INTRASPECIFIC VARIATION IN THE BRITTLE-STAR OPHIOPHOLIS ACULEATA (LINNAEUS) IN THE NORTHWESTERN ATLANTIC (ECHINODERMATA; OPHIUROIDEA)

¹ Department of Zoology, University of Maine, Orono, Maine 04473

1. Fourteen taxonomic characters were analyzed separately for Maine, Newfoundland and Greenland populations of O. aculeata.

2. The number of naked aboral disk plates, length of the arm spines and length-to-width ratio of the arm spines are characters that vary clinally.

3. The length-to-width ratio of the oral shields and the number of oral papillae are essentially the same in the Maine and Newfoundland populations but are significantly different in the Greenland population.

4. The length of the oral disk spines and morphology of the oral disk spine tip are essentially the same in the Newfoundland and Greenland populations but are significantly different in the Maine population.

5. The number of aboral arm platelets does not change clinally but is distinctly different in all populations.

6. The morphology of the oral disk spine tip, number of naked radial shields, presence of aboral arm platelet spines, length of the aboral disk spines, width of the arm spines and number of arm spines are characters essentially the same in all populations.

7. There are 2-6 oral papillae and 4-8 proximal arm spines present on O. aculeata.

8. The diagnostic characters of O. pilosa Dyakonov, 1954, fall within the range of variation displayed by O. aculeata.