Herpetology Notes, volume 11: 337-341 (2018) (published online on 22 April 2018) The genus Osteolaemus (Crocodylidae) in Angola and a new southernmost record for the genus Luis M. P. Ceríaco1,2,*, Sango dos Anjos Carlos de Sá3, Aaron M. Bauer1 Abstract. African Dwarf Crocodiles (genus Osteolaemus) are West and Central Africa endemics with a distribution extending from Senegal to Angola. In Angola the genus is only known to occur north of the lower Congo River in the Cabinda enclave, based on 19th century records. No modern specimens have been documented, despite its anecdotal occurrence in other parts of the country. We provide the first confirmed record of Osteolaemus (probably O. osborni) in “mainland” Angola based on a vagrant individual believed to have come from the Kwanza River system. This constitutes the southernmost record for Osteolaemus in Africa, by approximately 400 km. More information is needed to assess the systematic and conservation status of Dwarf Crocodiles in Angola, but the bushmeat and leather trades are likely sources of threat to Osteolaemus throughout their range Keywords: Osteolaemussp., Angola, Kwanza River, Distribution, Conservation Introduction The African Dwarf Crocodiles, genus Osteolaemus Cope, 1861, are endemic to West and Central Africa, occurring from Senegal to the northwestern borders of Angola, east to the Central Africa Republic and the north and central parts of the Democratic Republic of the Congo (Eaton et al., 2009). The genus was long considered monotypic, with Osteolaemus tetraspis Cope, 1861 described on the basis of a single specimen from the Ogobai (currently Ogooué) River Basin in Gabon. Schmidt (1919), based on specimens from the Congo Basin, described a new genus and species closely related to Ostelolaemus which he named Osteoblepharon osborni. Werner (1933), Mertens (1943) and Inger (1948), 1 Department of Biology, Villanova University, 800 Lancaster Avenue, Villanova, Pennsylvania 19085-1699, USA. 2 Departamento de Zoologia e Antropologia (Museu Bocage), Museu Nacional de História Natural e da Ciência, Universidade de Lisboa, Rua da Escola Politécnica 58, 1269- 102 Lisboa, Portugal. 3 Departamento de Gestão da Biodiversidade, Instituto Nacional Figure 1. Map of the localities with confirmed records of da Biodiversidade e Áreas de Conservação, Ministério do Osteolaemus sp. in Angola (purple dots), the new record Ambiente de Angola, Centralidade do Kilamba, Rua 26 presented here (Yellow star-centred dot), release area of the de Fevereiro, quarteirão Nimi ya Lukemi, edifício Q11, 3º specimen, and other relevant localities cited in the text (black andar, Angola. dots). Green area and rivers represent the Congo River Basin, * Corresponding author. E-mail: [email protected] Red the Kwanza River Basin, and Blue smaller coastal rivers. 338 Luis M. P. Ceríaco et al. Figure 2. View of a diorama representing the Kwanza River area in the Natural History Museum of Luanda, with stuffed specimens of two Osteolaemus sp. (far left and right) and a juvenile Crocodylus niloticus in the middle. The installation and arrangement of these dioramas date back to the pre-independence era (before 1975). Photo by L.M.P. Ceríaco. however, all considered Osteoblepharon as a junior extending to the northwestern Angolan province of synonym of Osteolaemus, although they maintained Zaire. However, the distribution of the first two species osborni as a full species. Wermuth (1953) treated from eastern Ghana to eastern Nigeria were considered osborni as a subspecies of O. tetraspis, an opinion that unknown and there were no molecular samples from has been accepted until very recently. Ray et al. (2001) south of southern Gabon. provided the first molecular evidence of high levels of Data on the distribution of the genus in Angolan genetic variability within Osteolaemus, suggesting that territory is extremely limited and derive from 19th more detailed studies would clarify the taxonomy of century of records of Osteolaemus sp. from the Cabinda the group. Based on skull morphology, Brochu et al. enclave (Bocage, 1866; Peters, 1877), and no confirmed (2007) elevated O. osborni to species level again. Eaton records exists for either O. tetraspis or O. osborni in et al. (2009a) provided a baseline molecular phylogeny Angola south of the Congo River (Figure 1; see also of the genus based on extensive sampling across West Pooley, 1982; Thorbjarnarson 1992). In the dioramas of and Central Africa using three mitochondrial and two the Natural History Museum of Luanda there are several nuclear genes. Their findings pointed to the existence mounted specimens of Osteolaemus sp., which are of three distinct lineages within the genus. These labelled as being from the Kwanza River Basin (Figure findings have since been corroborated by Eaton et al. 2). However, the catalogues of the museum were lost in (2009b), Shirley and Eaton (2010), Franke et al. (2012) the 1990s during an inundation of the museum stores, and Shirley et al. (2014a,b). Supported by molecular and, therefore, no more precise data exist for these analyses of newly collected samples. Smolensky et al. specimens. (2015) presented more detailed data on the distribution Data on the distribution of other crocodilians in of the three Osteolaemus lineages. According to their mainland Angola is also limited, especially when one results the undescribed Osteolaemeus lineage occurs takes into consideration the area of the country and the in West Africa, west of the Ogooué Basin (Senegal, vast river basins that drain it. Two species are currently Guinea-Bissau, Guinea, Sierra Leone, Liberia, Ivory confirmed to occur in mainland Angola – Crocodylus Coast and Ghana), O. tetraspis occurs in the Ogooué niloticus Laurenti, 1768 (see Bocage, 1866, 1867, 1895; Basin, including parts of Nigeria, Cameroon, Equatorial Peters, 1877; Ferreira, 1903; Monard, 1937; Hellmich, Guinea, Gabon, Republic of the Congo and Angola’s 1957; Branch and McCartney, 1992; Ceríaco et al., Cabinda enclave, and O. osborni is restricted to the 2014; Marques, 2015; Branch and Conradie, 2015; Congo Basin, especially in the southeastern areas of Conradie et al., 2016) and Mecistops cf. catraphactus Cameroon, northwestern tip of Gabon, eastern half (Cuvier 1825) (see Peters, 1877; Bocage, 1895; Laurent, of the Republic of the Congo, all northern and central 1964; Marques, 2015). Whereas the first species has an regions of the Democratic Republic of the Congo, and extensive distribution throughout the country, being The genus Osteolaemus in Angola and a new southernmost record for the genus 339 receives debris carried by the outflow of the Kwanza River, and it is likely that this crocodile followed the same path. It is highly improbable that the specimen came from the inland side of the bay, as the area is extremely urbanized and unsuitable for crocodilian populations. We also believe that it is unlikely that the Mussulo animal represents an escaped animal imported from north of the Congo for the bushmeat or handicraft trade. While some crocodile leather products, including those derived from Osteolaemus, are sold in the informal markets of Angola by Congolese nationals (see below), we presume that those reaching Luanda typically do so as raw or processed skins. Figure 3. Live specimen of Osteolaemus cf. osborni collected Results and Discussion in Mussulo, Angola. Photo by Sango dos Anjos Carlos de Sá. Morphological identification of O. tetraspis and O. osborni is difficult as no diagnostic external characters have yet been found to clearly separate the two taxa known from nine provinces (Cabinda, Lunda Norte, (de Boer, 2010). However, we tentatively identify Luanda, Malanje, Kwanza Sul, Benguela, Cunene, the Mussulo animal as O. osborni, as this species is Cuando Cubango; Pooley et al., 1982; Marques, 2015), expected to occur in the Zaire region (Smolensky et al., the latter is only known to occur in Cabinda and Lunda 2015). However, a more definitive identification can Norte provinces (Pooley et al., 1982) and Angolan only be made with the collection of fresh samples for populations have been considered by Shirley et al. genetic analysis. (2014a,b) and Grigg and Kirshner (2015) to represent Regardless of the specific identity of the Mussulo an undescribed species. In this paper we provide the crocodile, this record represents not only the first first confirmed record of an African Dwarf Crocodile “mainland” Angolan record for the genus, but also the in Angola south of the Congo, and briefly discuss its southernmost record of the genus in Africa, extending conservation implications. the range approximately 400 km southward from the limit of O. tetraspis in Cabinda and nearly as far from Materials and methods the predicted (Smolensky et al., 2015), but unvouchered, On 30 December 2015, one of us (SACS) was called range limit of O. osborni in Zaire Province. Although the by the local authorities to rescue a live adult specimen Kwanza River is the largest river in Angola and was an of an Africa Dwarf Crocodile at a beach in the Mussulo important navigation route during Portuguese colonial region (-8.8687ºN, 13.1528ºE; Figure 1), Angola. The times, its biodiversity remains very poorly explored. specimen was in good physical condition and did not This is also true for the northwestern parts of the country, exhibit any evidence of epizoic marine organisms. where the number of records for both amphibians and Mussulo is a peninsula south of Luanda, about 30 km reptiles is minimal. However, given this region’s climatic long and approximately 70 m wide at is base and 1.5 and vegetative similarities to southwestern Congo, it is km wide at its widest. It lies about 30 km north of the expected that many of the species occurring there also Kwanza River mouth and was formed from sediments extend into Angola. Recent fieldwork carried out during from the river swept north by the Benguela Current. environmental impact studies at two hydroelectric The peninsula forms a shallow, narrow bay fronting the dam sites on the Kwanza River in Malanje Province southern outskirts of Luanda.