median antenna absent. Palps with small palpostyles (Figure 29-2b), not 

 visible dorsally. Dorsal and ventral tentacular cirri small, equal in 

 length. Dorsal cirri small, papilliform, similar in length throughout 

 (Figure 29-2a,c). Ventral cirri present from setiger 3, equal in length 

 to dorsal cirri. Parapodia poorly differentiated from body (Figure 29- 

 2c). Body smooth except for few papillae on prostomium, parapodia and 

 dorsal and ventral cirri (Figure 29-2a-c). Hooked acicular notosetae 

 beginning on setigers 7-9, accompanied by internal aciculum (Figure 29- 

 2c). Neurosetae with entire to minutely bifid tips (Figure 29-2d,e), 

 numbering 2-4 per parapodium. Proboscis (Figure 29-2f) with longitudi- 

 nal series of chitinized spines. 



REMARKS: The above description of C. incerta differs from that given by 

 Pettibone (1966:178) in that the hooks begin on setigers 7-9 instead of 

 only 7. Also, the Gulf of Mexico specimens possess neurosetae with 

 minutely bifid tips, whereas they are unidentate on the Chesapeake Bay 

 specimens. 



PREVIOUSLY REPORTED HABITAT: 12 m; compacted sandstone, mud. 

 GULF OF MEXICO BLM-OCS OCCURRENCE: Off Florida and Texas (Figure 29-1); 

 15-75 m; medium-fine to fine-very fine sand, silty sand, clayey sandy 

 silt, sandy silty clay. 

 DISTRIBUTION: Virginia, Gulf of Mexico. 



Genus Sigambra F. Miiller, 1853 



TYPE SPECIES: Sigambra grubii F. Miiller, 1858. 

 REFERENCE: 



Pettibone, 1966:179. 



DIAGNOSIS: Palps not fused; palpostyles present. Three antennae pres- 

 ent, usually longer than palps. Two pairs of tentacular cirri present. 

 Acicular notosetae hooked. Neurosetae serrate, usually with minutely 

 bifid tips. Pygidium usually with a pair of long anal cirri. Integu- 

 ment smooth, areolated or wrinkled, not papillose. 



Key to the Gulf of Mexico BLM-OCS Species of Sigambra 



la. Median antenna longer than lateral ones, extending well beyond 

 palps (Figure 29-6a); integument smooth anteriorly, not wrinkled 

 or areolated (Figure 29-6a) 2 



lb. Median antenna equal in length to lateral ones, not extending 

 beyond palps (Figure 29-4a); integument areolated and wrinkled 

 anteriorly (Figure 29-4a) Sigambra wassi, p. 29-8 



2a. Notopodial hooks beginning on setigers 4-6; median antenna extend- 

 ing posteriorly to about setiger 6 (Figure 29-6a) 



Sigambra tentaculata, p. 29-8 



2b. Notopodial hooks beginning on setigers 10-15; median antenna (Fig- 

 ure 29-8a) extending posteriorly to about setiger 12 



Sigambra bassi, p. 29-10 



29-6 



