Spinosphaera barega, Nogueira, João Miguel De Matos & Hutchings, Pat A., 2007

Nogueira, João Miguel De Matos & Hutchings, Pat A., 2007, New species of terebellid polychaetes (Polychaeta: Terebellidae) from Australia, Zootaxa 1473, pp. 1-24 : 11-12

Spinosphaera barega sp. nov.

( Figs 4–6 )

Material examined. Type series. Holotype: AM W30726: coll. north end Long Island, Wallabi Group, Abrolhos Islands, Western Australia, 28º28.3’S 113º 46’3’E, St. WA 521, 8m, dead coral substrate, covered in coralline algae, by C. Bryce, 22nd May 1994, posteriorly incomplete and lacking all buccal tentacles, measuring 8 mm in length, 0.7 mm maximum width, with all notochaetigerous segments plus 14 segments with neuropodia only. Paratype: AM W22544: coll. 28º24’S 113º46.16’E, Wallabi Group, Abrolhos Islands, Western Australia, St. WA 551, 35m, dredged in scallop beds, with shell debris, by P. Hutchings, 30th May 1994, posteriorly incomplete, measuring 10.76 mm in length, 1.14 mm maximum width, with all notochaetigerous segments plus 14 segments with neuropodia only.

Description. Prostomium at base of upper lip; numerous small eyespots present in circular cluster on lateral margins of basal part of prostomium ( Fig. 4 A–D). Upper lip short, hood-like, broader than high; lower lip small and narrow ( Fig. 4 A–F). Anterior segments not dorsally inflated, compacted until segment 11. Segment 1 visible dorsally, ventrally and laterally; dorsally narrow, ventrally forming lobe below lower lip ( Fig. 4 A–F). Lateral lobes absent. Ventral shields on segments 2–14, all smooth, shield on segment 3 shortest ( Fig. 4 E), then progressively increasing in size until segment 14; from segment 15, shields replaced by mid ventral stripe extending posteriorly.

Notopodia beginning on segment 4 ( Fig. 4 A–F), extending until segment 26; first pair of notopodia about same size as following pairs and dorsally aligned to them, notopodia on segments 4–7 inserted progressively more laterally, subsequently vertically aligned ( Fig. 4 B–D). Notochaetae of both tiers of anterior notochaetigerous segments, until segment 9–10 (9 in holotype, 10 in paratype), as broadly winged bilimbate capillaries ( Fig. 5 A); on segments 10–11 (10 in holotype, 11 in paratype), chaetae of anterior tier as alimbate, serrate capillaries, with blade in angle with shaft, chaetae of posterior tier transitional, with limbation ending subdistally and serrated blade; from segment 11–12 (11 in holotype, 12 in paratype), chaetae of anterior tier alimbate, serrate capillaries, with blade in angle with shaft, chaetae of posterior tier characteristic “ spinosphaera chaetae”, with short broadly winged basal limbation, followed by portion with inflated and hispid shaft and finely serrate distal blade ( Fig. 5 B–D).

Neuropodia beginning from segment 5, as low rectangular ridges slightly raised from surface of body throughout. Uncini arranged in partially intercalated double rows ( Fig. 6 C–D) from segment 13 until penultimate notochaetigerous segment (in both specimens), last notochaetigerous segment with uncini in a single row ( Fig. 6 F); irregular double rows usually 1 uncinus on anterior row (with beak posteriorly directed) and 2– 3 uncini on posterior row ( Fig. 6 C–D). Uncini short handled throughout, with short, triangular heel, downwardly directed prow, dorsal button at about mid length of distance between base of main fang and tip of prow, somewhat closer to base of main fang, and main fang surmounted by about 5 rows of secondary teeth ( Fig. 6 ).

Nephridial papillae not seen. Pygidium unknown.

Remarks. A comparison between the species currently assigned to Spinosphaera is provided in Table 2 .

Spinosphaera barega sp. nov., is closer to S. harrisae and S. pacifica , as both these species have similar notochaetae and uncini arranged in double rows terminating before the end of thorax ( Table 2 ). Spinosphaera harrisae differs from S. barega sp. nov., in having different arrangement of eyespots, only 20 pairs of notopodia and nephridial papillae on segments 7–12 or 13, while S. barega sp. nov., has 23 pairs of notopodia and nephridial papillae are absent or, at least, not visible ( Table 2 ). Spinosphaera pacifica differs from S. barega sp. nov., in lacking eyespots and in having nephridial papillae on segments 3 and 6–20.

Etymology. The specific name “ barega ” refers to an aboriginal word for wind ( Endacott 1973), as the type locality for this species Houtman Abrolhos is noted for the strong winds which blow for most of the year on these islands.

Figures

FIGURE 4. Spinosphaera barega sp. nov. Holotype. A, anterior end, dorsolateral view; B, anterior end, left lateral view; C – D, anterior end, right lateral view; E, anterior end, ventrolateral view; F, superior view of oral area. Numbers refer to segments; ll = lower lip; P = basal part of prostomium; P (dp) = distal part of prostomium; po = pharyngeal organ; ul = upper lip. Scale bars: A-E: 0.2 mm; F: 0.15 mm

FIGURE 5. Spinosphaera barega sp. nov. Holotype. A, notochaetae, segment 6; B, notochaetae, segment 20; rectangular areas and letters refer to figures which show those specific areas in higher magnification; C, closer view of tip of one chaeta from the posterior tier of notochaetae, segment 20; D, closer view of chaetae on anterior tier of notochaetae, segment 20. Scale bars: A, D: 30 Μm; B: 50 Μm; C: 20 Μm.

FIGURE 6. Spinosphaera barega sp. nov. A, uncini, segment 5; B, E, G, posterior abdominal uncini; C, uncini, segment 20; D, closer view of some uncini from segment 20; F, uncini from segment 26, last notochaetigerous segment. Photos A, C – D, F from paratype, photos B, E, G from holotype. Scale bars: A, F: 20 Μm; B, E: 5 Μm; C: 30 Μm; D, G: 10 Μm.