Leodice antarctica (Baird 1869)

Eunice antarctica Baird, 1869

Eunice antarctica Baird, 1869:348.

Eunice pennata.—Hartman 1964:118 [in part, not Eunice pennata Müller, 1776].

MATERIAL EXAMINED.—Three syntypes, BM(NH) ZB 1972.70, Antarctic Seas, Erebus and Terror Southern Seas Expedition.

COMMENTS ON MATERIAL EXAMINED.—The type material consists of three syntypes and two posterior fragments. Two of the three syntypes are incomplete. The third syntype is complete and is described in detail below.

DESCRIPTION.—Syntype complete, of unknown sex, with 122 setigers; total length 102 mm; maximal width 3.5 mm; length through setiger 10, 11 mm.

Prostomium (Figure 10a) distinctly shorter than peristomium, about as wide as peristomium, less than as deep as peristomium. Prostomial lobes frontally rounded, dorsally inflated; median sulcus shallow. Eyes not observed. Antennae in a shallow horseshoe, evenly spaced, similar in thickness. Ceratophores ring-shaped, without articulations. Ceratostyles digitiform, with up to 10 irregular, distinct or very indistinct cylindrical articulations in A-III. A-I to end of peristomium; A-II to setiger 1 (setiger 3 in another syntype); A-III to setiger 3 (setiger 4 in another syntype). Peristomium cylindrical. Separation between rings distinct dorsally and ventrally; anterior ring of total peristomial length. Peristomial cirri to posterior end of prostomium, slender and digitiform, without articulations.

Jaws not examined.

Branchiae (Figure 10b) present, pectinate, distinctly shorter than notopodial cirri, not reduced in mid-body region, erect. Branchiae from setiger 3 to setiger 39–44. Branchiae terminating well before posterior end, present on less than 55% of total number of setigers. First 6–7 and last 2 branchiae with single filaments. Maximum 5 filaments at about setiger 15. Stems slender, cylindrical, shorter than filaments. Filaments shorter than notopodial cirri, tapering.

Median acicular lobes distally truncate with aciculae emerging at midline. Pre- and postsetal lobes follow outline of acicular lobes closely. First 3 ventral cirri digitiform, about half as long as notopodial cirri, becoming basally inflated from first branchial setigers. Inflated bases nearly spherical in most of branchial region, retaining digitiform, distally truncate tips. Inflated bases gradually lost in postbranchial region; last 30–40 ventral cirri slender, digitiform, increasing in length posteriorly, remaining less than half as long as notopodial cirri in all segments. Anterior notopodial cirri slender, medially inflated, usually with 1–2 articulations. Median and posterior notopodial cirri (Figure 10g) increasingly slender, digitiform in postbranchial region; articulations increasingly poorly marked; finally represented only by steps in width of cirri.

Limbate setae rather slender, marginally serrated. Shafts of pectinate setae (Figure 10d) wide, cylindrical. Blades tapering, flat. One marginal tooth much longer than other teeth, with ˜10 rather coarse teeth. Shafts of compound falcigers (Figure 10c) barely inflated; marginally smooth; distal beaks distinct. Appendages thick, bidentate, with very short teeth. Proximal teeth much smaller than distal teeth, triangular, directed laterally. Distal teeth gently curved, directed laterally. Guards symmetrically bluntly pointed, marginally serrated, without mucros. Pseudocompound falcigers and compound spinigers absent. Aciculae usually paired, yellow, slender, tapering, gently curved ventrally (Figure 10c); cross-section round. Subacicular hooks (Figure 10f) yellow, bidentate. Hooks first present from setiger 31–44, present in all setigers thereafter, always single (except for replacements). Hooks slender, tapering smoothly, with very large heads. Proximal teeth larger than distal teeth; both teeth directed distally.

UNKNOWN MORPHOLOGICAL FEATURES.—Jaw structure; pygidium and anal cirri.

EXPECTED STATES OF SELECTED UNKNOWN FEATURES.—Mx III long, but forming distal arc with left Mx IV.

CHARACTERS USED IN PREPARATION OF KEY NOT SCORED.—Inappropriate Characters: 56, 58, 59. Unknown Characters: 4, 6, 13, 14.

ASSUMED STATES FOR PURPOSE OF PREPARING KEY.—None.