Topic: Two Species of Skate
See the website and comment by Andy Horton below:
Two species of Skate: http://www.sciencedaily.com/releases/20 … 191048.htm
From the mid-19th century the Common Skate was described as two distinct species, the Flapper Skate, D. intermedia, and the Blue Skate, D. flossada.
Andy Horton:- Since this factsheet was produced, genetic research has revealed that the Common Skate, Dipturus batis, is in fact two distinct species. These have been named D.intermedia and D.flossada. Common names already in use for these species are the Flapper Skate and Blue Skate respectively, although it remains to be seen if these become widely accepted. The two species appear to have different distributions and biological characteristics. Of the two, D.intermedia is slower growing and reaches a larger size. The first data published suggests a size at 50% maturity of 197.5cm (♀) and 185.5cm (♂) for D.intermedia, compared to 122.9cm (♀) and 115cm (♂) for D.flossada. The largest positively identified specimen of D. flossada was 143.2cm in length. It seems the maximum total length of 285cm previously attributed to D. batis must be D. intermedia. While the ranges of the species overlap it appears that D.intermedia is limited to west Scotland and west Ireland, with D.flossada limited to the southern Irish and Celtic Seas and the Rockall Trough. This appears to be closely related to temperature. The most reliable means of distinguishing these species seems to be the colour of the iris. In D. intermedia it is dark green/olive, in D.flossada it is pale yellow. Other morphometric features to check are the malar thorns, lateral tail thorns, interdorsal space and tooth bases. Colouration can differ on the ventral surface and on the centre of the wings. For a full discussion of these differences see Iglésias et al., 2009, available online. http://www.sharktrust.org/.../common_sk … tsheet.pdf