Prionospio (Minuspio) multibranchiata Berkeley, 1927

Dagli, Ertan & Çinar, Melih Ertan, 2011, Species of the subgenus Minuspio (Polychaeta: Spionidae: Prionospio) from the southern coast of Turkey (Levantine Sea, eastern Mediterranean), with the description of two new species, Zootaxa 3043, pp. 35-53 : 46-47

Prionospio (Minuspio) multibranchiata Berkeley, 1927

( Figs 9–10 )

Prionospio multibranchiata Berkeley 1927: 414 , plate 1, fig. 1

Prionospio (Minuspio) multibranchiata ; Maciolek 1985: 365 –367, fig.15.

Material examined. Royal BC Museum's collection, 2 specimens, 5 April 2002, Bazan Bay ( Canada) 48º37ʹ41.78ʹ N–123º24ʹ16.90ʹ W, 10 m, silty, sandy mud, coll. Randall Glaholt.

Description. Largest specimen incomplete, 0.48 mm wide, 14.7 mm long, with 70 chaetigers. Body slender, enlarged anteriorly, gradually tapering to posterior end, color in alcohol opaque, pale yellow. Prostomium subrectangular, anteriorly rounded, tapered posteriorly, with a blunt caruncle ending at posterior edge of chaetiger 1, posterior portion of prostomium surrounding by nuchal organ. Anterior part of prostomium with five very small peaks ( Fig. 9 A). Two pairs of large eyes; anterior pair cup-shaped or spherical, posterior pair larger than anterior ones, crescent–shaped ( Fig. 9 A–B). Peristomium partly fused with chaetiger 1, forming moderate lateral wings.

Branchiae apinnate, present from chaetiger 2 to 11, numbering 10 pairs (8 pairs in other specimen); first pair (ca. 268 µm long) shorter than subsequent ones; next six pairs longest and largest (ca. 323 µm long); pairs 8 and 9 decreasing in size (ca. 270 µm long); last pair shortest and narrowest (ca. 155 µm long) ( Fig. 9 A–B). All branchiae 1.2 or 2 times longer than length of notopodial lamellae. Branchiae without cilia ( Fig. 10 A).

Notopodial lamellae lacking on chaetiger 1. Notopodial lamellae of chaetiger 2 short, subtriangular; becoming large, leaf–shaped between chaetigers 3 and 9; subtriangular between chaetigers 10 and 11; rounded or elliptical in middle of body; inconspicuous in posterior region ( Figs 9 A–B; 10A–C). Notopodial lamellae united across dorsum, forming very low crests from chaetiger 13 to 20 ( Figs 9 A, 10B).

Neuropodial lamellae small, rounded on chaetiger 1; ear shaped on chaetiger 2, dorsally pointed; largest in branchial region; gradually decreasing in size on following chaetigers ( Figs 9 A–B; 10A–C). Genital pouches absent.

Anterior noto– and neuropodial lobes with only capillary chaetae, arranged in two rows in anterior chaetigers, with thin sheath; all capillaries moderately granulated ( Fig. 10 F). Ventral sabre chaetae from chaetigers 11 to end of body; numbering one or three per fascicle; short, stout, slightly granulated, without a distal filament ( Fig. 10 D). Neuropodial hooded hooks first emerging from chaetiger 13–14; numbering up to 6–8 per fascicle; three pairs of small teeth above main fang ( Fig. 10 E). Notopodial multidentate hooded hooks first present on chaetiger 44; numbering up to 4–5 per fascicle. Hooks accompained by capillaries throughout.

Pygidium missing on all specimens.

Remarks. The morphological features of the specimens of Prionospio (Minuspio) multibranchiata collected near the type locality (Pacific coast of Canada) and examined in the present study agree with the original ( Berkeley 1927) and subsequent ( Maciolek 1985) descriptions of the species. However, the specimens collected in the eastern Atlantic and identified as P. (M.) multibranchiata by Mackie (1984) differs from the Canadian species. The Mackie’s specimens had small spherical eyes (large, cup or crescent-shaped in the Canadian specimens), no peaks on the anterior margin of the prostomium (five peaks in the Canadian specimens), the first branchiae occupying almost five segments (occupying almost one segment in the Canadian specimens), a caruncle extending to the middle of chaetiger 2 (extending to the posterior part of chaetiger 1 in the Canadian specimens) and subtriangular notopodial lamellae with rounded tips on chaetiger 2 (triangular with pointed tip in the Canadian specimens). Because of the characters indicated above, the Mackie’s specimens do not belong to P. (M.) multibranchiata but appear to belong to an undescribed species.

Prionospio (Minuspio) multibranchiata was previously reported elsewhere in the world oceans [i.e., from Japan ( Imajima 1990) to the Mediterranean ( Mackie 1984)]. The present study showed that P. (M.) multibranchiata probably does not occur in the Mediterranean Sea. Therefore, the reports of this species far from the type locality might belong to different species. The Canadian specimens that we examined in the present study did not match the description by Imajima (1990): for example, the Canadian specimens have hooks with three pairs of small teeth above main fang, whereas the Japanese specimens have hooks with four pairs of small teeth above main fang. The other important difference is the first appearance of the notopodial hooks (on chaetiger 44 in the Canadian specimens vs. on chaetigers 28–30 in the Japanese specimens).

Distribution. It seems that P. (M.) multibranchiata is a complex of species and reports from different localities should be re–examined. Its actual distribution seems to be restricted to the Pacific coasts of Canada and USA, and the Atlantic coasts of USA and Mexico.

Figures

FIGURE 9. Prionospio (Minuspio) multibranchiata Berkeley, 1927: A. Anterior end, dorsal view. B. Anterior end, lateral view. Scale bar: A – B 0.5 mm.

FIGURE 10. Prionospio (Minuspio) multibranchiata Berkeley, 1927: A. Parapodium of chaetiger 6 with branchia (fifth branchial segment), anterior view. B. Parapodium of chaetiger 13, anterior view. C. Parapodium of chaetiger 44, anterior view. D. Ventral sabre chaeta on chaetiger 18. E. Neuropodial hooded hook on chaetiger 15. F. Notopodial capillary chaeta on chaetiger 18. Scale bar: A 0.1 mm, B – C 0.09 mm, D 19 µm, E 16.5 µm, F 20 µm.