lateral spines. Webbing between fingers absent. Webbing between toes reduced with approximately 3 phalanges free on toe IV (webbing formula I2-2+II1-2+III3-3IV3+-2+V; Savage and Heyer, 1997). Single subarticular tubercles are present on both hands and feet. Palmar surfaces are smooth, while plantar surfaces have numerous, small, pale-colored spinose asperities, especially conspicuous along axes of fourth and fifth metatarsals. The tarsal tubercle is a pale-colored eminence capped by white spine. Fore- and hindlimbs are stout and muscular. Hindlimb length is 2.5 times greater than snout-vent length. The inner metatarsal tubercle is white, small, and approximately one-third the diameter of the eye. The dorsum is generally smooth, but males are covered in very small, white-pointed tubercles that extend laterally to mid-lateral surface of body. A thin, glandular ridge extends from the posterior margin of each eye, angling medially to level above posterior extent of tympanum but not converging with its fellow; a second, more posterior pair of slightly shorter also present. These glandular ridges diverge obliquely in reverse direction to position above mid-point of forelimb insertion, forming an X-shaped configuration. The dorsal skin of the forelimbs is smooth. Hindlimbs are smooth in the femoral region but become increasingly tuberculate from midpoint of tibio-fibula to foot. The posterior surface of thighs is generally smooth with white-tipped, small spinous tubercles interspersed with larger flattened warts. The ventral surface of the body is smooth, except for the gular region in males, which consists of series of longitudinal, unpigmented, distensible folds comprising the vocal pouch. Males have large, thick greyish, granular nuptial pad extending from origin of thumb to just beyond proximal subarticular tubercle.

The dorsum is dark brown with entire snout light orange-brown (pale-colored in preservation), sharply demarcated by transverse line running between eyelids. This pale area extends ventro-laterally and obliquely onto the upper lip from the anterior margin of eye. A large patch of the same contrasting color is present on the shoulder, upper arm and elbow. The upper lip is dark from posterior margin of pale patch and below eye to anterior margin of tympanum. The tympanum is dark. Rounded, pale patches extend antero-dorsally from anterior margin of origin of forelimbs to lateral margins of anterior pair of glandular ridges, and distally onto anterior surfaces of forearms to point near wrists. Dorsal aspects of hands are dark with darker band near each wrist. Hindlimbs have dark bands extending from thighs to feet, roughly equally-spaced. Hind limbs are pale brown with dark, thick transverse bands. Ventrum is immaculate or with diffuse grey mottling and yellowish tan or pale beige. The gular region is somewhat grayish.


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

Size

Phrynobatrachus irangi is the largest East African puddle frog species with females exceeding 50 mm (Channing and Howell, 2006). Snout-vent lengths vary from 36-46 mm (n = 14) in males and 45-51 mm (n=4) in females (Drewes and Perret, 2000).


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

Diagnostic Description

Phrynobatrachus iranigi has a stout habitus and is characterized by its ovular tympanum that is 3/4 the diameter of the eye, minute dorsal and lateral asperities, slight dilation of the digit tips, and only rudimentary to moderate webbing (3 phalanges free on toe IV). Tiny asperities are present on the central plantar surface of the foot in males and the majority of females. Males also exhibit one or two spines on the walking surface of the foot and several longitudinal, distensible vocal folds in the gular region.


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

Comparisons

Phrynobatrachus krefftii, the only other large species of puddle frog in East Africa, can be distinguished from P. irangi by it's slightly smaller size (SVL up to 36 mm in males and 41 mm in females), more extensive webbing (1-2 phalanges free on toe IV), larger inner metatarsal tubercle, and shorter fiifth toe. Breeding males of P. krefftii also have a sharply projecting snout, lack asperities on the plantar surface of the foot and exhibit a darkly outlined lower jaw with bright yellow throat.

There are also a number of osteological differences between the two species, revealed by cleared and double-stained specimens. The nasals of P. irangi are widely spaced, not greatly dilated medially and are not overlapped posteriorly by the sphenethmoids; P. krefftii nasals are more broadly dilated medially, less widely spaced, and overlapped by anterior projection of the sphenethmoids. The presacral vertebrae in P. krefftii are strongly imbricate; those of P. irangi are non-overlapping. The base of the omostemum in P. irangi is slightly notched; that of P. krefftii is moderately forked. The sternal style off P. irangi is near-rectangular, only slightly compressed medially, with a medial width greater than half the width of the anterior margin; that of P. krefftii is compressed medially, so that the medial width is half the width of the proximal margin of the structure. The bases of the thyrohyals originate posterior to a line drawn through the bases of the posterolateral processes in P. irangi. The thyrohyals of P. krefftii are deeply invasive into the corpus of the hyoid plate and extend anterior to the bases of the posterolateral processes.


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

Habitat and Ecology

This species is most likely dependent upon montane forest, and its currently known altitudinal range is approximately 1,900-2,300m asl. (Drewes and Perret, 2000; Drewes et al., 2004). Males have been found calling on the banks of small streams from under roots or logs, and from holes in the mud.


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

Population Biology

There is little information on population size or density since this species is difficult to locate (Drewes et al., 2004).


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

Activity and Special Behaviors

This species is diurnal (Drewes and Perret, 2000).


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

Advertisement Call

The advertisement call has been recorded from a chorus of many males, but no single voice was close enough for sonographic analysis (Drewes and Perret, 2000). The call was only emitted during the day was rather loud. The call was described by R. Keith (in her field notes, AMNH Archives) as "raugh-araugh-aaaaraugh-arararaugh-raraugh."


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

Reproduction

It most likely reproduces in the streams where males have been found calling, but this requires confirmation (Drewes et al., 2004).


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

Phylogenetics

No sequence data is currently available for this species.


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

IUCN Red List Category and Justification of Conservation Status

The IUCN Red List (2009) categorizes this species as Endangered because its Extent of Occurrence is less than 5,000 km2, all individuals are in fewer than five locations, and there is continuing decline in the extent and quality of its habitat in the Kenyan Highlands (Drewes et al., 2004).


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

Trends

Populations of this species are decreasing (Drewes et al., 2004).


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

Threats

It is possible that the Kimande population is now extinct because of severe modification of the native habitat by local subsistence farming, and loss of habitat is also likely to be a threat to the species elsewhere in its range (Drewes et al., 2004).


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

Conservation Actions and Management

This species has not been recorded from Mount Kenya and the Aberdares National Parks; however, it is possible that it does occur in these protected areas (Drewes et al., 2004).


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