Polycirrus brutus, 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 : 473-475

Polycirrus brutus n. sp.

( Fig. 21 )

Type material. Holotype: NTM W. 023152, Palfrey Island, 14°41'28.572"S, 145°26'29.940"E, 10 m, coll. Coleman & Smith, 9 Apr 2008, apparently complete specimen, in four pieces, some centimetres long, not measured due to state of preservation. Paratype: AM W.47691, CReefs, LI-10-021, Mrs Watson Beach, 14°39'41"S, 145°22'27"E, 10 m.

Description. Transverse prostomium attached to dorsal surface of upper lip; prostomium projecting laterally as one deeply grooved, tentacular prostomial process at each side; basal part as thick crest across dorsum, extending laterally and posteriorly, covering segment 1 laterally and terminating lateral to lower lip; poorly developed distal part, at base of upper lip, also extending along prostomial lateral processes ( Fig. 21 A–E). Few buccal tentacles remaining, of two types, short tentacles uniformly cylindrical, long ones slightly spatulated at tips ( Fig. 21 A–E). Peristomium forming lips; elongate and narrow upper lip, distinctly longer than wide, convoluted; small, button-like lower lip ( Fig. 21 A–E). Segment 1 only conspicuous mid-dorsally; segment 2 reduced, visible all around; body of uniform width and segments progressively 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 ( Fig. 21 A–F). Slightly papillated, poorly defined ventro-lateral pads, present on segments 3–15, last pairs smaller ( Fig. 21 A–B, D). Notopodia extending for 13 segments at least (depending on the specimen being complete anteriorly), until segment 15; distinctly elongate, bilobed notopodia, lobes of equal size, first pair shorter ( Fig. 21 A–E). Paratype (complete, gravid) with 16 pairs of notopodia. Pinnate notochaetae in both rows ( Fig. 21 G–H), those from posterior row only pinnate at tips. Beginning of neuropodia unclear due to state of preservation of specimen, but apparently neuropodia only beginning after termination of notopodia, as thin, elongate pinnules ( Fig. 21 A, F). Paratype with neuropodia beginning immediately after the last pair of notopodia. Uncini intermediate between types 1 and 2, with short neck, but otherwise as type 2 ( Fig. 21 G). Large nephridia, visible by transparency through body wall; nephridial and genital papillae present on segments 3–15, anterior and ventral to bases of notopodia ( Fig. 21 A–B, D). Pygidium smooth to crenulated, with rounded ventral papilla ( Fig. 21 A, F).

Remarks. The holotype of P. brutus n. sp. is a specimen broken in four pieces, with both anterior and posterior ends. It seems to be complete, but there is great difference in width between fragments and perhaps a piece with few anterior segments is missing. The specimen has prostomium only at base of upper lip; button-like lower lip; slightly papillated, poorly defined ventro-lateral pads; 13 pairs of notopodia (16 pairs in paratype), with neuropodia beginning immediately after the termination of notopodia, so noto- and neuropodia do not occur simultaneously on any segment. Notopodia bear pinnate chaetae in both rows and neuropodia have type 2 uncini with remarkably short neck for this type of uncini. Nephridial and genital papillae are present at the bases of all notopodia.

However, the most distinctive character of this specimen is the prostomium continuing laterally by one pair of long, deeply grooved tentacle-like extensions, like a pair of horns pointing posteriorly. The upper lip of P. brutus n. sp. is also remarkable, distinctly longer than wide, convoluted, resembling that of some telothelepodids (Nogueira et al. 2010, 2013).

The only other known species of Polycirrus with similar horn-like prostomial lateral extensions is P. nonatoi Carrerette & Nogueira, 2013 , which also has longer than wide upper lip. Members of these species differ, however, because among members of P. nonatoi the tentacle-like prostomial extensions are shorter, with shallower groove; the distal part of prostomium extends along the upper lip until near the anterior margin of the lip; the lower lip is distinctly larger, rounded, cushion-like across the ventrum, reaching the anterior margin of segment 4 midventrally; the ventro-lateral pads are clearly defined and highly papillated; notopodia have elongate post-chaetal lobe and bear narrowly-winged chaetae in the anterior row of notochaetae; and, although the original description states that members of P. nonatoi have type 1 uncini, these structures are intermediate between types 1 and 2, with strongly bent back and relatively short heel, but otherwise as type 2, although much shorter than those of other taxa with this type of uncini (Carrerette & Nogueira 2013). The holotype of P. brutus n. sp., on the other hand, has more typical type 2 uncini, although still intermediate between types 1 and 2, with a distinctly short neck for this type of uncini.

Although the prostomium is far less developed, not forming tentacular extensions, P. coccineus Grube, 1870 also has prostomial lateral extensions and narrow and elongate upper lip. In addition to the absence of tentacular extensions, members of this species differ from P. brutus n. sp. by having larger, cushion-like lower lip across ventrum; highly papillated, tessellated ventro-lateral pads; 20 pairs of notopodia, extending until segment 22, with longer post-chaetal lobe; and nephridial and genital papillae only present until segment 9 (Glasby & Hutchings 2014).

Etymology. We attribute the name “ brutus ” to this species after the character Brutus , from the cartoon “Popeye the Sailor”, in reference to the pair of prostomial horn-like lateral extensions, which resemble the curved arms of a very strong man.

Habitat. Coral rubble at 10 m.

Type locality. Palfrey Island, 14°41'28.572"S, 145°26'29.940"E, Lizard Island, Great Barrier Reef, Australia.

Distribution. Only known from the Lizard region.

Figures

FIGURE 21. Polycirrus brutus n. sp., holotype NTM W. 023152. A. Entire worm, ventral view (fragments arranged to simulate the animal is entire); B – C. Anterior end, ventral and dorsal views, respectively; D – E. Close ups of the anterior end, ventral and dorsal views, respectively; F. Posterior end, left dorso-lateral view; G – H. Progressively higher magnifications of the notochaetae of segment 14; I. Uncini, mid-abdominal segment. Numbers refer to segments. Abbreviations: ll = lower lip, P = basal part of prostomium, PLP = prostomial lateral process, ul = upper lip, * = distal part of prostomium. Scale bars: A = 1.5 mm, B – F = 0.5 mm, G = 30 µm, H = 15 µm, I = 10 µm.