Sabellaria lungalla, Hutchings & Capa & Peart, 2012

Hutchings, Pat, Capa, María & Peart, Rachael, 2012, 3306, Zootaxa 3306, pp. 1-60 : 44-46

Sabellaria lungalla n. sp.

Figs 6B, 24, 25, Table 4

Material examined. HOLOTYPE: NTM W16893, Northern Territory: Bing Bong, McAthur River , 15°23' S 136°30.35'E, 17.iii.1993, complete except for cauda, 3 mm in length, 1 mm in width, 12 chaetigers . PARATYPES: 2, NTM W16896), Drimmie Arm , Melville Bay, Gove, 12°14'S 136°42'E, 4 mm in length, 1.5 mm in width for 14 chaetigers, 3.45 mm in length 1.00 mm in width for 14 chaetigers; 2 , NTM W10043, Darwin Harbour, D 92A, 12°29.52' S 130°50.18' E, 7 m, 14.vii. 1993, 7 m, 3 mm in length, 1 mm in width, 18 chaetigers, 5 mm in length, 1 mm in width, 16 segments .

Additional material examined. Northern Territory: Bing Bong, McArthur River, Gulf of Carpentaria , 15°36.72'S 136°23.45'E, 18.iii.1993, 1, AM W37780 (mounted for SEM) ; Darwin Harbour , 12°29'S 130°50.18E, 14.vi.1993, 1, NTM W10043 ; 12°32.72'S 130°51.32'E, 24.iii.1994, 1, NTM W24725 ; 12°32.9'S 130°50.02'E, 15.vi.1993, 1, NTM W10042 ; 1, NTM W16889 . Majority of this material is posteriorly incomplete. Western Australia: Mermaid Sound, Dampier Archipelago , 20°52'S 116°44'E, WAM V3816 , 1981 .

Description. Holotype with short compact body, colourless except for scattered pigment around base of opercular lobes ( Fig. 24A). Operculum short, similar in width to length, with lobes completely separated along its length. Paleae arranged in three semicircular concentric rows ( Fig. 25A, B, D). Outer row with 22 pairs of geniculate golden paleae with flattened blades, smooth lateral margins and distal tip with midline plume and 5–7 smaller denticles on each side ( Figs 24F, 25A–C). Middle row with 10–11 pairs of paleae, short, geniculate, with broad and concave blades directed outwards and tapering tips and inner row with 11 pairs of similar in shape paleae, slightly smaller arranged in between the middle paleae directed inwards, broadly flattened, geniculate, yellow-brown, smooth, pointed tips ( Fig. 25A, D). Outer paleae 5–6 times longer than inner and middle rows, middle paleae not covering the inner opercular paleae ( Fig. 25A). Sixteen pairs of short opercular papillae ( Figs 24C, D, 25B) peripheral to outer paleae. Three pairs of nuchal spines present, slightly curved inwards with blunt tips ( Figs 24F, 25E). Tentacular filaments compound (branching) arranged in eight rows ( Fig. 24B,C). Palps slightly longer than length of operculum. Median organ present at dorsal junction of lobes of operculum, with eye spots on lateral margins. Segment 1 (chaetiger 1) with one pair of neuropodial cirri with small tuft of fine capillary chaetae on either side of U-shaped buccal organ ( Fig. 24B). Segment 2 (chaetiger 2) with one pair of elongated lateral lobes, connecting branchiae to neuropodia ( Fig. 24C, D). Neuropodia of segments 1 and 2 not vertically aligned, those of segment 2 situated more laterally, neurochaetae similar in structure on both segments. Five to six pairs of branchiae present (difficult to count as holotype slightly damaged). Branchiae narrow based, strongly ciliated, long and tapering to fine tip. Segment 3–5 (parathoracic) with two types of notochaetae arranged transversely ( Fig. 25H); six lanceolate chaetae, tapering to an elongate frayed tip ( Fig. 25H) and fine capillaries with frayed margins inserted between lanceolate ones ( Fig. 25H). Segments 3–5 with two types of neurochaetae arranged in compact lateral fascicle, with about six to eight lanceolate chaetae plus fine capillaries. Parathoracic notopodia more robust that neuropodia ( Fig. 24A). Abdominal region with 12 chaetigers. Notopodia as transverse tori, with long handled uncini, numbers per torus decreasing posteriorly, each uncinus with two vertical rows, each row with six to eight major teeth ( Fig. 25J), similar throughout abdomen. Neuropodia with ventral bundle of fine notochaetal capillaries with extended fine tips, shafts composed of stacks of thecae with margins extending to fine filamentous tip ( Fig. 25I), similar throughout abdomen. Cauda smooth and about half of length of abdomen on paratype.

Variation. Material examined varies from 3–5 mm in length, without cauda, 1–2 in width with 13–18 chaetigers, 22–23 pairs of outer paleae, 10–11 pairs of inner paleae, 11–12 pairs of middle paleae and 16–23 pairs of opercular papillae.

Remarks. Sabellaria lungalla n. sp., is characterised by the distal margin of the outer paleae being serrated with a midline plume, one kind of middle paleae which are geniculate with smooth pointed tips and inner paleae which are asymmetrical with short blunt tips, three pairs of nuchal spines and one pair of lateral lobes on segment 2, which no other species share (Table 4).

Sabellaria lungalla n. sp., can be separated from S. kooraltha n. sp., by the shape of the distal margin of the outer paleae: S. lungalla n. sp., has an elongate finely serrated distal plume ( Fig. 25C) whereas S. kooraltha n. sp., has a large central distal tooth which is smooth with two lateral teeth on either side ( Fig. 23D, E). The other Australian species S. pyramis n. sp., differs from S. lungalla n. sp., by the number and shape of the middle paleae ( Fig. 26E, F).

Sabellaria lungalla n. sp., belongs to a group of Sabellaria with only one kind of middle paleae (Table 4), and of those occurring in the Indo-Pacific they can be separated from S. lungalla n. sp., on the basis on the dentition of the single kind of mid-paleae. Sabellaria gilchristi ( McIntosh, 1925) has only two pairs of teeth on the distal margin of the outer paleae Sabellaria javanica Augener, 1934 described from Indonesia, has no teeth on the lateral margins and S. tottoriensis Nishi et al., 2004 , described from Japan, has only three teeth whereas S. lungalla n. sp., has 7–8 pairs of teeth.

Distribution. Gulf of Carpentaria, Northern Australia, and Dampier Archipelago, Western Australia.

Habitat. Intertidal in sheltered bays from intertidal to 15 m.

Etymology. The specific name lungalla refers to an Aboriginal word for a lagoon in the Northern Territory and this species is found in inshore shallow bays.