AMPHIBIAWEB
Callulina dawida
Taita Warty Frog
family: Brevicipitidae

© 2009 John Measey (1 of 4)

Country distribution from AmphibiaWeb's database: Kenya

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

It is distinguished from other members of the genus on the basis of the degree of digital expansion. The species further differs from other members of the genus based on molecular sequence comparisons and on its call. The morphological variation in the new species is given below, including a comparison of similarities and differences in internal and external characters and sexual dimorphism with other species of Callulina. The conservation status of the species, on the basis of its restricted distribution and land use changes in the area, is considered to be of high concern.


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

Etymology

The specific name dawida is a noun in apposition. It is derived from Dawida, the language spoken by the inhabitants of Taita Hills where this species is found. The local Ki-dawida name king’ombe refers to the similarity in the movement of the animal to that of a cow (Ng’ombe = Ki-swahili for Cow). The common name Taita Warty Frog is given to reflect the restricted distribution of this species to Dawida and Mbololo blocks of Taita Hills, Kenya.


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

Distribution

Specimens were recorded from Mbololo and Dawida blocks (Mbololo, Ngangao, Chawia, Fururu, Vuria, Ndiwenyi, Mwachora and Boma-Wundanyi forests; see Figure 2 in publication). Based on surveys conducted in the Taita Hills, it has been calculated that the spatial distribution of Callulina dawida. The estimated extent of occurrence of C. dawida is equal to 168.2 km2 and the estimated area of occupancy is about 4.3 km2. These are respectively the area included in the polygon (minimum convex hull polygon) obtained by linking the localities where presence of the species was recorded and the area of eight forest fragments in the Taita Hills where C. dawida is known to occur.


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

Osteology

(as diagnosis) The species is assigned to the genus Callulina based on the following characteristics: Truncated or expanded terminal phalanges (simple in Spelaeophyrne, Probreviceps, Breviceps, and Balebreviceps); single posterior denticulated row in the palate of Callulina (two denticulated rows in Probreviceps, and a glandular mass in Breviceps); moderately sized wedge shaped lobes on the mentomeckelian elements, posteroventrally directed (in Probreviceps, Balebreviceps, and Breviceps variously reduced and enlarged, Largen and Drewes, 1989); cultriform process of the parasphenoid with broad based but narrow alary processes, tapering laterally (cultriform process of the parasphenoids in known brevicipitids show wide diversity, Largen and Drewes, 1989); nasals almost meet at midline (broadly separated in Breviceps and Balebreviceps); clavicle well-developed and straight though slightly curved anteriorly at the point of contact of the coracoid and scapulae (clavicle straight in Breviceps, Probreviceps, and Spelaeophryne) (see Figure 3a in original description); omosternum large (rudimentary or small in Breviceps, Probreviceps, and moderate in Balebreviceps, Figure 3a in original description); tympanum present and usually well-differentiated (absent in Balebreviceps and Probreviceps uluguruensis); double condylar articulation between the urostyle and the sacral vertebra (fused in Balebreviceps, Breviceps, and Probreviceps, Figure 3b in original description).


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

Morphology

The species is assigned to the genus Callulina based on the following characteristics: Truncated or expanded terminal phalanges (simple in Spelaeophyrne, Probreviceps, Breviceps, and Balebreviceps); single posterior denticulated row in the palate of Callulina (two denticulated rows in Probreviceps, and a glandular mass in Breviceps); moderately sized wedge shaped lobes on the mentomeckelian elements, posteroventrally directed (in Probreviceps, Balebreviceps, and Breviceps variously reduced and enlarged, Largen and Drewes, 1989); cultriform process of the parasphenoid with broad based but narrow alary processes, tapering laterally (cultriform process of the parasphenoids in known brevicipitids show wide diversity, Largen and Drewes, 1989); nasals almost meet at midline (broadly separated in Breviceps and Balebreviceps); clavicle well-developed and straight though slightly curved anteriorly at the point of contact of the coracoid and scapulae (clavicle straight in Breviceps, Probreviceps, and Spelaeophryne) (see Figure 3a in original description); omosternum large (rudimentary or small in Breviceps, Probreviceps, and moderate in Balebreviceps, Figure 3a in original description); tympanum present and usually well-differentiated (absent in Balebreviceps and Probreviceps uluguruensis); double condylar articulation between the urostyle and the sacral vertebra (fused in Balebreviceps, Breviceps, and Probreviceps, Figure 3b in original description).


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

Size

There is some size morphological difference between the sexes, mean SVL males = 27.1 (n = 9: 21.2—31.3) whereas mean SVL females = 29.1) (n = 9: 24.1—38.3). Three specimens were immature and not sexed or analysed. Females are larger than males, though not significantly (t-test, p = 0.5962). The position and size of the tympanum between male and females differ. Males have a significantly larger tympanum, e.g. tympanum-snout urostyle (t-test = > 0.001); and the position of the eye to the tympanum (t-test = > 0.001) is also greater in males. Besides these differences, no other significant differences in body proportions were observed. Males often appear lighter or more brightly coloured than females.


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

Diagnostic Description

Callulina dawida is a slightly smaller, robust shaped Callulina that is morphologically distinct from the two other species in this genus (C. kreffti and C. kisiwamsitu). The new species is distinguished by the following characters: truncate finger tips, rounded at edges, and only slightly expanded (if at all) beyond the width of the subarticular tubercle (finger tips expanded beyond the width of subarticular tubercle in C. kisiwamsitu and C. kreffti; see Figure 4 in original description); terminal phalanges Y-shaped but not expanded beyond the width of the base of phalange. Callulina kisiwamsitu and C. kreffti have terminal phalanges expanded distally beyond the width of the base of the phalange, C. kreffti has T-shaped terminal phalanges and some individuals exhibit an intermediate ‘T’ and ‘Y’ shape (e.g. CAS162505).

Tubercles on the hands and feet were treated as diagnostic for species in Callulina; de Sá et al. (2004) stated that in C. kisiwamsitu “there is no contact between inner and outer metatarsal”, however an examination of additional specimens indicates that this character is more variable than previously considered. Because inner, mid and outer tubercles seem to be quite variable in their size and position, and definition they cannot consistently discriminate between these species. Given that tubercles can also be desiccated, they can be difficult to discern precisely. This character needs to be further examined, among and within populations of Callulina to determine its systematic utility in the genus. The species shows the inner and outer tubercles separated on the hand by a mid palmar tubercle (Figure 4 in original description) that is also present in other Callulina species.


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

Comparisons

A morphometric analysis on 101 Callulina specimens were carried out in Loader et al. (2009): Callulina kreffti (57 individuals), C. kisiwamsitu (23 individuals), and C. dawida (21 individuals). Using an ANOVA analysis, three sets (each species) for all measures including ratios using snout-urostyle length, were investigated for any statistically significant differences. Statistical significance was shown in the following characters: snout-urostyle length ratios, distal phalange width (p = ≥ 0.001), infraorbital distance (p = ≥ 0.001), and jaw width (p = ≥ 0.001) (Table 1). The degree of digital expansion is identified as a key diagnostic feature for discriminating Callulina species. Furthermore, the robust shape of the head is shown to be statistically different in the new species from other species, as indicated by the significant larger jaw width (Table 1 in the original description). The infraorbital distance is also shown to be significantly different between species. The size of the tympanum is largest in the new species, although not statistically significant. All other morphological characters examined were not shown to be statistically significant, reflecting the generally similar shape and morphology of all species of Callulina.


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

Habitat and Ecology

The species is presently only known from remnant forest patches in the Taita Hills, Kenya. This species is found at elevations between 1200 - 2200 m (Harper et al., 2010).


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

Advertisement Call

A detailed temporal analysis of 1.5 minutes of calling from a single male recorded on 15 September 2008 in Wundanyi forest. This period comprised 10 calls, each call being made up of a mean of 7 "chirps" (range 5 to 9; std dev 1.15) with a mean duration of 0.06 seconds (range 0.05 to 0.07; std dev 0.007), and a mean interval of 0.17 seconds between chirps (range 0.14 to 0.28; std dev 0.03), three such chirps are shown in Fig. 6 in original description. The interval between calls had a mean of 7.21 seconds (range 0.75 to 15.11, std dev 4.82). Peak dominant frequency of Callulina dawida is at 1.6 KHz, with a notable harmonic at 3.2
KHz. The call and harmonic fall below 3.5 KHz (Figure 6 in original description), whereas C. kisiwamsitu is always below 2 KHz,
and peak dominant frequency in C. kreffti is always above 2 KHz but below 3 KHz (de Sá et al, 2004). The
call can best be described as a fast repeated "brrr brrr brrr...".


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

Reproduction

Not known but presumed to be a direct developer.


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

Phylogenetics

In analyses, Callulina species form a well-supported clade – as demonstrated by high bootstrap values. Within this grouping, the geographically close Usambara species C. kreffti and C. kiswamsitu form a clade – albeit weakly supported – with C. dawida
a sister group to this clade. Overall the analyses demonstrate the genetic distinctiveness of the three Callulina species.


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

IUCN Red List Category and Justification of Conservation Status

Based on these spatial estimates we applied the criteria set out by the IUCN for assessing the conservation status of species. The area of occupancy, consisting of eight severely fragmented locations, was estimated to be less than 10 km2. In addition, some of the forest fragments in which this species occurs are under severe pressure from an increasing local population who utilise forest products (both cutting sticks and collecting dead wood). Therefore, according to the IUCN criteria, the species conservation status is critically endangered (CR B1a, b (ii, iii)).


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

Conservation Actions and Management

Positive steps are being made to conserve the indigenous forest of the Taita Hills. Several eucalyptus and pine plantations in the area have been earmarked for conversion back to indigenous forest, and it is hoped that these measures will increase the suitable habitats available for many of the endemic species of the Taita Hills.


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