AMPHIBIAWEB
Phrynobatrachus krefftii
family: Phrynobatrachidae

© 2016 Dr. Joachim Nerz (1 of 16)
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: Tanzania, United Republic of

 

View distribution map using BerkeleyMapper.

   

From the Encyclopedia of Life account:

Summary

Phrynobatrachus krefftii is a large species (SVL 36-41 mm) of puddle frog from the mountains of northeastern Tanzania. Members of this genus are identified by the presence of a midtarsal tubercle, elongate inner metatarsal tubercle, and outer metatarsal tubercle. This species is characterized by a distinct tympanum, strongly developed digital discs and extensive webbing (1-2 phalanges free on toe IV). Breeding males of P. krefftii have a sharply projecting snout, thickened nuptial pad on toe I, and a darkly outlined lower jaw with bright yellow throat.


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

Etymology

This species was named for Dr. P. Krefft who discovered the species in the Usambara Mountains.


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

Distribution

This species is known only from the East and West Usambara Mountains (including the Magrotto ridge) in north-eastern Tanzania (Loader et al., 2004).


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

Morphology

Canthus rostralis is indistinct; loreal region is slightly concave. Nostril is equidistant from eye and end of snout. The interorbital space is as broad as the upper eyelid. The tympanum is distinct; diameter is approximately two-thirds that of the eye. Fingers are moderately long, the first shorter than the second. Subarticular tubercles are small. Digital discs are strongly developed. Pedal webbing is extensive with 1-2 phalanges free on toe IV. Skin is smooth according to Boulenger (1909), but Barbour and Loveridge (1928) noted that there are dorsal asperities in males. Dorsum is brown or olive with darker spots. A darker cross-bar with a light edge in front is present between the eyes. Limbs have indistinct cross-bands. Venter whitish with belly and lower surfaces of limbs dotted with brown. A brown band present across the throat. The lower jaw is edged with dark brown. Breeding males have a sharply projecting snout, thickened nuptial pad on toe I, toes with plantar tubercles developed as sharp spines, and a darkly outlined lower jaw with bright yellow throat. Females and immature males have a white or greenish throat (Boulenger, 1909; Barbour and Loveridge, 1928; Channing and Howell, 2006).


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

Size

Phrynobatrachus krefftii is only one of two large East African puddle frog species with males reaching 36 mm and females reaching 41 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

This species is characterized by a distinct tympanum, strongly developed digital discs and extensive webbing (1-2 phalanges free on toe IV). Breeding males of P. krefftii have a sharply projecting snout, thickened nuptial pad on toe I, and a darkly outlined lower jaw with bright yellow throat.


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

Comparisons

Phrynobatrachus irangi, the only other large species of puddle frog in East Africa, can be distinguished from P. krefftii by it's slightly larger size (SVL up to 46 mm in males and 51 mm in females), less extensive webbing (3 phalanges free on toe IV), smaller inner metatarsal tubercle, and longer fiifth toe. Breeding males of P. irangi also have rounded snouts, asperities on the plantar surface of the foot and breeding males lack a 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

It is generally associated with montane and submontane forest, and is also found in rural gardens and in open areas, but generally not far from forest and certainly not in completely open landscapes (Loader et al., 2004). It is found in small streams, marshes, and pools (Channing and Howell, 2006) Its altitudinal range is 700-1,500m asl. (Loader et al., 2004).


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

Associations

Recorded food items include beetles, spiders, ants, bugs, weevils, millipedes, crabs, and cockroaches (Channing and Howell, 2006).


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

Population Biology

It is widespread and common within its small range (Loader et al., 2004)


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

Activity and Special Behaviors

Phrynobatrachus krefftii is diurnal.

It is the first species of anuran amphibian reported to perform nonaudible vocal-sac inflations during intraspecific male-male signaling behavior (Hirschmann and Hödi, 2006). Interactions between adult males are highly dominated by inflations of the bright yellow subgular vocal sac without sound production. Most (77%) inflations of the vocal sac were purely visual, while the remainder (23%) of the signals were accompanied by sound production. This behavior is presumably territorial (Harper and Vonesh, 2003).


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

Advertisement Call

Males call from the edge of shallow water or while under vegetation within the water. Calls consist of low-pitched notes that are produced rapidly at the beginning and becoming progressively slower. A typical call consists of 13 notes with a duration of 2.7 sec at an initial rate of approximately 8 notes/ sec. The emphasized frequency is 2.3 kHz (Channing and Howell, 2006).


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

Reproduction

This species begins to breed with the long rains in November (Channing and Howell, 2006). Breeding takes place in small streams, marshes and pools, egg masses being attached to rocks or vegetation above the water (Loader et al., 2004). Egg masses, containing around 15 – 30 darkly pigmented eggs, are attached to rocks or vegetation above the water (Harper and Vonesh, 2003).


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

Tadpole morphology

Length of body nearly twice the width and approximately one half the tail length. Nostrils slightly nearer the snout tip than eye. Eyes positioned dorsolaterally. The distance between the eyes is somewhat greater than the width of the mouth. The spiracle is on the left side, directed upwards, and much closer to the eye than the posterior end of the body; it is visible from above and below. Anal tube is horizontal in the lower edge of the subcaudal fin and slightly bent to the right. The tail is slightly more than fours times as long as deep and sharply pointed. The upper and lower fins rather narrow. The buccal disc is rather large and tranverse. The upper lip is slightly arched and edged with small, horny teeth. THe lower lip and sides fimbriated and with many blunt papillae. Two rows of fine horny teeth between the upper lip and horny beak, which is wide, arched, and well developed, considerably overlapping the well-developed but much smaller lower beak. Posterior to the beak, three long parallel series of horny teeth are present. The color is greyish above and whitish or transparent below. The tail is finely speckled with dusky brown (Barbour and Loveridge, 1928).


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

Phylogenetics

Mitochodrial sequence data from 12S rRNA, valine-tRNA, and 16S rRNA fragment, as well as combined sequence data from mitochondrial and nuclear (RAG-1) genes indicate that P. krefftii is the sister species to a clade of large-bodies puddle frogs from the Albertine Rift, including P. acutiroistris, P. dendrobates, P. petropedetoides, and P. versicolor (Zimkus, 2010). This group of puddle frogs in turn are sister to Phrynobatrachus sandersoni.


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 and its Area of Occupancy is less than 500 km2, its distribution is severely fragmented, and there is a continuing decline in the extent and quality of its habitat in the Usambara Mountains (Loader et al., 2004).


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

Trends

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


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

Threats

The encroachment and degradation of the forest for agriculture, human settlement and wood is probably adversely affecting this species to some extent, despite the fact that it is somewhat adaptable. Its habitat in the East Usambaras has recently come under serious threat as a result of the activities of illegal gold miners (Loader et al., 2004).


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

Conservation Actions and Management

It occurs in several forest reserves, including the Amani Nature Reserve and the University of Dar es Salaam's nature reserve at Mazumbai. There is a need for improved management and protection of forest reserves in the Usambara Mountains (Loader et al., 2004).


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