Radiata2008(3)e

Stephan Böhm Fig. 6.

Stephan Böhm Fig. 6. Radiographic photograph: the twelve round eggs are clearly visible. Photograph: G. Adlassnig To eliminate mirroring effects of the bottom glass pane and as a concession to the company fish (zebra cichlids [Archocentrus nigrofasciatus] and eight-lined cichlids [Cryptoheros octofasciatus]), a thin layer of river sand covers the bottom. This joint housing produces surprisingly little problems, and the zebra cichlids have by now successfully reproduced several times. The fish are highly territorial and even manage to drive away the by far larger turtle if they tend to a new clutch of eggs. They are also often the first to snatch up food at feeding time. The female’s basin sports a similar structure. There is a cave-like hiding place and a terrestrial part under which the turtle can dive. The latter was constructed from a 80 × 40 × 40 cm cement tub that is perched on two columns made of bricks. It is filled with playground sand beneath which there is a drainage layer of Leca ® balls (clay balls for hydroculture). The terrestrial section has been planted with a tuft of Cyprus grass. In order to create temperatures that are conducive to oviposition, a 150 W HQI flooder is directed at the terrestrial section. The basin is likewise heated to about 25 °C in winter and oxygenated by means of a membrane pump. However, it is additionally furnished with an external filter (Eheim 2213) that has been placed right in (!) the basin, mainly for the purpose of creating some surface current. Both animals spend their days in a fairly secluded manner and make use of the available shelters. They seek direct contact between the dorsal shell and solid material and are hardly to be seen when there is light. They only appear at dusk and under cover of night to forage for food. It is worth noting that the turtles present themselves as much shyer when they are housed in the brick basin (which is lined with black pond liner and can only be viewed from above) than when they are kept in an aquarium. This is probably due to the fact that the observer will look into the basin from above and is therefore more likely perceived as a potential threat. I have never observed the animals basking during the day, but every now and then they will do so in the early morning hours. Mating, oviposition and incubation While the sexes are together, the stereotypic courting behaviour typical of the genus 48 RADIATA 17 (3), 2008

Near-natural Husbandry of the Tuberose Side-necked Turtle, Phrynops tuberosus Fig. 7. Juvenile of a few days of age in ventral view. Fig. 8. Juvenile in dorsal view; an interesting feature is the roughness of the carapace surface. Fig. 9. The first juvenile after its egg was opened. Phrynops can be observed. A detailed account of this behaviour was given by Fritz & Mann (1993) for Phrynops hilarii. As to how far courtship of Phrynops tuberosus differs from this description would have to be investigated, but I have noted individual components, such as rapid head bobbing and fanning water with the front legs, to be identical. The male is by far not as aggressive as, for example, a male slider if the female is not ready for mating, but can be very uncompromising when he lets himself be carried around on the female’s back for extended periods of time. The female will often even feed while the male is perched on her back. Although I have witnessed courtship behaviour often, I was never privileged enough to be present when copulation took place. It would appear to me that mating only takes place under the cover of night. I routinely subject the female to palpation at irregular intervals. It was on one such occasion around the end of June in 2006 that I noted her to be gravid. Timing was particularly bad as I had to travel overseas in July and was still unsure whether the female would accept the terrestrial section of the newly built basin for laying her eggs when the time came. While I was away, she dug a few test pits, but had still not produced any eggs by the end of July when I returned. Her previous owner had told me that she had previously dropped her eggs in the water, and this made me decide to treat her, under the supervision of a veterinarian, with the labour-inducing medication Oxytocin ® . The injection was administered on 01.08.2006 and after an hour led to all twelve eggs being laid that were to be expected from X-rays that had been taken earlier. The eggs were almost perfectly round, measured 35 mm on average in diameter, had a mean weight of 22.5 g, and were hard-shelled and lime-white right from the beginning. A formation of a belt or whitening, as is commonly observed with eggs of other chelonians, was notable at no point of time. Also, there were no indications of blood RADIATA 17 (3), 2008 49