Pherusa moorei, Salazar-Vallejo, 2014

Salazar-Vallejo, Sergio I., 2014, Revision of Pherusa Oken, 1807 (Polychaeta: Flabelligeridae), Zootaxa 3886 (1), pp. 1-61 : 25-27

Pherusa moorei n. sp.

Figure 8

Stylarioides borealis .— Moore, 1903:487 (non Hansen, 1880).

Type material. Japan. Holotype ( USNM 5391 ), RV Albatross, Sta. 3775, off Kinkwasan Lighthouse ( Kinkasan Island , 38º17' N, 141º34' E), off Honshu Island, Northern Japan, 104 m, J.P. Moore, id.

Additional material. Philippine Islands. One specimen ( CAS 186932 ), without posterior region, Hearst Philippine Expedition 2011, M.V. DA-BFAR, Sta. P 28 (13.70° N, 120.68° E), 454–457 m, mud with coralline sand, 29 May 2011, Mooi et al., coll. (almost all tunic removed, many chaetae broken, many papillae eroded; 57 mm long, 5 mm wide, cephalic cage (broken) 13 mm long, 39 chaetigers; gonopodial lobes well developed, present on chaetigers 5 and 6) .

Description. Holotype (USNM 5391) without posterior end; some parapodia previously dissected, many chaetae broken, papillae of some areas completely eroded; body cylindrical, anteriorly thinner, muscular; remaining two-thirds of body wider, flaccid ( Fig. 8A ); 46 mm long, 5 mm wide, cephalic cage 19 mm long, 38 chaetigers. Body papillae in two markedly different sizes: anterior chaetigers with a single row of transverse, acute, long papillae; remaining body with small, abundant, round, slightly depressed papillae, about 25–30 transverse rows per segment.

Cephalic hood not exposed; not dissected to avoid further damage. Cephalic cage chaetae 4x longer than body width. Chaetigers 1–2 forming cephalic cage but second chaetiger with chaetae? as long as those present in chaetiger 1. Chaetiger 3 with chaetae half as long as those present in chaetiger 2. Chaetiger 1 with 18 noto- and 12 neurochaetae, arranged in a sinusoid series; chaetiger 2 with 10 noto- and 14 neurochaetae, arranged in a curved series. Chaetiger 3 with chaetae 1.5 x longer than those present in following chaetigers.

Anterior dorsal margin of first chaetiger with 2–3 long papillae, partially covered by first notopodia. Anterior chaetigers (2–4) with a series of transverse, long papillae along their anterior margin ( Fig. 8B ). Chaetigers 1–3 of similar size. Chaetal transition from cephalic cage to body chaetae abrupt; long, falcate, tapered anchylosed neurohooks from chaetiger 4. Gonopodial lobes reduced to flat rounded areas, barely visible on chaetigers 5 and 6 ( Fig. 8C ).

Parapodia poorly developed, slightly larger along the anterior region, chaetae emerge from low lobes. Parapodia lateral; medial neuropodia ventrolateral. Notopodia and neuropodia with 4–6 digitate, large interramal papillae.

Medial notochaetae arranged in transverse or oblique series; all multiarticulated capillaries, articles short basally, medium-sized medially and subdistally, long articles distally ( Fig. 8D ), 9-10 per fascicle, as long as?–2/5 body width. Neurochaetae long, multiarticulated capillaries in chaetigers 1–3; anchylosed, slightly curved, long, brownish neurohooks from chaetiger 4, arranged in transverse series, mostly 7–8 per fascicle ( Fig. 8E ), 6–7 thinner, delicate neurohooks in posterior chaetigers.

Posterior end unknown.

Remarks. Pherusa moorei n. sp. belongs in the group of species without sediment cover on their body papillae, and because their neurohooks start by chaetiger 4, it resembles P. hobsonae n. sp., P. mikacae n. sp., P. papillata ( Johnson, 1901) , and P. rullieri n. sp. However, P. moorei n. sp. is most similar to P. rullieri n. sp. and P. sibogae ( Caullery, 1944) n. comb., because they both have medial and posterior neurohooks slightly curved, aristate. The two main differences between these three species are the relative size of the cephalic cage, and the number of transverse series of papillae; in P. moorei n. sp. the cephalic cage is 4 x longer than body width, and there are 25–30 transverse series of papillae per segment, whereas in P. rullieri and P. sibogae the cephalic cage is shorter (twice as long as body width), and there are fewer series of papillae.

The Philippine Islands specimen ( CAS 186932 ) resembles this species, but there are some differences which may be due to collecting and preservation methods. For example, the tunic has been lost almost completely, and the larger body papillae, which are arranged in transverse series in anterior chaetigers in the holotype, are fewer in number. Further, because the additional specimen was preserved in 95% ethanol, some of the chaetal and body pigments might have been lost, such that chaetae are golden instead of being brownish. Better specimens would help clarify if they belong to the same species .

Etymology. The species name is derived after the late Dr. John Percy Moore, in recognition of his many publications on polychaetes, and especially because he noticed this specimen in his publication on the polychaetes dredged in Japan by the RV Albatross. The epithet is a noun in the genitive case.

Type locality. Off Kinkasan Island lighthouse, Honshu Island, Japan, in depths of 104 m.

Distribution. Only known from the type locality in Northern Japan (104 m depth), probably extends southwards to the Philippine Islands in deeper waters (454–457 m).

Figures

FIGURE 8. Pherusa moorei n. sp., holotype (USNM 5391). A. Dorsal view. B. Anterior end, dorsal view. C. Anterior end, ventral view. D. Chaetiger 12, notochaetae (insets: basal, medial and distal regions). E. Chaetiger 9, neurochaetae (inset: tips of two chaetae). F. Chaetiger 33, neurochaetae (insets: tips of chaetae). Scale bars: A: 2.2 mm, B: 1.7 mm, C: 1.5 mm, D: 0.4 mm, E: 260 µm, F: 200 µm.