Polycirrus oculeus, 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 : 475-477

Polycirrus oculeus n. sp.

( Figs 1 D–E, 5B–F, 22)

Type material. Holotype: NTM W.23159, Lizard Island, off SW Palfrey Island, 14°41'39.408"S, 145°26'29.724"E, coll. Glasby & Watson, 8 Apr 2008, complete specimen, with ~71 segments, 14 mm long, 0.6– 0.7 maximum width. Paratype: AM W.44612, MI QLD 2400, gravid, no eyespots remaining after preservation.

Description. In life, white to yellowish transparent body and buccal tentacles, with one pair of red eyespots near tips of buccal tentacles, apparently present on all tentacles, and one spot at pygidium ( Fig. 1 D–E). Transverse prostomium attached to dorsal surface of base of upper lip; basal part as thick semicircular crest across dorsum, extending lateral and posteriorly, covering segment 1 laterally and terminating lateral to lower lip; poorly developed distal part, as low lobe of uniform length at base of upper lip ( Fig. 22 A–H). Buccal tentacles of two types, short tentacles uniformly cylindrical, slightly expanded at tips, long ones spatulated at tips ( Fig. 21 A–H). Peristomium forming lips; elongate and narrow upper lip, longer than wide, slightly convoluted; small, button-like lower lip, rounded ( Fig. 22 B–D, H). Segments 1 and 2 reduced, both visible all around; body slightly broader until segment 5, gently tapering until segment 10, then of relatively uniform width, cylindrical ( Fig. 22 A–J); posterior thoracic segments with notopodia in ventro-lateral position, laterally to longitudinal crests bordering mid-ventral groove, same position as that of neuropodial pinnules on abdomen ( Fig. 22 B, I); large anterior abdominal segments, with thin body wall and poorly marked segmentation, posterior body with clearly defined, compacted segments ( Fig. 22 A–B, I); paratype with highly swollen anterior and mid-body regions, and cylindrical, gently tapering posteriorly ( Fig. 1 D). Highly papillated and clearly defined ventro-lateral pads, present on segments 3–11, last two pairs less developed ( Fig. 22 B–D, H). Notopodia extending for 18 segments, until segment 20; distinctly elongate, bilobed notopodia, lobes of equal size, first and last pairs slightly shorter ( Fig. 22 A–I). Narrowly-winged, acicular notochaetae in anterior row, wings inconspicuous under light microscopy; notochaetae of posterior row with pinnate distal half ( Fig. 5 B–C). Neuropodia beginning from segment 23, third after termination of notopodia, as thin, elongate pinnules ( Fig. 22 A–B, J). Remarkably few uncini per torus, 2 uncini per torus on anterior abdominal segments, 4 on posterior ones; type 2 uncini, with thin, elongate prow and heel, the latter obliquely directed downwards, crest with single elongate and sharp tooth in first row above main fang, surrounded by crown of minute teeth at base, and elongate neck ( Fig. 5 D–F). Nephridial and genital papillae present on segments 3–9, anterior and ventral to bases of notopodia, not visible on notopodia of segments 10–20 ( Fig. 22 B–D, F–I). Pygidium smooth to crenulated, with rounded ventral papilla ( Fig. 22 A–B, J).

Remarks. The holotype of P. oculeus n. sp. is complete, just over 1 cm in length; with distal part of prostomium at the base of the upper lip; longer than wide upper lip; short, button-like lower lip; highly papillated and clearly defined ventro-lateral pads; 18 pairs of notopodia, extending until segment 20, with evenly-sized lobes and narrowly-winged, acicular notochaetae in anterior row, and distally pinnate chaetae in posterior row; neuropodia beginning shortly after the termination of notopodia, on segment 23, as relatively thin and elongate pinnules, bearing type 2 uncini; and nephridial and genital papillae extending until segment 9. The most remarkable character of this species, however, is the presence of paired red spots near tips of tentacles, possibly eyespots, which are not known to occur in any other species of Polycirrus , but those spots are only visible in live material ( Fig. 1 D–E), disappearing after preservation.

Glasby & Hutchings (2014) report that only two previously known species of Polycirrus have 13–23 pairs of notopodia with neuropodia beginning after the termination of notopodia, these are P. bicrinalis Hutchings & Glasby, 1986 , originally described from Lizard Island, and P. decipiens (Gravier, 1905) , known from the Gulf of Aden, Indian Ocean. However, both these species have type 1 uncini, and therefore, are clearly different from P. oculeus n. sp.

Other species with 13–23 pairs of notopodia and neuropodia beginning close to the termination of notopodia, and with type 2 uncini include P. aquila Caullery, 1944 , P. coccineus Grube, 1870 , and P. medius Hessle, 1917 . Polycirrus aquila is a species originally described from Indonesia and members of this taxon differ from P. oculeus n. sp. in having almost circular upper lip; larger, rectangular, cushion-like lower lip, extending across the ventrum; 16 pairs of notopodia, extending until segment 18, with longer post-chaetal lobe and pinnate chaetae in both rows of notochaetae; neuropodia beginning shortly before the termination of notopodia, on segment 17; and nephridial and genital papillae present until the termination of notopodia (Glasby & Hutchings 2014).

Polycirrus coccineus was described by Grube (1870) from Red Sea material, which specimens have circular upper lip; 20 pairs of notopodia, extending until segment 22, with longer post-chaetal lobe and pinnate chaetae in both rows; and neuropodia beginning on the last segment with notopodia, segment 22 (Glasby & Hutchings 2014).

Members of P. m e di u s, a species originally described from Japan, present narrow, mid-ventral, rectangular and cushion-like lower lip, extending until the posterior part of segment 4; 17 pairs of notopodia, extending until segment 19, with pinnate chaetae in both rows of notochaetae; and neuropodia beginning shortly before the termination of notopodia, on segment 17 (Glasby & Hutchings 2014).

Etymology. The specific name “ oculeus ” refers to the presence of many eyes, as one pair of eyespots near tips of all tentacles, visible in live material; from the Latin “ oculeus ” = full of eyes.

Habitat. Collected amongst coral rubble in shallow water.

Type locality. Off SW Palfrey Island, 14°41'39.408"S, 145°26'29.724"E, Lizard Island Group, Great Barrier Reef, Australia.

Distribution. Known only from the Lizard region.

Figures

FIGURE 1. Live specimens. A. Polycirrus rubrointestinalis n. sp.; B – C. Polycirrus cruciformis n. sp.; D – E. Polycirrus oculeus n. sp. D, AM W. 44612, other specimens not preserved. Scale bars: A, D, E = 0.3 mm, B = 0.2 mm, C = 0.15 mm. All photos by Alexander Semenov.

FIGURE 5. Lysilla pacifica, AM W. 47520, A. Notochaetae, segment 8. Polycirrus oculeus n. sp., holotype NTM W. 23159, B – C. Progressively closer views of the notochaetae of segment 19; D. Uncini, segment 23; E – F. Uncini of two posterior neuropodia. Polycirrus rubrointestinalis n. sp., paratype AM W. 47658, G – H. Notochaetae, segments 6 and 12, respectively; I – K. Uncini, segments 6, 12 and 24, respectively. Scale bars: A – B, G = 30 µm, C, H = 20 µm, D – F = 5 µm, I – K = 6 µm.

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.

FIGURE 22. Polycirrus oculeus n. sp., holotype NTM W 23159. A – B. Entire worm, dorsal and ventral views (anteriorly), respectively, arrow points to the last notopodium; C – F. Progressively higher magnifications of the anterior end, ventral and dorsal views, respectively; G – H. Close ups of the anterior end, dorsal and ventral views, respectively; I. Transition between thorax and abdomen, ventral view; J. Posterior end, left lateral view. Numbers refer to segments. Abbreviations: ll = lower lip, P = basal part of prostomium, ul = upper lip, * = distal part of prostomium. Scale bars: A – B = 0.5 mm, C = 0.3 mm, D – H, J = 0.2 mm, I = 0.15 mm.