Reference : Biol. Bull, 136: 9-27. (February, 1969) THE TUBIFICIDAE (ANNELIDA, OLIGOCHAETA) OF CAPE COD BAY WITH A TAXONOMIC REVISION OF THE GENERA PHALLODRILUS PIERANTONI, 1902, LIMNODRILOIDES PIERANTONI, 1903 AND SPIRIDION KNOLLNER, 1935 x DAVID G. COOK Systernafics-Ecology Program, Marine Biological Laboratory, Woods Hole, Massachusetts 02543 The marine Tubificidae are an abundant, widely distributed, but poorly known group of Oligochaeta. The most recent account dealing with the fauna of the Cape Cod area is that of Moore (1905) who recognized seven species, mainly from littoral and estuarine environments. Material from a survey of the fauna of Cape Cod Bay which is being conducted by the Biotic Census of the Systematics-Ecology Program was found to contain a number of species which Moore did not see, five of these being new to science. Two of the species described here, Phallodrilus obscurus nov. sp., and Peloscolex intermedius nov. sp., are very closely related to some species described by earlier workers and differ from them only in minor details. However, two considerations are thought to be sufficient justification for describing them as new species. Firstly, the available descriptions of closely related species are generally poor and cannot be augmented at present as type material is not available. Secondly, even when descriptions are adequate and type series are available for comparison, material tends to be from widely separated geographical areas, and without more extensive collections it is impossible to decide whether the differences observed are due to a wide intraspecific variation over the species range, discontinuous variation merit-ing subspecific rank, or real specific differences. In this situation, where the taxa are morphospecies in the sense of Cain (1954), it is proposed that the least confusing action from the nomenclatural point of view, where doubt exists, is to keep specific limits narrow, erect new species names and synonomize, if necessary, when type material becomes available for the old species. At the generic level some rearrangments have been necessary to clarify defini-tions and to attain consistency between them. The major characters on which this has been based are the nature and position of the prostate glands and the form of the atria. Thus in Clitellio Savigny, 1820 (Fig. la) the prostate gland is lacking, or is a diffuse layer covering the long cylindrical atrium, while in Limnodriloides Pierantoni, 1903 (Fig. Ib) the prostate is a discrete organ with the attachment to the relatively short atrium localized to a small area. In Spiridion Knollner, 1935 (Fig. Ic) the attachment is further localized so that the prostate is truly penduncu-late and joins the atrium apically rather than subapically to medially as in Limno-driloides. Aktedrilus Knollner, 1935 is synonomized with Phallodrilus Pierantoni, 1902 (Fig. Id) on the basis of their common possession of two thickly-stalked prostate glands, attached to each short cylindrical atrium. 1 Contribution No. 162 from the Systematics-Ecology Program. 9
THE TUBIFICIDAE (ANNELIDA, OLIGOCHAETA) OF CAPE COD BAY WITH A TAXONOMIC REVISION OF THE GENERA PHALLODRILUS PIERANTONI, 1902, LIMNODRILOIDES PIERANTONI, 1903 AND SPIRIDION KNOLLNER, 1935
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