Dipolydora Verrill, 1881

Genus Dipolydora Verrill, 1881 View in CoL

Diagnosis. (after Blake et al. 2020): Prostomium entire or incised anteriorly, extending posteriorly as caruncle; eyespots present or absent. Setiger 1 with notosetae. Setiger 5 modified, with major spines of one type, with or without accompanying companion setae; spines arranged in single curved row; spines simple, falcate, with lateral flanges, teeth, and/or apical bristles, with superior notosetae dorsal to modified spines and companion setae. Posterior notopodial spines present or absent. Neuropodial hooded hooks bidentate, usually with recurved shaft without constriction or manubrium, main fang forming wide angle with shaft and narrow, acute angle with apical tooth; hooks first present from setigers 7 to 17. Pygidium disc-like, cuff-shaped, with 2, 3, or 4 lobes of various forms, or with four or more small papillae. Anterior part of digestive tract sometimes with enlarged, thick, gizzard-like structure.

Remarks. The genus Dipolydora Verrill, 1881 was revalidated and redescribed by Blake (1996),thus subdividing the formerly large genus Polydora into two genera. Dipolydora differs from Polydora in having notosetae on setiger 1 rather than lacking them; bidentate hooded hooks with a recurved shaft without a constriction or manubrium and with the main fang forming a wide angle with the shaft and a narrow, acute angle with the apical tooth rather than a distinct constriction on the shaft and with the apical tooth closely applied to the main fang. The pygidial morphology is variable rather than simple; and some Dipolydora species have a gizzard-like structure in the digestive tract, which Polydora species lack. To date, approximately 47 species of Dipolydora are recorded ( Read & Fauchald 2024a), including several that are poorly known and require study. In the present study, a new species of Dipolydora has been discovered as a borer in shells of the gastropod, Kanoia meroglypta from deep-water methane seep habitats in the Gulf of Mexico off Louisiana.