Loimia keablei n. sp.

(Figures 45–48)

Type material. Holotype: AM W.47733, CReefs, LI–10–62, MacGillivray Reef, 14°39'25"S, 145°28'22"E, 14.5 mm long, 1.5 mm wide. Paratypes: AM W.47787 (on 2 SEM pins), CReefs 2008, Linnet Reef, southwest of Lizard Island, 14°47'30"S, 145°20'12"E; AM W.47788, CReefs, LI–10–009, MI QLD 2188, North Direction Island, 14°44'43"S, 145°30'18"E, large complete specimen, in excellent state of preservation, in two pieces, total of 81 segments, 26 mm long, 4 mm wide; AM W.47734, CReefs, LI–10–074, MI QLD 2213, Day Reef, outer GBR, northeast of Lizard Island, 14°28'20"S, 145°31'25"E, complete specimen, ~ 14 mm long, 2 mm wide; NTM W. 023134, 14°38'44"S 146°27'11"E; AM W.47735 (3), CReefs, LI–10–62, MacGillivray Reef, 14°39'25"S, 145°28'22"E; AM W.47721, CReefs, LI–10–136, MI QLD 2245, High Rock, 14°49'34"S, 145°33'08"E.

Comparative material examined. Holotype of Loimia batilla Hutchings & Glasby, 1988, AM W.5162. Paratypes of Loimia batilla, AM W.7097, AM W.7098; AM W.7106, AM W.7107. Non-types of Loimia ingens (Grube, 1878), NTM W.6764, NTM W.6775, NTM W.17330. Holotype of Loimia ochracea (Grube, 1878), ZMB 906, MPW 583. Holotype of Loimia triloba Hutchings & Glasby, 1988, BMNH ZB 1986.97.

Description. Transverse prostomium attached to dorsal surface of upper lip; basal part with lateral eyespots extending from each lateral to level of branchiae; distal part shelf-like (Figs 45 E, H; 46I, J, L–N). Peristomium forming lips, hood-like upper lip, short, almost circular, partially covered by lobes of segment 1; short and swollen lower lip, button-like (Figs 45 B–D, G, I, L; 46B–D, I). Segment 1 dorsally narrow, with pair of large lobes directed anteriorly and reaching around ¾ of of upper lip length; lobes distally straight, laterally rounded, dorsal margins inserted at level of first pair of notopodia, laterally to first pair of branchiae; lobes higher ventro-laterally, laterally to mouth, mid-ventrally indented to partially expose lower lip. Segment 2 short reduced, dorsally conspicuous, covered by lobes of segment 3 laterally and partially fused to it mid-ventrally. Segment 3 with pair of relatively short, almost squared lobes, rounded at corners, reaching mid-length of lobes of segment 1; lobes with narrow base, ventral edges fused to upper corners of first mid-ventral shield, almost at mid-length of anterior neuropodial tori, dorsal margins inserted at level of dorsal edges of neuropodia; bases and tips of lobes about same width; lobes of segment 4 absent (Figs 45 A–I, L–M; 46A–D, G, I, K–N). Anterior segments slightly inflated dorsally. Paired dorso-lateral arborescent branchiae present on segments 2–4, dorsal to line of notopodia, with short branchial filaments branching dichotomously from secondary stems originating in a spiral from short basal stems; first pair slightly longer, about half body width at segment 2; pairs all longitudinally aligned (Figs 45 B–I, L–M; 46E–G, J, L–N). Trapezoidal mid-ventral shields present on segments 2–15, those of segments 2–3 almost completely fused into single crenulated structure, following shields progressively smoother, slightly crenulate until last; blood red region on segments 13–15; first 2 shields, on segments 2–3 and 4, much wider than those of following segments, then about same width, indented posteriorly by tori, last 2 shields, almost inconspicuous (Figs 45 B–D, G, I, L; 46B–D, I, M–N). From termination of notopodia, on segment 20, each segment with row of rounded tubercles of relatively uniform size, aligned with parapodia (Figs 45 J–K; 46A–B, O –Q; 47A). Notopodia beginning on segment 4, extending until segment 20; notopodia short, cylindrical to oblong, notopodia of segments 4–7 inserted progressively more laterally, then longitudinally aligned (Figs 45 A–I, L–M; 46A–H, K–N; 47B–D, F, I). Narrowlywinged notochaetae in both rows throughout, those from posterior row with wings at distal half (Figs 45 N–P; 47B– J). Neuropodia present from segment 5, as low, almost sessile ridges until termination of notopodia, as elongate and thin, rectangular pinnules, from segment 21, inserted progressively more ventrally, lateral to mid-ventral groove on posterior segments (Figs 45 A–D, F–G, I, K–M; 46A–B, D–E, H, L– O, Q). Pectinate short-handled avicular uncini, arranged in partially intercalated to completely separate double rows, in back to back arrangement, from segment 11 until termination of notopodia, on segment 20; uncini with short base, dorsal button at mid-length of base, and crest with single vertical series of 6 progressively shorter secondary teeth, on first pairs of neuropodia, 4–5 teeth from beginning of double rows to posterior body segments; main fang larger but not clearly defined, line of teeth aligned with tip of prow; under SEM, series of teeth with lateral fringe of minute teeth (Figs 45 Q–T; 47K–L; 48A– E). Nephridial papillae on segment 3, between dorsal margins of lobes and bases of branchiae, genital papillae on segments 6–8, posterior to notopodia; all papillae minute (Figs 45 E–H, L–M; 46H, L–N). Pygidium crenulate (Figs 45 A–B, J–K; 46A–B, O –Q; 47A). Tube unknown.

Variation. The number of eyespots and size of branchiae seem to be variable in this species, possibly due to artifacts of fixation as eyespots may fade or not, and branchiae may be contracted or relaxed at fixation.

Remarks. As also occurs in L. tuberculata n. sp. described above, L. keablei n. sp. also differs from all previously known Australian species of Loimia by the presence of a dorsal ring of round tubercles per segment, but in this species such a ring is only present after notopodia terminate, from segment 21, while in L. tuberculata n. sp. tubercles are found from segment 5. In addition to the different distribution of tubercles, L. keablei n. sp. differs from L. tuberculata n. sp. in having prostomial eyespots, uncini with fewer teeth (6 on anterior-most neuropodia, then 4–5), while in L. tuberculata n. sp. the uncini have 7 teeth anteriorly, then 6 teeth until posterior body and the lobes of segments 1 and 3 have different morphology between these species. The lobes of segment 1 are almost circular in L. tuberculata n. sp., only covering the base of the upper lip, and those of segment 3 have tips much wider than bases, extending laterally from dorsal margins. In L. keablei n. sp., in contrast, the lobes of segment 1 are distally straight and cover most extension of the upper lip, while the lobes of segment 3 are shorter, with bases and tips about same width, not extending laterally from bases.

Loimia keablei n. sp. can be easily distinguished from two other Australian species, L. batilla Hutchings & Glasby, 1988 and L. ingens (Grube, 1878) (which may represent a species complex-see Remarks under L. tuberculata n. sp.), because in both these species the lobes of segment 3 are connected to each other by a low collar across the ventrum, whereas in L. keablei n. sp. the lobes of segment 3 are completely separated. Loimia triloba Hutchings & Glasby, 1988 has angular lobes on segment 3, whereas in L. keablei n. sp. these lobes are almost rectangular to squared; in addition, L. triloba, as also occurs in L. pseudotriloba n. sp., has one pair of short lobes on segment 4, which are absent in L. keablei n. sp.

Etymology. We have named this species after Dr Steve Keable, Collection Manager of Marine Invertebrates, Australian Museum, who greatly assisted in all the loans associated with the workshop.

Type locality. Deep reef slope, MacGillivray Reef, 14°39'24"S, 145°29'34"E, Lizard Island, GBR, Australia.

Distribution. Widely distributed along Lizard Island region.