Polycirrus glossochelius, Nogueira, João Miguel Matos, Hutchings, Pat & Carrerette, Orlemir, 2015

Nogueira, João Miguel Matos, Hutchings, Pat & Carrerette, Orlemir, 2015, Polycirridae (Annelida, Terebelliformia) from Lizard Island, Great Barrier Reef, Australia, Zootaxa 4019 (1), pp. 437-483 : 453-456

Polycirrus glossochelius n. sp.

( Figs 8–9 )

Type material. Holotype: AM W.47642, between South and Palfrey Islands, Lizard Island Group, under rock, 20 m, coll. P. Hutchings, complete specimen, in excellent state of preservation, 35 mm long and 5 mm maximum width.

Description. Transverse prostomium attached to dorsal surface of upper lip; basal part as thick, curved crest across dorsum, extending laterally and posteriorly, covering segment 1 laterally and terminating lateral to lower lip; distal part at base of upper lip, as flaring lobes ( Fig. 8 A, E, I). Buccal tentacles of two types, both thin, slightly spatulated and with deeper groove at tip, long tentacles not very different from short ones, just longer and stouter ( Fig. 8 A–C, E–F, H–I). Peristomium forming lips; short, circular upper lip, hood-like, convoluted; small but elongate lower lip, tubular, projecting forwards as tongue-like process, not divided in two parts ( Fig. 8 B–C, E–F, H–I). Segment 1 not conspicuous all around; segment 2 reduced, visible mid-dorsal and mid-ventrally; body progressively broader and longer until segment 10, then abruptly tapering to uniformly cylindrical posterior body, beginning from the termination of notopodia; large anterior abdominal segments, with thin body wall and poorly marked segmentation, posterior body with clearly defined, compacted segments ( Figs 8 A–I; 9A). Smooth, oblong, distinctly inflated and poorly defined paired ventro-lateral pads, present on segments 3–15, last two pairs distinctly smaller ( Fig. 8 B–C, F–H). Notopodia extending for 13 segments, until segment 15; distinctly elongate, bilobed notopodia, lobes of same size, first and last two pairs slightly shorter ( Fig. 8 A–C, E–I). Pinnate notochaetae in both rows, those from posterior row only pinnate at tips ( Fig. 9 B–D). Neuropodia beginning from segment 15, last segment with notopodia, neuropodia as short, raised pinnules ( Figs 8 A–B, D, G; 9A). Type 2 uncini throughout, elongate prow and heel, the latter obliquely directed downwards, crest with single elongate and sharp tooth on first row of secondary teeth above main fang, surrounded by crown of minute teeth at base, and elongate neck ( Fig. 9 E– H). Large nephridia, visible through transparent body wall; nephridial and genital papillae present on segments 3– 17, anterior to bases of notopodia, extending for two segments after notopodia terminate; last four pairs of genital papillae distinctly larger, especially those of segments 14–15, with large openings ( Fig. 8 B–C, E–I). Pygidium with ventral papilla and low, crenulated lobe, of even height all around ( Figs 8 A, D; 9A).

Remarks. The holotype of P. glossochelius n. sp. is a stout, complete specimen, 35 mm long, with the distal part of prostomium at the base of the upper lip; circular and convoluted upper lip; short, rounded and protruding lower lip, tongue-like; smooth, inflated and poorly defined ventro-lateral pads; 13 pairs of notopodia, extending until segment 15, with evenly-sized lobes and pinnate chaetae in both rows of notochaetae; neuropodia beginning on the last segment with notopodia, segment 15, as relatively thin and elongate pinnules after notopodia terminate, bearing type 2 uncini. The most remarkable character of this species however, is the presence of genital papillae for two segments beyond the termination of notopodia, until segment 17, the last four pairs distinctly larger, especially those of segments 14 and 15.

Fifteen species of Polycirrus have 8–18 pairs of notopodia, considering the variation on the beginning of notopodia suggested by Glasby & Hutchings (2014), and neuropodia beginning before the termination of notopodia, but close to it. Of these, only three species have type 2 uncini, P. aquila Caullery, 1944 , P. medius Hessle, 1917 , and P. quadratus Hutchings, 1990 .

Members of P. aquila differ from those of P. glossochelius n. sp., as the former have a lower lip with different morphology, although also protruding; tessellated ventro-lateral pads; 16 pairs of notopodia, extending until segment 18, with longer post-chaetal lobe; neuropodia beginning from the penultimate segment with notopodia, segment 17; and genital papillae terminating before the termination of notopodia, on segment 16 ( Glasby & Hutchings 2014).

Polycirrus glossochelius n. sp. differs from P. m edi us because in this latter species the outer region of the lower lip is cushion-like, extending until near the posterior margin of segment 4; 17 pairs of notopodia, extending until segment 19; neuropodia begin from the fifth segment before the termination of notopodia, segment 15, and uncini have a single tooth above the main fang, while P. glossochelius n. sp. has uncini with a second row of minute secondary teeth at the base of the tooth above main fang; and genital papillae do not extend beyond segment 8 ( Glasby & Hutchings 2014).

Polycirrus quadratus differs from the holotype of P. glossochelius n. sp., as the former species has the distal part of prostomium extending until near the anterior margin of the upper lip; cushion-like outer region of the lower lip, extending until near the posterior margin of segment 5 (according to Glasby & Hutchings 2014: 100, Fig. 55a); there are 12 pairs of notopodia, extending until segment 14 and bearing winged chaetae in both rows; and genital papillae do not extend beyond segment 7 ( Glasby & Hutchings 2014).

Etymology. The specific name “ glossochelius ” derives from the Greek words “glossa” (= tongue) and “chelius” (= lip), in reference to the tongue-like shape of the lower lip.

Habitat. Under rubble on reef front, 20 m deep.

Type locality. Between South and Palfrey Islands, 14°41'48.61"S, 145°26'40.68"E, Lizard Island Group, Great Barrier Reef, Australia.

Distribution. Known only from the Lizard region.

Figures

FIGURE 8. Polycirrus glossochelius n. sp., holotype AM W. 47642. A – B. Entire worm, left dorso-lateral and ventral views (anteriorly), respectively; C. Thorax, ventral view; D. Posterior end, left lateral view; E – F. Anterior end, left dorso-lateral and ventral views, respectively; G. Transition between thorax and abdomen, ventral view, arrows point to genital papillae; H – I. Close ups of the anterior end, ventral and left dorso-lateral views, respectively. Numbers refer to segments. Abbreviations: ll = lower lip, ul = upper lip, * = distal part of prostomium. Scale bars: A – B = 1.5 mm, C – F, H – I = 1 mm, G = 0.6 mm.

FIGURE 9. Polycirrus glossochelius n. sp., holotype AM W. 47642. A. Posterior end, left lateral view; B – D. Notochaetae, segment 9. E – F. Uncini, segment 18. G – H. Uncini, posterior segment. Scale bars: A = 500 µm, B = 100 µm, C – D = 30 µm, E, G = 20 µm, F, H = 10 µm.