Grubeosyllis longiarticulata, 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 : 1788-1790

Grubeosyllis longiarticulata n. sp.

(®gure 5)

Material examined

Holotype and paratype 1 from Ilha dos Alcatrazes and paratypes 2± 5 from Laje de Santos . Holotype (MHN-BPO 68-0): complete specimen, 1.9 mm long, 0.13 mm wide, with 27 chaetigers. Paratype 1 (MHN-BPO 68-1): complete specimen, 1 mm in length, 0.14 mm wide, with 15 chaetigers; paratype 2 (MHN-BPO 68-2): incomplete specimen, 0.18 mm wide, with 24 chaetigers; paratype 3 (MHN-BPO 68-3): complete specimen, 1.25 mm long, 0.15 mm wide, with 22 chaetigers; paratype 4 (MHN-BPO 68-4): complete specimen, 2 mm long, 0.13 mm wide, with 28 chaetigers; paratype 5 (MHN-BPO 68-5): complete specimen, 2.47 mm long, 0.17 mm wide, with 28 chaetigers.

Description

Body small, slender, without colour markings. Prostomium rectangular to square, somewhat wider than long, partially covered posteriorly by peristomium; four lensed eyes in open trapezoidal arrangement and two anterior eyespots. Antennae with bulbous base and slender tips; lateral antennae originating on lateral margin of prostomium, between anterior eyes and eyespots, shorter than prostomium and palps together; median antenna inserted between posterior pair of eyes and longer than prostomium and palps together. Palps proportionally short and broad, shorter than prostomium, dorsally connected by a membrane, leaving a distal notch (®gure 5A). Peristomium long, similar in length to following segments, with two pairs of tentacular cirri similar in shape and size to the antennae; dorsal pair longer than ventral pair. Dorsal cirri of chaetiger 1 longer than the following; remaining anterior cirri with bulbous bases and slender tips, becoming more slender and longer progressively, from midbody to the posterior segments; dorsal cirri from chaetigers 2 and 3 short (®gure 5A). Ventral cirri digitiform and shorter than parapodial lobes. Parapodia each with six to eight heterogomph compound chaetae with long, bidentate blades, provided with long, thin spines basally, diminishing progressively in size and number towards tips, becoming smooth distally (®gure 5C, G), distal tooth slender, proximal tooth long, slender, slightly shorter than distal tooth; strong gradation dorsoventrally in size of blades; superior falcigers about 33±34 m m, midlength blades, 24±25 m m, and most inferior ones, 16±18 m m. Antero-posterior gradation not strongly marked, but blades of posterior compound chaetae somewhat shorter and wider than anterior (®gure 5C, G). Solitary dorsal simple chaetae from chaetiger 6 on holotype and even more anteriorly in other specimens (from chaetiger 2 on paratype 1), very thin, unidentate and minutely serrated (®gure 5F); solitary ventral simple chaetae on last chaetiger of holotype, somewhat thicker than dorsal, shorter, strongly bidentate, with smooth cutting edges, or provided with very short, straight spines (®gure 5H). Parapodia each with a solitary aciculum provided with a subdistal enlargement and an acuminate tip (®gure 5E), frequently protruding out from parapodia; anterior parapodia each provided with another aciculum, small and nearly straight (®gure 5D). Pygidium small, rectangular to trapezoidal, with one pair of long and slender anal cirri, and one to three papillae (®gure 5B). Pharynx long and narrow, extending through three or four segments, provided with a rhomboidal subterminal tooth. Proventriculum wide, occupying three or four segments, with about 24 rows of muscle cells (®gure 5A).

Etymology

As with the previous species, the name longiarticulata reēcts the size of the blades of compound chaetae.

Discussion

Several species of Grubeosyllis possess bidentate falcigers with marked dorsoventral gradation in size of the blades, but most of them have blades much shorter than those of G. longiarticulata n. sp. Grubeosyllis heterocirra ( Rioja, 1941) , for example, has a general body aspect very similar to this new species, but the spines of the blades of the uppermost falcigers are longer, extending for a proportionally longer extension, and, especially, the blades are much shorter (about 19 m m) (see Westheide, 1974b). Other species, such as G. clavata (ClapareÁde, 1863) , G. limbata (ClapareÁde, 1868) , G. rugulosa Verrill, 1900 and G. vieitezi (San MartõÂn, 1984a) are easily distinguished from G. longiarticulata n. sp. by shape and length of the blades of the compound chaetae and by the length of dorsal cirri on chaetiger 1, compared with the following cirri (see San MartõÂn, 1984a, 1991). On the other hand, G. euritmica ( SardaÂ, 1984) also has long chaetal blades, but it is diOEerent from G. longiarticulata n. sp. in having: (1) dorsal cirri of chaetiger 1 only slightly longer than those of the following segments; (2) parapodia each with about 12 compound chaetae; (3) strong anteroposterior gradation in size of the blades; (4) large and rounded gap between both teeth of the blades; (5) short spines all along cutting edges of the blades; (6) solitary dorsal simple chaetae bidentate; and (7) proventriculum with about 15±20 rows of muscle cells. Grubeosyllis longisetosa (Hartmann-SchroÈder, 1979) has long chaetal blades, similar to those of G. longiarticulata n. sp., but diOEers from it in having: (1) much longer dorsal cirri; (2) shorter spines on cutting edges of the blades of the compound chaetae, with proportionally shorter proximal tooth; and (3) pharynx shorter, with pharyngeal tooth located away from the margin, nearly in the middle of the pharynx (see Hartmann-SchroÈder, 1979). Grubeosyllis neapolitana ( Goodrich, 1930) is diOEerent in having: (1) blades with proximal tooth very small, resembling a spine; (2) acicula distally rounded; (3) solitary ventral simple chaetae unidentate; (4) pharynx with papillae on margin; and (5) pharyngeal tooth located away from margin of the pharynx (see JimeÂnez et al., 1994). Finally, G. nitidula Verrill, 1900 , diOEers because: (1) median antenna originates between anterior pair of eyes; (2) blades of the compound chaetae of anterior chaetigers are only slightly bidentate, with both teeth very close; (3) blades of compound chaetae of posterior chaetigers with short spines; (4) solitary dorsal simple chaetae bidentate; (5) pharynx and proventriculum shorter; and (6) proventriculum with only 16 rows of muscle cells.