Idanthyrsus australiensis ( Haswell, 1883 )

Hutchings, Pat, Capa, María & Peart, Rachael, 2012, 3306, Zootaxa 3306, pp. 1-60 : 6-13

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Idanthyrsus australiensis ( Haswell, 1883 )


Idanthyrsus australiensis ( Haswell, 1883)

Figures 1A, B, 2–5, 6A, Table 1

Sabellaria (Hermella) australiensis Haswell, 1883: 634 , pl. 12; figs 7–11.

Sabellaria australiensis .— McIntosh, 1885: 416.

Sabellaria sexhamata .— Collin, 1902: 742; not Grube, 1878: 219.

Sabellaria (Pallasia) pennata . — Augener, 1914: 79; not Peters, 1854.

Pallasia pennata .— Fauvel, 1917: 262. Augener, 1922: 33; 1926: 253; not Peters, 1854: 613.

Idanthyrsus pennatus . — Dakin, Bennett and Pope, 1953: 153; not Peters, 1854: 613.

Idanthyrsus glaessneri . — Kirtley, 1994: 97, fig. 6.7.

Material examined. TYPE?: Sabellaria (Hermella) australiensis Haswell, 1883 , BMNH 1882.2.22.71*, 47 mm in length excluding cauda, 6 mm in width (anteriorly), 47 chaetigers (in 2 parts, anterior fragment with 30 chaetigers and posterior with 17 chaetigers). Queensland: Thursday Island , 10°35'S 142°13'E, 7.8–12.3 m, collected by HMS Alert GoogleMaps .

Additional material examined. Queensland: Cape Yorke Peninsula, south of Fly Point , Putta Putta Beach, 10°45'S 142°36'E, 11.vii.1976, 1, AM W26926 View Materials GoogleMaps , on semi-exposed boulder bank; Thursday Island , 10°35'S 142°13'E, 4, AM W7087 GoogleMaps *, 1, AM W26683 View Materials (mounted for SEM) , 1, AM W26684 View Materials (mounted for SEM) , AM W26851 View Materials ; Gladstone, Calliope River , 23°55'S 151°10'E, 1, AM W199314 GoogleMaps *; Gladstone Harbour, 23°51'S 151°16'E, 06.xi.1975, 1, QM G10564 View Materials GoogleMaps ; Gladstone, Calliope River , 23°55'S 151°10'E, 5; Gladstone Harbour, 23°51'S 151°16'E, 06.xi.1975, 3, QM G10565 View Materials GoogleMaps *; Mary River , 26°23' S 152°45' E, 31.xii.1971, low tide, 1, AM W26928 View Materials GoogleMaps ; Hervey Bay, Point Vernon , 25°15'S 152°49'E, iv.1972, 1, AM W201700 GoogleMaps *; Maroochydore, Alexandra Headland, 26°39'S 153°06'E, 01.iv.1972, 1, AM W26929 View Materials GoogleMaps ; Caloundra , 26°48'S 153°08'E, viii.1945, 4, QM G4043 GoogleMaps , from south beach rocks; 2, QM G4044 ; 1938, 1, QM G212812 ; Moreton Bay, Peel Island, Horseshoe Bay , 27°30'S 153°21'E, 18.xii.1977, 1, QM G212813 GoogleMaps *, from under rocks submerged at low tide. New South Wales: Lennox Heads, 28°48'S 153°36'E, 27.iii.1972, 1, AM W26971 View Materials GoogleMaps ; south of Clarence River mouth, Minnie Water, 29°47'S 153°18'E, 2–3.xi.1963, 3, AM W26895 View Materials GoogleMaps ; 25.ii.1971, 1, AM W26901 View Materials , from shore reef, in crevices, covered in coralline algae, 1, AM W26900 View Materials , from shore reef, underneath boulders in rockpools; Wilson Headland, 29°50'S 153°17'E, 12.v.1984, 6, AM W26857 View Materials GoogleMaps ; off Coffs Harbour, Arrawarra Head , 30°04'S 153°12'E, 14.x.1974, 11, AM W9196 GoogleMaps *, cemented together forming small colony; Coffs Harbour, SW face of South Solitary Island , 30°12'S 153°16'E, 19.v.1972, 7.6–10.7 m, 5, AM W26917 View Materials GoogleMaps ; 17.v.1973, 15.2 m, 3, AM W26916 View Materials , from small boulders covered in ascidians; Coffs Harbour, west side of Solitary Island , 30°12'S 153°16'E, 18.v.1972, 1, AM W26923 View Materials GoogleMaps ; Toowoon Bay, near Tuggerah Lake , 33°22'S 151°30'E, 13.iv.1986, 0.6 m, 3, AM W26858 View Materials GoogleMaps , from rocks loosely piled, but cemented together, covered in Homosira banksii; off Avalon, 33° 38'S, 151° 20'E, 31.i.1973, 36.6 m, 1, AM W26849 View Materials GoogleMaps , from reef flat; Long Reef , 33°45'S 151°19'E, 16.xi.1970, 3, AM W4524 * (mounted for SEM) GoogleMaps , from on underside of rocks, in sandy, firm tubes; Long Reef, north side of reef, 33°45'S 151°19'E, 23.ii.1971, 1, AM W26902 View Materials GoogleMaps ; v.1967, 2, MV F78871 View Materials *; Port Jackson , 33°50'S 151°16'E, 10.i.1983, intertidal, 1, AM W198478 GoogleMaps *; North Head , 33°50'S 151°18'E, 26.v.1972, 28.9 m, 1, AM W6963 GoogleMaps *; 13.xii.1972, 28.9 m, 1, AM W26925 View Materials ; Maroubra , 33°57'06"S 151°17'37"E, 01.xii.1954, 1, AM W1575 GoogleMaps *; Kurnell, Potter Point, 34°03'S 151°13'E, 27.ix.1989, low tide, 4, AM W26863 View Materials GoogleMaps , from on and under rocks; Port Hacking , near Jibbon Head, 34°05'S 151°10'E, 23 m, 1, AM W16351 View Materials GoogleMaps *, from reef; north of Wollongong , Bellambi Reef, 34°26'S 150°53'E, 14.xi.1971, 1, AM W26968 View Materials GoogleMaps , from rock pool, in holdfast of seaweed; Shellharbour, 34°35'S 150°52'E, between tide marks, 5, AM W26903 View Materials GoogleMaps ; Shellharbour, near bluestone quarry, 34°35'S 150°52'E, 05.ix.1971, 7.6–9.1 m, 3, AM W26974 View Materials GoogleMaps ; Gerroa, Blackhead , 34°46'S 150°49'E, 25.ix.1982, mid tide, 1, AM W198479 GoogleMaps *; north of Broulee , 35°51'S 150°11'E, i.1971, 1, MV F78866 View Materials GoogleMaps *; near Jervis Bay, Wreck Bay , Cemetry Point, 35°11'S 150°38'E, 27.ii.1976, intertidal, 1, AM W26927 View Materials GoogleMaps , on coralline algae; Twofold Bay, Murrumbulga Point , 37°05'S 149°54'E, 09.x.1984, intertidal, 1, AM W199879 GoogleMaps *, from gravel and algal washings on rock platform; 27.iii.1985, intertidal, 1, AM W199889 *, cryptic fauna and rock platform;, subtidal, 2, AM W199880 *, crevice fauna and amongst Diopatra tubes on rock platform; Twofold Bay , Red Point, 37°05'S 149°54'E, 20.v.1995, 1, AM W26907 View Materials GoogleMaps ; Munganno Point , 37°05'S 149°54'E, 10.x. 1984, 6 m, 10, AM W199892 GoogleMaps * from erect bryozoan colony on wharf pile. Victoria: South tip of Mallacoota, Bastion Point, 37°34'S 149°46'E, 1, AM W26525 View Materials (mounted for SEM) GoogleMaps ; Western Port , Merricks, 38°24'S 145°07'E, 1969, 1, MV F78856 View Materials GoogleMaps *; Bass Strait, 5 km south of Point Reginald , 38°48'S 143°17'E, xi. 1981, 47 m, 1, MV F78883 View Materials GoogleMaps *; Western Port , Somers, 38°24'S 145°10'E, 2, MV F78853 View Materials GoogleMaps *; Flinders Ocean Beach, 38°29'S 145°02'E, 17.xii.1969, 1, MV F78872 View Materials GoogleMaps *; Venus Bay, west of Eagles Nest , 38°40'S 145°41'E, 01.ii.1966, 1, MV F78868 View Materials GoogleMaps *; Western Port , near Shoreham, Honeysuckle Point, 38°26'S 145°04'E, 14.xi.1970, 1, MV F78864 View Materials GoogleMaps *; Flinders, south reef, 38°29'S 145°02'E, 13.xi.1965, 1, MV F78863 View Materials GoogleMaps *; Airey's Inlet, 38°28'S 144°06'E, 31.i.1967, 1, MV F78869 View Materials GoogleMaps . South Australia: Sellicks Beach , 35°20'S 138°27'E, 16.iii.1979, 3, AM W198439 GoogleMaps *, York Peninsula, Gleeson's Landing , 34°35'S 137°43'E, 27.xi.1985, intertidal, 1, SAM E3093 View Materials GoogleMaps , from under rocks; 3, SAM E3094 View Materials , from under rocks; Aldinga Bay , 35°21'S 138°25'E, 12.x.1977, low tide, 1, AM W14055 View Materials GoogleMaps *, under rocks. Western Australia: King George Sound, Mistaken Island , 35°04'S 117°56'E, 1.i.1988, 1, AM W26894 View Materials GoogleMaps , crevice fauna; Cape Naturaliste, Bunker Bay , 33°32'S 115°02'E, 30.i.1972, low tide, 6, WAM V156 GoogleMaps , from amongst metamorphic rocks; Bunker Bay , 33°31' 5.48"S 115° 03 25.56'E, 30.i.72, low tide, many, WAM V284 GoogleMaps ; 2 km off North Point *, 32°01'S 115°30'E, 11.i. 1991, 30 m, 1, AM W26908 View Materials GoogleMaps , from reef and coral bommie surrounded by algal beds; Rottnest Island, Strickland Bay , 32°00'S 115°30'E, 20.i.1991, 1, AM W26904 View Materials GoogleMaps , from reef edge, rock and algae; Sandy Cape, Point Peron, 32°01'S 115°30'E, 1946, 2, AM W26856 View Materials , 1 , AM W26855 View Materials GoogleMaps ; 2 km south of Cape Peron, reef west of Groyne , 32°01'S 115°30'E, 26.xii.1983, 3, AM W26862 View Materials GoogleMaps , from sponges and gorgonaceans from cove on reef; Point Clone, 32°01'S 115°30'E, 29.xi.1945, 1, AM W26854 View Materials GoogleMaps ; Warnborough Sound, 32°20'S 115°43'E, 21.iii. 1993, 5 m, 1, AM W26909 View Materials GoogleMaps , from Posidonia sp. beds; Fremantle, South Mole , 32°03'S 115°44'E, 1, AM W26861 View Materials GoogleMaps ; Cockburn Sound , 32°01'S 115°45'E, 15.ii.1966, 1, WAM V3814 GoogleMaps ; Cottesloe Reef, near Groyne , 31°59'S 115°45'E, 29.iii.1973, 2, WAM V311 GoogleMaps , from under stones and in dead shells; Cottesloe Beach, 31°59'S 115°45'E, 08.i.1988, intertidal, 2, AM W26864 View Materials GoogleMaps ; 29.iii.1973, 2, WAM 72–74 View Materials , from under stones and in dead shells; Kendrew Island , Dampier Archipelago, 20°29'S 116°32'E, 03.iv. 1987, 10 m, 1, AM W26911 View Materials GoogleMaps , crevice fauna; Finucane Island , 20°18'S 118°33'E, 1970, AM W26914 View Materials GoogleMaps ; Roly Rocks, 20°33'S 116°32'E, 03.iv. 1987, 10 m, 1, AM W26910 View Materials GoogleMaps ; Port Hedland, Finucane Island , 20°18'S 118°33'E,, 1, AM W26912 View Materials GoogleMaps ; Broome, Gantheame Point, 17°59'S 122°11'E, 04.vii.1970, ELWM GoogleMaps spring, 2, AM W26859 View Materials ; 15.iii.1987, 12– 18 m, 2, NTM W4916 View Materials *, from rocky reef; 15.iii.1987, LWS, 1, NTM W4548 View Materials *, from rock slabs in silt; Broome, Cable Beach , 17°57'S 122°12'E, 29.ix.1984, LWS, 1, NTM W2280 View Materials GoogleMaps *, from under stones; 02.xii. 1981, 3 m, 2, MV F78852 View Materials ; Riddell Point, Broome , 17°56.30'S 122°12.33'E, 19.viii.1982, 1 WAM 1890 View Materials GoogleMaps . Northern Territory: Port Essington, Sandy Island , 11°06'S 132°18'E, 02.v. 1982, 14 m, 1, NTM W1122 View Materials GoogleMaps *, from muddy bottom; 1, NTM W1124 View Materials *, from muddy bottom; Port Essington, Burford , 11°29'S 131°57'E, 13.x.1981, 1, NTM W1120 View Materials GoogleMaps *, from reef flat; Cobourg Peninsula, Burford Island , 11°29'S 131°57'E, 13.x.1981, 1, NTM W25 View Materials GoogleMaps *; Charles Point, Beagle Gulf, 12˚18.96'S 130˚40.74'E, 23 m, 13.x.1993, NTM W23480 View Materials .

Other species examined for comparison. HOLOTYPE of Idanthyrsus glaessneri Kirtley, 1994 , LACM AHF N6277 View Materials , sand flat at low tide, Lakes Entrance , Victoria, 37.8°S 147.9° E, coll. B. Dew, 1.3 cm in length, 3.42 mm in width (maximum width of thorax without chaetae). GoogleMaps

Description. Type flesh coloured, with dark brown blotches on sides of operculum and anterior end and darkly pigmented cauda. Body compact and robust ( Fig. 1A). Operculum with completely separate lobes, longer than wide ( Figs 1A, 3B), with distal end sloped posteriorly (oblique to longitudinal axis). Fourteen pairs of paleae in outer row, with cylindrical shaft ( Fig. 3A, C), and flat, straight blade, ornamented with alternate, sharp-tipped, similar sized and slightly curved denticles on margins. Inner row with nine pairs of cylindrical and smooth paleae, tapering evenly to acute tip ( Figs 1A, B, 3A, D). Opercular papillae, 14 pairs, peripheral to outer row of paleae on each lobe ( Fig. 3A). Three pairs of nuchal spines with bent tips (hooks) on each side, concave margins smooth, limbation absent ( Figs 1B, 3A). Tentacular filaments, arranged in nine rows ( Fig. 3B). Median ridge and median organ present, extending to dorsal edge of junction of opercular lobes, raised and pigmented (illustrated in non type material, Fig. 2B, C). Numerous eyespots present on both sides of median ridge. Palps about half length of operculum. Segment 1 (chaetiger 1), with neuropodial lobe on either side of U-shaped buccal organ (illustrated in non type material Fig. 2B); capillary neurochaetae present, flattened and with finely denticulated margins ( Fig. 3E). Segment 2 (chaetiger 2) with three pairs of triangular lateral lobes, connecting dorsal branchiae to neuropodia; with similar neurochaetae as those on chaetiger 1. Neuropodia of chaetiger 1 and 2 not vertically aligned, those of chaetiger 2 situated more laterally ( Fig. 1B). Fourty six pairs of dorsal branchiae present from chaetiger 2, continuing along entire length of body but diminishing in size in posterior segments, some represented only by scars ( Fig. 1A). Branchiae conical, with transverse rows of cilia and blunt tips ( Fig. 1A, B). Segments 3–5 (parathoracic) with two types of chaetae arranged transversely, eight, straight, flattened, lanceolate, some with frayed twisted tips, majority represented only by stumps and eight fine, smooth capillaries, inserted between lanceolate chaetae ( Fig. 3F). Segments 3–5 with lancelolate neurochaetae arranged in two tiers of different lengths (longer about twice the length of shorter, as illustrated in non type material Fig. 4I). Notopodial parathoracic chaetae larger and more robust than neuropodial. Abdominal region with 42 chaetigers. Notopodia as transverse tori with uncini, decreasing in number posteriorly. Each uncinus with two vertical rows of teeth, each with about eight teeth ( Fig. 3I). Neuropodia with capillaries becoming longer posteriorly, with thin and flattened blades ornamented with thecal laminar extensions distally forming oblique rows and splayed tips ( Fig. 3G, H). Cauda smooth, about a quarter of abdominal length ( Fig. 1A).

Variation. As the type material and material from the type locality is in relatively poor condition we provide here some supplementary information based on the material from Arrawarra, northern NSW ( Fig. 2A–H). The median ridge and median organ ( Fig. 2C) have a line of eye spots on both sides. The lobes of chaetiger 1 have fine capillary neurochaetae laterally displaced in relationship to those of chaetiger 2 ( Fig. 2E). Chaetiger 2 with three pairs of triangular lateral lobes which connect the branchiae to the neuropodia ( Fig. 2D). The triangular shaped branchiae ( Fig. 2F) continue all along the abdomen. Parathoracic neuropodia were examined under SEM on material from Long Reef, NSW showing two tiers of lanceolate neurochaetae present ( Fig. 4I).

A large number of specimens were examined from several localities, including sexually mature individuals, that vary in length (4–60 mm), width (1–6 mm), number of chaetigers (25–52), number of outer opercular paleae (8–28 pairs), inner opercular paleae (6–17 pairs), opercular papillae (5–16 pairs), nuchal hooks (2–3 pairs), number of rows of tentacular filaments (8–11), number of branchiae (14–46 pairs), number of teeth on abdominal uncini (8–10) and number of abdominal chaetigers (15–49). These variations can be mainly attributed to size of the specimens, with larger animals tending to have more paleae, papillae, uncinial teeth and abdominal chaetigers. As minor differences in structure of paleae and nuchal hooks have been used previously to differentiate species, we illustrate these structures from material collected from Long Reef , Sydney , NSW ( Fig. 4A–M) and from Mallacoota , Victoria ( Fig. 5A–G) the type locality of Idanthyrsus glaessneri Kirtley, 1994 , in addition to material from type locality ( Fig. 3A–I). The outer paleae of specimens examined from each of these three localities vary slightly in terms of length of the denticles on margins, and we suggest that this represents a gradual gradation rather than separate species and represent a difficult character to measure ( Figs 3C, 4C, 5C). Lanceolate parathoracic notochaetae appear to be contractile within parapodia (compare Fig. 4H and Fig. 5E), and we suggest that these parapodia are highly mobile. Neurochaetae of the first two segments are missing from one side on holotype, but on non type material from type locality (eg. AM W26683 View Materials , AM W26684 View Materials ) they are present on both sides. Abdominal neurochaetae are similar in these three distant localities ( Figs 3G, H, 4J, K, 5F). Divergence of the opercular lobes varies and we suggest this may be a function of size and fixation .

Remarks. The diagnostic characters of I. australiensis are the combination of the absence of a limbation on the nuchal spines, the presence of three lateral lobes on segment 2, and the presence of branchiae on posterior segments. Kirtley (1994) primarily used the shape and thecal development of the outer and inner paleae to distinguish between species, but in most cases intraspecific variation was not considered. We have tried to group this variation observed in some groups regarding the arrangement, shape, relative length and relative numbers of denticles on both sides of outer paleae (Table 1). The structure of the notopodial chaetae of the parathoracic segments also differs between I. australiensis ( Figs 3F, 4H) and I. nesos n. sp. (see this paper), in the former the capillaries imbetween the lanceolate chaetae are thin whereas in the new species the capillaries have a wider distal end, resembling lanceolate chaetae ( Fig. 8F, G). However, for virtually all described species these parathoracic notochaetae are poorly if at all described and comparison cannot be made at this stage, and this is also true for the parathoracic neurochaetae and therefore these characters are not given in Table 1, but we suggest they may provide useful characters to distinguish between species.

Idanthyrsus glaessneri Kirtley, 1994 from Lakes Entrance, Victoria, Australia, was briefly described and only the outer and inner opercular paleae illustrated. In his key to species of Idanthyrsus, Kirtley (1994) separated this species from I. australiensis due to the length of denticles (without sharp tipped denticles in I. glaesneri and sharp in I. australiensis ), ornamentation of the thecae (irregular wavy lines across blade in I. glaesneri ) and overall shape of paleae (strongly bent in I. glaesneri and slightly sigmoidal in I. australiensis ). After examination of the holotype of I. glaesneri , which has been partially dried at some stage, is posteriorly incomplete, and has lost the majority of the outer row of paleae, we would describe the outer opercular paleae as with alternate denticles, slightly curved, with a ratio of 1:1. This together with other diagnostic features (presence of three lateral lobes on segment 2 and the presence of branchiae on posterior segments) appear to fall within the range observed for I. australiensis and we have therefore synonymised the two species.

Examining a large amount of material of I. australiensis from many localities ( Fig. 6A) has allowed us to assess the variability of characters such as the ornamentation of the paleae which Kirtley (1994) had largely relied upon to distinguish species and we have concluded that additional characters such as numbers and distribution of denticles on the outer paleae, number and shape of nuchal spines, numbers of lateral lobes on segment 2 and absence or presence of branchiae in posterior abdominal segments are useful to distinguish between species (see Table 1). In summary, we suggest that I. australiensis exhibits some variation in a suite of characters but no discrete geographical patterns can be detected along the distribution range of this species ( Fig. 6A).

Distribution. Australia wide from NE Queensland to NW Western Australia, except Tasmania ( Fig. 6A).

Habitat. Found from low intertidal to depths of 50 m attached to solid substrate, sometimes occurring as crevice fauna. Specimens typically form small colonies of 6–10 individuals, although specimens from Bunker Bay, in Western Australia, were found in larger colonies, consisting of several hundreds of specimens.


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Idanthyrsus australiensis ( Haswell, 1883 )

Hutchings, Pat, Capa, María & Peart, Rachael 2012

Idanthyrsus glaessneri

Kirtley, D. W. 1994: 97

Idanthyrsus pennatus

Dakin, W. J. & Bennett, I. & Pope, E. C. 1953: 153
Peters, F. A. 1854: 613

Pallasia pennata

Augener, H. 1922: 33
Fauvel, P. 1917: 262
Peters, F. A. 1854: 613

Sabellaria (Pallasia) pennata

Augener, H. 1914: 79

Sabellaria sexhamata

Collin, A. 1902: 742
Grube, A-E. 1878: 219

Sabellaria australiensis

McIntosh, W. C. 1885: 416

Sabellaria (Hermella) australiensis

Haswell, W. A. 1883: 634
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