CATTON, C. A.: Life history stages of Eusyllis habei Imajima, 1966 with notes on epitoky in the family Syllidae (Annelida: Polychaeta)

The life cycle of most polychaetes in the family Syllidae includes a brief pelagic larval stage followed by a benthic atokous (nonreproductive) stage. As adults, most species produce swimming reproductive individuals by either asexually budding stolons or by metamorphosing into epitokes. Descriptions of the atokous stages exist, but species-specific morphological characteristics are often lost or altered in the reproductive stages. However, several syllid species undergo reversal of epitokous metamorphosis, suggesting that many of the same characteristics might be present in both stages. Observations of the transitions between stages of Eusyllis habei Imajima, 1966, Eusyllis sp 13 Harris (undescribed), and Exogone (Exogone) dwisula Kudenov and Harris, 1995 verified the retention of key characteristics throughout metamorphosis in these epigamous species. Successful mating of E. habei in the lab further verified identical taxonomic traits between sexes for that species. The larvae produced from these matings were reared under laboratory conditions. The purple-tinted eggs of E. habei were approximately 80 mm in diameter. However, larvae of E. habei were non-feeding. Larvae settled at an early stage, before segmentation of the peristomium was complete. This species also developed a third pair of eyes at the nine-setiger stage, which was previously undescribed in E. habei.