Haplosyllis djiboutiensis Gravier, 1900

Lattig, Patricia, Martin, Daniel & Martín, Guillermo San, 2010, Syllinae (Syllidae: Polychaeta) from Australia. Part 4. The genus Haplosyllis Langerhans, 1879, Zootaxa 2552 (1), pp. 1-36 : 10-14

Haplosyllis djiboutiensis Gravier, 1900

Figs 6A–I , 7A–G

Syllis (Haplosyllis) djiboutiensis Gravier, 1900: 147–149 , pl. 9, fig. 3.

Haplosyllis djiboutiensis . — Lattig & Martin, 2009: 18 , fig. 12.

Haplosyllis spongicola .— Imajima, 1966: 220–221, tex-fig. a–h.— Lee & Rho, 1994: 132–134, fig. 1, a–f.

Examined material. AUSTRALIA. WESTERN AUSTRALIA. 33 specimens AM W36549, Kimberleys, south west corner of Lucas Island , 15º13'S 124º31'E, 2–30 m, coll . P. A. Hutchings, 24 July 1988. 90 specimens AM W36556, Reef south of Lucas Island, Brunswick Bay , Kimberley region , 15°16'S 124°29'E, 2 m, coll . P. A. Hutchings, 24 July 1988. 60 specimens, AM W36552, inshore reef off Ned's Camp, Cape Range National Park , 21º59'S 113º59'E, 1 m, in frilly Caulerpa , coll . J. K. Lowry, 2 January 1984. 8 specimens AM W36553, Bush Bay, 30 km south of Carnarvon , 25º10'S 113º39'E, 0.5 m, in extensive shallow sand flats, lumps of algae, coll . H. E. Stoddart, 6 January 1984. 53 specimens AM W36542, Goss Passage, Beacon Island , 28º25'30''0S 113º47'E, 8 m, dead plates of Acropora , covered in coralline algae, 22 May 1994, coll . P. A. Hutchings. 20 specimens AM W36559, Goss Passage, north end of Long Island, 28º28'18''S 113º46'18''E, 8 m, dead coral substrate, coralline algae, boring bivalves, coll. Bryce, 22 May 1994. 1 specimen AM W36547, southeast end of Long Island , 28º28'48''S 113º46'30''E, 8 m, dead coral covered in coralline algae, coll . P. A. Hutchings, 22 May 1994. 5 specimens AM W36551, Goss Passage, Beacon Island , 28º25'30''S 113º47'E, 10 m, branching dead coral covered in coralline algae, coll . P. A. Hutchings, 18 May 1994. 24 specimens AM W36555, north end of Long Island, Goss Passage , 28º27'54S 113º46'18''E, 6 m, dead coral covered in coralline and brown algae, coll. Bryce, 22 May 1994. 90 specimens AM W36554, Beacon Island , 28°28'48''S 113°46'18''E, 4–5 m, dead coral substrate, covered in coralline algae, coll . P. A. Hutchings, 25 May 1994. 8 specimens AM W36513, Beacon Island, Goss Passage , 28°25'30''S 113°47'E, 8 m, dead plates of Acropora , coll . P. A. Hutchings, 19 May 1994. 70 specimens AM W36548, Goss Passage, Beacon Island , 28º25'30''S 113º47'E, 20 m, dead plates of Acropora , covered in coralline algae, coll P. A. Hutchings, 20 May 1994. 28 specimens AM W36557, Beacon Island, of jetty adjacent to Fisheries Hut, 28º25'30''S 113º47'E, 12 m, dead coral, plate-like Acropora montipora , 23 May 1994. 2 specimens AM W36558, Warnbro Sound, west of Penguin Island , 32º20'S 115º43'E, 5 m, coll . P. A. Hutchings , 21 March 1993. 4 specimens AM W36541, Exmouth Gulf, beach at north end of Bundegi Reef, 21º49'S 114º11'E, 1–2 m, rocky rubble, brown alga with epiphytic growth, sticky sediment, coll . H. E. Stoddart , 4 January 1984 . NEW SOUTH WALES. 100 specimens AM W36491 (plus 3 specimens mounted for SEM), Look-At-Me-Now Headland, 30°18'50"S 153°08'55"E, 4–6 m, Ecklonia radiata holdfast, coll . S. Smith, 27 April 1994. 4 specimens AM W 36545, 150 m east of Burrill Rocks , 35°23'25''S 150°28'11''E, dead bryozoan encrusted with algae, 17 m, coll . K. Attwood, 1 May 1997. 1 specimen AM W36543, Murrays Beach, Jervis Bay , 35º7'30''S 150º45'30''E, 9 m, coll . P. A. Hutchings , 23 January 1973. 22 specimens AM W36628, Coff’s Harbour Jetty, 30º18'24''S 153º08'30''E, 4 m, finger sponge on jetty pilings, coll . R. T. Sprinthorpe, 9 March 1992. 120 specimens AM W26333, North Ledge, Cook Island , 28º11'26''S 153º34'40''E, 10 m, orange sponge, coll . A. R. Parker , 8 June 1993 . QUEENSLAND. 4 specimens AM W36546, Outer Yonge Reef, Great Barrier Reef, 14°36'S 145°38'E, 9 m, coral rubble, coll . P. A. Hutchings , 21 January 1977. 6 specimens AM W36550, Outer Yonge Reef, Great Barrier Reef, 14°36'S 145°38'E, 30 m, coral rubble, coll . P. A. Hutchings , 24 January 1977 . NORTHERN TERRITORY. 1 juvenile AM W36516, Darwin Harbour, East Point , 12°24'36''S 130°39'57"E, 7–10 m, dead coral rubble and algal washings, coll . P. A. Hutchings , 17 July 1993. 4 specimens AM W36544, Lee Point, Darwin, 12º20'0''S 130º53'48''E, 3 m, dead coral rubble washings, coll . P. A. Hutchings , 11 July 1993 .

Haplosyllis cf. djiboutiensis . WESTERN AUSTRALIA: 16 specimens AM W36512, Beacon Island, Goss passage, 28°25'30''S 113°47'E, 23 m, dead plates of Acropora , covered in coralline algae, 19 May 1994, coll. P.A. Hutchings. 5 specimens AM –W36514, Goss Passage, Beacon Island , 28º25'30''S, 113º47'E, 33 m, dead coral, embedded in fine sediment, coll. P.A. Hutchings, 23 May 1994. TASMAN SEA: 75 specimens AM W36515, Elizabeth Reef, reef flat near "Yoshin Maru Iwaki" wreck, 29°55'48"S 159°01'18"E, 0 m, from small heads of Acropora valida and Pocillopora damicornis , 14 Dec. 1987, coll. J.K. Lowry & R. Springthorpe.

Description. Body robust, from small to long sized 3–17 mm, for 30–92 segments; slightly widest at proventricle level, gradually tapering towards posterior end ( Fig. 7A ); pale white to yellowish when preserved. Round, small dorsal granules, abundant laterally at posterior end, almost absent in anterior end. Dorsal pigment pattern absent. Prostomium subpentagonal, wider than long, with two pairs of small red eyes in trapezoidal arrangement ( Fig. 6A ). Median antennae inserted on middle of prostomium, between eyes (11– 30 articles); lateral antennae on anterior margin (7–16 articles). Palps longer than prostomium, broadly triangular, fused at their bases but separated all along their length; ventral side of palps with sensory organs as rows of cilia ( Fig. 7C–D ); nuchal organs as lateral groups of cilia between prostomium and peristomium. Pharynx orange, extending through 4–6 segments; with long, triangular anterior tooth, crown of 10–12 soft papillae and inner ring of cilia ( Fig. 7B ); sometimes with trepan of very small triangular teeth, difficult to see as often covered by cilia. Papillae with groups of cilia on upper-ventral side making up the sensory organs. Proventricle long, cylindrical, dark-brown, as broad as pharynx, extending through 3–9 segments, with 30–50 muscle cell rows. Peristomium well defined, shorter than subsequent segments. Dorsal tentacular cirri longer than ventral ones, with 13–24 articles. Antennae, tentacular cirri and anterior dorsal cirri similar. Anterior dorsal cirri relatively long, with a well-defined length pattern: first cirri exceed body width (11–30 articles), second short (5–16 articles), third and fourth gradually longer, almost as body width (7–20 and 10–29 articles respectively), fifth short (4–16 articles), sixth intermediate (6–24 articles). Subsequent cirri alternating long (7–16 articles) and short (3–11 articles), gradually decreasing in length toward posterior end (1–9 articles) ( Fig. 6B ); median cirri, similar or shorter than body width. Ventral cirri digitiform, anterior ones similar in length than parapodial lobes ( Fig. 6C ); median and posterior ones shorter than parapodial lobes ( Fig. 6D ). Chaetae all bidentate, anterior ones with small MF and short denticles on US ( Figs 6E , 7E ). Median and posterior parapodia with 2–3 chaetae of two different sizes; long ones ( Figs 6G , 7F ) with LMF similar in length to SW; MJP straight and relatively long; US of MF with few, short denticles; apical teeth equal in length, often distal one slightly smaller than proximal. Small chaetae ( Figs 6H , 7G ) with MJP short and curved, wide angle between apical teeth. Two aciculae in anterior and median parapodia, one straight, other with curved tip ( Fig. 6F ); one in posterior parapodia with upwards-directed curved tip ( Fig. 6I ). Pygidium with two long cirri (8–10 articles) ( Fig. 6B ).

Reproduction. Haplosyllis djiboutiensis reproduces by acephalous stolons. Two specimens were in a reproductive stage, with the last 10 segments having pairs of black parapodial ocular spots and fascicles of capillary (i.e. swimming) chaetae and 4–5 chaetae similar to anterior ones (AM W36559).

Remarks. Haplosyllis djiboutiensis can be easily identified by the alternation of cirri on the median body, the abundant posterior dorsal granules, and the differences between long and short chaetae of median and posterior parapodia.

Haplosyllis djiboutiensis is very abundant and common in Australian waters allowing us to study its interpopulation variability. The specimens varied from small and medium-sized worms (3–10 mm long), to long specimens (up to 17 mm long), with variations in some chaetal measures. For example, in long-sized specimens, the median and posterior big chaetae have the distal tooth shorter than the proximal one, and the length of MJP is usually long. These features are very similar to those of the type specimen from Djubal (Red Sea) (see Lattig & Martin, 2009, fig. 12H), while in small to medium-sized worms the MJP is shorter and the apical teeth are equal in length ( Fig. 6G ).

The descriptions of Haplosyllis spongicola from Japan ( Imajima, 1966) and Korea ( Lee & Rho, 1994), agree with the morphology of H. djiboutiensis , which is different from the Mediterranean H. spongicola . The latter has long whip-shaped cirri and dorsal granules are absent (see Lattig et al. 2007; Lattig & Martin 2009).

Haplosyllis djiboutiensis resembles the Mediterranean H. granulosa ( Lattig, San Martín & Martin, 2007) in body shape, cirri length and presence of dorsal granules, but the latter has more chaetae (3–6 per parapodia), all similar, with long denticles on US of MF. Haplosyllis uncinigera (from the Philippines and Australia, see below) also resembles H. djiboutiensis , both in body shape and chaetal characters. The species may be distinguished by aciculae (4–5 straight or slightly upwards-directed posterior aciculae in H. unicinigera , vs. 1–2 in H. djiboutiensis ), and proventricle and pharynx (extending for more than 10 segments in H. uncinigera and for 4–6 segments in H. djiboutiensis ).

Haplosyllis djiboutiensis resembles H. cf. spongicola (see below) in the presence of abundant dorsal granules and in the cirri length alternation; but the chaetae strongly differ, being similar in each parapodium, with short and curved MJP in H. cf. spongicola .

Haplosyllis djiboutiensis is the most common and abundant species of genus Haplosylli s from Indo- Pacific waters. Small differences such as the presence of chaetal denticles, apical teeth size and length of MJP have been observed (with the use of SEM), between populations of different geographic areas (i.e. the Philippines, Coasts of Vietnam and Camboya, the Sea of Japan and Hawaii). According to our observations, we suggest that all these populations, including the Australian ones, constitute a species complex, the species of which are impossible to distinguish using morphological techniques. In order to clarify the geographic distribution of H. djiboutiensis and the taxonomic position of all these populations future research using molecular techniques will be necessary.

Distribution. AUSTRALIA (Western Australia, South Australia, New South Wales, Northern Territory); RED SEA (Djubal), KOREA; JAPAN.

Figures

FIGURE 6. Haplosyllis djiboutiensis. A—anterior end, dorsal view; B—posterior end, dorsal view; C—anterior parapodium, first chaetiger— D—median parapodium; E—anterior chaeta; F—anterior acicula; G—longest chaetae from median parapodium; H—shortest chaeta from median parapodium; I—posterior acicula. Scale: A, B = 250 µm; C, D = 100 µm; E–I = 20 µm. 1 specimen, 4 mm long (AM W36491).

FIGURE 7. SEM micrographs of Haplosyllis djiboutiensis. A—whole body, dorsal view; B—anterior end with everted pharynx, showing large tooth and soft papillae; C—palps, ventral view, square showing position of sensory organs; D— detail of sensory organs; E—anterior chaeta; F—median longest chaeta; G—median shortest chaeta. Scale: A = 1 mm; B = 100 µm; C = 50 µm; D, F = 5 µm; E = 10 µm; G = 20 µm. Two specimens (AM W36491).