A Review of the Genus Eunice - Smithsonian Institution Libraries

330 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
REMARKS.—Eunice unidentata was collected near Acapulco,
Mexico. It is first and foremost characterized by the
structure of the subacicular hooks and the very characteristic
bases of the antennae. The basal articulations appear to be
unique to the whole genus. The species is here considered valid
and is listed with similar species in Tables 27 and 28. It is listed
with other species with simple, spine-like subacicular hooks in
Table 50.
197. Eunice unifrons (Verrill, 1900)
FIGURE 113a-j; TABLES 41,42
Uodice unifrons Verrill, 1900:644.—Tread well, 1921:17-20, figs. 21-30, pi.
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 x li 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) - V2 of total antennal length; maximum 4 articulations in
A-I I and A-I 11. A-I to posterior peristomial ring; A-I I and A-I 11
to setiger 2. Peristomium cylindrical. Separation between rings
distinct on all sides; anterior ring less than 2 /3 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 113c,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 113b,g) slightly inflated
and marginally serrated. Anterior and median appendages long
and narrow with nearly parallel sides, bidentatc. 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 113e,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 FEA-
TURES.—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.
REMARKS.—Eunice unifrons is listed with similar species in
Tables 41 and 42. It is one of five species in Table 42 with blunt
guards on the compound falcigers. The other species include E.
aucklandica, E. multicylindri, E. tentaculata, and E. vittata. Of
these species, only E. multicylindri and E. unifrons have single
subacicular hooks throughout. The other species listed have at
least paired subacicular hooks in most setigers. The peristomial
cirri are articulated in E. multicylindri and lack articulations in
E. unifrons.