Bathyedithia berkeleyi (Levenstein 1971)

Bathyedithia berkeleyi (Levenstein)

Macellicephaloides berkeleyi Levenstein, 1971a:1429, fig. 1a–d; 1971b:29, fig. 7a–d.—Hartmann-Schröder, 1974:81, 85.

MATERIAL EXAMINED.—North Pacific, Aleutian Trench, 50°48.6′N, 173°29′W, 7000 m, clayey mud, Vitiaz sta. 6085, 1 May 1969, syntype of Macellicephaloides berkeleyi (IOASM).

DESCRIPTION.—Body flattened, slightly tapered anteriorly and posteriorly, with parapodia as long as body width, thick, closely appressed, having general appearance of pelagic phyllodocids. Length of syntype examined (IOASM) 29 mm, width with parapodia 13 mm, segments 25. According to Levenstein (1971a), length 28–30 mm, width 10–12 mm, segments 25–26.

Elytra (all missing) and large elytrophores 9 pairs, on segments 2, 4,5, 7, 9, 11, 13, 15 and 17, with dorsal cirri on posterior 8–9 segments (Figure 31a,d,j). Dorsal tubercles on cirrigerous segments absent, except for large pair on segment 6 (Figure 31g).

Prostomium bilobed, forming subtriangular frontal lobes, without median or lateral antennae; palps with large, rounded palpophores and moderately long, tapered styles; eyes lacking (Figure 31a; Levenstein, 1971a, fig. 1a). First or tentacular segment indistinct dorsally, with uniramous parapodia lateral to prostomium and fused to palpophores, without distinct acicular lobes or setae; 2 pairs of tentacular cirri with distinct cirrophores; styles of dorsal pair shorter than palps; styles of ventral pair about twice as long as dorsal pair; without facial tubercle (Figure 31a; Levenstein, 1971a, fig. 1a). Segment 2 with buccal cirri longer than following ventral cirri and attached to basal parts of parapodia (Figure 31d; Levenstein, 1971a, fig. 1a); notosetae (Figure 31e) and neurosetae (Figure 31f) similar to those of following segments.

Parapodia subbiramous; notopodia small, sub-conical, with projecting acicular processes; neuropodia large, subconical, upper part diagonally truncate, lower part rounded, with short, projecting, presetal acicular processes (Figure 31g,j; Levenstein, 1971a, fig. 1b); neuropodia of few posterior segments rounded, bulbous, directed posteriorly (Figure 31c). Notosetae (mostly missing) forming small tufts on upper sides of notopodia, thin, flattened, with 2 rows of denticles and long bare slender tips (Figure 31e,h; Levenstein, 1971a, fig. 1c). Neurosetae (mostly missing) numerous, forming fan-shaped bundles, stouter than notosetae, flattened, with spinous rows along both sides and tapered to rather short, bare tips; lower neurosetae somewhat stouter than upper ones (Figure 31f,i,k,l; Levenstein, 1971a, fig. 1d). Dorsal cirri witli short cylindrical cirrophores and long styles extending far beyond tips of neuropodia (Figure 31g; Levenstein, 1971a, fig. 1a,b); ventral cirri short, tapered, attached to middle of neuropodia (Figure 31g,j).

Pygidium forming rounded lobe with dorsal anus and truncate posterior part, medial to parapodia of posterior two segments (24, 25; Figure 31c); anal cirri lacking (broken off?). Nephridial papillae indistinct.

Pharynx (incorrectly figured and described by Levenstein, 1971a, fig. 1a) large, muscular, about third of body length; terminal opening encircled with 9 pairs of dorsal and ventral papillae, lateral pairs smaller than others and middle pair much longer and larger, cirriform (Figure 31b; cirriform papillae indicated as lateral in position by Levenstein, instead of dorsal and ventral); two pairs of dorsal and ventral interlocking jaws with denticled basal parts (each with about 8 teeth; Figure 31b; latter overlooked by Levenstein).

DISTRIBUTION.—North pacific (Aleutian Trench), in 7000 meters.

POLARUSCHAKOVINAE, new subfamily

TYPE-GENUS.—Polaruschakov, new genus.

Polaruschakovinae agrees in most respects with Macellicephalinae, though differing by the absence of median and lateral antennae. The pharynx is of the usual polynoid type, with two pairs of jaws and seven pairs of papillae, none enlarged, thus distinct from Bathyedithinae, where the jaws of the pharynx have denticled bases and the median pair of the dorsal and ventral papillae are elongate, cirriform.

Polaruschakov, new genus

TYPE-SPECIES.—Macellicephala polaris Uschakov, 1957. Gender: masculine.

DIAGNOSIS.—Body flattened, fusiform; segments variable in number (21–25; first achaetous). Elytra and prominent elytrophores 9 pairs, on segments 2, 4,5, 7, 9, 11, 13, 15 and 17, with dorsal cirri on posterior 4–8 segments. Cirrigerous segment 6 with pair of unique flattened scale-like structures. Prostomium bilobed, without median or lateral antennae; paired palps long, tapered; without apparent eyes (or pair of large eyes lacking pigment). First or tentacular segment fused to prostomium; 2 pairs of tentacular cirri lateral to prostomium, with distinct cirrophores and single small acicular lobe; achaetous. Segment 2 with buccal cirri attached to basal parts of parapodia lateral to mouth, longer than following ventral cirri. Parapodia subbiramous, with short notopodia and long neuropodia, both rami with elongate acicular processes. Notosetae more slender than neurosetae, spinous. Neurosetae numerous, delicate, transparent, flattened. Dorsal cirri with cylindrical cirrophores and long styles; ventral cirri short. Nephridial papillae small. Pygidium small, medial to reduced parapodia of posterior segments. Pharynx with 7 pairs of papillae and 2 pairs of jaws.

The following two species and one synonym are referred to Polaruschakov: P. polaris (Uschakov), new combination, as Macellicephala polaris Uschakov, 1957, Arctic, in 2245 meters. (Synonym: Macellicephala arclica Knox, 1959, Arctic, in 0–730 meters); P. reyssi new species, as Macellicephala arctica Knox by Reyss (1968), Mediterranean, in 750 meters.

ETYMOLOGY.—The genus is named for Professor P. V. Uschakov in recognition of his outstanding contributions to the study of the Polychaeta.

GENERAL CHARACTERISTICS.—The body is robust, flattened, spindle-shaped, slightly tapered anteriorly and posteriorly, with parapodia longer than the body width. It is relatively short and composed of a variable number of segments (21–25), the first one being achaetous, and the posterior ones much reduced and difficult to count. The elytra (all missing) numbering 9 pairs, are borne on prominent elytrophores medial to the notopodia of elytragerous segments 2, 4,5, 7, 9, 11, 13, 15 and 17, with dorsal cirri on a variable number of posterior segments (4–8). On segment 6, medial to the cirrophores of the dorsal cirri, is a pair of unique, flat, scale-like lobes (Figures 32a, 33a).

The prostomium is wider than long, bilobed, forming rounded lobes, lacking median and lateral antennae. The tentacular segment is fused with the prostomium, a narrow band being visible dorsally, with two pairs of tentacular cirri with prominent cirrophores lateral to the prostomium (Figures 32a, 33a). The ventral buccal cirri of segment 2 are attached basally on the neuropodia lateral to the mouth and extend beyond the distal tips of the parapodia (Figures 32a,b, 33a,b).

The subbiramous parapodia consist of small conical notopodia on the anterodorsal sides of the neuropodia, with projecting acicular processes; the long neuropodia are subconical with projecting presetal acicular processes (Figures 32a–d, 33a–d). The notosetae are more slender than the neurosetae, with spinous rows. The neurosetae are numerous, forming brushlike bundles; they are delicate, flattened, and spinous. The dorsal cirri have cylindrical cirrophores attached posterior to the notopodia; the ventral cirri are short and subulate (Figures 32c,d, 33a,d). The dorsal tubercles on the cirrigerous segments are small to absent.

The pygidium is small, with the anus situated between the reduced parapodia of the posterior segments; presumably there is a pair of anal cirri (missing). The nephridial papillae are small to inconspicuous; none appear to be enlarged. The pharynx was not extended, but, when cut open, there appear to be seven pairs of papillae and two pairs of jaws.