Sphaerosyllis mussismiliaicola, Nogueira, 2001

Nogueira, J. M. De M., 2001, Description of ® ve new species of Exogoninae Rioja, 1925 (Polychaeta: Syllidae) associated with the stony coral Mussismilia hispida (Verrill, 1868) in SaÄo Paulo State, Brazil, Journal of Natural History 35, pp. 1773-1794 : 1782-1784

Sphaerosyllis mussismiliaicola n. sp.

(®gure 3)

Material examined

Holotype and paratypes 1, 3 and 4 from Ilha dos Alcatrazes , paratype 2 from Laje de Santos . Holotype (MHN-BPO 71-0): complete specimen, 1.3 mm long, 0.17 mm wide, with 18 chaetigers. Paratype 1 (MHN-BPO 71-1): incomplete specimen, with only six anterior chaetigers, 0.18 mm wide; paratype 2 (MHN-BPO 71-2): complete specimen, 1.51 mm long, 0.16 mm wide, with 17 chaetigers; paratype 3 (MHN-BPO 71-3): complete specimen, 1.53 mm long, 0.22 mm wide, with 20

chaetigers; paratype 4 (MHN-BPO 71-4): complete specimen, 0.89 mm long, 0.19 mm wide, with 14 chaetigers.

Description

Body small, short, without colour markings. Prostomium ovate, wider than long; two pairs of large, lensed eyes in very open trapezoidal arrangement, nearly in line, and two anterior eyespots. Antennae with bulbous bases and relatively long, distally rounded tips; lateral antennae inserted on anterior margin of prostomium; median antenna far behind, between posterior pair of eyes. Palps short, wider than long, with some papillae, fused, except for a terminal notch. Peristomium covering posterior part of prostomium; tentacular cirri similar in shape to antennae, but shorter (®gure 3A, B). Dorsal cirri similar to antennae on anterior part of the body, becoming progressively longer, more elongated and the bases less bulbous, towards the posterior part of the body; on chaetiger 2, the dorsal cirrus is replaced by a large papilla (®gure 3A). Parapodia conical, papillated (®gure 3D), with seven to eight heterogomph compound falcigers, with shafts provided with short spines distally (®gure 3F, H); blades with dorsoventral gradation in size, cutting edges with moderate spinulation basally, spines become gradually shorter towards tip and disappear. Blades bidentate, proximal tooth minute, with a long and slender spine, almost reaching level of the distal tooth. On anterior parapodia, blades of falcigers about 26.5 m m in length, intermediate, 21.5 m m, and lower, 17 m m (®gure 3F); on midbody, blades of upper chaetae about 28 m m, intermediate, 24 m m, and lower, 17.5 m m long; on posterior body, upper chaetae 22.5 m m, intermediate, 20 m m, and lower, 17.5 m m (®gure 3H). Solitary dorsal simple chaetae, present from chaetiger 1 in holotype, slightly thinner than shafts of falcigers, with small spines and a longer subdistal spine, appearing bidentate (®gure 3E); solitary ventral simple chaetae only on last six parapodia in holotype, much shorter, thinner and more curved, almost lacking spinulation, but also with a subdistal spine (®gure 3I). Solitary acicula per parapodium, with subdistal curved enlargement and small acuminate tip directed upwards (®gure 3G). Pygidium small, conical, provided with several papillae and with a pair of anal cirri similar in shape to posterior dorsal cirri, but slightly longer and with a solitary papilla (®gure 3C). Pharynx short and slender, not surpassing chaetiger 1, except in holotype and paratype 4, in which it reaches chaetiger 2; large tooth on anterior margin of pharynx; proventriculum larger, extending through 2±3.5 chaetigers and with 14 muscle cell rows.

Etymology

The speci®c name was chosen because the specimens were associated with the coral Mussismilia hispida .

Discussion

Sphaerosyllis mussismiliaicola n. sp. is characterized by long dorsal cirri and compound chaetae with long blades, minutely bidentate, with a long spine arising from the tip of the proximal tooth. Some species show similar characters and therefore the diOEerences shall be pointed out here. Sphaerosyllis nathani San MartõÂn and LoÂpez, 1998 also has long dorsal cirri, but its cirri are even longer, and, besides that, it diOEers from S. mussismiliaicola n. sp. because: (1) the two pairs of lensed eyes are disposed in a rectangular arrangement, very close to each other; (2) antennae are very short and all inserted on the anterior margin of the prostomium; (3) palps are fused to the prostomium; (4) the pharynx is longer (four segments, against one or two in S. mussismiliaicola n. sp.), with the pharyngeal tooth placed near the midline of the pharynx; (5) the proventriculum has about 25 rows of muscle cells (against 14 in S. mussismiliaicola n. sp.); (6) tentacular cirri are minute; (7) papillae are regularly disposed on the dorsal surface of the body: one papilla on each lateral, between consecutive dorsal cirri, and three irregularly placed; (8) dorsal cirri are present on all chaetigers, even on the second; (9) there are four compound chaetae per parapodium, with much shorter blades (16 m m, against 26.5± 17.5 m m in S. mussismiliaicola n. sp.), without any gradation in length, unidentate, slender and with shorter spines (see San MartõÂn and LoÂpez, 1998). Sphaerosyllis bilineata Kudenov and Harris, 1995 also has a very papillate body, but the papillae, from midbody, are clearly disposed in two longitudinal rows, alternating long and short; moreover, this species is distinguished from S. mussismiliaicola because it has: (1) palps longer than wide; (2) median antenna longer; (3) pharynx much longer (four chaetigers) and pharyngeal tooth distant from the margin; (4) proventriculum with 20±23 rows of muscle cells; (5) blades of the compound chaetae very diOEerent, unidentate, cutting edges with short spinulation; (6) solitary simple chaetae dorsal and ventral unidentate (see Kudenov and Harris, 1995). Another very papillated species is S. parvoculata Russell, 1989 , easily separated from S. mussismiliaicola n. sp. because of: (1) its whitish body, especially anteriorly, due to epidermal granules; (2) two pairs of eyes disposed in a large trapezium, with the posterior pair situated on peristomium or on chaetiger 1; (3) median antenna placed on the anterior margin of the peristomium; (4) pharyngeal tooth not placed on the anterior half of the pharynx and, due to the whitish appearance of the body, it is not possible to be precise whether it is situated more posteriorly or if there is no pharyngeal tooth at all; (5) blades of compound chaetae are clearly bidentate, with secondary tooth at least as long as the main one and even thicker (see Russell, 1989). Sphaerosyllis bilobata Perkins, 1980 diOEers from S. mussismiliaicola n. sp. in having: (1) six lensed eyes; (2) two nuchal folds at the margin of the peristomium, covering the eyes; (3) the pharynx with soft lobes on its anterior margin and thick, brown glands; (4) dorsal cirri shorter; and (5) the blades of compound chaetae shorter (20± 10 m m) and clearly bidentate, with teeth well separated (see Perkins, 1980). Sphaerosyllis erinaceus ClapareÁde, 1863 , as described by Imajima (1966), diOEers from S. mussismiliaicola n. sp. because: (1) lateral antennae are not inserted on the margin of the prostomium, but between the anterior pair of eyes and the eyespots; (2) proventriculum extending through four chaetigers; (3) blades of compound chaetae unidentate, without subdistal spine; (4) solitary simple dorsal and ventral chaetae unidentate; (5) acicula straight and with blunt tip (see Imajima, 1966). Finally, the species closest to S. mussismiliaicola n. sp. is probably S. belizensis Russell, 1989 , from which it is separated by having: (1) three pairs of lensed eyes; (2) nuchal lobes originating from the anterior margin of the peristomium and covering the posterior pairs of eyes; (3) much shorter dorsal cirri; (4) blades of compound chaetae unidentate, with a long subdistal spine in some parapodia; (5) in all parapodia, only the superior falcigers with spinulation on the cutting edges of the blades; (6) smooth solitary dorsal and ventral chaetae (see Russell, 1989). Hartmann-Schr oÈder described several subspecies of S. erinaceus , for instance, S. erinaceus bidentata (see Hartmann- SchroÈder, 1974, 1992b) and S. erinaceus serrisetosa (see Hartmann-SchroÈder, 1982), the morphologies of which are similar to S. mussismiliaicola n. sp. but they diOEer from this last one in details of the blades of the compound chaetae.