POLYCHAETE WORMS, PART 1 295 



Family Apistobranchidae 



Body elongate, vermiform, cylindrical, fragmenting readily. Pro- 

 stomium and buccal segment fused, oval, with a pair of nuchal folds 

 and a pair of long contractile spioniform tentacular palps (deciduous, 

 may be missing or short regenerating). 



Body divided mto 2-3 more or less distmct regions: (1) Anterior 

 thoracic region (7 setigers) with well-developed neuropodia with 

 numerous rows of simple setae, with fimbriated subpodal flanges on 

 some segments, with cjdindrical notopodia with delicate mternal 

 acicula, without notosetae, with interramal cu-ri (figs. 77,a-e; 78,a,b) ; 

 (2) middle or transitional region (setigers 8-11) with smaller bundles 

 of nem-osetae, with fimbriated subpodal flanges, with notopodia more 

 slender (may be absent, figs. 776, 78c) ; (3) posterior abdominal 

 region with slender cylindrical notopodia with internal acicula, with 

 cylindrical nem'opodia supported by acicula and few slender neuro- 

 setae (figs. 776, 78^). 



Pygidium with anal cirri. Without branchiae, although the noto- 

 podia and interramal cirri are ciliated externally and have extensions 

 of the coelomic cavity and thus may have branchial functions. Pro- 

 boscis eversible, globular, disclike. Evidently the apistobranchids 

 live in tubes on soft bottom. They are probably bottom deposit 

 feeders. They are small and delicate, and are easily overlooked. 



The Apistobranchidae as established by Mesnil and Caullery (1898) 

 and as herein defined is limited to a single aberrant genus and species. 

 It is allied to the Orbiniidae (parapodia supported by acicula, with 

 some fimbriated postsetal lobes as in Orbinia, with some interramal 

 cirri), Paraonidae (smooth setae with mucronate tips), and Spionidae 

 (pau'ed tentacular palps, prostomimn and buccal segment fused). 



Contains only one known genus. 



Genus Apistobranchus Levinsen, 1883 



Ethocles Webster and Benedict, 1887; type (monotypy): Ethocles typicus Webster 

 and Benedict, 1887; — Apistobranchus tullbergi (Theel, 1879). 



Skadaria Wesenberg-Lund, 1951; type (monotypy): Skadaria fragmentata Wesen- 

 berg-Lund, 1951; = ApistobrancMis tullbergi (Theel, 1879). 



Type (author's designation): Apistobranchus tullbergi (Theel, 1879). 

 Contains only one known species. 



Apistobranchus tullbergi (Theel, 1879) 



Figures 77-78 



Aricia tullbergi Th6el, 1879, p. 45, pi. 3, figs. 40-43. 

 Ethocles typicus Webster and Benedict, 1887, p. 733, pi. 6, figs. 77-85. 

 Apistobranchus tullbergi Eliason, 1916, p. G, pi. 1, fig. 7, text-figs. 1-2; 1920, 

 p. 39.— Southward, 1956, p. 2G8, fig. l,g-<.— Uschakov, 1958a, p. 87, fig. 6. 

 Skadaria fragmentata Wesenberg-Lund, 1951, p. 59, figs. 1-4. 



