Abstract
Freshwater crabs are important elements in the aquatic biota of brooks, rivers, lakes and ponds, from both ecological and the socio-economic aspects. Trichodactylidae comprises 51 endemic species from the Neotropical region. Among all the species of this family, Trichodactylus fluviatilis Latreille, 1828 has the widest geographic distribution throughout Brazil. Despite that, there are few published contributions on the biology of this species. The present study investigated the following aspects of T. fluviatilis: relative growth, mean size at onset of morphometric maturity, sexual dimorphism, laterality and heterochely. Specimens were collected monthly from September 2010 through August 2011, from the Velha Eugênia Brook, municipality of Santa Teresinha, State of Bahia. Carapace width (CW), carapace length (CL), major cheliped length (MaCL) and minor cheliped length (MiCL), major cheliped height (MaCH) and minor cheliped height (MiCH), and width of the fifth abdominal segment (5AB) were measured to evaluate the presence of sexual dimorphism; the major difference between the sexes was in the CW vs. 5AB ratio. Heterochely was observed in males and females,with the right cheliped larger than the left in 89% of males and 81% of females. Crab size at the onset of morphometric maturity (= puberty molt) was estimated based on the ratio between CL, cheliped dimensions, 5AB and CW (independent variable). Females were larger than males when they reached morphometric maturity in all studied relations. We recommend the use of chelipeds and abdominal width relationships to estimate the size at the morphometric maturity in males and females, respectively.
Highlights
Trichodactylidae comprises 51 endemic species from the Neotropical region
Published studies on relative growth in brachyuran crabs often find a relationship between allometric growth and morphometric maturity, since the puberty molt is usually marked by a significant change in the allometric growth rate of some body structures such as the carapace, chela and abdomen (HARTNOLL 1978)
This study investigated the relative growth and average size of T. fluviatilis crabs at the onset of morphometric maturity, in order to provide information that could contribute to efforts to protect this species in the state of Bahia, Brazil
Summary
Trichodactylidae comprises 51 endemic species from the Neotropical region. All members of the family are considered “true freshwater” crabs (sensu YEO et al 2008), because they have direct development and complete their entire life cycle independently of the marine environment (MÜLLER, 1892, YEO et al 2008). Trichodactylus Latreille, 1828 includes 11 valid species, nine of which have been reported from Brazil (MAGALHÃES 2003). Trichodactylus fluviatilis Latreille, 1828 has a wide geographic distribution along the Brazilian coast, from the state of Pernambuco to the state of Rio Grande do Sul (MAGALHÃES 2003). Despite this wide range, little is known about the biology of the species (MANSUR et al 2005). LIMA et al (2012) reported on the allometric growth and average size of T. fluviatilis crabs from southeastern Brazil at the onset of morphometric maturity. 2014 Sociedade Brasileira de Zoologia | www.sbzoologia.org.br | www.scielo.br/zool All content of the journal, except where identified, is licensed under a Creative Commons attribution-type BY-NC
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