BANSE: REDESCRIPTIONS OF SOME SPECIES OF CHONE AND EUCHONE 



Parachonia has been included in Choyie by 

 Johannson (1927), Meioc/iot^e by Fauvel (1927; 

 see also Hartman, 1942b). 



The type species of Megachone Johnson, M. 

 aurantiaca, is redescribed below, based in part 

 on the holotype. Contrary to the statement by 

 Johnson (1901), the species does have ordinary 

 spatulate setae in the thoracic notopodia and thus 

 agrees in every respect with Cho7ie. 



The diagnosis as given has one weakness: The 

 original reason of Kroyer (1856) in creating 

 Chone was the funnel-like appearance of the 

 lophophores, or branchial crown, caused by the 

 palmate membrane. This membrane is not of 

 so unique value as a generic character as orig- 

 inally thought. Sars (1862) was the first to 

 point out that the membrane occurs also in other 

 genera. More important is that it may be pre- 

 sent or absent in the closely related Eucho7ie 

 (Banse, 1970). If the palmate membrane were 

 considered also in Chone as a specific character, 

 Dialychone Claparede would become a synonym 

 of Chone (cf. Fauvel, 1927). For the practical 

 need of identification, however, considerable dif- 

 ficulties would result. For example, a large spe- 

 cies of Oriopsis Caullery and Mesnil (cf. 0. rivu- 

 laris Annenkova, with bayonet-type thoracic 

 notosetae) would externally be distinguishable 

 from Chone only by the absence of the postsetal 

 glandular girdle on the second setiger. Anatom- 

 ically, Oriopsis would, of course, be quite dif- 

 ferent because it belongs to the thoracogoneate 

 Fabriciinae (Zenkevitch, 1925) with their 

 unique gonoducts. Because eggs may occur in 

 thoracic segments also in abdominogoneate sa- 

 bellids (cf. Euchone hancocki Banse), identifi- 

 cation without anatomical study may sometimes 

 not be possible. In view of these problems it 

 seems wise to define Chone as above until in- 

 tensive anatomical studies of representatives of 

 the various subgroups of Fabriciinae have been 

 made. These may yield a more natural and 

 hence more convincing system than is available 

 now. 



Among most species of Chone, the collar has a 

 very narrow dorsal gap. C. trilobata has a col- 

 lar with deep lateral notches. The bayonet-type 

 setae (also called basal or geniculate setae) were 

 described in some species by previous authors 



(cf. Fauvel, 1927; Eliason, 1962) but seem to 

 be present in all members of the genus. The 

 lower posterior thoracic notosetae are sometimes 

 subspatulate, as in C. filicaudata Southern and 

 C. eniivetoke^isis (Reish). 



The abdominal uncini with square bases and 

 few teeth, thought to be typical for Chone (cf. 

 Figure Ik) are found in many species only in 

 anterior abdominal segments, as is the case also 

 in Euchone (Banse, 1970). The uncini of pos- 

 terior setigers can have instead small rounded 

 bases and a high crown of accessory teeth (cf. 

 Figure 6i) . Such uncini occur similarly in other 

 genera of Sabellidae and in related families and 

 are thus phylogenetically more primitive than 

 the typical hooks of Chone. Further, they can 

 be present in the same tori together with typical 

 ones, as in C. ecaudata Moore and C. albocincta 

 new species (cf. Euchone elegans) . Their po- 

 sition shows that ontogenetically they have been 

 formed first. Also this points to the primitive- 

 ness of the posterior uncini. Likewise Okuda 

 (1946) has shown in a developmental study of 

 ?C. ecaudata (see below) that the abdominal 

 uncini first formed are of the primitive type and 

 similar to those found, for example, in Oriopsis; 

 initially they occur even in the thorax. 



In spite of the clarification of diagnostic char- 

 acters, very little can yet be said about the re- 

 lations among species of Chone. Certainly, spe- 

 cies with ventral shields are more primitive than 

 those with fully glandularized epidermes because 

 reasonably primitive Sabellidae should have 

 shields. Significantly, the typical abdominal 

 uncini with square bases seem to be present 

 throughout the abdomen only among Chone spe- 

 cies having a fully glandularized epidermis (pos- 

 sibly also in C. e7iiwetokensis, according to Reish, 

 1968). 



CHONE INFUNDIBULIFORMIS KROYER 



Figure 1 



CHONE INFUNDIBULIFORMIS Kroyer, 1856, 

 p. 33.- Malmgren, 1866, p. 404; 1867, p. 214.- 

 Hofsommer, 1913, p. 332.- Mcintosh, 1916, 

 p. 35, 39.- Imajima, 1961, p. 98.- Hartmann- 

 Schroder, 1971, p. 520. See also p. 465. 



461 



