Syllis cruzi Núñez & San Martín, 1991

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 : 309-312

Syllis cruzi Núñez & San Martín, 1991

Figures 5 , 6

Syllis cruzi Núñez & San Martín, 1991 : 238, Fig. 2 . San Martín 2003: 397, Figs 217, 218. Typosyllis cruzi .— Licher 1999: 169, Fig. 75.

Material examined. Type specimens. SPAIN. Tenerife. Agua Dulce, 28º11'22"N, 16º25'34"W Corticium camdelabrum sponge, 5 m depth, 1991, Holotype ( TFMC AN 0180); Candelaria, 28º21'20"N, 16º22'18"W Dendrophyllia ramea, 115 m depth, 1991, 1 paratype ( TFMC AN 0187); Barranco Hondo, 28º23'54"N, 16º21'27"W Dendrophyllia ramea, 113 m depth, 1991, 1 paratype ( TFMC AN 0188).

Non-type specimens. SPAIN. COLUMBRETES ISLANDS. North of Columbrete Grande, 29º54’02"N, 00º41’15"E, 47 m depth, coll. Fauna Ibérica III (1994), 12 Jul 1994, 1 specimen ( MNCN 16.01/6744). BALEARES ISLANDS. Mallorca Island, Punta de La Foradada, 39º45'80"N, 02º33'51"E, 74 m, 1 specimen ( MNCN 16.01/6745). AUSTRALIA. QUEENSLAND. Lizard Island, MacGillivray Reef, 14°38'52"S, 145°29'12"E, coral rubble and coarse sand, 14 m depth, 31 Aug 2010, CReefs Lizard Island Expedition 2010, 1 specimen mounted for SEM (AM W41692.001). WESTERN AUSTRALIA. Woodside Kimberley Survey, 2009: Adele Island, Montgomery Reef, 15°33'28"S, 123°08'02"E, 12.5 m depth, 18 Oct 2009, 1 specimen (AM W41665). Woodside Kimberley Survey 2010: Cassini Island, lower mid-littoral reef platform, 13°57'06"S, 125°37'27"E, 3 m depth, 18 Oct 2010, 1 specimen (AM W42527). Goss Passage, Beacon Island, 28°25'S, 113°47'E, dead plates of Acropora sp. covered with algae, 8 m depth, 22 May 1994, 1 specimen (AM W46280). PHILIPPINES. PALAWAN ISLAND. “Twin Rocks”, El Nido, 11º17'50"N, 119º19'06"E, coral rubble, 3–17 m depth, 17 Dec 2010, 1 specimen ( MCZ 25423).

Morphologically similar species. Syllis yallingupensis ( Hartmann-Schröder, 1982) , Australia, Northern Territory, Darwin Harbour, Bangalow, 12°27'18"S, 130°46’00”E, intertidal sand, 9 Jul 1993, 3 specimens (AM W29546).

Description. Longest complete specimen 9.5 mm long, 0.8 mm wide, with 53 segments. Smaller specimens slender ( Fig. 5 A), larger specimens robust ( Fig. 6 A). Usually lacking colouration, but one specimen with a thin, brown-reddish dorsal line on some anterior body segments. Oval prostomium with two pairs of red eyes in trapezoidal arrangement, and sometimes a pair of anterior eyespots ( Figs 5 A, 6A–B). Median antenna inserted in the middle of prostomium, between posterior eyes, longer than combined length of prostomium and palps, with 18– 20 articles, fewer articles in small specimens ( Figs 5 A, 6A–B); lateral antennae inserted in front of anterior eyes, with 14–15 articles ( Figs 5 A, 6A–B). Triangular palps, slightly longer than prostomium ( Fig. 5 A). Nuchal organs as two cilliary bands between prostomium and peristomium ( Figs 5 A, 6C). Peristomium slightly shorter than subsequent segments ( Figs 5 A, 6B). Dorsal tentacular cirri with 16–17 articles, ventral ones shorter, with 10–12 articles ( Figs 5 A, 6A–C). Dorsal cirri long ( Fig. 6 A–B), with 25–27 articles (shorter in juvenile specimens, Fig. 5 A), alternating long and short cirri in midbody and posterior segments. Anterior parapodia each with 8–9 heterogomph falciger chaetae ( Figs 5 B, 6D); bidentate blades, both teeth similar, or proximal tooth slightly larger than distal one, short spines on margin; one or two distal spines longer, reaching proximal tooth ( Figs 5 B, 6D); shafts with few and short distal spines ( Figs 5 B, 6D). Midbody and posterior parapodia each with 5–7 heterogomph falciger chaetae, with shorter blades than those in anterior chaetigers, proximal tooth slightly larger than distal one ( Figs 5 C, 6E–F); one or two distal marginal spines longer than remaining, reaching proximal tooth; shafts of ventral chaetae slightly wider that of dorsal ones, with few distal spines on margin ( Fig. 6 F). Dorsoventral gradation in length of blades throughout, more obvious on anterior parapodia (28 µm long dorsally, 13 µm ventrally) than on midbody and posterior ones (20 µm long dorsally, 17 µm ventrally). Dorsal simple chaetae on posterior parapodia only, unidentate in large specimens (bifid to bidentate in small specimens, Fig. 5 D). Ventral simple chaetae on posteriormost parapodia only, thick, smooth on margin, strongly bidentate, with proximal tooth similar or slightly larger than distal tooth ( Fig. 5 E). Anterior parapodia with 3 aciculae each (2 in juveniles, Fig. 5 F), two straight and one distally knobbed, decreasing in number to only one acuminate, distally pointed acicula on posterior parapodia ( Fig. 5 G). Pharynx and proventricle similar in length; pharynx extending through 12 segments (8 in juveniles); pharyngeal tooth located on anterior margin ( Fig. 5 A). Proventricle through 10 segments (3–4 segments in juveniles), with about 57 rows of muscle cells ( Fig. 5 A). Pygidium small, with two long anal cirri and small stylus.

Remarks. The morphology of the juvenile specimens examined agreed with the types from the Canary Islands and the Western Mediterranean Sea (which were also small specimens), except for the lack of the bidentate dorsal simple chaetae. However, the larger specimens illustrated by San Martín (2003, Fig. 218) presented a unidentate dorsal simple chaeta as in larger Australian specimens. No previous descriptions mention any colour pattern, but in one Australian specimen we have seen very light, brown-reddish thin stripes on anterior segments. The absence of colouration may be due to an inadequate preservation method, since some authors also pointed out the colouration in living specimens (Aguado et al. 2008). Aguado et al. (2008) described the species as Syllis cf. cruzi since it also presented some glands on lateral and posterior segments that were not present in the Mediterranean or Australian specimens. However, Aguado et al. (2008) only found one specimen of Syllis cf. cruzi , and a larger number of specimens should be compared in order to confirm that they are the same species. The material collected in the Philippines only differs from the Australian one in the dorsoventral gradation in length of the blades, which is similar in all parapodia. Once again, we could be facing another case of cryptic speciation, which might be solved using a molecular approach. The most morphologically similar species to S. cruzi is Syllis yallingupensis , especially in regard to the shape of the falciger chaetae, but the latter presents long pseudospiniger chaetae, that are absent in S. cruzi .

Habitat. Sponges, deep-corals communities, coral rubble and coarse sand; from shallow waters to about 115 m.

Distribution. Canary Islands, Mediterranean Sea, Philippines, Indonesia, Australia (Queensland, Western Australia).

Figures

FIGURE 2. Syllis broomensis (Hartmann-Schröder, 1979) n. comb. Scanning Electron Micrographs (AM W 42547). A, anterior end, dorsal view. B, prostomium, dorsal view. C, compound chaetae, anterior parapodium; D, falciger chaetae, anterior parapodium. E, compound chaetae, mid-posterior parapodium. F, falciger chaetae, mid-posterior parapodium. G, compound chaetae, posterior parapodium.

FIGURE 5. Syllis cruzi Núñez & San Martín, 1991 (AM W 46280). A, anterior end, dorsal view (juvenile specimen). B, falciger chaetae, anterior parapodium. C, falciger chaetae, posterior parapodium. D, dorsal simple chaeta. E, ventral simple chaeta. F, aciculae, anterior parapodium. G, acicula, posterior parapodium. Scale: A, 0.1 mm; B – G, 20 µm.

FIGURE 6. Syllis cruzi Núñez & San Martín, 1991 (AM W 41692). A, anterior end, dorsal view. B, prostomium, dorsal view. Scanning Electron micrographs: C, prostomium, dorsal view. D, falciger chaetae, anterior parapodium. E, falciger chaeta, midbody parapodium. F, falciger chaetae, posterior parapodium.