Hard-shell mating in Neohelice granulata: the role of ecdysone in female receptivity and mate attraction

Abstract

Most brachyuran females become receptive during the intermolt period, a condition considered "derived". However, as far as we know, studies testing the existence and function of pheromones in decapods are based on species which have mating linked to molting, a condition considered as "ancestral". For the first time, we studied some physiological and morphological processes involved in Neohelice granulata intermolt female crabs becoming receptive and potentially attracting males. We found that receptive females have mobile vulvae opercula due to a softening process of the cuticle hinge which showed lower calcium levels compared to the hinge of unreceptive females. Local softening of the hinge was stimulated by a low concentration of ecdysone during the intermolt period. A putative pheromone liberated by receptive females to attract males is presumed to be released through the mobile vulvae and not through the urine.

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

“…An alternative but not mutually exclusive explanation is that there is some mechanism by which males can sense female receptivity and hence invert more in subduing the female. There is evidence suggesting that even under coercion, females may retain the opportunity to indirectly choose mates through the release of sex pheromones (Okamura & Goshima, 2010), although that is frequently accompanied by other morpho-physiological changes related to receptivity, such as the softening of the vulvae opercula (Sal Moyano et al ., 2017), a trait not observed in these species. Nevertheless, given the turbidity of the shallow waters inhabited by P. meridionalis chemical cues probably play a role in intraspecies agonistic interactions and further study is required on this (Rodgers et al ., 2011).…”

A new subfamily classification of the highly diversified Dorippidae H. Milne Edwards, 1837 (Crustacea, Decapoda, Brachyura, Dorippoidea), using morphological, molecular and palaeotonlogical data, with special emphasis on its unique female reproductive system

“…The condition in which mating is restricted to the moulting period (when soft-shell females become receptive) has been considered 'ancestral': a post-moult mating is observed in Cancridae and most Portunidae (Jivoff et al 2007). Conversely, in the 'derived' condition, moulting and reproduction would be delinked, with mating occurring during the intermoult period, when both sexes have hard-shelled exoskeletons, as in ocypodids, grapsoids and varunids (Sal Moyano et al 2017).…”