Sabellaria kooraltha, Hutchings & Capa & Peart, 2012

Hutchings, Pat, Capa, María & Peart, Rachael, 2012, 3306, Zootaxa 3306, pp. 1-60 : 36-44

Sabellaria kooraltha n. sp.

Figures 6B, 21, 22, 23, Table 4

Material examined. HOLOTYPE: 1, AM W27333 *, 18 mm long, 2 mm wide, 22 chaetigers . PARATYPE: AM W27195*, 19 mm long, 3 mm wide, 22 chaetigers, from Albany Passage , Queensland, Australia, 10°45'S 142°37'E, 10 m; paratype AM W37820.001 (mounted for SEM) Shell Island , East Arm, Darwin Harbour, Northern Territory, St. RH 88/37, 12˚ 29.4''S 130˚ 53.2''E, rocky intertidal, 18 iii. Mar 1988 .

Additional material examined. Northern Territory: West of Elizabeth Reef , Cape Hotham, Beagle Gulf , 12˚4.02'S 131˚20.04'E, 21 m 29.x.1993, 1, NTM W23479, 09 .x.93, 1, NTM W23477 ; 2 nm E of Quail Isl., Bynoe

Harbour , Beagle Gulf, 12˚31.02'S 130˚28.98'E, 28 m, 6.x.1993, 1, NTM W23478 ; East Arm , Shell Island, Darwin Harbour, 12°29'S 130°53'E, 18.iii.1988, low water, rocky intertidal, 1, AM W37820 *, (mounted for SEM) ; Darwin Harbour , 12˚32.72'S 130˚51.32'E, DW 105A, 7 m, coll. 24.iii.1994, 1, NTM W15033 ; 12˚32.72'S 130˚51.32'E, DW 1054, 7 m, coll. 24.iii.1994, 1, NTM W15031 ; 12˚36.17'S 130˚46.87'E, DW 76A, 4 m, coll. 17.iii.1994, 1, NTM W15023 ; 12°32.9'S 130°50.02E, 1, D103A, 8 m, coll. 15.vi.1993, 1, NTM W10042 ; 12°31.98'S 130°50.09'E, DH 100A, 24.iii. 1994, 15 m, coll. 24.iii.94, 1, NTM W15030 ; 12˚29.27'S 130˚49.48'E, DW 204A, 14 m, coll. 25.iii.1994, fine & coarse sand, 1, NTM W15026 ; 12˚30.07'S 130˚55.88'E, DW 187A, 4 m, coll. 22.iii.1994, 2, NTM W15027 ; 12˚26.93'S 130˚46.5'E, DW 544, 14 m, coll. 16.iii.1994, 1, NTM W15032 ; 12˚34'S 130˚52.22'E, DW 116A, 12 m, coll. 18.iii.1994, 1, NTM W15024 ; 12˚34'S 130˚52.22'E, DW 116A, 18.iii. 1994, 12 m, 1, NTM W15035, 12 ˚31.68'S 130˚51.3'E, DW 101A, 8 m, coll. 24.iii.1994, 1, NTM W15028 ; 12˚31.7'S 130˚51.28'E, 8 m, 14.vii.1993, 1, NTM W23482 ; 12˚31'54''S 130˚50'25''E, 24.iii.1994, 1, NTM W15029 ; 12˚27'57''S 130˚46'30''E, 08.vi.1994, 1, NTM W10046 ; 12˚28'57''S 130˚50'25''E, 17.iii.1994, 1, NTM W15034 ; Melville Bay , Gove, 12˚11.7'S 136˚41.3'E, 8.vii.1991,7.5 m, 1, NTM W16880, 1 , NTM W16887, 1 , NTM W16890 ; Melville Bay , Gove, 12˚12'31''S 136˚40'30''E, 9.vi.1991, 1, NTM W16882, 1 , NTM W6881 ; 12˚10'31''S 136˚39'E, Nov 1991 – March 1992, 1, NTM W08265 ; NW of Granite Islet , Melville Bay, Gove, 12˚14'S 136˚40'E, 22.iii.1992, 12.9 m, 1, NTM W16891 ; Bing Bong , McArthur River, Gulf of Carpentaria, 15˚37'S 136˚23'E, ix. 1992 – iii. 1993, 8 m, 1, NTM W007737 , 1 , NTM W16899 .

Description. Holotype with speckled faint brown pigment on ridged cilated dorsum ( Fig. 21C), rectangular pigment patches across ventrum of chaetiger 5 (3 rd parathoracic). Operculum similar in width to length, with lobes completely separated, and three rows of golden paleae arranged in concentric semicircles ( Figs 21B, 23A). Outer row with 12 geniculate paleae with flattened blades, smooth lateral margins and serrated distal margins with a middle tapering denticle occupying half of distal end which has marked surface ornamentation ( Figs 21B, 22G, 23D, E, 22D, E). Twelve pairs of middle geniculate paleae, with smooth concave shafts and tapering blades pointing towards to outer edge of operculum ( Figs 21B, 22H, 23C, F). Fourteen pairs of inner paleae, strongly geniculated, concave blades, similar to middle paleae but wider, shorter and pointing inwards to center of operculum ( Fig. 21B). Outer paleae longer than those of inner rows. Opercular papillae, 19 pairs, short, peripheral to outer paleae on each lobe ( Figs. 21B, C, 22D, 23B). Three pairs of nuchal spines present (four in paratype), stout, flattened, slightly curved, with smooth blunt tips ( Figs 21B, 22I, 23G). Tentacular filaments, compound, arranged in 14 horizontal rows ( Fig. 22A). Median ridge and median organ present. Eyespots present. Palps slightly longer than opercular lobes. Segment 1 (chaetiger 1) with lobe-shaped neuropodia, with capillary neurochaetae, on either side of U-shaped buccal organ ( Fig. 22B). Segment 2 (chaetiger 2) with one elongate triangular shaped lateral lobe, connecting branchiae to neuropodia, with fine capillary neurochaetae ( Figs 21A, C, 22E, F). Neuropodia of chaetigers 1 and 2 not vertically aligned, those of chaetiger 2 situated more laterally ( Figs 21B, 23H). Sixteen pairs of dorsal branchiae present from segment 2 ( Figs 22F, 23H), continuing along entire length of body, with broad base and strongly ciliated ridges and slightly pigmented, all detached except one, which tapers distally with filiform tip, more remain on paratype ( Figs 21A, 23H). Segments 3–5 (parathoracic) with two types of notochaetae arranged transversely, seven (many represented only by stumps) lanceolate with frayed tips and short, flattened smooth shafts with strongly frayed tips, and fine short capillaries with expanded theca inserted between lanceolate ( Fig. 23I). Segments 3–5 with two types of neurochaetae arranged in compact fascicle, with seven lanceolate and seven fine capillaries ( Fig. 23H). Parathoracic notopodia larger than neuropodia ( Fig. 22J). Abdominal region with 16 chaetigers. Notopodia as elongate, erect tori, with long-handled uncini, numbers per torus decreasing posteriorly, each uncinus with two vertical rows, each with seven teeth. Neuropodia becoming considerably elongated posteriorly ( Fig. 22I) with ventral bundle of capillaries ( Fig. 23J). Cauda smooth and more than half length of abdomen ( Figs 22I,K, 23L). Paratype a gravid female with eggs released from between posterior abdominal notopodia.

Variations. Material examined varies from 4–12 mm in length, 1–2 mm in width with 12–22 chaetigers, but much of the material is posteriorly incomplete, 12–16 pairs of outer paleae, 10–12 pairs of middle paleae, 16–19 pairs of opercular papillae and 3–4 pairs of nuchal spines.

Remarks. Sabellaria kooraltha n. sp., is characterised by the following combination of characters: 12–16 pairs of outer paleae with a smooth median distal spike which has marked thecal bands, and two smaller, smooth basal, lateral spines ( Fig. 23D, E) and 11–12 pairs of middle paleae which are geniculate and with a broad based triangular shaped central tooth ( Fig. 23F), one pair of lateral lobes on chaetiger 2 and branchiae absent from posterior abdominal segments. This species can easily be separated from the other species of Sabellaria recorded from Australia by the structure of the outer paleae. Sabellaria kooraltha n. sp., has a smooth midline tooth or spike although the thecae are very conspicuous on the outer paleae ( Fig. 23D, E) whereas Sabellaria lungalla n. sp., (this paper) has a finely serrated distal plume on the outer paleae ( Figs 24G, 25C).

With regard to other Indo-Pacific species which have one kind of middle paleae, both S. gilchristi ( McIntosh, 1925) described from South Africa, and S. javanica Augener, 1934 , described from Indonesia, have outer paleae with midline plume whereas S. kooraltha n. sp., has a smooth distal spike. The value of SEM is highlighted for the characterisation of this species although the strongly ornamented midline plume of the outer paleae can be seen under high magnification using a compound microscope. Details of the other described species of Sabellari a are given in Table 4.

Distribution. North-eastern Australia, from Albany Passage, just south of Cape York in North Queensland and Darwin Harbour, Northern Territory.

Habitat. No information on habitat is available for the type locality, but co-ordinates suggest a depth of 10 m and collected by dredging. Non type material collected from muddy substrates from low water mark to 15 m.

Etymology. The specific name kooraltha is an Aboriginal word for spotted ( Endacott 1973) and refers to the pigmented nature of the dorsum.