Oncopagurus gracilis (Henderson, 1888)

da Silva, Adriane Candiotto Caio S. Nogueira Laura Schejter Alexandre R., 2023, Sexual and size dimorphism in two deep-water hermit crabs (Decapoda: Parapaguridae) from the Western Atlantic Ocean, Nauplius (e 2023026) 31, pp. 1-14 : 5-6

Oncopagurus gracilis

The shape of CPS (Hotelling T ² = 98.62, F = 4.28, p <0.001), MaP (Hotelling T ² = 68.77, F = 6.83, p <0.001), and MiP (Hotelling T ² = 79.43, F = 5.7, p <0.001) were different between male and female individuals. The discriminant analysis accurately classified 90 %, 82.05 %, and 82.72 % of individuals based on their CPS, MaP, and MiP shape, respectively.

The shape of the CPS of females was observed to be wider anteriorly than that of males ( Fig. 2A), while the posterior margin of this structure was wider in males than in females ( Fig. 2A). The variation of the MaP and MiP shapes exhibited a similar pattern. The manus region of MaP and MiP was more robust in males than in females ( Fig. 2B). Furthermore, the fixed finger of the MiP was also found to be more robust in males than in females ( Fig. 2C).

Sexual size dimorphism between males and females was detected in almost all structures, except CPS (t -test; t = 1.53, p = 0.18). In contrast, the size of MaP (t -test; t = -5.99, p <0.001) and MiP (t -test; t = -4.91, p <0.001) differed significantly between the sexes ( Fig. 3A).