provided by NMNH Antarctic Invertebrates

Pholoe antipoda, new species

(Plate 7, Figs. B, C)

Records: 3:6b sta. 969 (2); 6:11 sta. 558 (fgm); 9: la sta. 740 (10, TYPE); 11:3 sta. 993 (6).

Description: Length of a larger specimen is 3.1 mm, width 1 mm and setigerous segments number 24. The body is small, depressed, trun­cate at both ends, and smooth on dorsum and ventrum. Elytra are broadly imbricated, completely cover the dorsum and may number 12 or 13 pairs; they are inserted as typical of the genus. The prostomium, covered by the first pair of elytra, is small, somewhat compressed be­tween the first pair of segments ; it has four subequally large, dark eyes in trapezoidal arrangement with the posterior pair the wider apart ; the median antenna has a large, thick base ; a nuchal papilla is lacking. The proboscis, everted in one individual, has four horny, brown jaws and a surrounding sheath which terminates in six dorsal and six ventral well spaced, short papillae; they are separated laterally by a hiatus.

Elytra are nearly or quite smooth, except for sparse, inconspicuous papillae at lateral margins or along the exposed parts; the first are rhomboid in shape, and later ones are broader and excavate at the an­terior margin. Fig. B shows the approximate position of the scar and the entire margins of an anterior elytrum; most have a minutely crenu­lated margin along the posterior edge.

The first parapodium is reduced to a pair of cirri of which the dorsal one resembles the median prostomial antenna and the ventral one is much smaller ; setae are absent. Other parapodia are biramous ; notopodia are smaller and shorter than neuropodia. Notosetae are in close fascicles, consist of 20 to 30 very slender capillary setae, and are supported by a rodlike, yellow aciculum which is only about half as thick as the cor­responding neuro-aciculum. Neuropodia are larger, longer, directed lat­erally, and have series of composite falcigers of one kind, with the su­periormost slightly the longest, and the inferiormost the shortest but no significant difference between them. The shaft is distally oblique and has a row of denticles along the longest edge ; the appendage is distally fal­cate and the cutting edge has a row of minute denticles ( Fig. C).

Pholoe antipoda differs from other species of the genus in its much smaller size, reduced number of segments, and the details of elytra and parapodial falcigers.

This is the first record of the genus from Antarctic seas.

Distribution: Tierra del Fuego, in 229-265 m; Falkland Islands, in 646-845 m; Drake Passage, in 384-494 m; and South Shetland Is­lands, in 300 m.”

(Hartman, 1967)

Comprehensive Description

provided by Smithsonian Contributions to Zoology
Laubierpholoe antipoda (Hartman, 1967)

Pholoe antipoda Hartman, 1967:40, pl. 7: figs. B,C [part; not sta 969, 558; = Pholoe polymorpha].

MATERIAL EXAMINED.—SOUTH ATLANTIC OCEAN: Drake Passage, 56°06′S, 66°19′W, 384–494 m, Eltanin sta 740, 18 Sep 1963, 17 syntypes (USNM 55500, 55501). Scotia Sea, Isla Orcada cruise 575, 1975: sta 73, 2 Jun, 56°16′S, 27°30′W, 208–375 m, 42 specimens (USNM 127216); sta 95, 9 Jun, 54°11′S, 37°41′W, 68–80 m, 1 specimen (USNM 127218); sta 98, 10 Jun, 54°11′S, 37°36′W, 57–79 m, 2 specimens (USNM 127217). South Shetland Islands, 61°25′S, 56°30′W, 300 m, Eltanin sta 993, 13 Mar 1964, 4 specimens (USNM 55896).

NEW ZEALAND: 49°49′S, 178°52′E, 86–95 m, Eltanin sta 2141, 26 Feb 1968, 1 specimen (USNM 127219).

DESCRIPTION.—Largest syntype 3 mm long, 1.5 mm wide, with 27 segments, with developing young in elytra; 2 smaller complete syntypes 2 mm long, 1–2 mm wide with 21 and 25 segments. Larger specimens from Isla Orcada sta 73, 2–3 mm long, 1.5 mm wide, with 26 segments; smaller specimens 1–2 mm long, 1.0–1.2 mm wide, with 13–21 segments.

Body small, depressed, truncate at both ends, with parapodia as long as body width; dorsal and ventral surfaces smooth, without papillae or tubercles. Elytra large, imbricated, covering dorsum and parapodia, with only tips of neurosetae visible. Elytra squarish to subreniform, smooth, with few (up to 7) papillae along lateral margin, sometimes few papillae on surface (Figure 3F; Hartman, 1967, pl. 7: fig. B). Some middle elytra with developing juveniles inside (Figure 3G,H). Dorsal tubercles nodular.

Prostomium and tentacular segment fused; prostomium oval, bilobed, median antenna with ceratophore in anterior notch, style enlarged basally, about twice as long as prostomium; 2 pairs of large eyes; tentaculophores anterior and lateral to prostomium, each with dorsal tentacular cirrus similar to median antenna and very small ventral tentacular cirrus nearly hidden in dorsal view; pair of long tapering palps lateral to tentaculophores; without facial tubercle (Figure 3A,B). Segment 2 with first pair of large bulbous elytrophores, biramous parapodia, and long ventral buccal cirri on bulbous cirrophores lateral to mouth (Figure 3A,B). Extended pharynx with 9 dorsal and 9 ventral border papillae and 2 pairs of jaws.

Notopodia subconical, smaller and shorter than neuropodia; neuropodia with long conical presetal acicular lobe and short rounded postsetal lobe (Figure 3C). Notosetae numerous, slender, slightly curved, with capillary tips, none strongly bent; upper ones shorter, more strongly curved, ventral anterior and posterior ones longer, slightly curved (Figure 3C,D). Neurosetae moderate in number, compound, with shafts distally oblique and with row of subdistal denticles; blades short, with row of minute denticles and entire, falcate tips; upper ones with blades slightly longer than lower ones (Figure 3C,E; Hartman, 1967, pl. 7: fig. C). Ventral cirri short, tapered (Figure 3C). Pygidium with pair of anal cirri.

DEVELOPMENT.—The largest complete syntype had 4 large developing eggs and embryos within segments 10–14, a developing juvenile in the 6th left elytron (on segment 11) (Figure 3G), and the additional large 7th left elytron (on segment 13) from which the juvenile had escaped. Fertilization must be internal because the ova develop into embryos, with no visible segmentation, then pass into the elytra, which have a delicate membrance, and develop into juveniles. The juvenile, which was removed from the elytron, showed evidence of up to 11 setigerous segments, developlng neuropodia with acicula, compound neurosetae, elytra, anal cirri, and head appendages (Figure 3H).

DISTRIBUTION.—South Atlantic Ocean off South America, in 57–494 meters; off New Zealand, in 86–95 meters.
bibliographic citation
Pettibone, Marian H. 1992. "Contribution to the polychaete family Pholoidae Kinberg." Smithsonian Contributions to Zoology. 1-22. https://doi.org/10.5479/si.00810282.532