Eunice arenosa Kinberg 1865

Eunice arenosa Kinberg, 1865

Eunice arenosa Kinberg, 1865:563.—Hartman, 1948:78.

MATERIAL EXAMINED.—Two syntypes, RM 426, Tahiti, 16 m, Eugenie expedition.

COMMENTS ON MATERIAL EXAMINED.—Kinberg (1865:563) gives the locality information as “Mare pacificum juxta urbem Papieti insulae Tahiti, fundo arenosa 9 orgyiarum.” One syntype is complete; the other is currently in two pieces. The latter specimen is here illustrated and described in detail. Both specimens are mature females with large eggs in the body cavity.

DESCRIPTION.—Complete syntype with 79 setigers; other syntype incomplete, with 60 setigers, 16 mm long, maximal width 0.75 mm at setiger 10; length through setiger 10, 2.5 mm. Body cylindrical anteriorly, dorsoventrally flattened posteriorly.

Prostomium (Figure 13e) about as long as peristomium, about as wide as peristomium, as deep as of the peristomium. Prostomial lobes elongated, frontally rounded, dorsally flattened; median sulcus shallow. Palpal region separated by distinct frontal, horizontal grooves. Eyes not observed. Antennae in a horseshoe, evenly spaced, similar in thickness. Ceratophores ring-shaped in all antennae, without articulations. Ceratostyles slender and digitiform, with up to 8 long, cylindrical articulations in A-III. A-I to setiger 1; A-II to setiger 3; A-III to setiger 5. Peristomium tapering towards anterior end. Separation between rings distinct on all sides; anterior ring of total peristomial length. Peristomial cirri to middle of prostomium, slender and tapering, with 4 articulations.

Jaws unknown.

Branchiae present, pectinate, distinctly longer than notopodial cirri, not reduced in mid-body region, erect. Branchiae from setiger 3 through setiger 25–26. Branchiae terminating well before posterior end, present on less than 55% of total number of setigers. First 5 and last 2–3 pairs single filaments; maximum 5 filaments first reached at about setiger 15. Filaments short, digitiform, about as long as notopodial cirri where best developed.

Anterior neuropodial acicular lobes truncate, becoming distally rounded in posterior setigers; aciculae emerging at midline. Pre- and postsetal lobes low, transverse folds. Anterior ventral cirri thick and tapering. Median ventral cirri basally inflated from about setiger 5 through setiger 20. Bases ovate, narrow tips tapering. Posterior ventral cirri increasingly digitiform, increasing in length, nearly as long as notopodial cirri in far posterior setigers. Anterior notopodial cirri thick and tapering, decreasing in girth, but not in length posteriorly.

Limbate setae longer than all other setae, marginally serrated. Pectinate setae unknown. Shafts of compound falcigers (Figure 13f) slender, distally tapering without distinct marginal serrations; distinct distal beak absent. Appendages long, narrow; head large, bidentate. Anterior proximal teeth short, slender, becoming triangular in posterior setigers, directed slightly basally. Distal teeth longer than proximal teeth, curved, directed laterally. Guards narrow, symmetrical, slender, terminating in distinct mucros. Most guards distally rounded with mucro appended, but mucros appearing as continuations of guards proper in some setae. Pseudocompound falcigers and compound spinigers absent. Aciculae single, yellow, tapering with straight, narrow tips; cross-section round. Some aciculae with narrow sharply pointed guards (Figure 13h). Separation between core and sheath indistinct in aciculae, distinct in subacicular hooks. Subacicular hooks (Figure 13g) yellow, tridentate with teeth in a crest. Hooks first present from setiger 16, present in all setigers thereafter, always single (except for replacements). Main fang curved, strongly tapering; secondary fang curved, rather slender; distal fang very poorly developed, blunt, indistinct in some posterior setigers.

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

EXPECTED STATE OF SELECTED UNKNOWN FEATURES.—Mx III long, straight, located behind left Mx II.

CHARACTERS USED IN PREPARATION OF KEY NOT SCORED.—Inappropriate Characters: 56, 58, 59. Unknown Characters: 1, 2, 13, 14, 65–68.

ASSUMED STATES FOR PURPOSE OF PREPARING KEY.—None.