Syllis crassicirrata ( Treadwell, 1925 ) Treadwell, 1925

Álvarez-Campos, Patricia, Riesgo, Ana, Hutchings, Pat & Martín, Guillermo San, 2015, The genus Syllis Savigny in Lamarck, 1818 (Annelida, Syllidae) from Australia. Molecular analysis and re-description of some poorly-known species, Zootaxa 4052 (2), pp. 297-331 : 306-309

Syllis crassicirrata ( Treadwell, 1925) n. comb.

Figures 3 , 4

Typosyllis crassi-cirrata Treadwell, 1925: 113, Fig. 10 A–C.

Typosyllis crassicirrata — Hartman 1966: 198; Licher 1999: 196, Fig. 85.

Typosyllis (Typosyllis) crassicirrata — Hartmann-Schröder, 1979: 90, Figs 62–66; 1980: 49; 1981: 25; 1987: 33; 1989: 20; 1992: 53.

Non Typosyllis magnapalpa Hartmann-Schröder, 1978 (contra Licher 1999).

Typosyllis (Typosyllis) krohni non Ehlers, 1864 — Hartmann-Schröder, 1991: 28 –29 (in part only).

Material examined. Non-type specimens. AUSTRALIA. QUEENSLAND. Lizard Island, CReefs Expedition: Yonge Reef, 14°34'40"S, 145°37'E, 8 m depth, 10 Sept 2010, 1 specimen (AM W41236); Turtle Beach, 14°39'09"S, 145°27'03"E, coral rubble, 9.5 m depth, 7 Sept 2010, 3 specimens (AM W41709); MacGillivray Reef, 14°39'23"S, 145°29'31"E, coral rubble, 22 m depth, 29 Aug 2010, 1 specimen (AM W41710); Watsons Bay, 14°39'26"S, 145°27'03"E, coral rubble, 4.5 m depth, 28 Aug 2010, 2 specimens (AM W41711); Coconut Beach reef platform, 14°41'03"S, 145°28'E, coral rubble, intertidal, 25 Aug 2010, 2 specimens (AM W41712). Heron Island, CReefs Expedition: “Twin Peaks”, outer fore-reef, 23°28.341'S 151°57.028'E, 2 m depth, 13 Nov 2009, 2 specimens (one mounted for SEM) (AM W46276). NEW SOUTH WALES. Esmeralda Cove, Broughton Island, 32°37'12"S, 152°19'E, kelp holdfast, 11 May 1978, 2 specimens (AM W46279). Off Coffs Harbour, 50 m west of Split Solitary Island, 30°14'S, 153°10'48"E, sponges and ascidians on rocks, 15–17 m depth, 7 Mar 1992, 1 specimen (AM W46285). East of Burrill Rocks, surface of sponges, 18–19 m depth, 1 May 1997, 3 specimens (AM W46282). VICTORIA. Port Phillip Bay, under Half Moon Pier, 38°06'11"S, 144°26'15"E, rock covered with epibionts, 1 m depth, 9 Feb 2010, 1 specimen (AM W42514). WESTERN AUSTRALIA. Woodside Kimberley Survey: Cassini Island, mid-littoral reef platform, 13°56'01"S, 125°37'09"E, 25 Oct 2010, 1 specimen (AM W42513); Montgomery Reef, mid-littoral fore-reef ramp, 15°52'35"S, 124°19'48"E, intertidal, 20 Oct 2009, 2 specimens (AM W42517); same locality, mid-littoral channel ramp, 15°57'35"S, 124°16'09"E, coral rubble, 22 Oct 2009, 2 specimens (AM W42524 ); same locality, mid-littoral fore-reef ramp, 15°53'54"S, 124°10'54"E, intertidal, 21 Oct 2009, 1 specimen (AM W42525). Cape Range National Park, inshore limestone reef off Ned’s Camp, 21°59'S, 113°55'E, Caulerpa sp., 1 m depth, 2 Jan 1984, 1 specimen (AM W46278); same locality, intertidal, Caulerpa sp. 1 specimen (AM W46284). NEW ZEALAND. NORTH ISLAND. Cavalli Islands, Rainbow Warrior wreck, 36° 50′ 32.66″ S, 174° 46′ 17.68″ E, Aglaophenia sp. hydrozoans, 25 m depth, 1 Feb 2012, 1 specimen ( MNCN 16.01/16869).

Additional specimens. Typosyllis (Typosyllis) crassicirrata . WESTERN AUSTRALIA. Broome, coll. and id. G. Hartmann-Schröder, 1 specimen ( HZM P–1662).

Morphologically similar species. Typosyllis (Typosyllis) magnapalpa , HAWAII. Maui, Paiia, algae with Enteromorpha , Mytilus and detritus, 19 May 1959, Holotype ( HZM P–14471). Syllis variegata . SPAIN, NW Mallorca Island, 39º45'80"N, 02º33'51"E, 74– 72 m depth, 25 Jun 1994, 1 specimen ( MNCN 16.01/8440); Galicia, O’ Grove, 42°29'43"N 8°51’51”W, 1 specimen ( MNCN /ADN 9619). Typosyllis (Typosyllis) krohni . AUSTRALIA. QUEENSLAND. Heron Island, North Reef, coralline sand, 4 Feb 1976, coll. and id. G. Hartmann-Schröder, 13 specimens ( HZM P- 21006).

Description. Longest complete examined specimen 8 mm long, 0.45 mm wide, with 72 segments, one stolon attached, with 28 segments ( Figs 3 A, 4A). Large, robust body, some specimens dark and others yellowish, with 3– 4 red-brown dorsal stripes on each segment, and some irregular spots on prostomium and appendages ( Fig. 4 A–B). Oval prostomium with two pairs of reddish eyes in trapezoidal arrangement, anterior ones slightly larger than posterior ones ( Fig. 3 A). Median antenna inserted in the middle of prostomium, between posterior pair of eyes, longer than combined length of prostomium and palps, with 20–22 articles; lateral antennae slightly shorter, inserted on anterior margin of prostomium, with 15–17 articles ( Figs 3 A, 4B–C). Triangular palps, longer than prostomium, fused at base, with distinct median groove ( Fig. 4 C). Two ciliary bands on lateral anterior edges of peristomium ( Fig. 4 D). Peristomium slightly shorter than subsequent segments, usually covering posterior part of prostomium ( Figs 3 A, 4B–C). Dorsal tentacular cirri longer than antennae, with 25–27 articles, ventral ones shorter, with 16–18 articles. Dorsal cirri of anterior segments distinctly thick, usually coiled over dorsum, covering prostomium and anterior segments ( Figs 3 A, 4A–C), with 30–35 articles. Midbody and posterior dorsal cirri shorter and thinner than anterior ones, with about 20–24 articles. Digitiform ventral cirri, inserted proximally, reaching distal end of parapodia ( Fig. 4 A). Anterior parapodia with 12–14 heterogomph falciger chaetae each, blades dorsoventrally decreasing in length (44–26 µm); bidentate blades, with similar teeth, short spines on margin; shafts with few distal spines ( Figs 3 B, 4E). Seven to nine heterogomph falciger chaetae on midbody parapodia, similar to those of anterior ones, but with less marked dorsoventral gradation in length of blades (35–27 µm); bidentate blades with distal tooth slightly larger than proximal one, and long spines on margin ( Figs 3 C, 4F). Posterior parapodia with 6–8 heterogomph falciger chaetae, blades strongly bidentate, with short spines on margin; shafts smooth, with an enlarged spur, more marked on ventral chaetae. Dorsoventral gradation in length of blades less evident (28–20 µm) ( Figs 3 D, 4G–H). Dorsal and ventral simple chaetae on posterior parapodia only, bidentate, with short distal spines ( Fig. 3 E–F). Anterior parapodia with about 6 aciculae each, three pointed, two distally blunt and one distally curved at tip ( Fig. 3 G); midbody parapodia with two distally pointed aciculae each, one protruding from parapodial lobes ( Fig. 3 H); posterior segments with one blunt, slightly acuminate acicula per parapodium ( Fig. 3 I). Pharynx similar in length or shorter than proventricle, through 12 segments; conical tooth on anterior margin ( Fig. 3 A). Proventricle extending through 15 segments, with about 39 rows of muscle cells ( Fig. 3 A). Pygidium conical with two anal cirri and a short median stylus.

Reproduction. Scissiparity. Non mature stolon attached to the stock, white pale in colour with three brown lines on each segment not reaching the parapodia, the first one much more marked than the other two, 3.3 mm long, 0.5 mm wide with 28 segments ( Fig. 4 A).

Remarks. The morphology of the specimens agreed with previously published descriptions, except for the spinulation in the midbody chaetae that was not mentioned in Licher’s (1999) redescription. The species is characterized by its large and robust body (up to 17.2 mm long, with 115 chaetigers, following Licher 1999), its remarkable colouration in well-preserved specimens, the thick anterior cirri, and the protruding and thick aciculae in the midbody parapodia. The AM specimens only differ from those collected in New Zealand in their colouration since the latter present black stripes instead of the red-brown ones of the Australian material. Syllis variegata Grube, 1860 is the most similar species morphologically, but it has a narrower body, with fewer aciculae in the anterior parapodia and without the spurs on the shafts of posterior chaetae ( Fig. 3 D). After examining the holotype of S. magnapalpa , we concluded that the synonymy with S. crassicirrata ( Licher 1999) is not valid, since the chaetae of the former are almost unidentate, instead of distinctly bidentate as in the latter. Furthermore, we also conclude that one of the specimens identified as Typosyllis (Typosyllis) krohni by Hartmann-Schroder (1991) from Heron Island, belongs in fact to S. crassicirrata n. comb. and the specimen identified as S. variegata by Aguado et al. (2012) from Galicia ( Spain) belongs to S. compacta Gravier, 1900 .

Habitat. Algae, coarse sediment.

Distribution. Hawaii, Polynesia, New Zealand, Australia (Queensland, New South Wales, Western Australia, Victoria).

Figures

FIGURE 3. Syllis crassicirrata (Treadwell, 1925) n. comb. (AM W 46279). A, anterior end, dorsal view. B, falciger chaetae, anterior parapodium. C, falciger chaetae, midbody. D, falciger chaetae, posterior parapodium. E, dorsal simple chaeta. F, ventral simple chaeta. G, aciculae, anterior parapodium. H, aciculae, midbody parapodium. I, acicula, posterior parapodium. Scale: A, 0.4 mm; B – I, 20 µm.

FIGURE 4. Syllis crassicirrata (Treadwell, 1925) n. comb. (AM W 46276). A, Complete specimen, lateral view. B, prostomium, dorsal view. Scanning Electron micrographs: C, prostomium, dorsal view. D, nuchal organs and detail of peristomium. E, falciger chaetae, anterior parapodium. F, falciger chaetae, midbody parapodium. G, dorsalmost falciger chaetae, posterior parapodium. H, ventralmost falciger chaetae, posterior parapodium.

FIGURE 10. Scanning Electron Micrographs: Syllis gracilis Grube 1840. A, anterior end, dorsal view. B, dorsalmost falciger chaeta, anterior parapodium. C, ventralmost falciger chaetae, anterior parapodium. D, falciger chaetae, midbody parapodium. E, ypsiloid chaetae, mid-posterior parapodium. Syllis picta (Kinberg, 1866) n. comb. F, anterior end, dorsal view. G, falciger chaetae, anterior parapodium; H, ypsiloid and falciger chaetae, midbody parapodium. I, ypsiloid and falciger chaetae, posterior parapodium.