Ecological traits of two neotropical oniscideans (Crustacea: Isopoda)(In English)
Aline Ferreira QUADROS, Paula Beatriz ARAUJO
D e p a r t a m e n t o d e Z o o l o g i a , I B , U n i v e r s i d a d e F e d e r a l d o R i o G r a n d e d o S u l , A v . B e n t o G o n & c c e d i l ; a l v e s 9 5 0 0 , p r . 4 3 4 3 5 , 9 1 5 0 1 - 9 7 0 , P o r t o A l e g r e , R S , B r a s i l
Two terrestrial isopods,Atlantoscia floridana (Philosciidae) and Balloniscus glaber (Balloniscidae) that differ in size, morphology and behaviour were studied with respect to the influence of the environmental variation on their reproduction and population structure. Samples were taken at Parque Estadual de Itapuã, Brazil from May 2004 to April 2005. Twelve cores of litter and soil were extracted each month, and hand-searched in the lab. All specimens were sexed and measured. Overall, 2540 individuals were captured. Atlantoscia floridana reproductive females were present throughout the year, while B. glaber showed a shorter reproductive period, from early spring to early autumn, and both species showed high numbers of reproductive females and mancasduring spring.Mean density of A. floridana was 114 ind./m2 and 133 ind./ m2 for B. glaber. The increased dryness observed in the summer of 2005 affected the populations differently, as it reduced population size of A. floridana while B. glaber population remained stable. It seems that the differences in morphology, more specifically body size and presence of pleopodal lungs, confer upon B. glaber a higher tolerance to desiccation. Moreover, B. glaber may rely on behavioral strategies, such as burrowing, to increase the survival of the young, and even the survival of the adults under stressful climatic conditions. It is postulated that the continuous reproduction, lower time to maturity and higher proportion of reproductive females of A. floridana are responses to its high juvenile mortality[Acta Zoologica Sinica 53(2): 241– 249, 2007].