a) Dorsal view, b) detail of dorsal view, c) dorsal view of prostomium
and first four segments, GOL: globular ocular lobes, CMA: ceratophore of the median antenna, EL: elytrophores, d) neuropodium of segment 5, NB: neurosetae bidentate, NBwET: neurosetae bidentate with one extra tooth, e) parapodium from segment 5, PCGP: parapodium covered with globular papillae, CI: ventral cirrus, f) elytrum from segment 2, g) dorsal cirrus from segment 3.
trapezoidal, with three antennae, paired palps, and a pair of red eyes.
websteri showed variation in palp pigmentation pattern, the shape of the anterior edge of the prostomium
, the shape of the major spines on chaetiger 5, and shape of the pygidium (Table III).
Other authors (Ewing, 1984; Read, 2000) have suggested that the first segment posterior to the prostomium
, or peristomium, is dorsally subdivided, and includes two segments, a position that we agree with, due to the fact that in C.
Remarks: This species is recognized by the absence of a caruncle (fleshy outgrowth of the nuchal organs in the prostomium
) and neurochaetae with simple hooks (Yanez-Rivera, 2009).
During metamorphosis, the once-planktonic larva's body elongates, trochal cilia are shed, the prostomium
elongates, and capillary setae protrude (Biggers et al., 2012).
with a medium antenna originated from the middle zone of the eye pair (Fig.
transverse, short, longitudinally striated; dorsal setae of anterior body region single, ventral setae doubled, no setae in posterior body region; ventral tuberculum single.
The specific name naso is a noun derived from the Latin word nasus (nose) and the Roman personal name Naso, emphasizing the nose-like prostomium
of this worm.
Morphologically, it is characterized by a blunt prostomium
forming a hood over its mouth.
The operculum (Figure 1a) is a thick muscular plate which forms the anterodorsal surface of the (fused) prostomium
Antennae and peristomial cirri are articulated; the antennae have teardrop shaped distal segments and the 3 to 4-segmented peristomial cirri reach to the middle of the prostomium
. Branchiae are pectinate and begin at setiger 3, they are longer than the articulated dorsal cirri.