Morphological variability in populations of the fiddler crab Leptuca uruguayensis (Nobili, 1901) (Crustacea, Decapoda, Ocypodidae) from South America

Abstract

A comparative study on size and shape of Leptuca uruguayensis was carried out between populations from Garças River, Brazil (BP), and Solís Grande River, Uruguay (UP). The size of the onset of sexual maturity was also estimated for UP. A total of 36 crabs BP and 387 crabs UP were analyzed. In the relative growth analysis, carapace width (CW) for both sexes, major cheliped length (LMC) for males and abdomen width (AW) for females were measured. The centroid size of carapace (1.40±0.19 cm BP and 1.88±0.30 cm UP) and cheliped (1.16±0.22 cm BP and 1.58±0.45 cm UP) differed significantly (p<0.001). The shape also differed significantly (p<0.001), having UP wider carapace than BP, rostrum projected forward and posterior margin positioned more anteriorly; the cheliped of UP was also wider than BP. In UP, males' CW ranged 4.28-19.5 mm and females' 2.53-16.3 mm CW; males' LMC ranged 1.79-31.60 mm and females' AW, 0.80-8.53 mm. The onset of sexual maturity of UP was estimated in 12.20 mm CW for males and 7.81 mm for females. These differences are likely related to abiotic variables acting distinctly in the two localities.

An illustrated key to the fiddler crabs (Crustacea, Decapoda, Ocypodidae) from the Atlantic coast of Brazil

“…comm. ), while in Uruguayan estuaries L. uruguayensis inhabit stream lowlands (Masunari et al 2017).…”

“…Small crabs: males with CW up to 12.0 mm in a population from Itacuruçá mangrove, Sepetiba Bay, southeastern Brazil (Bedê et al 2008). Leptuca uruguayensis, however, can attain up to 19.5 mm CW in the population from Solís Grande River, Uruguay (Masunari et al 2017).…”

Differentially expressed morphological characters depend on sex and ontogenetic stage in the crab Goniopsis cruentata (Crustacea: Grapsidae)

“…The allometric analysis showed that males acquired a larger average body size than females for the G. cruentata population captured in a tropical estuarine mangrove, and the same growth pattern was also described by Botelho et al (2004). Accord- ing to Masunari et al (2017), the size variation between the sexes can be explained by differentiated reproductive needs, as size dominance in male crabs increases opportunities for victory during intraspecific competition, courtship and handling the female during copulation.…”