Investigators identifying large numbers of syllids may find it 

 helpful to initially sort to subfamily, insofar as possible. The Auto- 

 lytinae and Exogoninae are readily recognizable taxa. However, the same 

 cannot be said for the Eusyllinae and Syllinae in that characters typi- 

 cally used to separate these taxa overlap considerably. Some species 

 referred to Pionosyllis in the Eusyllinae, for example, have distinctly 

 articled dorsal cirri, while a few species of the Syllinae, such as 

 Syllis ( Ehlersia) f errugina , have mostly smooth dorsal cirri. Further- 

 more, it is often difficult to determine whether the palps are fused 

 basally. Many members of the Syllinae examined herein appear to have 

 basally fused palps. These two subfamilies can perhaps best be sepa- 

 rated by the presence of articled dorsal cirri, even though this crite- 

 rion is not always definitive. Sexual stolons may not be readily iden- 

 tifiable to subfamily because certain diagnostic characters, such as 

 head appendages, pharynx and proventricle, are considerably modified or 

 absent. In such cases some level of identity can usually be determined 

 by examining the setae. 



Several major taxonomic characters contribute to generic separa- 

 tions, including body form, appendages and sensory structures, the kinds 

 of setae, and especially, dentition of the pharynx. In general, the 

 pharynx may be either unarmed, or armed in one of several ways: with a 

 single large tooth (e.g., Syllis ), the relative position of which is 

 important; with a trepan of distinct teeth (e.g., Autolytus) or denticu- 

 lation (e.g., Eusy His ) on the anterior margin; or with a series of 

 teeth in a ventral arc ( Odontosyllis ). The body may be cylindrical, as 

 in most syllids, or dorsoventrally flattened (e.g., Trypanosyllis ). The 

 presence of an occipital flap on the head region is diagnostic of 

 Odontosyllis , while body papillae are characteristic of Sphaerosyllis. 

 The number of pairs of tentacular cirri is important. Shape of the 

 dorsal cirri is sometimes diagnostic, particularly in the Exogoninae. 

 In the Eusyllinae and Syllinae, dorsal cirri usually are smooth or 

 distinctly articled. In the Autolytinae, the presence of well-developed 

 dorsal cirrophores is an important generic character. 



Kinds of setae and setal morphology are of great significance at 

 both the generic and specific levels. Setae are usually composite 

 falcigers, but composite spinigers may be present as well in a number of 

 genera. The setae of Haplosyllis and Geminosyllis are entirely simple. 

 In other genera, simple setae usually occur, but are restricted to one 

 or two per fascicle, and often are found only on the poster iormost 

 setigers (e.g., in Syllis ). Modifications of these basic setal types 

 are extremely variable, and are used to diagnose several genera and a 

 large proportion of species. 



Important specific criteria include pharyngeal and setal morpholo- 

 gy, body pigmentation, and the shape and location of such structures as 

 the antennae, nuchal organs, parapodia, dorsal and ventral cirri, and 

 the proventricle. However, many of the soft appendages are quite vari- 

 able, and are susceptible to loss or distortion if the specimen is 

 handled roughly or is poorly preserved. It is therefore advisable to 

 rely primarily on hard setal structures and pharyngeal dentition pat- 

 terns for definitive species identifications. The use of a compound 

 microscope is essential to accomplish this task. Setae are best exam- 

 ined using a high magnification immersion objective. Small specimens 

 can easily be mounted whole on slides; with larger specimens it is best 

 to remove and mount several parapodia from different body regions. 



30-2 



