HERPETOLOGICAL JOURNAL, Vol. 8, pp. 3-6 (1998)

TANZANIAN BUFONID DIVERSITY: PRELIMINARY FINDINGS

J.C. POYNTON

Department of Zoology, Natural History Museum, London SW7 5BD, UK

The toad family Bufonidae is being studied as part of a review of Tanzanian amphibians. The current list includes 6 genera (one undescribed), and 28 described and undescribed species. This represents 40% of the bufonid genera and 31 % of the bufonid species known in sub-Saharan Africa. Two genera and fifteen species are considered to be endemic. Tanzania appears to have the richest bufonid fauna of any sub-Saharan country. Bufonid distribution conforms with the tendency in Tanzania towards marked differences between upland and lowland biotic communities. Separation of the Afromontane Nectophrynoides and the lowland Mertensophryne and Stephopaedes is particularly striking. Fifty-seven per cent of the bufonid species recorded in Tanzania appear to be associated with forest. Precise data concerning the rate and extent of forest disturbance and deforestation are lacking, and the potential for forest-associated bufonids to survive these perturbations is unknown. Effective conservation action requires more information and improved understanding of the many factors involved.

INTRODUCTION ·Buja reesi Poynton. Kihanzi-Kilombero floodplain, The author is part of an informal network of scien­ southern Tanzania. Floodplain grassland. tists currently working on the amphibian fauna of Buja steindachneri Pfeffer. North-eastern Tanzania, Kenya, eastern Uganda, Somalia across to northern Ni­ Tanzania. This paper reports on the first phase of a geria. Wooded grassland and bushland. study of the toad fam ily Bufonidae, which brings out the extraordinary richness of the Tanzan ian amphibian (2) KERINYAGAE DIVISION fauna. Work is based on material in the Natural History Buja kerinyagae Keith. Highland areas of Tanzania, Museum, London (NHM), augmented by loans particu­ Uganda, Kenya, Ethiopia. Grassland and cleared for­ larly from the American Museum of Natural History, est. New York (AMNH); Museum of Comparative Zool­ ogy, Cambridge (MCZ); and Museum National (3) MACULATUS DIVISION d'Histoire Naturelle, Paris (MNHN). Buja maculatus Hallowell. Sub-Saharan Africa ex­ Bufonid taxonomy throughout sub-Saharan Africa cluding most of Botswana, Namibia and South Africa. lacks proper analysis, and inadequate sampling gives a Wooded grassland to forestedge. very incomplete picture of species' ranges. I estimate that some 89 bufonid species can presently be dis­ (4) REGULARIS DIVISION cernedin the subcontinent. Twenty-eight of these (3 1 % Buja gutturalis Power. South-eastern Uganda and of the total) occur in Tanzania, a number which sur­ Kenya to the Eastern Cape, westwards to Angola­ passes even Cameroon's reported total of some 24 Namibia. Wooded grassland to forest edge. species to reveal Tanzania as having the richest bufonid Buja kisaloensis Loveridge. Highland areas of fauna in Africaac cording to current taxonomic assess­ Kenya, Uganda, Rwanda, eastern Zaire, western Tan­ ment. zania, northern Malawi. Forest. Fifteen endemicbufon id species can so far be recog­ Buja xeras Tandy, Tandy, Keith & Duff-MacKay. nized in Tanzania (54% of the total), although some of Tanzania to Senegal. Sparsely wooded grassland and these may yet be found in northern Mozambique or thicket. north-eastern Zambia, areas that are still poorly col­ (5) lected. The following species list indicates Tanzanian SUPERC!l!ARIS DIVISION endemics by an asterisk, and outlines total range and ·Buja brauni Nieden. Eastern Arc Mountains of Tan­ habitat type. In Tanzania, diversity within the genus zania, but not the southern highlands. Forest to forest Buja is considerable not only at species level. To indi­ edge. cate the degree of high-ranking diversity, species are (6) TA!TANUS DIVISION grouped according to the 'divisions' of Poynton (1996). Classification of land cover follows Thompson Buja lindneri Mertens. Eastern Tanzania, northern (1996). Mozambique, south-eastern Malawi. Wooded grass­ land. BUFO LAURENTI Buja taitanus Peters. South-western Kenya, mainly (!) FUNEREUS DIVISION western Tanzania, Malawi, northern Zambia. Wooded Buja fu liginatus Witte. Upland areas of south-west­ grassland. ern Tanzania, northern Zambia and southern Zaire. ·Bufo uzunguensis Loveridge. South-westernTanza­ Woodland to forest. nia. Swampy grassland. 4 J. C. POYNTON

' Bufo sp. (lonnbergi complex). South-western Tan­ semi-desert, as reflected by the absence of members of zania. Probably grassland. the arabicus and blanfordii divisions of the arid Hom of Africa. During drier phas�s of the Quaternary, (7) URUNGUENSIS DIVISION Tanzania was evidently part of an 'arid corridor' which Bufo urunguensis Loveridge. Mountains in Tanzania connected the flora and fauna of north-eastern and and Zambia bordering southern end of Lake Tangan­ south-western Africa (Poynton, 1995). Among yika. Woodland to forest. bufonids, residual fragments of this arid corridor appear to be represented by the very limited, disjunct (8) VERTEBRA LIS DIVISION distribution in Tanzania of B. xeros, an arid savanna member of the ecologically diverse regularis division. Bufo parkeri Loveridge. Lake Natron Basin of Tan­ B. garmani, another member of the regular is division zania and Kenya. Sparsely wooded grassland. inhabiting dry savannas, shows a patchy distribution SCHISMADERMA SMITH with no confirmed records in Tanzania; its distribution pattern may also represent fragments of the arid Schismaderma carens (Smith). Tanzania, south­ eastern Zaire, to Eastern Cape border. Wooded corridor (Poynton, 1995). Tanzania is also included in a grassland. break in the known distribution of the mainly dry­ savanna vertebra/is division of small-sized toads NECTOPHRYNOIDES ROUX (Poynton, 1995). B. parkeri is the only member of this 'Nectophrynoides cryp tus Perret. Uluguru Moun­ division known to occur in Tanzania, recorded in the tains above 2000 m. Forest. Lake Natron Basin. 'Nectophrynoides minutus Perret. Uluguru Moun­ The taitanus division of small-sized toads, whose tains at about 1500 m. Forest. members show a preference foropen but moister situa­ 'Nectophrynoides tornieri (Roux). East Usambaras tions, is represented by B. lindneri, B. taitanus, B. through to the Udzungwas between about 1500 m and uzunguensis, and a hitherto unrecognized species of the 500 m; not lowland forests. Forest or forest margins, in­ lonnbergi complex from Mbeya Mountain in the south cluding plantations of exotics. (Poynton, in press). This complex is currently recorded ' Nectophrynoides viviparus (Tornier). Southern from grassy highlands of Malawi and Kenya (Poynton, Tanzanian highlands and (possibly a diffe rent form) in press); a single NHM specimen which cannot be as­ the Uluguru Mountains. Forest. signed to the Malawian or Kenyan taxa indicates that 'Nectophrynoides wendyae Clarke. Udzungwa es­ this complex is also represented in high open situations carpment. Forest. in Tanzania. 'Nectophrynoides sp. West Usambaras. Forest. Grassy highland is an important element of the ' Nectophrynoides sp. Uluguru North Forest Reserve. Afromontane region (Meadows & Linder, 1993 ); B. Forest. kerinyagae, apparently most closely related to B. 'Nectophrynoides sp. Kihansi Falls, Udzungwa asmarae of Ethiopia, is limited to it. The southern Range. Forest. record of this species is the Ngorongoro Crater rim in Tanzania. UNDESCRIBED GENUS The widespread savanna member of the regularis 'Nectophrynoides-like species, undescribed. High division, B. gutturalis, is well represented in Tanzania, Ukaguru mountains. Forest. as is the similar B. maculatus. B. reesi of the ecologi­ cally diverse fu nereus division is known only from a STEPHOPAEDES CHANNING small area of open floodplain. Its limited known range 'Stephopaedes loveridge i Poynton. South-eastern is probably a reflection of limited collecting in Tanza­ Tanzania. Forest, forestedge and woodland. nia. B. steindachneri, another member of the fu nereus ' division, reflects the same situation; this species is Stephopaedes sp. North-eastern Tanzania (includ­ . ing Mafia Island). Forest. based on a single specimen collected near the eastern edge of the Nguru Mountains in 1888, deposited in th.e MERTENSOPHRYNE TIHEN Hamburg Museum but destroyed in World War II. It is Me rtensophryne micranotis (Loveridge). Eastern still the only Tanzanian record of the species. Speci­ Tanzania (including Zanzibar and Songo Songo is­ mens that appear to belong to this species have been lands) and south-eastern Kenya. Forest or woodland. collected from the Kenyan coastal lowlands and be­ yond, but their identification needs to be confirmed by BUFO AND SCHISMA DERMA fresh topotypic material. Another member of the division, appears to be a Species of the genus Bufo occupy a wide spectrum of fu nereus B. fu liginatus, habitats in Africa ranging from semi-desert to forest, vicariant of B. fu nereus centred in Zaire; hitherto unre­ although the highest species diversity is in moist and corded in Tanzania, the NHM has a specimen collected relatively cool areas (Poynton, 1996). Tanzania in the last century apparently in highlands west of Lake provides a complete range of these habitats, apart from Rukwa. TANZANIAN BUFONIOS 5

B. fu liginatus may be included among the fo ur distribution of these toads is in lowland or transitional mainly forest-associated Bufo species in Tanzania, the forest in south-eastern Kenya, Tanzania, and eastern remainder being B. kisoloensis, B. brauni and B. Zimbabwe (Grandison & Ashe, I 983; Poynton & urunguensis. B. kisoloensis is a montane member of the Broadley, I 988; Poynton, I 99 1 ). The ranges of the East regularis division, hitherto unrecorded in Tanzania but African species are more extensive than those of most re presented by two NHM juveniles fr om the Mahale Ne ctoph!ynoides species, which is evidently linked to Mountains bordering Lake Tanganyika; the species the more continuous distribut ion of lowland forest could well occur in several patches ofmontane fo rest in throughout the Quaternary (Livingstone, I 993). In the under-collected western Tanzania. B. brauni, common case of the two Tanzanian Stephopaedes species, in forests above 500 m, is closely re lated to B. vicariation may have resulted from range separation superciliaris of West African forests. The affinities of caused by the Great Ruaha-Rutiji Basin. The B. urunguensis have yet to be determined. undescribed species that occurs north of this gap shows This rich mix of Bufo species has exploited all terres­ a very fragmented range which suggests it is verging on trial and freshwater habitat types in Tanzania with the extinction. exception of lowland forest; no known species of Bufo The altitudinal separation between the Nectoph1y­ is restricted to it and none enter deeply into it. The noides group and Mertensoph1Jme/Stephopaedes is part known distributions of all Bufo species are patchy and of a general pattern shown by easternTanzanian forest show the need for systematic sampling; nevertheless, am phibians. Nectoph1ynoides appears to belong to a the available data suggest a separation of much of the mainly Afromontane group whose members are distrib­ toad faunainto lowland and upland or Afromontane el­ uted from Table Mountain in the Cape through East ements, whether in wooded or open habitats. This Africaand Ethiopia to We st African mountains (Grand­ separation has been recognized for many years ison, I 98 I; Gauld & Underwood, 1986). The (Loveridge, 1937; Poynton, I 962), but locality data are taxonomic affinities of Mertensoph1yne and Stepho­ still insuffic ient to allow the degree of analysis and paedes have yet to be clarified; a knowledge of their quantification now possible in more southern areas history should contribute to understanding the broader (Poynton & Boycott, 1996). issues of biogeography and evolution in East Africa. Schismaderma carens, another large-sized toad, reaches its known northernmost limit in Tanzania. At SURVIVAL PROSPECTS present no ecological explanation is available for its Some 57% of the Tanzanian bufonid species are as­ limitation in the region, although its preference for sociated with forest. While destruction of fo rest in deep pools or impoundments for breeding may limit its Tanzania is widespread, there is little precise informa­ distribution in the drier north. tion about where it is occurring and how rapidly it is taking place (Anon. 1995). Also lacking is precise in­ NECTOPHRYNOIDES, MERTENSOPHRYNE AND formation about the extent to which forest-associated STEP HOPA EDES amphibians can survive deforestation. Howell (1993) recorded remaining in deforested areas 'as Of special interest is the occurrence of the montane B. brauni long as adequate cover of some dense vegetation per­ Nectophrynoides and an undescribed related Ukaguru sists,' and the same appears true of many other 'forest' Mountain form, and the more lowland Mertensophryne amphibians (Poynton, 1996). It is, however, not known and Stephopaedes. All these small-sized bufonids are how long such species may continue breeding in dis­ associated with forest and do not breed in open water. turbed conditions. Informed and effective conservation Nectophrynoides (sensu Dubois, 1987) is recorded only action re quires an improved knowledge of the rate, ex­ from Tanzania. Eggs are retained in the oviduct in spe­ tent, and the short and long-term effects of forest cies whose larval stage is known, and fu lly formed disturbance and deforestation. It may be hoped that this individuals emerge from the vent. The selective advan­ wi ll be achieved before the opportunity to study the tage of this retention still has to be investigated in wide range of natural communities is lost. detail. The ranges ofmost species are limited to particu­ lar forest blocks, no doubt the re sult of vicariation in ACKNOWLEDGEMENTS ecologically isolated areas of montane forest. The number of known species is rapidly increasing as more This study was centred in the Natural History Mu­ forests become explored. seum, London; the staff of the Amphibian and Reptile In contrast to the ovoviviparous Nectophrynoides, Section, particularly B. T. Clarke, are thanked forre ady Mertensophryne and Stephopaedes lay eggs in water­ assistance in many ways. New collections and re levant filied treeholes and other small containers that are information were provided by those involved in the normally available only in forests (references in Frontier-Tanzania project, particularly N. Burgess, K. Howell and P. Clarke. M. Klemens and M. Cherry have Poynton, I 99 1 ). The tadpoles of both genera are very similar, although the adults diffe r sufficiently to sug­ made available their Tanzanian collections and have provided valuable information and discussion. gest generic separation (Poynton, I 99 1 ). The 6 J. C. POYNTON

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