Two new species of Aphelochaeta (Polychaeta: Cirratulidae) from deep water off northern California

Abstract

Two new species belonging to the genus Aphelochaeta (Polychaeta: Cirratulidae) are described from continental slope sediments off northern California. Specimens were collected during extensive monitoring of the San Francisco Deep Ocean Disposal Site off the Farallon Islands from 1996 to 2004. The genus Aphelochaeta is one of the more speciose genera collected from depths of 2400–3200 m. A. bullata sp. nov. is characterized by the presence of four peristomial annulations, a pronounced dorsal crest, and elongated, natatory-like simple capillaries in the noto- and neuropodia of the thoracic region. A. guttata sp. nov. has a unique methyl green staining pattern consisting of speckles all over the body, thoracic segments that are swollen ventrally, and weakly inflated posterior segments. Comparison is made with the type species A. monilaris (Hartman, 1960) and other continental shelf and slope species from California. Morphological characters important for differentiation of these species are discussed; these include characters related to the peristomium, shape of abdominal segments and methyl green staining patterns. The generic definition is emended to include numbers of asetigerous peristomial annulations.