Galeus melastomus Rafinesque 1810

• Main Authors: Gordon, Cat A., Hood, Ali R., Ellis, Jim R.
• Format: Other/Unknown Material
• Language: unknown
• Published: 2016
• Subjects: Biodiversity; Taxonomy; Animalia; Chordata; Elasmobranchii; Carcharhiniformes; Scyliorhinidae; Galeus; Galeus melastomus; Norway; Canicula; Northeast Atlantic
• Online Access: https://zenodo.org/record/5631376; https://doi.org/10.5281/zenodo.5631376

Galeus melastomus Rafinesque, 1810 Distribution. Black-mouth catshark (G. melastomus) is distributed widely on the outer continental shelf and upper slope in the Northeast Atlantic, from Norway to Senegal, including the Mediterranean Sea (Stehmann & Bürkel, 1984). Despite being relatively widespread, this is a deeper-water species and so eggcases are rarely washed ashore and reported to the Great Eggcase Hunt. Only two verified specimens have been submitted to the Great Eggcase Hunt at the time of writing, one from North Uist (Outer Hebrides) and the other from Rossnowlagh, Donegal (Ireland). Material examined. Seven samples were examined in total, of which one from North Uist was recorded by the Great Eggcase Hunt. The remaining six specimens were from museum collections (BMNH 1934.8.8.3a, BMNH 1934.8.8.4a, BMNH 1928.9.18.13–16), with two recorded from southwest Ireland and the remainder of unknown provenance. Description. The eggcase of G. melastomus (Figure 8 a; Table 2) is similar in shape and appearance to S. canicula however it lacks the curly tendrils of Scyliorhinus. The mean eggcase length is 58.9 ± 11.3 mm (33.6–65.0 mm) and eggcase width is 20.4 ± 1.8 mm (17.1–23.0 mm). It is a small and neatly-formed eggcase with longitudinal striations visible on the capsule surface. The capsule is flattened towards the anterior neck and biconvex towards the wider posterior end. Keels are absent and in their place are small ridges that join the dorsal and ventral sides together. In place of tendrils, this eggcase has short anterior horns which form small hooks that curve inwards. The posterior horns are also short and hooked, curving in to meet each other. Remarks. This species displays multiple oviparity, and 13–14 eggcases have been found in a female’s oviduct (Costa et al., 2005). Several studies have reported concentrations of G. melastomus eggcases on biogenic habitats (Treude et al., 2011; Henry et al., 2013). The eggcase of the related Atlantic sawtail catshark Galeus atlanticus (Vaillant, 1888), which ...