Syllis armillaris (O. F. Müller, 1771)

Martín, Guillermo San, Lucas, Yolanda & Hutchings, Pat, 2023, The genus Syllis Savigny in Lamarck, 1881 (Annelida: Syllidae: Syllinae) from Australia (Part 3): new species and redescription of previously described species, Zootaxa 5230 (3), pp. 251-295 : 252-255

Syllis armillaris (O. F. Müller, 1771)

Figure 1

Nereis armillaris O. F. M̧ller, 1771: 150, pl. 9, Figs 1–5 .

Syllis armillaris .— Johnston 1840: 145, pl. 9, Figs 1–2 .—San Martín 2003: 423, Figs 232, 233.— Musco & Giangrande 2005: 472, fig. 4.

Typosyllis (Syllis) armillaris .— Langerhans 1879: 535.

Syllis (Typosyllis) armillaris .— Fauvel 1923: 264, Figs 99 a–f.— Day 1967: 249, Figs 12.4 a–d .

Typosyllis armillaris .— Marenzeller 1890: 3.—Campoy 1982: 436, pls. 55.57.— Hutchings & Murray 1984: 34.— Licher 1999: 189, fig. 84.

Typosyllis (Typosyllis) armillaris . — Hartmann-Schröder 1984: 13; 1985: 65; 1986: 37; 1987: 32; 1989: 19.

Material examined. AUSTRALIA, NEW SOUTH WALES: 50 m west of Split Solitary Island , 30° 14’ S, 153° 10’ 48” E, coll. 7 March 1992, hand collected on SCUBA, Herdmania momus , rocks, sponges and ascidians , 16 m,

AM W.53827, 2 specimens . NSW 697, 100 m north west of Split Solitary Island , 30° 14’ S, 153° 10’ 48” E, coll. 7 March 1992, hand collected on SCUBA, under rock ledges, 15 m , AM W.29500, 1 specimen . NSW 457 , North West Solitary Island, Manta Reef , 30° 01’ 30” S, 153° 16’ 30” E, coll. 25 June 1992, hand collected on SCUBA, associated with lace bryozoan, 19 m , AM W.53831, 5 specimens . NSW 443, 100 m south of Split Solitary Island , 30° 15’S, 153°10’30” E, coll. 23 June 1992, hand collected on SCUBA, 16.6 m, AM W.53829, 2 specimens . NSW 3427 , north east of Kurnell , “Anchor Reef”, 34° 00’ 33” S, 151° 13’ 51” E, coll. 16 March 2009, hand collected on SCUBA, coarse-medium shelly sediment with echinoid spines, 17.6 m, AM W.35409, 1 specimen . NSW 1278, 150 m east of Burrill Rocks , 35° 23’ 25” S, 150° 28’ 11” E, coll. 1 May 1997, by airlift on SCUBA, surface of sponge, 18 m, depth , AM W.53828, 1 specimen . NSW 1288, 150 m east of Burrill Rocks , 35° 23’ 25” S, 150° 28’ 11” E, coll. 1 May 1997, hand collected on SCUBA, AM W.53830, 3 specimens . SOUTH AUSTRALIA: SA 112 , Boston Bay, Port Lincoln , 34° 51’ S, 135° 51’ E, coll. 12 Feb 1985, coll. I. Loch, washing from sheltered weedy rock, 2 m, id. A. Murray , AM W.26345, 2 specimens . Billy Lights Point, Port Lincoln , 34º 45’S, 135º 53’E, coll. 15 Feb 1985, coll. I, Loch, stone washings from sheltered intertidal rocks, det. A. Murray , AM W.26346, 3 specimens . SA 115 , Pondalowie and Marion Bays, York Peninsula , 34º 14’S, 136º 50’E, coll. 12 Feb 1985 by I. Loch, Caulerpa and green algae washings, 3 m , AM W.53833, 1 specimen . WESTERN AUSTRALIA: WA 511 , Houtman Abrolhos Islands, Beacon Island, Goss Passage , 28° 25’ 30” S, 113° 47’ E, coll. 18 May 1994, hand collected on SCUBA, dead branching coral covered in coralline algae, 10 m, AM W.53836, 1 specimen . Houtman Abrolhos Islands, West side of Rat Island , 28° 44’ S, 113° 47’ E, coll. 21 June 2008, by M . T. Aguado & G. San Martín, dead coral, 2 m, coll ., AM W.53832, 3 specimens . WA 539 , off south end of Long Island, Beacon Island , 28° 28’ 48” S, 113° 46’ 18” E, coll. 25 May 1994, hand collected on SCUBA, 4 m , AM W.53834, 1 specimen . North end of Long Island, Goss Passage , 28° 27’ 54” S, 113° 46’ 18” E, coll. 22 May 1994, hand collected on SCUBA, 5 m , AM W.53835, 3 specimens .

Diagnosis. Body elongate, antennae, tentacular and dorsal cirri short, with few articles. Midbody dorsal cirri thick, fusiform. Midbody compound chaetae falcigers with short, triangular, unidentate or almost unidentate blades; anterior compound chaetae with moderately elongated, bidentate blades. Posterior aciculae acuminate.

Description. Longest examined specimen 11 mm long, 0.45 mm wide, for 107 chaetigers. Body long and slender, elongated. Prostomium pentagonal; four eyes in trapezoidal arrangement. Palps robust, similar in length to prostomium. Median antenna inserted on posterior part of prostomium, between posterior eyes, with 14–16 articles, similar in length to combined length of prostomium and palps; lateral antennae shorter than median one, with 10 articles each, shorter than median antenna. Peristomium similar in length to subsequent segments ( Fig. 1A ). Dorsal tentacular cirri slightly longer than median antenna, with about 13–17 articles each; ventral tentacular cirri about half length of dorsal ones. Dorsal cirri short all along body, shorter than body width, slightly longer and slender on anterior segments, and shorter and thicker, more or less fusiform, from midbody onwards ( Fig. 1A, B ), with well defined cirrophores and articles; articles basally and distally smaller than medially; anteriormost dorsal cirri with about 17–13–15–17 articles in the first four segments ( Fig. 1A ); from midbody onwards, all cirri becoming shorter and markedly thicker, with about 9–10 articles ( Fig. 1B ). Parapodia conical. Ventral cirri digitiform, longer than parapodial lobes on anterior parapodia, becoming shorter from midbody onwards. Chaetae mostly broken but some parapodia with complete fascicles all along the body. All compound chaetae heterogomph falcigers. Anterior parapodia each with about 10–12 chaetae, blades elongated, bidentate, both teeth similar, and short spines on margin ( Fig. 1C ), blades about 38 μm long above, 27 μm long below; midbody parapodia with 4–5 compound chaetae ( Fig. 1D ), with thick shafts and short unidentate to weakly bidentate blades, with short spines on margin, apparently smooth under low magnifications, 20–15 μm long; posterior parapodia with 3–4 compound chaetae ( Fig. 1E ), similar to those of anterior parapodia but shorter. Dorsal and ventral simple chaetae on far posterior segments of some specimens; dorsal simple chaetae slightly bidentate, with minute spines on margin ( Fig. 1I ); ventral simple chaetae smooth, slightly bidentate ( Fig. 1J ). Anterior parapodia with 3–4 slender aciculae ( Fig. 1F ), two at midbody ( Fig. 1G ), and single in posteriormost parapodia, acuminate ( Fig. 1H ). Pharynx long, extending through about 9–10 segments; pharyngeal tooth on anterior margin of pharynx ( Fig. 1A ). Proventricle similar in length to pharynx, through about 10 segments, with 32–35 muscle cell rows. Pygidium triangular, with two articulated anal cirri and one stylus.

Remarks. This species is easily recognized by having short dorsal cirri, thickened in midbody, and having midbody compound chaetae with short falcigers, not fused to shafts. It is similar to other species such as Syllis picta (Kinberg, 1865) , Syllis gracilis Grube, 1840 , and some other species which have a similar body and chaetae, but these species have some or all midbody chaetae with blades totally or partially fused to shafts. Probably, the most similar species is Syllis pseudoarmillaris Nogueira & San Martín, 2002 , from Brazil; however, S. pseudoarmillaris has the midbody compound chaetae distinctly bidentate, and the posterior aciculae are more markedly acuminate, subdistally more inflated than S. armillaris ( Nogueira & San Martín, 2002) . Syllis mayeri Musco & Giangrande, 2005 , from Belize, is also very similar, especially with regards to the chaetae, but differs in having distinctly longer antennae, tentacular and anterior dorsal cirri, longer pharynx and a shorter proventricle ( Musco & Giangrande, 2005); furthermore, S. mayeri is a symbiotic species in sponges.

Syllis monilaris Savigny in Lamarck, 1818, the type species of the genus is also similar; however, S. monilaris is a larger species, the dorsal cirri are not thickened in midbody, and all the chaetae are unidentate or very slightly bidentate (see Álvarez-Campos et al. 2015a, b; San Martín et al. 2017). It is also similar to S. hyalina (see below).

Habitat. Common on all kind of hard substrates. From intertidal to more than 100 m depth.

Distribution. Apparently cosmopolitan, reported from all oceans and seas, from polar to tropical. A detailed molecular study of the different populations is necessary to confirm this widespread distribution or whether it represents a suite of cryptic species.

Figures

FIGURE 1. Syllis armillaris (O. F. M̧ller, 1776). AM W.53831. A, anterior end, dorsal view. B, long and short dorsal cirri, midbody. C, falcigers, anterior parapodium. D, falcigers, midbody parapodium. E, falcigers, posterior parapodium. F, aciculae, anterior parapodium. G, aciculae, midbody. H, acicula, posterior parapodium. I, dorsal simple chaeta. J, ventral simple chaeta. Scale. A: 0.2 mm. B: 0.1 mm. C–J: 20 µm.

FIGURE 2. Syllis augeneri Haswell, 1920. AM W.32040. A, anterior end, dorsal view. B, long-bladed compound chaeta, anterior parapodium. C, falcigers, anterior parapodium. D, long-bladed compound chaeta, midbody. E, falcigers, midbody. F, long-bladed compound chaeta, posterior parapodium. G, falcigers, anterior parapodium. H, dorsal simple chaeta. I, ventral simple chaeta. J, aciculae, anterior parapodium. K, aciculae, midbody parapodium. L, acicula, posterior parapodium. Scale. A: 0.2 mm. B–I: 20 µm.

FIGURE 3. Syllis beneliahuae (Campoy & Alquézar, 1982). AM W.29542. A, anterior end, dorsal view. B, long and short dorsal cirri, midbody. C, pseudospiniger, most anterior parapodia. D, falcigers, most anterior parapodia. E, pseudospiniger, midbody. F, falcigers, midbody. G, pseudospiniger, mid-posterior parapodia. H, falcigers, mid-posterior parapodia. I, aciculae, anterior parapodia. J, aciculae, midbody. K, acicula, posterior parapodium. Scale. A, B: 0.2 mm. C–K: 20 µm.

FIGURE 4. Syllis busseltonensis (Hartmann-Schröder, 1982), n. comb.AM W.53906.A, anterior end, dorsal view. B, falcigers, anterior parapodium. C, falcigers, midbody parapodium. D, falcigers, posterior parapodium. E, aciculae, anterior parapodium. F, aciculae, midbody parapodium. G, acicula, posterior parapodium. H, dorsal simple chaeta. I, ventral simple chaeta. Scale. A: 0.2 mm. B–I: 20 µm.

FIGURE 5. Syllis hyalina Grube, 1863. AM W.53905. A, anterior end, dorsal view. B, falcigers, anterior parapodium. C, falcigers, midbody parapodium.D, falcigers, posterior parapodium.E, dorsal simple chaeta. F, ventral simple chaeta. G, aciculae, anterior parapodium. H, aciculae, midbody parapodium. I, acicula, posterior parapodium. Scale. A: 0.2 mm. B–I: 20 µm.

FIGURE 12. Syllis patriciae (Hartmann-Schröder, 1981 n. comb. AM W.29487. A, anterior end, dorsal view. B, long and short dorsal cirri, midbody. C, compound chaetae, anterior parapodium. D, compound chaetae, midbody parapodium. E, compound chaetae, posterior parapodium. F, dorsal simple chaeta. G, ventral simple chaeta. H, aciculae, anterior parapodium. I, aciculae, midbody parapodium. J, K, acicula, two views, posterior parapodium. Scale. A, B: 0.2 mm. C–K: 20 µm.