Caligus gayi Nicolet, 1849

This species, as “ Calygus Gayi ”, was described by Nicolet (1849) from “a fish in Chiloe” (southern Chile). The description, in Spanish, was brief, but a colour illustration of an ovigerous adult female was published subsequently in the accompanying Atlas (Gay, 1854). The body length was given as “2 lineas” – which is equivalent to 4.23 mm. When Wilson (1905) described Caligus teres Wilson, 1905, he commented that it resembles Caligus gayi “in many particulars, but there is still enough difference, particularly in the coloration, to render it certain that the two are distinct species.” Wilson’s females of C. teres were 4.75 mm long.

Colour has rarely been used to distinguish between parasitic copepods, especially when making comparisons with early nineteenth century, hand-painted illustrations. However, because of the lack of detail in the description of C. gayi, it is not possible to unequivocally identify this species and it is treated here as a species inquirendum, following Parker (1968) who included it in his “List of Caligus species named prior to 1899 considered nomina nuda or species inquirenda ”.