THE TUBIFICIDAE (ANNELIDA, OLIGOCHAETA) OF CAPE COD BAY. II: ECOLOGY AND SYSTEMATICS, WITH THE DESCRIPTION OF PHALLODRILUS PARVIATRIATUS NOV. SP

¹ National Museum of Natural Sciences, Ottawa, Ontario, Canada, K1A ON8 and Systematics-Ecology Program, Marine Biological Laboratory, Woods Hole, Massachusetts 02543

(1) Ten species of Tubificidae are recorded from Cape Cod Bay, as follows: Adelodrilus anisosetosus, Limnodriloides medioporous, Peloscolex apectinatus, P. benedeni, P. intermedius, P. nerthoides, Phallodrilus coeloprostatus, P. obscurus, P. parviatriatus and Tubifex longipenis.

(2) Phallodrilus parviatriatus nov. sp. is characterized by small erect atria and simple-pointed posterior setae.

(3) The original description of Tubifex longipenis Brinkhurst, 1965, is confirmed and expanded.

(4) On the basis of species distributions in relation to sediment types, two major tubificid communities are recognized.

(5) P. intermedius and L. medioporus constitute a free-burrowing, fine-sand and silt community (median particle size of the substrate between 3 to 7 \g=fscr\).

(6) P. benedeni and T. longipenis are the free-burrowing components of a coarse-sand community (-1 to 2 median \g=fscr\) which also contains A. anisosetosus, Peloscolex apectinatus, P. nerthoides, Phallodrilus coeloprostatus, P. obscurus and P. parviatriatus; some, or all, of the last six species are probably interstitial.