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POLYCHAETOUS ANNELIDS 



Part IV. Pectinariidae 



With a Review of All Species from the Western Hemisphere 



(Plates 49-52) 



By Olga Hartman 

 Allan Hancock Foundation 



The family PECTINARIIDAE (sometimes called Amphictenidae) 

 is usually recognized for 5 genera or subgenera, including ( 1 ) Amphic- 

 tene Savigny with type A. auricown (O. F. Miiller), (2) Cistenides 

 Malmgren with type C. granulata (Linnaeus), (3) Lagis Malmgren 

 with type L. koreni Malmgren, (4) Pectinafia Lamarck (sensu Malm- 

 gren) with type P. helgica (Pallas), and (5) Petta Malmgren with type 

 P. pusilla Malmgren, Three of these, Amphictene, Pectinaria, and CAs- 

 tenides, are much more nearly related to one another than to any of the 

 others, and 2 of these, Cistenides and Pectinaria, are sometimes separated 

 with difficulty. Originally, Malmgren (1866, p. 358) distinguished Pec- 

 tinaria as having a straight tube, 13 uncinigerous segments, and uncini 

 with 7 or 8 major teeth, whereas Cistenides was said to have an arcuate 

 tube, 12 uncinigerous segments, and uncini with 3 major teeth. However, 

 several species have been found in both genera in which these characters 

 intergrade. Fauvel (1927, p. 220) considers Lagis, Amphictene, Pecti- 

 naria, and Cistenides as subgenera of Pectinaria Lamarck, and separates 

 the last 2 by the character of the tube, whether straight or arcuate, as 

 Malmgren had done. Nilsson (1928, p. 23) also retains Cistenides as a 

 subgenus, referring to it those species that have a higher number of 

 scaphal hooks (6-10-22 pairs) covered by a small fold of skin, and sub- 

 genus Pectinaria for those whose scaphal hooks number only about 4-6-12 

 pairs, not covered by a fold of skin. These characters are also difficult to 

 distinguish in some species, since they show intergradations from one to 

 the next. 



A striking morphological character concerns the structure of the 

 uncini and may permit a more natural line of separation. In one group, 

 Pectinaria (with type P. belgica), the major teeth of the uncini are dis- 

 posed in 2 or more series as seen in frontal view, making usually for a 

 thicker, though smaller, hook, one not apt to lie flat. In another group, 

 Cistenides (with type C. granulata) , the major teeth of the uncini are 



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