Population dynamics of the pea crab Austinixa aidae (Brachyura, Pinnotheridae): a symbiotic of the ghost shrimp Callichirus major (Thalassinidea, Callianassidae) from the southwestern Atlantic

Abstract

The Pinnotheridae family is one of the most diverse and complex groups of brachyuran crabs, many of them symbionts of a wide variety of invertebrates. The present study describes the population dynamics of the pea crab Austinixa aidae (Righi, 1967), a symbiont associated with the burrows of the ghost shrimp Callichirus major (Say, 1818). Individuals (n = 588) were collected bimonthly from May, 2005 to September, 2006 along a sandy beach in the southwestern Atlantic, state of São Paulo, Brazil. Our data indicated that the population demography of A. aidae was characterized by a bimodal size-frequency distribution (between 2.0 and 4.0 mm and between 8.0 and 9.0 mm CW) that remained similar throughout the study period. Sex ratio does not differ significantly from 1:1 (p > 0.05), which confirms the pattern observed in other symbiontic pinnotherids. Density values (1.72 ± 1.34 ind. • ap.-1) are in agreement with those found for other species of the genus. The mean symbiosis incidence (75.6%) was one of the highest among species of the Pinnotheridae family, but it was the lowest among the three studied species of the genus. Recruitment pattern was annual, beginning in May and peaking in July, in both years, after the peak of ovigerous females in the population (from March to May). Our findings describe ecological and biological aspects of A. aidae similar to those of other species of this genus, even from different geographic localities.

Host-use pattern and sexual dimorphism reveals the mating system of the symbiotic pea crabAustinixa aidae(Crustacea: Brachyura: Pinnotheridae)

“…This colour might be adaptive for males when out of the burrows, reducing the probability of detection by potential predators (see above). This male roaming behaviour might continue for approximately one year as indicated by preliminary studies on the population dynamic of this species (Peiró & Mantelatto, 2011) or until early death due to predation.…”

Reproductive traits of the symbiotic pea crab Austinotheres angelicus (Crustacea, Pinnotheridae) living in Saccostrea palmula (Bivalvia, Ostreidae), Pacific coast of Costa Rica

“…Representatives of the family Pinnotheridae have evolved a series of adaptations to cope with their symbiotic life style (Hines 1992; Peiró and Mantelatto 2011), which makes them an interesting model to study the evolution of associations between decapods and other invertebrates. Here we present results on reproductive features of Austinotheres angelicus , which lives in association with oysters.…”

“…Members of this family are known to exhibit symbiotic relationships with numerous other invertebrates, including mollusks, polychaetes, echinoderms, brachiopods, and other decapods (Manning and Morton 1987, Feldmann et al 1996, Baeza 1999, Lardies and Castilla 2001, McDermott 2006, Peiró and Mantelatto 2011, Trottier et al 2012). The type of symbiotic relationships ranges from parasitism to commensalism, and pinnotherids live in a facultative and/or obligate association with their hosts (Silas and Alagarswani 1965, Schmitt et al 1973, Stevens 1990, Hamel et al 1999).…”

Relative growth and sexual dimorphism of Austinixa aidae (Brachyura: Pinnotheridae): a symbiont of the ghost shrimp Callichirus major from the southwestern Atlantic

“…The wider and slimmer (anterior-posterior) body facilitates the locomotion inside the burrows constructed by its hosts. Peiró & Mantelatto (2011) pattern can be influenced by several factors that have not been evaluated by us as fitness payoffs to hosts and their symbionts, spatial patterning or density of the host population, and the ability of symbionts to recognize suitable hosts and to initiate and maintain the symbiotic relationship (see Grove & Woodin, 1996, for review).…”