INVESTIGADORES
POMPOZZI Gabriel Alejandro
congresos y reuniones científicas
Título:
MATING BEHAVIOR OF GRAMMOSTOLA DOERINGI HOLMBERG 1881 (ARANEAE: THERAPHOSIDAE), A BUROWING SPECIES FROM ARGENTINA
Autor/es:
NELSON FERRETTI; SOFÍA COPPERI; GABRIEL POMPOZZI; FERNANDO PÉREZ-MILES
Lugar:
Alexandroupoli
Reunión:
Congreso; 25th European Congress of Arachnology; 2009
Institución organizadora:
Democritus University of Thrace
Resumen:
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The Theraphosidae
are widely distributed in tropical and subtropical regions of the world, but
their biology is poorly known. Due to theraphosid basal phylogenetic location
among spiders, the studies of their biology can provide important perspective
for evolutionary hypotheses. Studies on the mating behavior of this family have
been limited to a few species, namely Acanthoscurria suina, Aphonopelma
chalcodes, Brachypelma klassi, Catumiri uruguayense, Eupalaestrus weijenberghi,
Grammostola mollicoma, Grammostola schulzei, Plesiopelma longisternale and
Sickius longibulbi. A common pattern emerges from the available literature
on theraphosids: male courtship includes body vibrations and palpal drumming,
usually followed by clasping, hooking female´s fangs with the male tibial apophysis.
Mating always occurs with the male located in front of the female, and raising
the female´s body. In this position, the male is able to reach the genital
opening with his palpal organs. Grammostola doeringi is a large and
burrowing tarantula that lives in the suburbs of Bahía Blanca, Buenos Aires
province, Argentina. This species make their burrows always in meadows and
males can be seen seeking for females at late spring (October). Here we
describe the mating behavior of Grammostola doeringi heretofore unknown
in laboratory conditions based on 11 successful matings. Six males and eight
females were collected by hand during October November 2008 at the locality
of Bahía Blanca (38º 42´ 2.77" S, 62º 16´ 9.21" W), Buenos Aires,
Argentina. A total number of 30 encounters were carried out in rectangular
cages of 30 x 35 and 30 high. The cages had a substrate of 10
cm and a burrow was excavated simulating natural conditions
and allowing for observation of female´s behavior. All interactions were videotaped
and analyze. All males initiated courtship when touched the female´s silk over
the substrate. The courtship involved palpating as the first unit registered,
that consisted in the two palps moving up and down in an alternating phase
hitting the soil at constant velocity, quite different from palpal drumming
where the bout started at low velocity and increased sequentially. Males made a
mean number of 30.72 ± 29.74 SD, being highly
variable with a range of 2 to 114 bouts per courtship and had a mean duration
of 1.46 s ± 0.57 SD. He also made
body vibrations caused by the contraction of the third pair of legs. The mean
number of this unit per courtship was 15.66 ± 28.65 SD (range = 2 117) and the mean duration
was 1.88 s ± 0.36 SD. The male
sometimes beat the substrate with legs I, that consisted in elevating a leg,
extended it and lowered rapidly over the soil. Males made a mean number of
24.57 ± 21.79 SD (range = 2 71) bouts. The
courtship duration in minutes was 12.64 ± 15.76 SD (range = 1.89 56.3). Then, the male approached the female,
touching her with the first pair of legs and beating spasmodically with legs II
over the female´s body. In G. doeringi, when the female raised her body
and opened fangs, then the male clasped onto her fangs using the tibial
apophysis and legs III and IV were maintained over the substratum. After the
contact, latency was observed, where the pair stayed motionless. Then, the male
pushed the female to reach an angle of 80° approximately and began a series of
palpal insertions on the female genital opening. The mean number of insertions
was 11.45 ± 8.72 SD (range = 3
26). The mean duration of each insertion was 11.89 s ± 5.65 SD. Palpal insertions usually were difficult
to see, but seemed to occur with many fail insertions, where the bulb tried to
enter and undo. The mean duration of copulation in minutes was 5.65 ± 3.20 SD (range = 2.13 11.88). Afterwards the
male unclasped beating spasmodically and moved away from the female. The mean
number of spasmodicals beats during clasping and unclasping was 13.25 ± 9.54 SD per courtship. For several minutes, the
female stayed totally immobile. Afterwards, she recovered and walked into the
burrow. The mean duration in minutes of this immobile condition was 33.39 ± 14.36 SD (range = 6.96 48.52). The mating took
place at the burrow entrance. Females accepted males by leaving the burrow
because mating does not occur inside it. Moreover, males tried to take out
females entering the burrows and courting inside. In conclusion, the mating
behavior of G. doeringi was similar to the prevalent theraphosid
pattern. Males of Grammostola doeringi made a large number of insertions
as other species of theraphosids. The failed insertions were also observed in Grammostola
mollicoma. The duration of copulation of G. doeringi was short even
with fail insertions that consumed time, but that was related with shorter
duration of each effective insertion.