Parapolyeunoa flynni ( Benham, 1921 ) Benham, 1921

Barnich, Ruth, Gambi, Maria Cristina & Fiege, Dieter, 2012, Revision of the genus Polyeunoa McIntosh, 1885 (Polychaeta, Polynoidae), Zootaxa 3523, pp. 25-38 : 31-34

Parapolyeunoa flynni ( Benham, 1921) n. comb.

Fig. 3 A–J

Hololepidella flynni Benham, 1921: 33 , pl. 5 figs. 14–20.

Polyeunoa flynni: Pettibone (1969) : 48.

Polyeunoa laevis: Monro (1936) : 102 [part]; Knox (1960): 85 [see also remark in Knox & Cameron (1998), p.34]; Averincev (1972): 134, pl. 14 figs. 1–3 [part].

Polyeunoa rhombigera: Hartman (1967) : 39 [part, not Enipo rhombigera Ehlers, 1908 ].

Polyeunoa monroi Averincev, 1978: 65 .

Type material. Syntypes of Hololepidella flynni Benham, 1921 (off Maria Island, Tasmania, in 1300 fathoms) deposited at the Otago Museum ( New Zealand) and holotype of Polyeunoa monroi Averincev, 1978 (SE of New Zealand in 1100–1200 m) deposited at the Zoological Institute of the Russian Academy of Sciences in St. Petersburg (ZISt.P 1/43282), not available for study.

Additional material. South Georgia: 2 spms (af), SMF 16478, RV “Eltanin“, St. 684, 54 °55’S 38°4.6’W, 595–677 m, 25 August 1963, from galls on Errina aspera sensu Boschma & Lowe, 1969 .

Bellingshausen Sea: 2 spms. (cs), Exp. BENTART 2006, St. MB 26, 70.2420° S, 95.0330° W, 20 January 2006, Agassiz trawl, 1958 m, together with? Thouarella sp. (gorgonarian coral), coll. M.C. Gambi. 2 spms. (2 af, 1 mf), SMF 21634 ( Fig. 3 A–J), Exp. BENTART 2006, St. MB 26, 70.2420° S, 95.0330° W, 20 January 2006, Agassiz trawl, 1958 m, coll. M.C. Gambi.

Ross Sea: 1 spm., SMF 16479, RV “Atka“, St. 23, near Cape Hallett, 72°5.8’S 172°15.2’E, 1958, from gall on stylaroid coral Errina inferiolabiata /labiata.

Diagnosis. Prostomium with distinct cephalic peaks. Antennae and cirri not very long. Tip of neuropodial acicular lobe extended to short, digitiform supra-acicular process. Neurochaetae all bidentate. Ventral cirri short, not reaching to tip of neuropodia.

Description (based on additional specimen (SMF 21634) in rather good condition, except for loss of appendages, and Benham (1921) for description of appendages).

Prostomium bilobed, with distinct cephalic peaks ( Fig. 3 A); ceratophore of median antenna in anterior notch, style smooth, tapering, longer than palps; lateral antennae inserted ventrally to median antenna, styles smooth, tapering, half the length of median antenna; anterior pair of eyes situated dorsolaterally at widest part of prostomium, posterior pair dorsally near hind margin of prostomium; palps tapering.

First or tentacular segment with a pair of tentaculophores inserted laterally to prostomium, without notochaetae, but with a dorsal and a ventral tentacular cirrus, styles smooth, tapering ( Fig. 3 A). Second or buccal segment with first pair of elytra, biramous parapodia and long tapering ventral or buccal cirri. Following segments with ventral cirri short, not reaching to tip of neuropodium ( Fig. 3 D).

Elytra more than 15 pairs, on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, 32, and 35, distributed irregularly after segment 35; elytra smooth, more or less covering dorsum, at least in anterior segments ( Fig. 3 B). Cirrigerous segments with distinct dorsal tubercles; dorsal cirri with cylindrical cirrophore, styles smooth, tapering ( Fig. 3 C).

Parapodia biramous; notopodia and neuropodia with prominent acicular lobe, tip of neuropodial acicular lobe extended to short, digitiform supra-acicular process; tips of noto- and neuroacicula penetrating epidermis ( Fig. 3 D). Notochaetae few, about as stout as neurochaetae, with faint rows of spines and blunt tip ( Fig. 3 E,F); neurochaetae more numerous, with distinct rows of spines distally and bidentate tip, secondary tooth stout, distinctly set off ( Fig. 3 G–J).

Measurements. Specimen figured herein (in two fragments, with few posterior segments missing): L 27 mm, W 5 mm for 46 segments ( Fig. 3 , SMF 21634). Largest syntype according to Benham (1921): L 40 mm, W 5.5 mm for 63 segments.

Species / character Polyeunoa laevis McIntosh , Parapolyeunoa flynni Neopolynoe antarctica (Kinberg,

1885 ( Benham, 1921) n. comb. 1858) n. comb.

Cephalic peaks Poorly developed or absent Distinct Distinct

Position of anterior pair At widest part of prostomium At widest part of prostomium Slightly in front of widest part of

of eyes prostomium

Number of elytra 15 pairs or more More than 15 pairs 15 pairs

Distribution. In the SW Pacific (off Tasmania and New Zealand) and around Antarctica (Ross Sea, Bellingshausen Sea and off South Georgia) in 500–2300 m depth. Often associated with hydrocorals ( Errina sp.) and octocorals ( Primnoidae ,? Thouarella sp.)

Remarks. Unfortunately, the type material of Hololepidella flynni Benham, 1921 and Polyeunoa monroi Averincev, 1978 was not available for study. The original descriptions and figures of both species, however, are sufficiently detailed and agree well with the specimens present in our material. Averincev reports some conical microtubercles on the elytra which could not be confirmed by our material and were also not described by Benham. For differences between Polyeunoa laevis and Parapolyeunoa flynni n. comb., see remarks related to P. laevis above and Table 2.

Figures

FIGURE 3. Parapolyeunoa flynni (Benham, 1921) (SMF 21634). (A) anterior end; styles of antennae and cirri missing; (B) right anterior elytron from unknown segment; (C) dorsal cirrus, free in vial; (D) right, elytrigerous parapodium from segment 13, posterior view, chaetae omitted; (E) long notochaeta; (F) tip of same; (G) distal part of middle neurochaeta; (H) tip of same; (I) tip of upper neurochaeta; (J) tip of lower neurochaeta. (Scales: A – C = 2 mm; D = 1 mm; E, G = 250 µm; F, H – J = 100 µm).