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

Abstract

Summary:We describe the most noteworthy changes occurring during the post-metamorphic phase in both sexes of the purple stone crab Platyxanthus crenulatus. Spatial structure of the populations by size and early changes in colour pattern and relative growth of chelae suggest an ontogenic migration from intertidal to deeper waters. Before reaching maturity and laying eggs, females undergo a tight sequence of morpho-physiologic changes over a narrow size range (44-64 mm carapace width [CW]). In contrast, males undergo two main phases related to sexual maturity. Early in their lives, they develop sperm and accelerate the relative growth of the chelae (35-45 mm CW). Morphologic maturity of males comes later, when relative growth rate reaches the maximum and decelerate (65-70 mm CW). Adult males are larger and develop conspicuously largest chelae than females. Morphometric analyses were performed by two different techniques: the traditional procedure, which describes relative growth relationships as power functions; and an alternative, smoothing spline-based model that is nondependent on previous assumptions. The results of the alternative analysis were coherent with other reproductive indicators and ancillary observations, allowing a more comprehensive understanding of the relative growth. We provide supporting material containing the respective script written in R program to be used freely in future studies.Keywords: sexual maturity; stone crabs; southwestern Atlantic; alternative methods; relative growth.Uso de hábitat, crecimiento relativo y talla de madurez, calculada mediante diferentes modelos, del cangrejo violeta Platyxanthus crenulatus (Decapoda: Brachyura) Resumen: Se describen los eventos más remarcables durante la ontogenia de la fase post-metamórfica del cangrejo violeta de las rocas Platyxanthus crenulatus. Las poblaciones estudiadas aparecen estructuradas por talla, lo que sumado a cambios tempranos en el patrón de coloración y en la tasa de crecimiento relativo de las quelas de ambos sexos, sugiere la existencia de una migración ontogénica desde el intermareal hacia aguas más profundas. Antes de alcanzar la madurez y extruir huevos, las hembras atraviesan una serie de cambios morfo-fisiológicos en un rango de tallas estrecho (44-64 mm). En contraste los machos muestran dos fases bien diferenciadas en relación a la madurez sexual. Tempranamente desarrollan esperma y aceleran el crecimiento relativo de las pinzas (35-45 mm). La madurez morfológica se alcanza posteriormente cuando la tasa de crecimiento relativo alcanza su máximo y comienza a desacelerarse (65-70 mm). Los machos adultos son más grandes y tienen quelas de mayor tamaño que las de las hembras. Los análisis morfométricos fueron realizados aplicando paralelamente dos técnicas diferentes: el procedimiento tradicional, que describe al crecimiento relativo como una función potencial, y un método alternativo, no dependiente de supuestos a priori, basados en splines. Los resultados del análisis alternativo fueron coherentes con los demás indicador...

Population, Reproductive and Fishery Dynamics of Spotted Box Crab (Calappa philargius), a New Claw-Only Fishery Species, in the Southern Taiwan Strait, China

“…The pattern of sexual size dimorphism, however, is largely species specific. For example, Callinectes danae, C. sapidus, C. philargius, Chaceon macphersoni, Chaceon affinis, Chionoecetes tanneri, Cancer borealis Johngarthia lagostoma, M. haanii, Platyxanthus crenulatus, and Ranina ranina (Krajangdara and Watanabe, 2005;Hartnoll et al, 2009;Sforza et al, 2010;Keller et al, 2012;Groeneveld et al, 2013;Farias et al, 2014;Biscoito et al, 2015;Jivoff et al, 2017;Truesdale, 2018;Lin et al, 2021; this study) are No samples in May-July 2019. Data (average and range) from the number of trap vessels surveyed monthly.…”

Opposites attract: Multiple evidence of sexual antagonistic coevolution driving extreme male-biased sexual size dimorphism inPanopeus meridionalis

“…Once in laboratory the specimens were sexed, the presence of eggs in females recorded, and the carapace width (CW, hereafter simply referred as “size”), pleon width (PW) and crusher chela length (CrL) measured to the nearest 0.1 mm. Sexual differences in size frequency distributions were tested by applying and comparing Kernel density estimators (KDEs) to the size frequency distributions for each sex (Farias et al ., 2014). Briefly, KDEs are a non-parametric way to estimate the probability density function of a random variable.…”