Radiata2008(3)e

Stephan Böhm Fig. 2.

Stephan Böhm Fig. 2. Female, ventral view. shows an obscure grey pattern on both head and plastron. According to Vetter (2005), the distribution range of Phrynops tuberosus extends from parts of Venezuela, through the Guianas and northern Brazil, to the Rio São Francisco, which drains into the Atlantic Ocean between Maceió and Aracaju. No finds have become known from Central Amazonia (north of Mato Grosso). Souza (2005), who associated the distribution ranges of South American turtles with certain biomes, provided a similar distributional overview for Phrynops tuberosus. Fig. 3. Captive-bred specimen, ventral view. (during the reproductive season) males searching for potential mating partners. Preferred habitats appear to be side arms and similar extensions, but not the actual main streams of water courses (Cisneros-Heredia 2006). Souza (2005) assigned Phrynops tuberosus to a category of species that would occur in areas with open crown cover (i.e., with a scattering of trees) and distinct dry and rainy seasons as can be found, for example, in the Cerrados, Pantanal and Caatinga. This category also included other representatives of Neotropical Chelidae such as Acanthochelys macrocephala, Bufocephala vanderhaegei and Batrachemys tuberculatus. Souza (2004) presumed that (based on studies on Rhinemys rufipes by Magnusson et al. 1997) Phrynops geoffroanus might have a small home range of less than 0.8 ha if prey was sufficiently abundant. In nature, oviposition of Phrynops geoffroanus usually coincides with the dry season (February through August in the Brazilian southeast), with hatchlings emerging during the first half of the rainy season (De- Life history in the wild In the wild, Phrynops tuberosus is described as having diurnal habits (Souza 2004), but, on the other hand, there are also reports of nocturnal hunting in Phrynops geoffroanus (Medem 1960). Colonies of up to twenty specimens have often been observed basking on logs extending into, or lying in, the water. This behaviour would be particularly common during the afternoon hours, while the mornings and evenings are typically spent foraging and Fig. 4. Captive-bred specimen without a tail. 46 RADIATA 17 (3), 2008

Near-natural Husbandry of the Tuberose Side-necked Turtle, Phrynops tuberosus cember and January). Corresponding differences in incubation periods are also known from Phrynops hilarii (Souza 2004). The dietary spectrum of Phrynops geoffroanus comprises for the largest part insects and their larvae that have fallen into, or live in, the water (Ephemeroptera, Odonata, Plecoptera, Trichoptera), as well as fish. The latter account for a larger portion during the dry seasons when the natural habitats of fish begin to shrink and so make catching them easier. All these observations refer to Phrynops geoffroanus while next to nothing is known in this regard about Phrynops tuberosus. Souza (2004) emphasized that there were no details available on activity patterns, reproduction and diet of this species in the wild. However, considering that these two species are very closely related, it is safe to suppose that at least some of the data and behavioural patterns will also apply to Phrynops tuberosus and can therefore be used for both species. Husbandry and behaviour in the terrarium At present, the group in my care consists of 1.1 adult specimens, two captive-bred ones from my own stock from 2006, and another captive-bred one of about 15 cm in length that lacks a tail and cannot therefore be sexed. The adult female has a carapace length of 32 cm and a weight of about 3,300 g, while the adult male measures about 30 cm and weighs approximately 2,000 g. When I received Fig. 5. Anal region of the older juvenile; note the missing tail. these two animals in 2005 they were about one centimetre smaller and a little lighter. Growth markings are evident. My Phrynops tuberosus are periodically separated by sex, as the previous owner had pointed out that the male would sometimes spend days perched on the female’s back and let himself be carried around. During the periods when the sexes are not kept together, the male is housed in a 630 l aquarium measuring 130 × 70 × 70 cm (length × width × height). For her part, the female spends the entire year in a basin I have built myself. It takes about 900 l in volume and measures 190 × 80 × 60 cm and also houses a female Batrachemys raniceps. The male’s quarters are furnished with a decay catcher and several shelters and offers a basking spot on cork bark that floats on the surface of the water. Water temperature is kept at about 25 °C in winter, and the tank is illuminated with two 40 W fluorescent tubes. There is no filter system in a classical sense, but the water is oxygenated by means of a membrane pump. At the spot where the bubble stone lies, a 50 × 10 × 10 cm piece of filter mat is wedged in, ensuring that the bacteria colonizing it are provided with oxygen. RADIATA 17 (3), 2008 47