Haplosyllis ohma ( Imajima & Hartman, 1964 ) Imajima & Hartman, 1964

Lattig, Patricia & Martin, Daniel, 2009, A taxonomic revision of the genus Haplosyllis Langerhans, 1887 (Polychaeta: Syllidae: Syllinae), Zootaxa 2220, pp. 1-40 : 23-25

Haplosyllis ohma ( Imajima & Hartman, 1964) new comb.

( Figs 15 A–D, 16A–F)

Trypanosyllis (Trypanoseta) ohma Imajima & Hartman, 1964: 129 –130, pl. 31, fig. a–d.

Geminosyllis ohma .— Imajima, 1966: 233 –235, fig 43, a–g.— Kudenov & Harris, 1995: 71, fig. 1.26.

Examined material. Northern Japan, Shirikishinai. Holotype LACM – AHF Poly 0 857, littoral zone. Paratype NSMT 18772, 120 m. coll. M. Imajima, June 1959.

Description. Body subcylindrical, variable in size. Holotype length 25 mm, for 65 segments, width 1.2 mm; paratype robust, length 32 mm, for 82 chaetigers, width 2 mm ( Fig. 15 A, C). Preserved specimens yellow-pale. Prostomium subpentagonal, with two pairs of small red eyes in trapezoidal arrangement. Median antenna (30 articles) inserted on median part of prostomium, between posterior eyes. Lateral antennae (25 articles) inserted on anterior margin of prostomium. Palps long, broadly triangular, fused at their bases, separated all along their length. Cilia on palps and nuchal organs not seen. Pharynx cylindrical, extending about 12 segments; anteriorly with triangular tooth, surrounded by crown of 10 soft papillae; trepan with 10 triangular teeth ( Figs 15 B, D); cilia on papillae not seen. Proventricle cylindrical, extending about 12 segments, obscured by body robustness. Peristomium well defined, shorter than subsequent ones. Dorsal tentacular cirri longer than ventral one, with 30 and 12 articles, respectively. Antennae, tentacular cirri and dorsal cirri similar, slender. Anterior dorsal cirri long, first cirri longer than remaining ones (31–36 articles), second short (16–18 articles), third, fourth and fifth slightly longer (24–29 articles), sixth long (32 articles); subsequent cirri long, with 28–35 articles, gradually decreasing to posterior end. Ventral cirri digitiform, not longer than parapodial lobe. All chaetae bidentate, anterior ones smaller, with short spines on US of MF ( Fig. 16 A–B). Midbody chaetae broad, with MJP straight, long; LMF shorter than SW; apical teeth long, well separated ( Fig. 16 C–E). Four to six chaetae per anterior parapodia, five to eight on midbody chaetigers. Aciculae enlarged, with rounded tip ( Fig. 16 F), three or more per parapodia. Pygidium not seen.

Reproduction. Unknown

Host. Unknown

Distribution. Northern Japan; Russia (Kurile Islands); Southern California, USA (?).

Remarks. The holotype was much shorter than the paratype, but also the depth from which collected (shallow vs. 120 m, respectively) and pharynx morphology (triangular, small teeth vs. terminal soft lobules, respectively) were different ( Fig. 15 B, D). This material (a holotype with chitinized trepan and a paratype with soft lobules) are the types on which the description of Trypanoseta as new genus was based. Thus, either they really belong to different species or this population has exactly the same variability in the pharyngeal anterior end as the Mediterranean Haplosyllis (i.e. H. spongicola and H. granulosa ). Accepting the second as the valid hypothesis may confirm the synonymy between Trypanoseta and Haplosyllis .

The chaetal morphology of the paratype resembles H. cratericola , which also seems to lack pharyngeal trepan (but has twice the number of chaetae and aciculae present per parapodia). Additional material from the type locality needs to be examined in order to clarify the status of these types.

The record of the species in Southern California, USA ( Kudenov & Harris 1995), which consist only of small sexually immature individuals, must be regarded as tentative until additional material is available or the existing material re-examined.

Figures

FIGURE 15. Haplosyllis ohma. Holotype: A—whole body, dorsal view; B—anterior end showing trepan; Paratype: Cmedium body, ventral view; D— anterior end showing trepan. Scale bars: A = 2 mm; B = 0.4 mm; C – D = 1 mm.

FIGURE 16. Haplosyllis ohma. Chaetae from holotype: A—second chaetiger; B—fourth chaetiger; C—midbody chaetiger; D—posterior chaetae. Paratype: E—midbody chaetae; F—midbody aciculae. Scale bar 20 Μm