Polycirrus papillatus, 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 : 462-465

Polycirrus papillatus n. sp.

( Figs 14–17 )

Type material. Holotype: AM W.45149, MI QLD 2442, complete specimen, in good state of preservation, ~ 1.9 mm long, 0.4 mm maximum width. Paratypes: AM W.47661 (1 mounted on SEM pin), North Direction Island, lagoon patch reef, 14°44'43"S, 145°30'18"E, 4 Sep 2010, CReefs; AM W.47660, MI QLD 2396; AM W.44271, MI QLD 2344; AM W.44622, MI QLD 2413 (on SEM pin); AM W.44527, MI QLD 2387 (2, 1 mounted on slide); AM W.47690, MI QLD 2203.

Description. Minute worms, with transverse prostomium attached to dorsal surface of base of upper lip; basal part as thick, curved crest, distal part poorly developed, as low lobe of uniform length at base of upper lip ( Figs 14 A–C, E–G; 15A–K; 16B–C). Buccal tentacles of two types, both of almost uniform width, spatulated at tips, with deeper groove, long ones with slightly thinner, uniformly cylindrical peduncle before spatulated tip ( Figs 14 A–C, E–G; 15A–K; 16A–C). Peristomium forming lips; short, circular upper lip, hood-like; short, swollen lower lip, button-like, restricted to oral area ( Figs 14 B, E–F; 15B, F–H, K; 16B–C). Segment 1 reduced, visible dorsal and ventrally, laterally covered by expanded prostomium; segment 2 visible all around, distinctly narrower than following segments, with relatively large, rectangular mid-ventral shield ( Figs 14 A–C, E–G; 15A–K; 16B–C). Highly papillated ventro-lateral pads of anterior segments, pads present until segment 11, last 2 pairs poorly developed; segments 12–14, last 3 segments with notopodia, distinctly swollen, pads inconspicuous ( Figs 14 B, D– F; 15B, D, F–H, K; 16B–C). Notopodia extending for 11–12 segments, until segments 13–14; elongate, bilobed notopodia, lobes of same size ( Figs 14 A–G; 15A–L; 16A–C; 17A–B, D, F). Narrowly-winged, acicular notochaetae in anterior row, with fewer chaetae, pinnate chaetae in posterior row; winged chaetae distinctly shorter, wings inconspicuous under light microscopy, as short hairs under SEM ( Figs 14 H–I; 17A–F). Neuropodia beginning from segment 5, first and second pairs of neuropodia with 1–2 uncini only at each side ( Fig. 15 L); minute, type 1 uncini until first segment after termination of notopodia, with short, triangular heel directed posteriorly, single, elongate and sharp tooth in first row above main fang, with two rows of shorter, irregularly sized teeth at base, and short neck ( Figs 14 J; 17F–G); and larger, type 2 uncini from second abdominal segment, with thin, elongate prow and heel, the latter obliquely directed downwards, crest with single elongate and sharp tooth on first row above main fang, surrounded by crown of minute teeth at base, and elongate neck ( Figs 14 K; 17H–I). Nephridial and genital papillae present at bases of all notopodia, ventral to notopodia on segments 3–4, anterior to notopodia after beginning of neuropodia ( Figs 15 B, D, F–H, K–L; 16B–C; 17A, F). Pygidium smooth ( Figs 14 A–B, D; 15A–B; 16A–B, D).

Variation. We noticed considerable variation amongst the material examined, regarding anterior end characters, which are commonly used for species distinction in this genus. The upper lip may have thinner, convoluted walls, or stouter, straight margins (compare Figs 14 A–B, E–F; 15B, F–G, K; 16B–C). We attribute these to methods of preservation and consider it as an intraspecific variation. In addition, there is also a slight variation in the number of pairs of notopodia present, as most specimens, including the holotype, have 12 pairs, extending until segment 14, while some others, such as paratype AM W.44622 (mounted on SEM pin), have only 11 pairs, on segments 3–13 ( Fig. 16 A–C).

Remarks. This is another species of minute worms a few millimeters in length, with the distal part of prostomium at the base of the upper lip; button-like lower lip; clearly defined and highly papillated ventro-lateral pads; 12 pairs of notopodia, on segments 3–14, with evenly-sized lobes, winged chaetae in anterior row of notochaetae and pinnate chaetae in posterior row; neuropodia beginning anteriorly, from segment 5, with type 1 uncini on thoracic chaetigers, and type 2 from the second abdominal segment; and nephridial and genital papillae extending until the last pair of notopodia.

The species with few pairs of notopodia and neuropodia beginning from anterior segments are the same as discussed for P. rubrointestinalis n. sp. with the addition of P. norvegicus Wollebaek, 1912 , with 16 pairs of notopodia, on segments 3–18, since P. papillatus n. sp. has 12 pairs of notopodia. Of these species, however, only three have type 1 uncini on thoracic segments and type 2 uncini on abdomen: P. clavatus ( Kinberg, 1867) , P. holthei Londoño-Mesa & Carrera-Parra, 2005 , and P. porcatus Knox & Cameron, 1971 , this latter species originally described from Port Phillip Bay, Victoria, Australia.

Polycirrus clavatus is distinguished from P. papillatus n. sp. in having 15 pairs of notopodia, on segments 3– 17, with pinnate chaetae in both rows, and nephridial and genital papillae are absent on last pairs of notopodia, only present until segment 11 ( Carrerette & Nogueira 2013; Glasby & Hutchings 2014).

Polycirrus holthei also has pinnate chaetae in both rows of notochaetae ( Glasby & Hutchings 2014), while the holotype of P. porcatus , originally described from Victoria, differs from P. papillatus n. sp. in having the same type of chaetae on both rows, although we suspect from the line drawings provided by Glasby & Hutchings (2014: 95, Fig. 52c) that these chaetae would appear pinnate under SEM, instead of “hirsute”, as described originally by Knox & Cameron (1971); and uncini with conspicuous dorsal button below main fang ( Glasby & Hutchings 2014), while in P. papillatus n. sp. the dorsal button is inconspicuous.

Etymology. The specific name “ papillatus ” refers to the highly papillated ventral pads.

Habitat. Several sites around Lizard Island, North Direction Island and Yonge Reef in amongst Halimeda , and under rubble in shallow water.

Type locality. North West of Watson’s Bay, 14°39'41.2"S, 145°26’26”E, Lizard Island, Great Barrier Reef, Australia.

Distribution. Known only from the Lizard Island region.

Figures

FIGURE 14. Polycirrus papillatus n. sp., holotype AM W. 45149. A – B. Entire worm, dorsal and ventral views, respectively; C. Anterior end, dorsal view; D. Posterior end, ventral view; E. Anterior end, ventral view; F – G. Close ups of the anterior end, ventral and dorsal views, respectively, arrow points to first neuropodium; H. Notochaetae of anterior row, segment 4; I. Tips of notochaetae of posterior row, segment 4; J. Uncini, segments 7 – 8; K. Uncini, segment 18. Numbers refer to segments. Abbreviations: ll = lower lip, P = basal part of prostomium, ul = upper lip, * = distal part of prostomium. Scale bars: A – B = 200 µm, C – E = 100 µm, F – G = 70 µm, H – I = 30 µm, J = 7 µm, K = 20 µm.

FIGURE 15. Polycirrus papillatus n. sp., paratype AM W. 47661. A – B. Entire worm, dorsal and ventral views, respectively; C. Anterior end, dorsal view; D – F. Thorax, left lateral, right dorso-lateral and ventral views, repectively; G – J. Anterior end, ventral, left lateral, right dorso-lateral and dorsal views, repectively; K. Close up of the anterior end, ventral view; L. Notopodia, segments 4 – 5, white arrows point to nephridial papillae, black arrow points to first neuropodium. Numbers refer to segments. Abbreviations: ll = lower lip, P = basal part of prostomium, ul = upper lip, * = distal part of prostomium. Scale bars: A – B = 400 µm, C – D, F, I = 200 µm, E = 300 µm, G – H, J = 75 µm, K = 50 µm, L = 10 µm.

FIGURE 16. Polycirrus papillatus n. sp., paratype AM W. 44622. A – B. Entire worm, left dorso-lateral and ventral views, respectively; C. Thorax, ventral view; D. Posterior end, left lateral view. Scale bars: A – B = 0.4 mm, C = 0.2 mm, D = 0.1 mm.

FIGURE 17. Polycirrus papillatus n. sp., paratype AM W. 47661. A – E. Progressively closer views of one notopodium and notochaetae of segment 7, under different magnifications and angles of visualization; arrow points to genital papilla of segment 8; F. Parapodia, segments 13 – 14, last thoracic and first abdominal segments; G – I. Neuropodia, segments 11 (thoracic), 15 and posterior one (both abdominal), respectively. Scale bars: A, D, F = 20 µm, B = 15 µm, C = 2 µm, E = 10 µm, G = 3 µm, H = 4 µm, I = 5 µm.