Austrolaenilla pelagica (Monro 1930)

“Antinoë pelagica, n.sp.

St. 45. 6. iv. 26. 2∙7 miles S 85° E of Jason Light, South Georgia. Bottom. 238-270 m. Gear NCS—T. One specimen.

St. SS 18. 15. xii. 27. 54° 58' S, 27° 32' W. 50—0 m. Gear N 70 V. One specimen.

DESCRIPTION. The body is slender and delicate. The complete specimen measures

11 mm. by 1^∙5 mm. without the feet: the measurement from tip to tip of the bristles is 6 mm. There are about 35 chaetigers and 15 pairs of elytra, which completely cover the body up to the pygidium. The elytra are faintly touched with brown on their edges ; otherwise there is no colour.

The head (Fig. 16, a) is broader than long and deeply incised in front. The lateral tentacles are inserted ventrally. There are two pairs of eyes, of which the anterior is situated laterally and half-way down the head, and the posterior at the outer corners. The median tentacle is very long, reaching to the 8th chaetiger when laid along the back, and the lateral tentacles are extremely small. The palps are very slender and slightly longer than the median tentacle, which itself is longer than the tentacular cirri. The dorsal cirri are long and reach to the tips of the bristles, and the ventral cirri just reach to the end of the feet. The tentacles and cirri are hirsute, but the palps appear smooth.

The first pair of elytra is rounded, and the remainder are oval. Around the outer edge (Fig. 16, b) are a few sparse cilia, and the outer half of the scale is thinly dotted with small conical tubercles.

The feet (Fig. i6, c) are biramous and harmothoid in type, with long sheathed acicula protruding from both branches. The dorsal bundle consists of a number of backwardly curved scaly bristles (Fig. i6, d) ; just above the aciculum there are two chaetae that differ slightly from the rest : one (Fig. 16, e) is unusually broad and short, with its end projecting a short distance from the chaeta sac, and the other is of the same kind as the rest of the dorsal bristles but larger (Fig. 16, f) in all dimensions. All the dorsal bristles have a smooth tip.

The ventral bristles (Fig. 16, g) are about twice the length of the dorsal, and slender, with smooth unidentate tips and fine spirally arranged whorls of teeth going up the shaft. There is a pair of long pygidial styles.

REMARKS. This pelagic polynoid has much in common with Herdmanella gracilis, Ehlers (Ehlers, 1908, p. 44). The shape of the head appears to be similar, and there are great resemblances in the structure of the bristles. In Ehlers' species the lateral ten­tacles are relatively longer, and there are only eight pairs of elytra. It is possible that H. gracilis may be a young stage of the present species, just as the present species is probably the pelagic phase of some bottom living form.

I have attributed this example to the genus Antinoë on the ground of the fine hairlike ventral bristles.”

(Monro, 1930)