Eunice interrupta Treadwell 1906

Eunice interrupta Treadwell, 1906

Eunice interrupta Treadwell, 1906:1167–1168, figs. 45, 46.

MATERIAL EXAMINED.—Holotype, USNM 5211, and 5 paralectotypes, USNM 5417, Albatross sta 3850, 79–84 m, coarse sand and broken shells; 1 paralectotype, USNM 5418 and 1 paralectotype, CAS TY74 (IZ No. 018795), Albatross sta 3940, Hawaii, Leeward lands, Laysan Island Light S84°, E7.0′, 16 May 1902, 108–128 m, white sand and broken shells.

COMMENTS ON MATERIAL EXAMINED.—Both paratypes from station 3940 have been dried out and are not considered further. The description is based on the holotype, but comments about variable features are included.

DESCRIPTION.—Holotype incomplete, of unknown sex, with 65 setigers; length 55 mm; maximal width 2 mm; length through setiger 10, 9 mm. Paratypes from sta 3850 2 complete specimens with 79 and 69 setigers, respectively; other paratypes incomplete.

Prostomium (Figure 58a) distinctly shorter and narrower than peristomium, as deep as of peristomium. Prostomial lobes frontally rounded, dorsally flattened; median sulcus deep. Eyes at base of A-I, dark. Antennae in horseshoe, evenly spaced, similar in thickness. Ceratophores long in all antennae, without articulations. Ceratostyles tapering, with up to 27 moniliform articulations in A-II and A-III, articulated to bases of styles. A-I to middle of anterior peristomial ring; A-II and A-III to setiger 2. A-III incomplete in holotype, complete in several paratypes. Peristomium cylindrical, long; anterior margin flared in holotype, but not in paratypes; muscular lower lip distinct. Separation between rings distinct only ventrally; anterior ring of total peristomial length. Peristomial cirri to middle of anterior peristomial ring, slender and tapering, with 5 to 7 articulations.

Maxillary formula of paratype from USNM 5417 1+1, 4+5, 6+0, 4+7, and 1+1. Jaws completely decalcified, soft and fragile.

Branchiae present, palmate, distinctly shorter than notopodial cirri, reduced in mid-body region in some specimens. Branchiae from setiger 5–7 either to setiger 24–26 or continued to near the posterior end. Present on more than 65% of total number of setigers in some specimens. Maximum 3 filaments at or near setiger 15. Most specimens with branchiae to setigers 24–26; holotype and one of 2 complete paratypes with single branchial filaments also present in posterior end starting at setiger 50 (Figure 58b) or 55, continuing to posterior end. Other complete paratype with branchiae only near anterior end. Filaments digitiform.

Anterior neuropodial acicular lobes distally truncate; median acicular lobes rounded; posterior acicular lobes triangular; aciculae emerging at midline. Pre- and postsetal lobes low, transverse folds. First 6 ventral cirri thick, tapering. Ventral cirri basally inflated from about setiger 7. Inflated bases ovate; narrow tips tapering. Ventral cirri increasingly slender and digitiform from about setiger 35. Notopodial cirri slender, with up to 5 distinct articulations; articulations present in all setigers.

Shafts of compound falcigers (Figure 47d) inflated, marginally smooth. Appendages thick, relatively short, with large heads, bidentate. Proximal teeth smaller than distal teeth, tapering, directed laterally. Distal teeth thick, bent, with small notch sometimes appearing as rudimentary third teeth. Guards nearly symmetrically sharply pointed; mucros absent. Pseudocompound falcigers and compound spinigers absent. Aciculae (Figure 48c) paired, yellow, tapering, gently curved; cross-sections round. Separation between core and sheath indistinct in both aciculae and subacicular hooks. Subacicular hooks (Figure 57e) yellow, tridentate with teeth in a crest. Hooks first present from setiger 24–27, present in all setigers thereafter, always single (except for replacements). Hooks with 3 very large fangs decreasing evenly from main to distal fangs.

UNKNOWN MORPHOLOGICAL FEATURES.—Relationship between between Mx III and left Mx IV; pygidium and anal cirri.

EXPECTED STATES OF SELECTED UNKNOWN FEATURES.—Mx III long and located behind left Mx II.

CHARACTERS USED IN PREPARATION OF KEY NOT SCORED.—Inappropriate Characters: 34, 56, 58, 59. Unknown Characters: 1, 2, 4, 6, 39, 40, 42, 47, 50, 63.

ASSUMED STATES FOR PURPOSE OF PREPARING KEY.—None.