Eunice unifrons (Verrill 1900)

Eunice unifrons (Verrill, 1900)

Leodice unifrons Verrill. 1900:644.—Treadwell. 1921:17–20, figs. 21–30, pl. 1: figs. 5–9.

Eunice vittata.—Hartman, 1942:9 [in part, not Nereis vittata Chiaje, 1929].

MATERIAL EXAMINED.—Holotype, YPM 1241, Bermuda, 1898, A.E. Verrill and company coll.; YPM 1321, Platts Village, Bermuda, beach to 10 feet, A.E. Verrill and company, 1898, 4 specimens.

COMMENTS ON MATERIAL EXAMINED.—The holotype material now consists of an anterior fragment of 31 anterior setigers and a median fragment of about 60 setigers; the specimen has been completely dried out at one time (Treadwell, 1921:20 reported the type dry); the only information gained from the specimen concerns the structure of the subacicular hooks and other setae and some details of branchial distribution.

The four specimens from YPM 1321 were part of the original material, but were not designated as types; they are in better shape than the holotype even if they are rather soft and have lost most of the antennae.

DESCRIPTION.—All specimens from YPM 1321 incomplete with up to 90 setigers; specimen described and illustrated with 75 setigers; length 28 mm; maximal width 1 mm at setiger 10; length through setiger 10, 5 mm.

Prostomium (Figure 113a) distinctly shorter and narrower than peristomium, as deep as of the peristomium. Prostomial lobes frontally rounded, dorsally inflated; median sulcus distinct ventrally and at frontal edge, but not dorsally. Eyes not seen. Antennae in a horseshoe, with A-I isolated by a gap, similar in thickness. Ceratophores ring-shaped in all antennae, without articulations. Ceratostyles digitiform, with cylindrical articulations; innermost articulation (other than ceratophoral ring) ∼ of total antennal length; maximum 4 articulations in A-II and A-III. A-I to posterior peristomial ring; A-II and A-III to setiger 2. Peristomium cylindrical. Separation between rings distinct on all sides; anterior ring less than of total peristomial length. Peristomial fold covering base of prostomium is unfolded on all 4 specimens. Peristomial cirri to middle of anterior peristomial ring, slender, digitiform, with 5 articulations.

Maxillary formula of 1 specimen 1+1, 8+8, 5+0, 8+10, and 1+1. Mx VI missing. Mx III behind left Mx II, but relatively short.

Branchiae (Figure 113d) present, pectinate, distinctly longer than notopodial cirri, not reduced in mid-body region, erect. Branchiae from setiger 3 through setigers 45–54 (of more than 70 setigers, no specimens complete). First 4 and last 10 pairs single filaments; maximum 5 filaments at about setiger 15–30. Branchial stems slender. Filaments slender.

Anterior neuropodial acicular lobes rounded with a distinct, short nipple-like projection near middle of lobe and posterior to emergence of aciculae. Median and posterior neuropodial acicular lobes conical; aciculae emerging at midline. Pre- and postsetal lobes low, transverse folds. First 5 ventral cirri conical. Ventral cirri basally distinctly inflated from about setiger 6. Inflated bases ovate; narrow tips digitiform. Posterior ventral cirri increasingly tapering with inflated portion less noticeable. Anterior notopodial cirri basally inflated, becoming slender and digitiform in branchial region. All notopodial cirri with 2 or 3 cylindrical articulations.

Limbate setae slender, finely serrated. Pectinate setae (Figure 113 c,f,i) tapering, flat. One marginal tooth very much longer and heavier than all other teeth; 7–10 teeth present. Shafts of compound falcigers (Figure 113 b,g) slightly inflated and marginally serrated. Anterior and median appendages long and narrow with nearly parallel sides, bidentate. Teeth very similar in size, both sharply pointed. Proximal teeth directed laterally. Distal teeth distinctly bent. Posterior appendages (Figure 113j) very much shorter with slender teeth; proximal teeth shorter than distal teeth. Guards distally asymmetrically bluntly pointed and marginally serrated; mucros absent. Pseudocompound falcigers and compound spinigers absent. Aciculae single; clear yellow, distally tapering, straight; cross-sections round. Separation between cores and sheaths indistinct in both aciculae and subacicular hooks. Subacicular hooks (Figure 113 e,h) yellow, tridentate in a crest. Hooks first present from setiger 25 in holotype and from setigers 26–31 in other specimens, present in all setigers thereafter, always single (except for replacements). Hooks with large curved main fangs and very small tertiary fangs; 2 distal fangs forming group separated from main fang.

UNKNOWN MORPHOLOGICAL FEATURES.—Pygidium and anal cirri.

EXPECTED STATES OF UNKNOWN MORPHOLOGICAL FEATURES.—None.

CHARACTERS USED IN PREPARATION OF KEY NOT SCORED.—Inappropriate Characters: 56, 58, 59. Unknown Characters: 1, 2, 13, 14, 38, 63.

ASSUMED STATES FOR PURPOSE OF PREPARING KEY.—38,2.