Revista Chilena de Historia Natural 79 (2): 147-154, 2006
RESEARCH ARTICLE
Effects of the rhizocephalan Loxothylacus armatus (Cirripedia: Rhizocephala) on
the crab Paraxanthus barbiger (Decapoda: Brachyura) in Chile
In the marine realm, several biological associations are distributed worldwide and are
highly specific, but remain poorly studied in Chile. Here, we describe quantitatively the infection by the barnacle
Loxothylacus armatus Boschma 1949 (Cirripedia: Rhizocephala) in the crab Paraxanthus barbiger
(Poeppig 1836) (Decapoda: Brachyura), and assess if the parasite effects are similar to rhizocephalan-decapod associations
elsewhere. To do this, 513 crabs were collected by hand while scuba diving between September and October, 2003 in the shallow
subtidal zone of Lenga (37°S), Chile. Maximum prevalence reached ca. 60 % in small body size hosts, producing total castration of
males, inhibiting the gonadic development of female crabs and modifying the size of sexual characters in both sexes, thus revealing
that this parasite imposes a great demand upon its host. These results are closely similar to others involving rhizocephalans, and
suggest that taking into account symbiosis like this one in the study of benthic communities in Chile could lead to new interpretations
about the abundance and reproductive patterns of P. barbiger, which is a prominent predator in these
communities.
Key words:
biological associations,
Rhizocephala-Decapoda, Chile, community ecology, parasitic castration
