Haplosyllis spongiphila (Verrill, 1885)

(Figs 19A –F, 20A–E)

Syllis spongiphila Verrill, 1885: 435 –436.— Horst, 1922:196.— Hartman, 1944: 435, pl. 24, fig. 10.— Pettibone, 1963: 114, fig. 31 a–h.

? Syllis spongiphila .— Imajima, 1966: 250 –251, fig. 49 a–k.

Haplosyllis spongiphila .— Licher, 1999: 283, fig. 10D.

Examined material: NW Atlantic, U.S.A.>100 cotypes USNM 9864. Massachussets, Martha’s Vineyard, 127–580 m, 4 September 1880.

Description. Body robust, length 1–2 cm for 60–80 chaetigers, about 0.8 mm width (excluding parapodia) (Fig. 20 A). Frequently, posterior segments in poor condition. Preserved specimens yellow-pale. Prostomium subpentagonal, wider than long, with two pairs of small red eyes in trapezoidal arrangement. Median antennae inserted on medium of prostomium, with 43–55 articles; lateral antennae inserted on anterior margin, with 21– 31 articles. Palps long, broadly triangular, fused at their bases, divergent all along their length. Sensory organs on palps and nuchal organs not seen. Pharynx orange, very long, extending 14–21 segments; with large anterior tooth surrounded by crown of about 10 papillae; ring of cilia not seen. Proventricle cylindrical, dark-brown, shorter than pharynx, extending 7–13 segments, with 56–69 muscular cell-rows. Peristomium shorter than subsequent ones. Dorsal tentacular cirri very long, with 28–45 articles, ventral cirri smaller. Dorsal cirri similar to antennae and tentacular cirri, very long, slender, whip-shaped. First cirri long (41–50 articles), second and third slightly shorter (24–30 and 38-48 articles respectively); fourth very long (50-72 articles), fifth short (27– 35 articles), sixth long (48–59 articles). Subsequent cirri exceed body width, slightly alternate with long (46–61 articles) and short (18–42 articles), but difficult to observe. Posterior cirri usually broken. Anterior ventral cirri digitiform, broad, longer than parapodial lobes (Fig. 19A), midbody ventral cirri, slender, slightly longer than parapodial lobe (Fig. 19 B). Chaetae all bidentate, anterior ones, with blade partially fused to shaft (Figs 19 C–D, 20B–C). Midbody chaetae completely simple, with narrow mark of fusion between blade and shaft (Figs 19 E, 20D–E); LMF shorter than SW, but progressively longer from anterior to posterior chaetae; numerous short spines on US of MF; a long denticle on posterior chaetae; MJP long, relatively straight; apical tooth equal in length, well separated. Four to six chaetae on anterior parapodia; two or three at midbody. Aciculae straight and broad, two or three per parapodia (Fig. 19 F). Pygidium broken.

Reproduction. Unknown

Host. It has been reported as common and often abundant among sponges and hydroids (Hartman 1944), but without references to the specificity of the association.

Distribution. NW Atlantic, Massachusetts. Caribbean Sea.

Remarks. Haplos y llis spongiphila was first considered as a Syllis, but the original chaetal description was inaccurate. The chaetae were reported as having blades partially fused to shafts, resembling H. anthogorgicola (Pettibone 1963), as compound and pseudocompound (Imajima 1966) and more recently, as simple, and therefore must belong to Haplosyllis (Licher 1999) . Our observations confirm that midbody chaetae are simple, but the anterior ones are similar to pseudocompound chaetae, showing clear traces of the fusion of blade and shaft. However, this has been previously reported for other Haplosyllis species (e.g. H. anthogorgicola and H. loboi). Thus, we agree with Licher (1999) in that the species must be considered as belonging to Haplosyllis .

Haplosyllis spongiphila is currently considered a cosmopolitan species occurring in the Caribbean (Perkins & Savage 1975; Verrill 1885), NW Atlantic (Hartman 1944; Pettibone 1963) and Japanese (Imajima 1966) waters. However, the specimens from Japan were reported as having well defined compound chaetae, suggesting that the Indo-Pacific populations could be a different species, not belonging to Haplosyllis .