Sexually dimorphic body proportions in the catshark genus Scyliorhinus (Chondrichthyes: Carcharhiniformes: Scyliorhinidae)

Abstract

Intersexual differences in morphometrics were investigated in five species of the catshark genus Scyliorhinus. ANCOVA was used to test 59 measurements, considering capture location and total length as covariates. In all examined species, pelvic–anal distances and pelvic‐fin inner margin lengths were greater in males than in females, representing a clear pattern for the genus.

The intraspecific diversity of tooth morphology in the large‐spotted catshark Scyliorhinus stellaris: insights into the ontogenetic cues driving sexual dimorphism

“…The overall jaw geometry may also be considered as another potential driver of the mesio‐distal patterning. As for the dental lamina, its effects on the mesio‐distal patterning may however be non‐linear: The sexually dimorphic heads in mature scyliorhinids would also affect the shape of jaw cartilages (Ellis and Shackley, 1995; Soares, 2019; Soares and Carvalho, 2019). This would suggest a sexual dimorphism in the gradient of cusp–crown ratio by affecting differently the labial‐lingual local curvature of the dental lamina where the tooth buds develop.…”

“…Another developmental parameter in which variation was associated with this shape relationship is epithelial growth rate (Salazar‐Ciudad and Jernvall, 2010), for example, the rate of cell division in the tooth bud that is growing from the dental lamina. Finally, the dental lamina characteristics (acting on diffusion rates and cell division rate) might exhibit sexual dimorphism, as a consequence of sexually dimorphic head dimensions in Scyliorhinidae (Ellis and Shackley, 1995; Soares, 2019). The longer and narrower jaw in males compared to females at mature stage is actually a recurrent feature in elasmobranchs and gives support to this hypothesis (Ellis and Shackley, 1995; Braccini and Chiaramonte, 2002; Erdogan et al ., 2004; Geniz et al ., 2007; Soares et al ., 2016; Soares, 2019).…”

“…Finally, the dental lamina characteristics (acting on diffusion rates and cell division rate) might exhibit sexual dimorphism, as a consequence of sexually dimorphic head dimensions in Scyliorhinidae (Ellis and Shackley, 1995;Soares, 2019). The longer and narrower jaw in males compared to females at mature stage is actually a recurrent feature in elasmobranchs and gives support to this hypothesis (Ellis and Shackley, 1995;Braccini and Chiaramonte, 2002;Erdogan et al, 2004;Geniz et al, 2007;Soares et al, 2016;Soares, 2019). Labial curvature of the jaw cartilages may then impact the physical constraints on dental lamina.…”