AMPHIBIAWEB
Probreviceps durirostris
family: Brevicipitidae

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

View distribution map using BerkeleyMapper.


Conservation Status (definitions)
IUCN (Red List) Status Endangered (EN)
See IUCN account.
CITES
Other International Status None
National Status None
Regional Status None

   

From the Encyclopedia of Life account:

Etymology

The name durirostris is derived from the latin “dura” meaning hardened and “rostris” meaning nose. The name is used in reference to the distinctive hardened nose of the new species.


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/

Summary

P. durirostris is a medium sized Probreviceps which can be easily distinguished from all other species by its markedly pointed snout, which is hardened white with ridges along the canthus to the apex of the snout, tympanum that is sexually dimorphic with respect to tympanum size, presence of finger ridging, although not as strongly as P. uluguruensis, vent that opens posteroventrally, and differing advertisement call from all other species recorded.


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/

Distribution

This species is known only from the Ukaguru Mountains in eastern Tanzania between 1,500 and 1,900m asl. It is thought likely to be endemic to the Ukaguru Mountains.


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/

Osteology

The species is a brevicipitid on account of the following combination of characters, mainly associated with the retention of the shoulder girdle (Parker, 1934, see Fig. 3): (1) Omosternum cartilaginous (2) Fully developed clavicles and procoracoid cartilages (3) Dilated coracoids (4) Cartilaginous sternum (5) Expanded vomer. The species is assigned to the genus Probreviceps based on the following characters, which separate it from other brevicipitines: (1) Fusion of the urostyle and the sacral vertebra (unfused in Callulina and Spelaeophryne). (2) Palate smooth with two serrated denticulate ridges sensu Parker, (1934); Largen and Drewes, (1989) (absent in Breviceps, single row in Callulina, Spelaeophryne, Balebreviceps). (3) Omosternum moderately large (reduced/vestigal in Breviceps and Spelaeophryne) (4) Moderately dilated coracoids (as in Spelaeophryne and Callulina but strongly in Balebreviceps, Breviceps) (5) Terminal phalange simple (expanded in Callulina). 


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/

Morphology

Description of holotype: The SUL is 34.3mm. The head is flat on top with a protruding snout, 5.0mm, the canthal ridges, tip of snout and the upper lip are white and hardened. The canthal ridges, which form an apex at the anterior of the snout are continuous with the ridged skin of the eyelids. The apex of the snout is ridged and slightly raised and pointed in profile. Loreal region is almost vertical, slightly concave. Snout tip to mouth 3.0mm. Maximum head width 14.0mm. Nostrils are round, situated midway between lip and top of snout, with the openings visible laterally. Tongue longer than wider, posterior half and lateral edges not adhered to the lower jaw. Choanae are small and round. Internostril distance 3.3. Snout tip to nostril 2.2mm, and nostril to eye 2.5mm. The eyelid (4.7mm) extends back as a strong supratympanic ridge to above the arm as a fold in the dorsal skin. The eyes are visible from below, eye 3.6mm. Interorbital distance measured across the top of the head 4.3mm. The anterior corners of the eyes are 6.2mm apart. The tympanum is round, 2.8mm, placed 2.5mm from eye, and aligned vertically when viewed from the front. The tubercles of the hand are pale, large with faint skin ridges. First finger is the shortest, with second and fourth toe slightly larger, the third being the longest. Length of third finger to include basal tubercle 7.25mm. The legs are relatively short, with a tibia length 17.2mm. First toe is the shortest, with second and fifth toes slightly longer, roughly similar in length, third toe is nearly twice as long as second and fifth, with the fourth the longest. The length of the fourth toe, including the outer metatarsal tubercle 18.6mm. The subarticular tubercles of the toes are rounded, pale, with faint skin ridges. Inner metatarsal tubercle well developed, rounded, length 2.9mm, while outer is large but flattened. Skin rough with small distinct glands that tend to merge on the lower back and upper legs. They are small anteriorly, becoming bigger posteriorly. The only parts not covered with glands are the plantar surfaces of the hands and feet. The vent opens posteroventrally. The following are the body proportions: Maximum head width/SUL 0.35, snout/eye 1.39, eye/ SUL 0.09, eye-tympanum distance/horizontal tympanum 0.89, tympanum/SUL 0.07, anterior corners of eyes/head width 0.44, snout tip to mouth/internostril distance 0.91, internostril/nostril-eye 1.32, third finger/head width 0.52, tibia/head width 1.23, tibia/SUL 0.43, fourth toe/SUL 0.40, inner metatarsal tubercle/fourth toe 0.16.


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/

Comparisons

P. durirostris is a medium sized Probreviceps which can be easily distinguished from all other species: (1) Snout morphology: P. durirostris has a markedly pointed snout, which is hardened white with ridges along the canthus to the apex of the snout. Probreviceps m. rungwensis has a pointed snout, but is not hardened, white in colour, nor does it have a ridged canthus. All other species of Probreviceps have relatively rounded snouts. (2) Tympanum size: P. durirostris is sexually dimorphic with respect to tympanum size, which varies from 13 to 16% of SUL in males, and 4 to 7% in females. This is similar to P. m. rungwensis, which varies from 9 to 14% in males, and 4 to 7% in females. Both P. m. loveridgei and P. m. macrodactylus males do not possess such large tympani, varying from 4 to 7% in males, and 3 to 5% in females. Four P. rhodesianus specimens measured vary in typmanum size 3–5% of SUL. P. uluguruensis does not have a visible tympanum. (3) Finger ridging: Parker reported a fleshy ridge along the inner side of the second and third finger in P. uluguruensis. Finger ridging is present in P. durirostris, though in some specimen only faintly and not as strongly as P. uluguruensis. Similarly, in P. m. rungwensis and P. rhodesianus finger ridging is present, though very slight in the latter. The ridge is almost entirely absent in P. m. macrodactylus and P. m. loveridgei. (4) Position of vent: The vent opens posteroventrally in P. durirostris (as in P. m. macrodactylus, P. m. loveridgei, and P. m. rungwensis) (opens ventrally in P. rhodesianus, and P. uluguruensis). (5) Advertisement call: the new species can be distinguished from all other species recorded. The call of P. durirostris is a very slow series of clicks, slightly faster than one every two seconds. This contrasts with the calls of three taxa of Probreviceps in Tanzania that are rapidly pulsed chirps (Mkonyi et al 2004), varying from a mean of 20/sec (P. uluguruensis); 38/sec (P. m. macrodactylus) to 90/sec (P. m. loveridgei). The calls of P. m. rungwensis from Mount Rungwe and the Udzungwa Mountains in Tanzania, and P. rhodesianus from Zimbabwe, are unknown.


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/

Habitat and Ecology

All records are from leaf litter in montane forest. It probably cannot tolerate forest clearance. It presumably breeds by direct development, like other members of its genus, without any dependence on water.


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/

Advertisement Call

Males call actively during the day, with some residual calling at night. Calling takes place from within leaf litter or while the animals are concealed under logs or other forest debris. Choruses form rapidly after an individual starts calling. Males were recorded in the field at the Mamiwa-Kisara Forest Reserve. The call is a slow series of clicks, produced at a rate of approximately 32/minute. Each click consists of a single high-energy pulse with a duration of 6 ms. No real harmonics are present, although significant energy is present at 1.2, 1.6, 2.6, 4.3 and 5.4 kHz.


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/

Reproduction

No details of breeding are known, but brevicipitines are considered to be direct developers (McDarmid and Altig, 1999).


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/

Phylogenetics

In summary, the tree demonstrates that Probreviceps durirostris is monophyletic, and is the sister species to Probreviceps m. rungwensis. Probreviceps m. rungwensis is also shown to have two divergent lineages, which each correspond to distinct areas- the Udzungwa and Southern Highlands. For further details of the analysis of species and intrageneric relationships in brevicipitines, see
Loader et al. (2004).

One alternative tree arrangement was investigated to evaluate a previous taxonomic hypothesis based on morphology (Parker, 1934), i.e. the monophyly of P. macrodactylus. Using parsimony, a Templeton test (Templeton, 1983) compared the optimal treewith constrained suboptimal topology. Likelihood tests (Shimadairo-HasegawaTest) were similarly applied to compare optimal and suboptimal trees. The best suboptimal trees including a constrained monophyletic P. macrodactylus subspecies complex, are a significantly worse fit to the data than the optimal arrangements. This result indicates, as shown by Loader et al. (2004), that P. macrodactylus requires re-evaluation, the subject of a paper in preparation.


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/

IUCN Red List Category and Justification of Conservation Status

Listed as Endangered because its Extent of Occurrence is less than 5,000 km2, all individuals are in a single location, and there is continuing decline in the extent and quality of its habitat in the Ukaguru Mountains.


Author: Loader, Simon
License: http://creativecommons.org/licenses/by-nc/3.0/