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A remarkable new species of Callulina (Amphibia: Anura: Brevicipitidae) with massive, boldly coloured limb glands

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Abstract

A large new species of Callulina is described from a series of 22 specimens from the montane and upper montane forest of the Nguru Mountains, Tanzania. The most striking features of Callulina meteora sp. nov. are the massive and boldly coloured glands on the arms and legs and a metallic sheen to the skin. The new species is distinguished further on the basis of acoustic and molecular data. The position, size and conspicuousness of the enlarged glands in the new species are strik-ingly similar to those of Nectophrynoides viviparus, a toad found also in the Eastern Arc Mountains of Tanzania. The new species is known from a single forest reserve and is of high conservation concern.
Accepted by M. Vences: 4 Oct. 2011; published: 10 Nov. 2011
ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)
Copyright © 2011 · Magnolia Press
Zootaxa 3095: 1526 (2011)
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15
A remarkable new species of Callulina (Amphibia: Anura: Brevicipitidae)
with massive, boldly coloured limb glands
MICHELE MENEGON1,2, DAVID J. GOWER3 & SIMON P. LOADER4
1Tropical Biodiversity Section, Trento Science Museum, Via Calepina 14, I–38100 Trento, Italy. E-mail: menegon@mtsn.tn.it
2Department of Environmental & Geographical Sciences at Manchester Metropolitan University, Manchester, UK.
3Department of Zoology, The Natural History Museum, London SW7 5BD, UK
4Department of Environmental Science, Institute of Biogeography, University of Basel, Switzerland.
Abstract
A large new species of Callulina is described from a series of 22 specimens from the montane and upper montane forest
of the Nguru Mountains, Tanzania. The most striking features of Callulina meteora sp. nov. are the massive and boldly
coloured glands on the arms and legs and a metallic sheen to the skin. The new species is distinguished further on the basis
of acoustic and molecular data. The position, size and conspicuousness of the enlarged glands in the new species are strik-
ingly similar to those of Nectophrynoides viviparus, a toad found also in the Eastern Arc Mountains of Tanzania. The new
species is known from a single forest reserve and is of high conservation concern.
Key words: aposematism, Eastern Arc, glands, Nectophrynoides, Nguru, Tanzania
Introduction
Patterns of species distributions in the Eastern Arc Mountains of Tanzania and Kenya are characterised by high lev-
els of endemism (Myers et al., 2000; Burgess et al., 2007). However, much of the documented endemism is patchy,
with greatest diversity being found in the East Usambara, Uluguru and Udzungwa Mountains (Fig. 6). This patchi-
ness can, in part, be attributed to uneven sampling (Burgess et al., 2007; Ahrends et al., 2011). Increasing under-
standing of other mountain blocks in the Eastern Arc suggest that high levels of endemism are more widely
distributed throughout the region, but many species remain to be described (Menegon & Davenport, 2008; Mene-
gon et al., 2008, 2011; Loader et al., 2011a). The Nguru Mountains is one part of the Eastern Arc from where a
number of new amphibians, with highly restricted distribution, have been described recently (Poynton et al., 2009;
Loader et al., 2010a,b, 2011b) and more reported to await description (Menegon et al., 2008; Loader et al., 2009b).
Potentially this area might be considered as one of the richest areas for biodiversity in the Eastern Arc Mountains
and therefore globally.
The eight nominal species in the genus Callulina Nieden 1911, are almost entirely restricted to submontane
and montane forest of the Eastern Arc Mountains (Loader et al., 2010b). A hotspot of species richness for this
genus is the Nguru Mountains, with two species recently described (Loader et al., 2010b), one from the Nguru
South Forest Reserve (C. hanseni) and another from Kanga Forest Reserve (C. kanga). We describe here the third
new species endemic to the Nguru Mountains. A fourth probably new species (“Callulina sp. 3”) was mentioned by
Menegon et al. (2008) but is not described here because it has a more complex distribution, is less easily diag-
nosed, and is the subject of ongoing research.
Material and methods
Specimens were collected from two separate surveys conducted in the Nguru South Forest Reserve in 2004 and
2008. Specimens and tissues collected in 2004 are deposited in the collection of Museo Tridentino di Scienze Nat-
MENEGON ET AL.
16 · Zootaxa 3095 © 2011 Magnolia Press
urali, Trento, Italy (MTSN) and were fixed and preserved in 70% ethanol. Specimens collected in 2008 are depos-
ited in the collection of the Natural History Museum, London, UK (BM), were fixed in 5% formalin and are
preserved in 70% ethanol. Corresponding tissues are held at the Institute of Biogeography, University of Basel,
Switzerland. Photographs and sound recordings are deposited in the Museo Tridentino di Scienze Naturali, Trento,
Italy, and in the collections of the Department of Zoology and Marine Biology, University of Dar es Salaam, Dar es
Salaam, Tanzania.
All specimens were measured using a Mitutoyo CD-6”CS electronic caliper. Measurements were taken to the
nearest 0.1 mm by SPL. Following Loader et al. (2009a, 2010a, b), the measurements taken and abbreviations used
here are: ED, horizontal diameter of eye; ETD, eye–tympanum distance; HL, upper arm length; HW, head width at
level of jaw articulation; IOD, interorbital distance; LF3, length of finger 3, measured from the distal edge of the
basal subarticular tubercle; LT4, length of toe 4, measured from the proximal edge of the basal subarticular tuber-
cle; ND, nostril diameter; NED, nostril–eye distance; NLD, nostril–lip distance; SUL, snout–urostyle length; TD,
horizontal diameter of tympanum; TL, tibiofibula length; TSL, length of tarsus; WDF3, width of disc of finger 3;
WDTF3, width of finger 3 at level of distal subarticular tubercle. Summary statistics are provided in Table 1. The
data were compared with previous Callulina morphometric datasets (de Sá et al., 2004; Loader et al., 2009a,
2010a,b). Specimens examined and locality data are provided in the species account.
TABLE 1. Morphometric data for all Callulina meteora sp. nov. specimens (n= 22), all measurements in mm. See Materials
and Methods for explanation of abbreviations.
Skeletal characters were examined from radiographs and cleared and stained specimens. Two specimens
(MTSN 8132, BMNH 2008.464) were cleared and double-stained for bone and cartilage based on the method of
Taylor & Van Dyke (1985). Radiographs were made for MTSN 8129, 8131, and 8133-34 to check characters
revealed in the cleared and stained specimens. Comparative material examined is listed in previous publications
(Loader et al. 2010a, b). Calls were recorded using a Sharp MT 877 mini-disc recorder, and analysed using Raven
(Charif et al. 2004). Methods for DNA extraction (from ethanol preserved tissue samples), PCR, sequencing and
subsequent analyses exactly follow the approach outlined by Loader et al. (2010a). Sequences were generated for
parts of the mitochondrial (mt) genes 12S, 16S and cytochrome b (cytb) for new samples of the new species, com-
plementing previous datasets (Loader et al. 2009, 2010a,b). New sequences were deposited in Genbank, FN563060
– 3065.
Callulina meteora sp. nov.
(Figs. 1–3, 5–7; Table 1)
Callulina sp. 1 Menegon et al. (2008: p.114, appendix 1, tables 3, 4).
Holotype. BMNH 2008.450 (Field tag MW 6825) a mature female (Fig. 1). Collected from the Maskati side of the
Nguru South Forest Reserve, Tanzania, 6.069027778 S - 37.50066667 E, 1980 m (Fig. 6) by David Gower, Roy
Hinde, Simon Loader, Hendrik Müller, Maria Müller, and Mark Wilkinson in January 2008.
Paratypes. MTSN 8129-8134 (MTSN 8134, 39 ova in vitellogenesis; MTSN 8130 cleared and stained),
MTSN 8141, collected by Michele Menegon between October 26 and November 02, 2004 in the Nguru South For-
est Reserve, 6.06630176 S - 37.49802743 E, Nguru Mountains, Morogoro Region. Tanzania. BMNH 2008.118-
451-452-453-454-455-456-457-458-459-460-461-462-463-464 same collection data as holotype.
Diagnosis. The species is assigned to Callulina within Brevicipitidae based on the following morphological
features: Moderately sized wedge-shaped lobes on the mentomecklian elements, posteroventrally directed (vari-
ably reduced/enlarged in Probreviceps, Balebreviceps, and Breviceps, see Largen & Drewes 1989); cultriform pro-
SUL TL TD ETD ED ND NED HW LF3 LT4 TSL HL NLD WDF3 WDTF3 IOD
Min. 13.9 4.6 0.5 1.1 1.9 1.1 1.3 4.8 1.7 1.9 3 3.7 0.7 0.5 0.5 2.5
Max. 40.6 14.6 2 2.8 4.5 2.6 3.2 15.7 5.6 7.3 11.3 12.8 1.9 1.4 1.6 6.8
Mean 31.7 11.5 1.3 2 3.6 2.1 2.4 11.8 4.2 5.5 8.8 9.9 1.5 1.2 1.1 5.6
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NEW CALLULINA FROM NGURU MOUNTAINS OF TANZANIA
cess of the parasphenoid with broad base but narrow alary processes, tapering laterally (cultriform process of the
parasphenoids widely variable in breviciptids, Largen & 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 between coracoid and scapulae (clavicle straight in Breviceps, Probreviceps, Spelaeophryne);
omosternum large (rudimentary or small in Breviceps, Probreviceps, moderate in Balebreviceps); tympanum pres-
ent and usually well-differentiated (absent in Balebreviceps and Probreviceps uluguruensis); double condylar artic-
ulation between the urostyle and the sacral vertebrae (fused in Balebreviceps, Breviceps, and Probreviceps);
truncated terminal phalanges (simple in Spelaeophyrne, Probreviceps, Breviceps, and Balebreviceps); single poste-
rior denticulated row in the palate of Callulina (two denticulated rows in Probreviceps, glandular mass in Brevi-
ceps).
FIGURE 1. Dorsal, ventral and lateral views of the female holotype (BMNH 2008.450) of Callulina meteora sp. nov.
MENEGON ET AL.
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FIGURE 2. Callulina meteora sp. nov. in life from the type locality, showing some of the species variability.
Callulina meteora is morphologically distinct from most other species of Callulina (C. kreffti, C. kisiwamsitu,
C. dawida, C. kanga, C. laphami and C. stanleyi) in having large glands on the limbs. The new species is distin-
guished from C. shengena and C. hanseni (also with enlarged limb glands) by the presence of a tympanum (absent
in C. shengena) and limb glands that are distinctly differently coloured to the rest of the limbs (no distinctive gland
colour in C. hanseni).
Description of holotype. Female. Body stout, head short but as wide as body. Snout truncate in lateral view,
snout-tip extending slightly beyond upper and lower jaws. Snout tip rounded at edges, flattened not pointed at
apex. Canthus rostralis rounded. Dorsal aspect of head covered by small, rounded, irregular-shaped warts. Ventral
region with larger, granular like warts on chin and underside. Eyelids smooth with very small irregular shaped
warts. Pupil was horizontal before preservation. Tympanum distinct, suboval (not as tall as long), smooth, with
granular warts on slightly raised rim around edge of disc. Dorsum of body with small, irregular glandular masses
giving warty appearance. Ventral surface with larger irregular shaped glandular masses, slightly larger and more
granular on flanks. Forelimb slender. Massive continuous glands covering dorsal and ventral aspects of forearm.
Surface of massive arm gland with smaller, irregular, slightly smoother bumps. Webbing almost absent on hand,
only marginal rudimentary skin joining each finger. Distal phalanges moderately long, thick, truncate, expanded
only slightly, rounded at edges. Inner tubercle smaller than outer tubercle, separated by a mid-palmar tubercle. First
finger shortest, followed by second, fourth, third. Tubercles darker than silvery/metallic background of hand. Hind
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NEW CALLULINA FROM NGURU MOUNTAINS OF TANZANIA
limbs stout, tibia, metatarsus and carpal area of tarsus covered by an enlarged glandular mass. Distal phalanges of
feet moderately long, thick, truncate, expanded only slightly, rounded at edges. First toe marginally the shortest,
followed by second, third, fifth, fourth. On toes and fingers, terminal phalanx darker, with a fold of skin, marked by
a white line at the dorsal junction between the penultimate and ultimate phalanges. Webbing almost absent on foot,
only marginal rudimentary skin joining each toe. Inner and outer tubercle in contact, equal in size. Vent ventro-pos-
teriorly positioned.
FIGURE 3. Sonograms of Callulina species.
MENEGON ET AL.
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Measurement of holotype. SUL = 38.2; TL = 13.5; ED = 4.2; TD = 2.0; ETD = 2.2; ND = 2.5; NED =2.8; JW
= 13.8; LF3 = 4.4; LT4 = 5.7, TSL = 11; HL = 12.1; NLD =1.7; WDF3 = 1.3; WDTF3 = 1.2; IOD = 6.1.
Colour. In preservative, the holotype dorsal ground colour is pale grey/brown, with darker brown patterning as
irregular lateral dorsal markings. The flanks are a paler grey/brown. The dorsal and ventral surfaces of the thighs
are dark brown, contrasting strongly with the silvery/metallic colouration of the glands. The ventral surface of the
body is cream, with a dark brown colouration on the lateral edges. In life, the holotype has the same patterning as in
preservative but with more vivid colours. The massive glands on the limbs are silvery, giving a striking metallic
sheen to the surface (see Fig. 2).
Variation. The tympanum is usually distinct in Callulina meteora, but in some paratypes (BMNH 2008.464,
BMNH 2008.453-455, BMNH 2008.461, BMNH 2008.451) it is poorly demarcated and was measured by dissect-
ing the skin around the region. Otherwise there is little notable (non-colour) morphological variation among indi-
viduals apart from between the sexes. Males are significantly smaller in body length (T-test: <0.05, females, SUL=
34.8–40.6 mm, x= 41.55 mm, number= 8; males, 26.5–35.4 mm, x= 30.1 mm, number= 9), and head width (T-test:
<0.05). All other morphological characters analysed are not significantly different between the sexes.
Colour variation. Callulina meteora individuals show wide colour variability with some rather constant pat-
terns. In all examined individuals, the massive limb glands are paler than surrounding areas, often whitish or sil-
very with, as in the rest of the body, a metallic sheen (see Fig. 2). The body can be almost completely white or
coppery brown, with darker areas on the dorsum, inguinal, axillary and tympanic zones and on limbs. In some
specimens (e.g., MTSN 8129), darker areas on the dorsum are extensive and almost black. The entire animal has a
metallic sheen that persists after preservation. Eye colour in life is bright yellow to orange.
Call. Advertisement calls of two males Callulina meteora were recorded at the collecting site by M.M.
between October 26 and November 2 2004 both during the day and the night. Calling males were seen at the base
of trees. The call is composed of a single periodic pulse train, introductory notes, and repeated notes. These three
elements are sometimes arranged in different ways: a single periodic pulse train could be heard with or without
introductory notes. Full calls in rainy weather were heard to comprise three or four modules of introductory notes
followed by a single pulse train and a final introductory note followed by a group of similar pulse trains. The pres-
ence of the introductory note was previously known for the recently described C. kanga only (Loader et al.,
2010b). The last call element of C. meteora considered alone shows temporal properties similar to the call of the
other Callulina species. The single periodic pulse train is composed of six pulses and has a length ranging from
0.067 to 0.078 sec, but the temporal properties of repeated note remains the same. The introductory notes usually
rising in intensity are composed of 16 to 21 pulses and have a length ranging from 0.203 to 0.238 sec. All sound
emissions have an average intensity maximum around 1.6 kHz (see Fig. 3).
FIGURE 4. Views of the habitat at the type locality of Callulina meteora sp. nov.
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NEW CALLULINA FROM NGURU MOUNTAINS OF TANZANIA
Habitat and natural history. Callulina meteora is partly sympatric with C. hanseni (Loader et al., 2010b) and
seems to be restricted to the montane and upper montane forest of the Nguru South Forest Reserve (Menegon et al.,
2008). All specimens were collected between 1950–2100 m asl but calls were heard up to 2200 m. This distribution
is similar to that reported for Arthroleptis nguruensis (Poynton et al., 2009). Some specimens were found during
the day by digging in soft soil and leaf litter accumulating at the base of large trees. This microhabitat together with
the presence of strongly keratinized and well-raised metatarsal tubercles is suggestive of semifossoriality. On the
basis of the presence of large eggs found in the oviduct of a dissected female, we presume that the species is ovipa-
rous with direct development. Although no direct evidence is known for the genus Callulina, oviparity with direct
development is regarded as the most likely reproductive mode for this genus of breviciptids (Müller et al., 2007).
FIGURE 5. Phylogenetic tree of all nominal species of Callulina, using a) Maximum likelihood, with bootstrap results given
above and symbols below show the results of Kishino–Hasegawa tests of differences in log likelihoods between optimal and
the best suboptimal trees obtained from converse topological constraints. Presence (+) or lack (-) of support at the p 0.05
level, b) Maximum Parsimony, numbers above branches are bootstrap proportions, numbers below internal branches are decay
indices. The symbols following the decay index values show the results of Templeton tests of differences in length between the
MPTs and the best suboptimal trees obtained from converse topological constraints. Presence (+) or lack (-) of support at the p
0.05 level.
Conservation status. Based on current knowledge of the species’ distribution and habitat preference, the esti-
mated extent of occurrence of Callulina meteora is equal to or less than 42 km2, and the estimated area of occupancy
not larger than 26 km2; these are respectively the area including the elevational distribution (1980–2100 m) of this spe-
cies in the Nguru South Forest Reserve and the area included in the polygon obtained by linking the localities where the
presence of the species was recorded (Fig. 6). Therefore, according to Red List (IUCN 2009) categories based on the
criterion of an extent of occurrence estimated to be less than 100 km2, the presence of one population at only a single
location, compounded with an observed decline in area, extent and quality of the habitat (IUCN, 2010), we suggest that
MENEGON ET AL.
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C. meteora qualifies as critically endangered or, more technically, CR B1b (iii). The proposed conservation status
would need to be re-evaluated if specimens are recovered below 1980 m, but herpetological surveys examining species
turnover between 800–2200 m have been conducted in the area over the past seven years (S.P.L. and M.M. unpublished
data; Owen et al., 2008) and C. meteora has never been recovered below 1980 m. Currently the population density
appears to be locally high but with increasing pressure due to land-use changes in the region (pers. obs.), and predicted
climate-mediated changes that could affect the high montane zone, the species is clearly facing threats.
Etymology. The specific epithet is used as an adjective and derives from the greek word meteoron, meaning
"thing high up," in reference to the type locality of the species, situated close to the top of the Nguru Mountains.
Molecular analyses. To examine the distinctiveness of and relationships among Callulina species, we analy-
sed sequence data for 12S, 16S, and cytb mt genes for all nine nominal species, including C. meteora. The dataset
comprised 24 individuals and 1124 unambiguously aligned characters, of which 707 were constant, 140 variable
and uninformative, and 277 informative under parsimony. Breviceps mossambicus was used to root trees and Pro-
breviceps m. macrodactylus and Spelaeophryne methneri were used as additional outgroups (see Loader et al.
2010a).
Parsimony analysis yielded two most parsimonious (MP) trees of 915 steps (Fig. 5b). These topologies differ
from the optimal likelihood tree (Fig. 5a). The two MP trees differ in the position of C. shengena and C. kanga. In
one MP tree, C. shengena is sister to C. laphami, and in the other it is sister to all other (except C. laphami) Callu-
lina species. Callulina kanga is recovered as sister to a clade comprising a Nguru radiation (C. meteora, C. han-
seni), C. dawida, C. stanleyi and C. kisiwamsitu in the former MP tree. In the second, C. kanga is sister to C. kreffti.
Neither of the alternative topologies is well supported. Most analyses supported the monophyly of Callulina (best
trees with a non-monophyletic Callulina are significantly suboptimal in Templeton but not likelihood topology
tests). All nominal species are robustly monophyletic (Fig. 5). Likelihood analysis recovered a tree similar to that
presented by Loader et al. (2010a: fig. 8b) differing only in the position of C. shengena. In Loader et al. (2010a) C.
shengena was sister to all other Callulina species (but not well supported) whereas here C. shengena is sister to C.
laphami, also only very weakly supported. The new species, C. meteora, forms a clade with C. hanseni in all anal-
yses. Pairwise distances values highlight the genetic distinctiveness of all named Callulina species (as previously
shown in Loader et al., 2010b), including the new species C. meteora (3.8–4.0 % different to its sister group C.
hanseni). Despite the genetic distinctiveness of the nominal species, the phylogenetic signal in the available mt
sequence data is insufficient to provide a compelling resolution of their interrelationships using the methods
employed here.
Revised key to the species of Callulina
Externally, Callulina species are distinguished from other breviciptids by their truncate to expanded toe and finger
tips.
1a. Tympanum present, though often obscured superficially by granular skin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
1b. Tympanum absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2a. Finger tips expanded, wider than the distal subarticular tubercle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
2b. Finger tips truncated, not expanded beyond the width of the first subarticular tubercle . . . . . . . . . . . . . . . . . . . . . . . .C. dawida
3a. Ratio between the width of Finger 3 at the level of the distal subarticular tubercle and the width of its finger tip > 0.75 . . . . .5
3b. Ratio between the width of Finger 3 at the level of the distal subarticular tubercle and the width of its finger tip < 0.75.. . . . . 4
4a. Distance between tympanum and eye usually less than tympanum diameter. Distinctive call, known only from East Usambara
Mountains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C. kreffti
4b. Distance between tympanum and eye usually greater than tympanum diameter. Distinctive call, known only from Nguru
Mountains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C. kanga
5a. Large, distinctive and continuous glands on arms and legs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
5b. No large, distinctive and continuous glands on arms and legs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
6a. Large, robust head. Distinctive call, known only from South Pare Mountains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. stanylei
6b. Less robust head. Distinctive call, known only from West Usambara Mountains . . . . . . . . . . . . . . . . . . . . . . . . . C. kisiwamsitu
7a. Prominent, distinctly coloured glandular mass on arms and feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C. meteora
7b. Prominent, but not distinctly coloured glandular mass on arms and feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. hanseni
8a. Prominent glandular masses on arms and feet absent. Distinctive bright red (or green) interocular band connecting the opposite
anterior and posterior margins of the eyelids. North Pare Mountains. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. laphami
8b. Prominent, relatively pale glandular mass on arms and feet. A less distinct and less continuous interocular band sometimes
present. South Pare Mountains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. shengena
Zootaxa 3095 © 2011 Magnolia Press · 23
NEW CALLULINA FROM NGURU MOUNTAINS OF TANZANIA
FIGURE 6. Map of the Eastern Arc Mountains of Tanzania showing the distribution of the species in the genus Callulina and
distribution of C. meteora sp. nov. (red outlined shaded area) in the Nguru Mountains.
Discussion
Making confident evolutionary inferences from the available phylogenies is hampered by the lack of robust resolu-
tion of relationships. Although we can draw confidence on some areas of agreement between the results from dif-
ferent methods, we generally have a preference for Maxmimum Likelihood over parsimony analyses of DNA
sequence data. Taking the topologies at face value, we identify two patterns of interest. First, the Callulina from the
southern part of the Eastern Arc (South of the Taita, Pare and Usambara Mountains) are nested relatively deeply
within the tree, indicative of a more northerly origin of the extant Callulina lineage as a whole. Although tentative,
this topology is also supported by morphology, with the southern Callulina (including probably additionally unde-
scribed species from Mountain blocks not yet sampled in molecular phylogenies) having more expanded toes. Sec-
ond, although most sister species are allopatrically distributed on isolated mountain blocks, suggesting a possibly
vicariant mode of speciation, the Nguru species (and at least C. meteora and C. hanseni) are each other’s closest
relatives. At least the sister pair of C. meteora and C. hanseni are syntopic in the montane forests of the Nguru
Mountains, indicating a potentially different mode of speciation from most other Callulina. The former pattern of
allopatric/geographic speciation is thought to characterise many Eastern Arc lineages, with high diversity possibly
explained by expanding and contracting cycles of moist forest cover, connecting and disconnecting populations
(Lovett et al., 2005; Burgess et al., 2007). Given that the pattern of one species of Callulina per each mountain
block does not hold, the recent taxonomic and molecular phylogenetic work, while indicative of interesting pat-
terns, raises questions that will only be answered by sampling Callulina from the southernmost mountains in the
Arc.A particularly remarkable and distinctive feature of the new species is the strongly contrastingly coloured and
large glandular masses on the arms, legs and feet. The detailed function of these conspicuous glandular masses is
unknown, but their similarity in position, size and conspicuousness to glandular masses of the Tanzanian endemic
toad Nectophrynoides viviparus is striking (Fig. 7). Nectophrynoides viviparus was described in 1905 by Tornier
MENEGON ET AL.
24 · Zootaxa 3095 © 2011 Magnolia Press
but the function of the glands has not been examined in detail (as noted by Barbour & Loveridge, 1928). The con-
vergence of these atypical features in two distantly related species from different families (Bufonidae and Brevicip-
itidae) raises questions of function and origin.
FIGURE 7. Similarity in enlarged limb glands in Callulina meteora sp. nov. (above) and Nectophrynoides viviparus (below).
Both species exude a sticky white substance from these glands (Menegon & Loader pers. obs.) that we assume
is toxic. We suggest that the combination of bold colour and conspicuousness of the glands relative to the limbs
may act as a warning signal, although we note that most aposematic organisms are more colourful. The two species
share a similar habitat and habit, in being found often within leaf litter in moist montane forest, though the degree
to which they might be sympatric or syntopic is not currently clear. The most obvious explanations that come to
mind are random (non-causal) similarity; similarity through aposematism in poisonous species that are relatively
drably coloured because of somewhat cryptic habits; similarity through display of toxicity to the same or similar
predators (at least when the features first evolved); similarity caused by mimicry. Clearly, much further research is
required to test these and other possible hypotheses.
In addition to the presence of massive limb glands, a further interesting characteristic of Callulina meteora is
the metallic sheen of the skin. Among African amphibians, a similar feature is known in the terrestrial hyperoliid
Chrysobatrachus cupreonitens Laurent 1951, a species from the high altitude grassland of the Itombwe Mountains,
in eastern Democratic Republic of Congo (Schiøtz, 1999) and in the arboreal bufonid Churamiti maridadi Chan-
ning & Stanley 2002 from Mamiwa-Kisara forest in the Ukaguru Mountains of Tanzania. Further investigations
might assess whether there is any causal relationship between the presence of this peculiar feature and any environ-
mental variables, such as altitude.
Zootaxa 3095 © 2011 Magnolia Press · 25
NEW CALLULINA FROM NGURU MOUNTAINS OF TANZANIA
Acknowledgements
We thank the Tanzania Commission for Science and Technology (COSTECH research permit RCA 2007-153,
RCA 2004-335-ER-98-13), the Tanzania Wildlife Research Institute (TAWIRI), the CITES management authority
in Tanzania, and the Wildlife Division for issuing permits for the export of specimens, in particular Nebo Mwina,
Fredrick Ambwene Ligate, Julius Keyyu, and H. M. Nguli. Thanks are due to David Loserian, Ernest Benson, Roy
and Zoe Hinde, Paul Kapange and the people of Maskati, Pemba and Kanga villages who assisted in conducting the
fieldwork. We are also grateful to Nike Doggart, Kim Howell, Charles Msuya, Hendrik Müller, Wilirk Ngalason,
Maria Perkins and Mark Wilkinson for providing assistance in the field, advice and support. Fieldwork in 2004 was
supported by DANIDA through the PEMA program. Fieldwork in 2008 was funded by the CI/CEPF Conservation
International/Critical Ecosystem Partnership Fund and the Natural History Museum, London, recent surveys were
funded by the ‘Gino Zobele fund for research’. We gratefully acknowledge their assistance in conducting this
research, in particular Tim Halliday, Jim Collins and Lynn Turck, MM thanks Giovanna Lipparini and family.
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... Alignments of partial 12S, 16S, cytochrome b (cytb), recombination-activating gene 1 (rag1) and chemokine (CXC motif) receptor 4 (cxcr4) sequences were assembled based on previously published (Loader et al., , 2010aMenegon et al., 2011) and newly generated data. We sampled all specimens for three mitochondrial gene sequences and sampled seven representatives of the main EABR lineages for rag1 and cxcr4 (Appendix S1). ...
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