Adyte hyalina ( G. O . Sars, 1873 ) G.O. Sars, 1873

Bock, Gordon, Fiege, Dieter & Barnich, Ruth, 2010, Revision of Hermadion Kinberg, 1856, with a redescription of Hermadion magalhaensi Kinberg, 1856, Adyte hyalina (G. O. Sars, 1873) n. comb. and Neopolynoe acanellae (Verrill, 1881) n. comb. (Polychaeta: Polynoidae), Zootaxa 2554, pp. 45-61 : 54

Adyte hyalina ( G. O. Sars, 1873) n. comb.

Figure 2 A–G

Hermadion ? hyalinus G. O. Sars, 1873: 96.

Hermadion assimile McIntosh, 1874: 194 ; McIntosh (1876): 387, pl. 70 figs. 4–6 [new synonymy]. Adyte assimilis: Pettibone (1969) : 5, figs. 2, 3. Barnich and Fiege (2003): 27, fig. 8A–J.

Type material examined. Hermadion ? hyalinus Sars, 1873: ZMUO C2028, holotype (af), Norway, Storeggen, 80–100 fathoms.

Comparative material examined. SMF 10428/1, 1 spm. (af), "Urania" LM 99, St. 164, 11 January 2000, Elba, 42°43.45'N, 10°06.96’E, 72–85 m, epibenthic dredge, leg. H. Zibrowius, det. R. Barnich [in Barnich and Fiege (2003) as Adyte assimilis ].

Description (based on holotype of Hermadion ? hyalinus). Anterior fragment with 17 segments. At anterior end ( Fig. 2 A) prostomium bilobed, without cephalic peaks; ceratophore of median antenna in anterior notch, style missing; lateral antennae inserted ventrally to median antenna, styles smooth, tapering abruptly subdistally; 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 of dorsal ones missing. Second or buccal segment with first pair of elytra, biramous parapodia and long tapering ventral or buccal cirri. Following segments with shorter ventral cirri.

Only nine pairs of delicate elytra present in holotype (specimen incomplete), on segments 2, 4, 5, 7, 9, 11, 13, 15, 17; posterior half of elytra and posterior margin with few scattered papillae; ( Fig. 2 B,C). Cirrigerous segments with distinct dorsal tubercles, dorsal cirri with cylindrical cirrophore, styles missing.

Parapodia biramous; notopodia with elongate acicular lobe, notoaciculum penetrating epidermis; neuropodia with truncate, rounded acicular lobe, without supra-acicular process, neuroaciculum not penetrating epidermis ( Fig. 2 D). Notochaetae stouter than neurochaetae, with few, scattered rows of spines and blunt, slightly notched tip ( Fig. 2 E); neurochaetae more numerous, with semi-lunar pocket subdistally, numerous faint rows of spines only distally, and unidentate or minutely bidentate tip (with secondary tooth often abraded) ( Fig. 2 F, G).

Measurements. Holotype of Hermadion ? hyalinus: af, L 6 mm, W 3 mm for 17 segments.

Remarks. We examined the holotype of Hermadion ? hyalinus G. O. Sars, 1873, an anterior fragment of 17 segments, which according to an accompanying label has been checked by Pettibone in 1971 (and is therefore not included in her revision of 1969) and referred by her to Adyte hyalina ( G. O. Sars, 1873) . We agree with Pettibone's unpublished opinion, since the holotype shows the main characters of the genus, except for the number of segments. Moreover, the comparison with the descriptions and figures of Adyte assimilis ( McIntosh, 1874) in Pettibone (1969) and Barnich and Fiege (2003) showed that both species are identical, with the same type of elytra covered by scattered papillae, neuropodia with a very typical truncate, rounded acicular lobe, and neurochaetae with a semi-lunar pocket and minutely bidentate or unidentate tips. A. assimilis ( McIntosh, 1874) becomes a junior synonym of A. hyalina ( G. O. Sars, 1873) n. comb., which is redescribed here.

Distribution and habitat. Northeastern Atlantic, North Sea, Mediterranean Sea; in 9 to 293 m; facultative commensal of echinoids.

Figures

FIGURE 2. Adyte hyalina n. comb. (holotype ZMUO C 2028). (A) Anterior end; styles of median antenna, dorsal tentacular cirri and dorsal cirri missing; (B) right elytron from unknown segment in anterior body region; (C) detail of posterior margin of same; (D) right elytragerous parapodium from segment 9, posterior view; (E) distal half of long notochaeta; (F) distal part of middle neurochaeta; (G) tip of upper neurochaeta. (Scales: A = 1 mm; B = 250 µm; C, E, F, G = 50 µm; D = 500 µm).