Sexual dimorphism in Aegla marginata (Decapoda: Anomura)

Abstract

A study on sexual dimorphism in Aegla marginata was conducted using geometric morphometric methods. The carapace of 47 females and 75 males and the left and right cheliped propodus of 29 females and 40 males were analyzed. Eighteen landmarks were established in the carapace and 10 in the cheliped propodus. A Generalized Procrustes Analysis based on landmark configurations was used to separate the components of size and shape. A Student t-test was used to determine whether statistically significant sexual dimorphism was shown by the carapace and the cheliped propodus. The variation in the shape of the structures was evaluated with a discriminant analysis. Our results show that there is no sexual dimorphism in the carapace of A. marginata. However, the size of the propodus differed statistically between the sexes. The carapace shape differed between the sexes: the females showed a wider posterior area and a narrower anterior area than the males. The shape of the cheliped propodus also differed between the sexes: overall, the females had a longer and narrower cheliped propodus than the males. The variations in the carapace shape found in this study confirm the results of other studies on aeglid morphology; however, the information presented by this study regarding variation in the shape of the cheliped propodus is new to the literature. The geometric morphometric approach applied in this study provided useful tools for achieving the proposed objectives.

Variación fenotípica de la langosta espinosa Panulirus argus (Decapoda: Paniluridae) en el Caribe Suroccidental

“…De manera similar, la placa esternal de P. argus exhibió dimorfismo sexual en la conformación, aspecto descrito en otras estructuras de crustáceos tales como el caparazón en C. maenas (Ledesma et al, 2010), en A. marginata (Trevisan et al, 2012), en el langostino colorado M. rugosa (Claverie & Smith, 2010) y en los pleópodos de estados juveniles de L. depurator (Guerao & Abelló, 2011). Este dimorfismo podría resultar de respuestas sexualmente variables a diferentes presiones de selección natural, como ocurre en otras especies como C. maenas, en las que las fuerzas de selección parecen favorecer la conformación de caparazones lateralmente más comprimidos, aumentando la convexidad del caparazón de la hembra (Ledesma et al, 2010).…”

“…En su conjunto, estos estudios han mostrado que las langostas pueden exhibir dimorfismo sexual, alometría, diferencias inter-poblacionales y plasticidad fenotípica. Hallazgos similares se han encontrado en estudios morfométricos de otros crustáceos tales como Aegla marginata (Trevisan et al, 2012), Austropotamobius pallipes (Bertocchi, Brusconi, Gherardi, Buccianti, & Scalici, 2008), Carcinus maenas (Ledesma, Van der Molen, & Barón , 2010;Silva, Alves, Paula, & Hawkins, 2010;Souza , Ilarri, Campos, Marques, & Martins, 2011), Cyrtograpsus affinis (Lezcano, Gonzá-lez, Spivak, & Dellatorre, 2012), Cyrtograpsus angulatus (Idaszkin, Márquez, & Nocera, 2013), Liocarcinus depurator (Rufino, Abelló, & Yule, 2004;Guerao & Abelló, 2011), Munida gregaria (Pérez-Barros, Calcagno, & Lovrich, 2011), Munida rugosa (Claverie & Smith, 2010) y Ucides cordatus (Alencar, Lima-Filho, Molina, & Freire. 2014), entre otros.…”

Variation in Morphometric Characters in Four Sand Crab (Albunea symmysta) Populations Collected from Sumatra and Java Island, Indonesia

“…Wardiatno and Tamaki (2001) studied the morphological characters of two Japanese ghost shrimps, Nihonotrypaea japonica and N. harmandi, to separate the two species by identification. Some researchers have used morphological characters to show sexual dimorphism in decapod crustaceans using their chelipeds (e.g., Shimoda et al 2005;Claverie & Smith 2010;Trevisan et al 2012), which was believed to be a consequence of the common male habits of combat, contest, and courtship (e.g., Hartnoll 1974).…”

Dimorfismo sexual em Hepatus pudibundus (Crustacea, Decapoda, Brachyura)

“…Técnicas de morfometria geométrica são utilizadas para verifi car diferenças signifi cativas na forma e no tamanho de determinadas estruturas corpóreas, para responder questões relacionadas às variações intra e interespecífi cas, questões evolutivas e ecológicas de maneira geral (Klingenberg, 2010;Mitrovski-Bogdanović et al, 2014;Bower & Piller, 2015), como a alometria ontogenética e o dimorfi smo sexual (Trevisan et al, 2012;Ponssa & Candioti, 2012;Accioly et al, 2013 diferenças morfológicas mínimas em estruturas corporais, e tem sido utilizada em Decapoda principalmente devido ao rígido exoesqueleto e à facilidade na obtenção de marcos anatômicos (Rohlf & Marcus, 1993;Alencar et al, 2014). Com a compreensão da variação morfológica de caracteres homólogos é possível discutir o direcionamento da seleção sexual com base na morfologia de cada sexo bem como inferir sobre as pressões ecológicas (Tatsuta et al, 2004).…”