by the spider Ctenus medius (Araneae: Ctenidae)

Herpetology Notes, volume 2: 99-100 (2009) (published online on 19 July 2009 )
Predation on Leptodactylus marmoratus (Anura: Leptodactylidae)
by the spider Ctenus medius (Araneae: Ctenidae)
in the Atlantic Forest, southeast Brazil
Fausto E. Barbo1, 2*, Murilo G. Rodrigues1, 3, Fernando M. Couto1, 2 and Ricardo J. Sawaya1
Abstract. We report herein a case of predation by the ctenid spider Ctenus medius on a leptodactylid frog Leptodactylus
marmoratus, observed in a remnant of the Atlantic Forest, municipality of São Vicente, São Paulo state, southeast Brazil. This
is the first record of predation by C. medius upon L. marmoratus. Nevertheless, due to the high abundance of both groups, we
suggest that the interaction between spiders and amphibians could be very common on the floor of the Atlantic Forest.
Keywords. Amphibia, leaf litter, anurans, Neotropical region.
Predation is one of the most important regulators in
terrestrial anuran communities (Duellman & Trueb
1986). Such interaction may be common in the wild due
to the abundance and gregarious behaviour of anurans
(Pombal-Junior 2007). Spiders feed on a variety of vertebrates such as small mammals, birds, and lizards (McCormick & Polis 1982; Corey 1988; Rubbo et al. 2001)
and are also frequently eaten by amphibians (Sas et al.
2007; Dietl, Engels & Solé 2009). However, in some
cases they also act as predators of amphibians. Predation on anurans has been recorded more frequently in
the last decade (see reviews in Menin, Rodrigues &
Azevedo 2005; Toledo 2005). In the Neotropical region, most records on anuran predation are attributed
to the spider families Pisauridae, Ctenidae, Lycosidae,
Sparassidae, and Theraphosidae (Menin, Rodrigues &
Azevedo 2005).
1 Laboratório Especial de Ecologia e Evolução, Instituto
Butantan. Avenida Dr. Vital Brazil, 1500, 05503-900 São
Paulo, SP, Brazil;
e-mail RJS: [email protected]
2 Programa de Pós Graduação em Biologia Animal, Instituto de
Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista, Rua Cristóvão Colombo, 2265, 15054-000 São
José do Rio Preto, SP, Brazil;
e-mail FEB: [email protected]; e-mail FMC:
[email protected]
3 Departamento de Zoologia, Programa de Pós Graduação
em Ecologia, Instituto de Biologia, CP 6109, Universidade
Estadual de Campinas, UNICAMP, 13083-970, Campinas,
SP, Brazil.
e-mail MGR: [email protected]
* corresponding author
During a herpetofaunal survey conducted on the 26th
May 2009 in Parque Estadual Xixová-Japuí (municipality of São Vicente, São Paulo state, southeast Brazil), we
observed a juvenile ctenid spider Ctenus medius (16,2
mm cephalothorax + abdomen length) capturing an
adult individual of the leptodactylid frog Leptodactylus
marmoratus (15,9 mm; 0,4 g) on the leaf litter of the for-
Figure 1. Predation of Leptodactylus marmoratus (voucher:
ZUEC 15914) by the ctenid spider Ctenus medius observed in
Parque Estadual Xixová-Japuí, municipality of São Vicente,
southeast Brazil. Upper, frog’s legs paralyzed; Lower, detail of
the spider innoculating its chelicerae on frog’s dorsum.
100
Fausto E. Barbo et al.
est floor. The predation was observed at 19:20 h beside
a trail in the secondary Atlantic Forest (23°59’19.55”S,
46°22’57.15”W, ca. 68 m above sea level). The spider
jumped on the frog’s dorsum and readily sank its chelicerae into it (Figure 1). The frog tried to escape but its
legs were completely paralyzed, remaining motionless
for about five minutes and dying forthwith. Both predator and prey were collected and deposited together in
the collection of Museu de Zoologia da Universidade
Estadual de Campinas (voucher: ZUEC 15914). Some
records on Ctenus preying upon anurans of the genus
Leptodactylus are already available in the literature. In
the Amazonian region, Menin, Rodrigues & Azevedo
(2005) recorded about two ctenid species, Ctenus villasboasi and Ctenus sp. preying upon Leptodactylus andreae. However, in the Atlantic Forest of southeast Brazil,
L. marmoratus is one of the most abundant species in
anuran assemblages (Sawaya 1999; Centeno 2009) and
also Ctenus spiders can reached high population densities (Gasnier 1996). Although this is the first record
of predation by C. medius upon L. marmoratus, such
interaction may occur frequently. Thus, spiders could be
important predators of the abundant leaf litter dwelling
species L. marmoratus, and �����������������������������
further detailed studies are
needed in order to prove these suppositions.
Acknowledgement. We would like to thank A. Brescovit for
identification of the spider, Cléris and Eduardo from Parque
Estadual Xixová-Japuí for helping during the field work,
Alexandru Strugariu and two anonymous referees for valuable
suggestions. Financial support was provided by Capes, CNPq,
and FAPESP. Collecting permit was issued by IBAMA (process
number 2007/10423-1).
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Accepted by Angelica Crottini; Managing Editor: Alexandru Strugariu