Metavermilia

Nishi, Eijiroh, Kupriyanova, Elena & Tachikawa, Hiroyuki, 2007, Metavermilia ogasawaraensis sp. nov. (Serpulidae: Sabellida: Polychaeta: Annelida) from deep-sea locations off Ogasawara Island, Japan with a literature overview of the genus, Zootaxa 1447, pp. 47-56 : 49

Key to Metavermilia species

1. Operculum simple conical or globular......................................................................................................... 6

- Operculum complex, distal part composed of several tiers or disks ........................................................... 2

2. Operculum composed of 4–10 parallel tiers or disks fringed by simple or bifurcated spines..................... 3

- Operculum composed of several smooth radially striated tiers or disks with entire margins ..................... 4

3. Distal horny part of the operculum terminates with flat disk; tube with 5–9 longitudinal keels................... .......................................................................................................................................... M. nates ( Fig. 4 F)

- Distal horny part of the operculum terminates with a single distal spine or hook; tube with one or three irregular longitudinal ridges ........................................................................... M. acanthophora ( Fig. 4 H, I)

4. Spines of opercular disks bifurcated with round tips, the most distal star-shaped, consists of several spines (Fig. 3M); tube with 2 thick keels perforated by a row of pits and few peristome-like transverse annuli.... .................................................................................................................................................... M. truncata

- Spines of opercular disks simple or bifurcated with sharp pointed tips ( Fig. 4 J, L); tube with 5–6 keels.. 5

5. Thoracic membranes to chaetiger 5; tube dotted with rectangular pits between about 4 longitudinal ridges, with an occasional transverse annulus .......................................................................................... M. spicata

- Thoracic membranes to chaetiger 6; tube without flaring peristomes..................................... M. yamazotoi

6. Operculum simple globular membranous, no horny distal plate ( Fig. 4 N, O); tube with 5 – 7 longitudinal ridges ............................................................................................................................................... M. inflata

- Operculum globular or conical, with chitinous flat or concave distal plate or convex distal cap............... 7

7. Operculum conical, covered with chitinous flat or concave distal plate ..................................................... 8

- Operculum globular, covered with convex distal cap................................................................................ 11

8. Operculum conical with (nearly) flat chitinous distal plate......................................................................... 9

- Operculum conical with concave distal plate ............................................................................................ 10

9. Distal horn part of the operculum terminates with flat disk; tube surface without keels, with multiple flar- ing peristomes ....................................................................................................... M. ogasawaraensis n. sp.

- Distal plate of the operculum without central conical tubercle; tube surface with honey-comb sculpture made of numerous longitudinal keels and transverse ridges ......................................................... M. arctica

10. Operculum conical, covered with thick concave distal plate that carries an ovoid process with 2 hooks ( Fig. 4 P, Q); thoracic membranes to thoracic chaetiger 5; tube with 5 irregular longitudinal keels and somewhat flaring mouth .................................................................................................................. M.ovata

- Operculum conical, covered with concave distal plate, no ovoid processes with two hooks, thoracic mem- branes to thoracic chaetigers 3–4; tube with 4 – 6 irregular longitudinal ridges .......................................... ........................................................................................................................ M. annobonensis ( Fig. 4 D, E)

11. Thoracic membranes to the end of thorax ................................................................................................. 12

- Thoracic membranes to chaetigers 4–6 ..................................................................................................... 13

12. Thoracic membranes fuse ventrally to form an apron; tube with 5–7 longitudinal keels and some trans- verse annuli ........................................................................................................................... M.multicristata

- Thoracic membranes do not fuse ventrally, no apron; tube smooth, very thick walled ............... M. taenia

13. Thoracic membranes to chaetiger 4; tube surface with 3 longitudinal keels and without transverse annuli. .............................................................................................................................................. M. nanshaensis

- Thoracic membranes to chaetigers 5–6; tube with 2 keels and some transverse annuli ........... M. gravitesta

Figures

FIGURE 4. Operculum of Metavermilia species. A— multicristata. B, C— taenia. D, E— annobonensis. F— nates. G— arctica. H, I— acanthophora. J— yamazatoi. K— gravitesta. L— spicata. M— truncata. N, O— inflata. P, Qovata. R, S— ogasawaraensis n. sp. T, U, V— nanshaensis. Figures are drawn from the figures of paper, traced using black ink on the transparent sheet. A to F after Zibrowius (1971), G from Kupriyanova (1993), H to Q after Imajima (1996), R and S are original, T—V after Sun (1998).