Bathykurila zenkevitchi (Uschakov 1955)

Bathykurila zenkevitchi (Uschakov)

Macellicephala zenkevitchi Uschakov, 1955:313, fig. 1a–d.—Knox, 1959:106.—Reyss, 1971:250.—Levenstein, 1971b:24; 1973:130.

Macellicephala (Macellicephala) zenkevitchi.—Hartmann-Schröder. 1974:76, 84.

MATERIAL EXAMINED—Northwest Pacific, kurile-Kamchatka Trench. 8100 m. Vitial sta. 162. 1949. 2 syntypes (ZIASL 787).

DESCRIPTION.—Length of two syntypes 15 and 21 mm, width with parapodia 9 mm, width with setae 12 mm, segments 15. Body flattened, fusiform.

Elytra (all missing) and large prominent elytrophores (Figure 24a,c,g) 7 pairs, on segments, 2, 4,5, 7, 9, 11 and 13, with dorsal cirri on posterior 1–2 segments (last segment very small, apparently lacking dorsal cirri). Dorsal tubercles on cirrigerous segments large, bulbous (segment 3) to conical (Figure 24a,f).

Prostomium deeply bilobed, forming subtriangular anterior lobes with slender frontal filaments (Figure 24a,b; called cephalic peaks by Uschakov, 1955, fig. 1a). Median antenna with oval ceratophore in anterior notch, with short, filiform style; ceratophore connected posteriorly to pair of thickened or slightly raised, diagonal areas. Paired palps long, tapered, smooth, emerging ventral to tentacular parapodia. Without eyes. Tentacular segment fused to prostomium, not visible dorsally (Figure 24a,b). Uniramous parapodia lateral to prostomium, with 2 pairs of tentacular cirri; styles wider basally, with long slender tips, subequal in length to palps; prominent conical acicular lobe medial to and extending beyond cirrophores of tentacular cirri, without setae. Ventral buccal cirri of segment 2 with prominent cirriphores attached to ventral bases of parapodia, lateral to mouth; styles much longer than following ventral cirri, extending beyond tips of neurosetae (Figure 24a–c); noto- and neurosetae similar to those of following segments, except latter more slender (Figure 24d,e).

Parapodia biramous, with notopodia as long as or longer than neuropodia (Figure 24a–c,f,g; Uschakov, 1955, fig. 1b). Notopodia expanded subdistally, with projecting acicular processes on lower part; neuropodia subcorneal, with projecting presetal acicular processes. Notosetae moderate in number, short to longer, forming radiating bundles, stouter than neurosetae, with row of widely spaced teeth (4–14) along one side and blunt tips (Figure 24d,h; Uschakov, 1955, fig. 1c). Neurosetae numerous, forming fan-shaped bundles, long, slender, with 2 rows of spines and slightly tapered to blunt or pointed tips (Figure 24e,i; Uschakov, 1955, fig. 1d). Dorsal cirri with long cylindrical cirrophores attached posterodorsally on notopodia and extending beyond them; styles rather short, wider basally, with long filiform tips (Figure 24a,f). Ventral cirri attached on middle of neuropodia, short, tapered.

Four pairs of nephridial papillae on segments 10–13, somewhat larger than others. Pygidium large, bulbous, wedged between parapodia of posterior two segments, with pair of anal cirri. Pharynx (dissected) with opening encircled by 8 pairs of papillae—7 dorsal and ventral and one lateral, with 2 pairs of jaws.

DISTRIBUTION.—Northwest Pacific (Kurile-Kamchatka and Japan Trenches), in 6670 to 8135 meters.

MACELLICEPHALOIDINAE, new subfamily

TYPE-GENUS.—Macellicephaloides Uschakov, 1955.

Macellicephaloides was plated in the Lepidonotinae by Hartman (1959:93), in her catalog, and in the Macellicephalinae by Hartmann-Schröder (1974:75), in her revisionary study of the subfamily. The absence of lateral antennae, the different type of pharynx and parapodia would separate Macellicephaloides from Lepidonotinae. The last two mentioned features separate it from Macellicephalinae.

TYPE-SPECIES.—Macellicephaloides grandicirra. Uschakov, 1955, designated by Hartman (1959: 93). Gender: feminine.

DIAGNOSIS.—Body flattened, fusiform; segments 16–21 (first achaetous). Elytra and small, highly displaced elytrophores 8 pairs, on segments 2, 4,5, 7, 9, 11, 13 and 15. Prostomium fused with tentacular segment, bilobed, without lateral antennae, with or without paired frontal filaments; median antenna with large ceratophore in middle of prostomium and long style; paired palps with elongated palpophores; without eyes. Tentacular segment completely fused to posterior part of prostomium; 2 pairs of tentacular cirri with distinct cirrophores, without acicular lobes or setae. Segment 2 with buccal cirri only slightly longer than following ventral cirri, attached to basal parts of parapodia, posterolateral to mouth. Parapodia subbiramous, with long, projecting achaetous notopodial acicular lobes and subcornical neuropodia with short projecting acicular processes. Neurosetae numerous, slender, tapering to fine tips, with 2 rows of spines. Dorsal cirri with long cylindrical cirrophores and short styles; ventral cirri small, attached to neuropodia subdistally. Nephridial papillae small to indistinct. Pygidium medial to large parapodia of posterior 1–3 segments. Pharynx with 10 papillae—2 dorsal and 3 lateral pairs, middle lateral pair elongate, cirriform; dorsal jaws fused; pair of ventral jaws.

Four species are retained in the genus Macellicephaloides Uschakov, all originally described from the Kurile-Kamchatka Trench: M. grandicirra Uschakov, 1955, Kurile-Kamchatka Trench, in 8100–9960 meters; M. verrucosa Uschakov, 1955, Kurile-Kamchatka Trench, in 7210–7230 meters; M. vitiazi Uschakov, 1955, Kurile-Kamthatka Trench, in 7210–8420 meters; M. uschakovi Levenstein, 1971, Kurile-Kamchatka Trench, in 8120 meters.

Levenstein (1962:1143) referred some fragments, collected in the Mariana Trench in 10,630 to 10,710 meters, to Macellicephaloides species; the record is based on a few stout acicula and a pharynx showing the characteristic, elongate, cirriform lateral papillae.

Macellicephaloides berkeleyi Levenstein, 1971, is herein assigned to a new genus, Bathyedithia, and new subfamily, Bathyedithinae.

GENERAL CHARACTERISTICS.—The body is generally robust, flattened ventrally, arched dorsally, slightly tapered anteriorly and posteriorly, with parapodia longer than the body width. It is relatively short and composed of 16 (M. verrucosa, M. vitiazi), 17 (M. grandicirra) or 20–21 (M. uschakovi) segments, the first one being achaetous (Uschakov, 1955, figs. 3a, 4a; Levenstein, 1971b, fig. 4c,d).

The elytra (all missing) number eight pairs, borne on small, button-like elytrophores medial to the notopodia of segments 2, 4,5, 7, 9, 11, 13 and 15 (Figures 25a,g, 26a,g,i, 27a–c, 28a). Dorsal cirri are borne on segments 3, 6, 8, 10, 12, 14 and 16 (or to the end of the body). The cirrophores of the dorsal cirri are attached posterior to the bases of the notopodia; they are cylindrical, moderately long to very long; the styles are relatively short, appearing as terminal appendages on the elongate cirrophores (Figures 25b,h,j, 26h, 27b,d, 28d,f). The dorsal tubercles, corresponding in position to the elytrophores, are usually absent; they are nodular in M. verrucosa (Figure 27b,d).

The prostomium is relatively small, bilobed, forming two anterior oval lobes, somewhat withdrawn into and fused to the first or tentacular segment (Figures 25a,b, 26a,b, 27a, 28a,b). The median antenna has a large cylindrical ceratophore attached to the middle of the prostomium, with style short to long and tapering; lateral antennae are lacking; minute frontal filaments are usually absent (may be present in M. grandicirra, Figure 25a). The palps have elongate palpophores, which are inflated or bulbous dorsally, and tapered palpostyles; eyes are lacking. The tentacular segment encloses the prostomium, with lateral parapodia forming cirrophores for the dorsal and ventral tentacular cirri; the styles are rather short and tapering; acicular lobes and setae are lacking (Figures 25a,b, 26a,b, 27a, 28a,b). The second or buccal segment bears the first pair of elytrophores, biramous parapodia, and ventral or buccal cirri attached to the basal part of the neuropodia on small cirrophores posterolateral to the ventral mouth; the styles are short, subulate, somewhat larger than the following ventral cirri (not as long as usually found in the Polynoidae; Figures 25a,b, 26a,b, 28a,b,e).

The subbiramous parapodia are longer than the body width; the notopodia are represented by prominent acicular lobes containing very stout, yellow acicula, the tips of which may break through and project beyond the lobes, far beyond the neuropodia; the latter have longer presetal subconical lobes extending into short digitiform to subtriangular processes and shorter subconical postsetal lobes (Figures 25a,b,g,h,j, 26a,b,f–i, 27a–d, 28a,b,d–g). Notosetae are absent. Neurosetae are numerous, forming fan-shaped bundles, delicate, slightly wider more basally, tapering distally to slender tips, with 2 rows of spines (Figures 25h,i, 26h,j, 27c,e, 28f–h). The ventral cirri (except for the buccal cirri on segment 2) are small, tapered, and attached distally, just medial to the neurosetae (Figures 25g,h, 26h, 27c, 28f,g).

The somewhat elongate bulbous pygidium, with a dorsal anus, is medial to a variable number of posterior segments; the posterior parapodia are long, not reduced in size; anal cirri are apparently lacking (Figures 25j, 26f, 27b, 28d). The nephridial papillae are not especially enlarged and may be indistinct (Figure 25h).

The very large muscular pharynx occupies the anterior third of the body. The pharyngeal opening has papillae and jaws but they differ from the usual type and arrangement found in the Polynoidae. There are four subequal dorsal papillae and three pairs of dorsolateral papillae of unequal size, the middle pair being longer (greatly elongated and cirriform in M. vitiazi and M. verrucosa); the ventral part of the pharynx may be differentiated into a pair of collar-like or scroll-like ventral folds (Figures 25c–e, 26c, 28c). The pharynx is armed with a dorsal jaw consisting of 2–3 fused pieces, and a pair of ventral jaws (Figures 25f, 26c–e, 28c). The elongate lateral papillae on the stout muscular pharynx have the superficial appearance of some members of the pelagic polychaete family Alciopidae, rather than to some representatives of the aphroditoid families Polyodontidae (=Acoetidae) and Bathyedithinae of the Polynoidae, described herein, with their elongate middorsal and midventral papillae.

The integument usually appears smooth or somewhat wrinkled; in M. verrucosa, segmental middorsal nodular tubercles are present, in addition to nodular dorsal tubercles on the cirrigerous segments (Figure 27b,d).