Preliminary notes on mating and reproductive success of Grammostola doeringi Holmberg 1881 (Araneae; Theraphosidae) in captivity.

FERRETTI NELSON; FERRERO ADRIANA

São Pedro, São Paulo, Brasil

Congreso; 17th International Congress of Arachnology; 2007

Universidad de São Paulo e Instituto Butantan

Because mygalomorphs have plesiomorphic features, studies of their biology can provide important perspective to evolutionary hypotheses. Grammostola doeringi Holmberg 1881 is a large tarantula that lives in burrows. Three females and three males were collected by hand at the locality of Bahía Blanca (38º 42´ 2,77061" S, 62º 16´ 9,21647" W) , Buenos Aires, Argentina. The specimens were kept in rectangular glass cages of 30 x 14 cm. with water provision and were fed with Tenebrio sp. larvae. Females molted on February of 2004, so they become “virgin” again and adult males made the sperm induction during this period too. In March we carried out six encounters male-female in cages of 30 x 35 x 30 cm. height, and a burrow was excavated against the glass wall using a vial to keep the structure allowing the observation constituting an arena with burrow. Four successfully mating occurred. The male started courtship with palpal drumming over the substrate and alternated with leg tapping. The display body vibrations caused by the third pair of legs was rare and only performed by one male. At a distance of approximate 10 cm, the female left the burrow and oriented towards him, then the male made spasmodicals beats (characteristic of the genus) over the female and her adopted the raise position. After clasping the chelicerae, the male performed a series of insertions and with spasmodicals beats again, finalized the copulation and escaped from female. Towards the ending of the year, at 19th December, one female built a white oval sac in her retreat and maintained it with the first pairs of legs. Juveniles emerged 69 days after oviposition (2005) and made their first molt out from the egg sac. Then we counted, measured them and were separated from female’s retreat. 219 juveniles were found alive and 27 were dead, with 2 mm. of carapace. 21 days after we registered 39 deaths; 54 days after, we counted 170 juveniles with 10 deaths. At 175 days after we found only 52 juveniles alive. At 63 days after and now in 2006, 48 juveniles had their second molt after emerge. The juveniles had 2,7 mm. of carapace and 5,5 mm. of total length. The molt period took 103 days. At January 3rd of 2007 finally survived 5 individuals that had their third molt and took 73 days. Their carapace had 3 mm. and the total length of them was of 6 mm.