A comparative study of the reproductive cycles of 3 northumberland uk populations of chaetozone setosa polychaeta cirratulidae
Journal of the Marine Biological Association of the United Kingdom 65(1): 239-254
The morphological characteristics and reproductive cycles of 3 Northumberland populations of C. setosa were compared. There are differences between the 3 populations in the relative position of the tentacular palps and branchiae and in the appearance of the posterior segments. These morphological differences are sufficient to allow confident separation of specimens belonging to each population. The overall pattern of gametogenesis in the 3 populations is similar but the onset of gametogenesis, the rates of gametocyte development and the times of spawning differ. Spawning occurs in March-April in the intertidal Newton populations, and in Nov.-Dec. in the interidal Holy Island and subtidal Station P populations. All 3 populations produce yolky eggs measuring 120-160 .mu.m in diameter and these gives rise to larvae with lecithotrophic development. Holy Island males produce sperm with elongated heads whereas Newton and Station P males produce sperm with small round heads. The evidence indicates that this cosmopolitan species may represent a sibling species complex.