Growth curve of Balloniscus glaber Araujo & Zardo (Crustacea, Isopoda, Oniscidea) from Parque Estadual de Itapuã, Rio Grande do Sul, Brazil

Abstract

Based on field data, this study presents the growth curve of Balloniscus glaber Araujo & Zardo, 1995, a terrestrial isopod species found in Parque Estadual de Itapuã (PEI), Rio Grande do Sul, Brazil. Specimens were monthly sampled, from May 2004 to April 2005, at PEI. Captured individuals were sexed, their cephalothorax width was measured, and the growth curve was described according to von Bertalanffy's model. Male and female growth curves are described by the equations: Wt = 2.256[1-e-0.00394(t+91.128)] and Wt = 2.588[1-e-0.00301(t+101)], respectively. Curves show differential growth between males and females, with females reaching higher W<FONT FACE=Symbol>¥</FONT>, and a slower growth rate than males. Based on theses curves, life span was estimated.

Balloniscus glaber (Crustacea, Isopoda, Balloniscidae), a habitat specialist species in a disturbed area of Brazil

“…However, the sex ratio of terrestrial isopod populations may vary between populations and species (Dangerfield & Hassall, 1994). Even so, a juvenile female predominance was observed in 1-and 2-month-old isopods [according to the growth curve (Meinhardt et al, 2007) and life table ] in the population at the beginning of the winter (July 2011) and during the late summer (April 2012) in the impacted area. This pattern reflects the individuals' growth time to reach adulthood and sexual maturity for the reproduction period.…”

“…Only ten years after the description of B. glaber, the species was recorded in three distinct altitudinal gradients in the state of Rio Grande do Sul (Lopes et al, 2005). Meinhardt et al (2007) described its species' growth curve and demonstrated that females reach a larger size, live longer, and have a slower growth rate compared to males. Quadros et al (2009) investigated two sympatric populations of Atlantoscia floridana (van Name, 1940) and B. glaber at PEI and found that females of the latter species became reproductive at approximately 7.5 months old and incubated 5-20 eggs for approximately 40 days.…”

“…The density data were log 10 (n + 1) transformed as in , and the CW values were arranged by month and interval class in histograms (I-XXI) (Meinhardt et al, 2007). Following , the reproductive period was defined, as the monthly operational sex ratio (OSR), which is based on the rate of males and females that are apt to reproduce at a given time (Emlen & Oring, 1997), and the ovigerous females' categorization (females with eggs, EG; females with embryos, EM; females with manca, MA; and post-ovigerous females, PO).…”

Diversity and population characteristics of terrestrial isopods (Crustacea, Oniscidea) across three forest environments in southern Brazil

“…The biology of B. glaber has been studied in detail in the latter years (almerão et al, 2006;meinhardt et al, 2007;QuadroS & araujo, , 2008QuadroS et al, 2009;QuadroS, 2010). It is known to be a habitat specialist (QuadroS et al, 2008), justifying it's nearly absence in the Pinus plantation.…”

Growth ofLigia exotica(Isopoda: Oniscidea: Ligiidae) in two estuarine regions of Patos Lagoon, Rio Grande do Sul, Brazil

“…Haddad & Verani (1984) analysed postmarsupial growth of Balloniscus sellowii (Brandt, 1833) under laboratory conditions and Araujo & Bond-Buckup (2004) estimated growth of a wild population of Atlantoscia floridana (van Name, 1940) based on the increment of cephalothoracic length. Meinhardt et al (2007) studied the growth the Balloniscus glaber Araujo & Zardo, 1995 based in the von Bertallanfy model. Meinhardt et al (2007) studied the growth the Balloniscus glaber Araujo & Zardo, 1995 based in the von Bertallanfy model.…”