Morphometric and gonad maturity of the spider crab Libinia spinosa (Crustacea: Brachyura: Majoidea: Epialtidae) in Argentina

Abstract

Morphometric and gonad maturity of Libinia spinosa on the coast of Mar del Plata, Argentina, were assessed. In both sexes various morphometric features were measured to determine the morphometric maturity, and through macroscopic inspection of gonads and analysis of its content, different stages of gonad maturity were described and the physiological maturity was estimated. In females, the carapace width ranged from 8 to 56.5 mm while in males from 4.6 to 81.97 mm. The size at which 50% of females were morphometrically mature was calculated at 40.6 mm. Based on the allometric growth of the abdomen, two morphometric groups of females were recognized as juvenile and adult phases. In males, results of principal component analysis showed that the most suitable variables that efficiently represent the size and sexual differentiation factor were the carapace width and cheliped length respectively. The size at which 50% of males were morphometrically mature was estimated at 58.9 mm. Based on the allometry of the cheliped growth, two morphometric groups were recognized as immature and mature phases. Males maintained under laboratory conditions moulted and growth was related to regular and terminal moults. Males reached their terminal moult at a wide size-range, from 48.5 mm to 61.4 mm of carapace width. This terminal moult coincided with the size of morphometric maturity. In both sexes four stages of gonad development were described, two corresponded to immature phases and two to mature phases. The size at which 50% of females and males reached gonad maturity was LC 50 ¼ 40.33 mm and LC 50 ¼ 33.6 mm, respectively. In females, both morphometric and gonad maturity occurred at a similar size. In males, gonad maturity is acquired prior to morphometric maturity, thus three different types of males were characterized: (1) those with small carapace width and cheliped, without spermatophores in their vas deferens; (2) those with large carapace width and small cheliped, bearing spermatophores in their vas deferens; and (3) those with large carapace width and cheliped, bearing spermatophores in their vas deferens.

The relative growth and sexual maturity of the freshwater crab Dilocarcinus pagei (Brachyura, Trichodactylidae) in the northwestern region of the state of São Paulo

“…This type of differential growth was also observed for the specie investigated in the present study by Mansur et al (2005) Rathbun, 1920;Sal Moyano et al (2011) for Libinia spinosa (Milne-Edwards, 1834) and Lima et al (2013) for Trichodactylus fluviatilis Latreille, 1828.…”

Morphology and ultrastructure of the adult ovarian cycle in Mithracidae (Crustacea, Decapoda, Brachyura, Majoidea)

“…However, in histological and ultrastructural analyses, we could identify four stages of development, as described for other Majoidea [6,13,14,16,29,30]. In our macroscopic analyses, the four stages of development were not identified because of the variable relationship between the ovary and hepatopancreas.…”

“…Based on macroscopic and histological characteristics, ovarian development in Majoidea can be divided into four stages, two corresponding to the immature and two to the mature phases [6,13,14]. These four stages are characterized by the presence of lipid and neutral polysaccharides and the absence of acid polysaccharides in all stages of the development [14].…”

“…In females, the evaluation of physiological maturity encompasses the study of these functional and structural characteristics. Ovarian development until ovulation is commonly assessed by macroscopic analyses using the color and proportion of the gonads in the cephalothorax for several brachyuran groups, including portunids, aethrids and majoids [4][5][6]. Although macroscopic analyses are common, detailed information about ovarian…”

Habitat use, relative growth and size at maturity of the purple stone crab <em>Platyxanthus crenulatus</em> (Decapoda: Brachyura), calculated under different models

“…Consequently, estimations of the size at maturity of crabs have been traditionally based on a combination of direct observations of the qualitative traits related to reproduction (hereafter "reproductive indicators") and morphometric analysis (e.g. López-Greco and Rodríguez 1999, Hall et al 2006, Sal Moyano et al 2010. Reproductive indicators, such as the morphology of gonads, seminal receptacles and vulvae, have discrete response values (mostly binary as mature/inmature) that are readily observable, so the classification of an individual as mature usually pose no further problems.…”