Zootaxa, Taxonomy of Serpulidae (Annelida ... - Magnolia Press

Peduncular shape. Normally, the opercular peduncle is lacking pinnules and it is 1.5–3 times thicker than
normal unmodified radioles. One of the notable exceptions is the genus Hyalopomatus, with the peduncle as
wide as the normal radioles (Fig. 3C). However, a number of serpulids, such as Paraprotis pulchra,
Filogranula exilis, Nogrobs grimaldii, and Bathyditrupa hovei, possess pinnules on the operculum-bearing
peduncle. Filogranula species other than F. exilis typically have smooth peduncles, although Zibrowius
(1968a) mentions that a pinnulated peduncle may occasionally occur. In Nogrobs grimaldii and Bathyditrupa
hovei, an inverse conical opercular ampulla is reinforced with a chitinous endplate as in many serpulins, and
the peduncle, though pinnulated, is very thick and is clearly a modified radiole (Fauvel 1909, Kupriyanova
1993b). A peduncle without pinnules is smooth in most genera, but it is clearly wrinkled in Neovermilia
globula (Fig. 4E) and Janita fimbriata.
In cross-section, the opercular peduncle is most often cylindrical or slightly sub-cylindrical, but in some
serpulids (e.g., Pomatoceros), it is nearly triangular. It is flattened in Bathyditrupa, Dasynema, Janita,
Neovermilia, and Pomatostegus. The genus Metavermilia has a very characteristic flat ribbon-like peduncle
(Fig. 4C).
Peduncular distal wings. Below the operculum, the peduncle may be modified to form distal wings
(Pomatoceros, Spirobranchus, Galeolaria, Pomatoleios, and Pomatostegus). These wings can be narrow,
spine-shaped (Pomatoceros), or wide and flattened (Galeolaria) and running the entire length of the peduncle
(Pomatostegus). In some Spirobranchus species, the wings are rounded, entire, in others they are distally
digitated (Fig. 3E, dw) or crenulated. It is unclear whether small latero-dorsal distal “winglets” found on the
peduncle of Dasynema, Neovermilia (Fig. 4E) and the syntypes of Vermiliopsis glandigerus are homologous
to the larger wings described above or are caused by flattening of the peduncle.
Peduncular proximal wings. Dasynema, Paumotella, Vermiliopsis glandigerus (as observed by us in the
syntypes, though not explicitly mentioned by Gravier 1906), and V. leptochaeta show a long, one-sided lateral
extension along the basal 2/3rds of the peduncle, which also might be termed a wing. In Vermiliopsis
striaticeps, the presence of this proximal wing appears to be size related, being absent in small specimens, and
present in large ones. The character is not always mentioned in existing descriptions. However, being
unpaired and basal, the proximal wing most probably is not homologous with the distal ones discussed above.
The collar and the thoracic membranes
Collar. The base of the branchial crown of sabellids and serpulids is surrounded by a membranous peristomial
collar, which is absent in sabellariids. The collar in serpulids is usually trilobed, sub-divided into one medioventral
and two latero-dorsal lobes (Fig. 5D, lcl, vcl). Commonly, the medio-ventral lobe is wider and longer
than the lateral ones. The medio-ventral lobe may have an additional incision as in Floriprotis and Tanturia,
thus making the collar quadrilobed. Also, the ventral lobe may bear an additional tongue with 2 lateral
incisions, thus making the collar pentalobed as in Janita fimbriata. Rarely, the serpulid collar is non-lobed as
in Ditrupa, Ficopomatus, Paraprotis, and Bathyditrupa. The collar edge is normally smooth in most serpulids
(see note under thoracic membranes).
Tonguelets. Small tongue-shaped outgrowths, tonguelets, located between the dorso-lateral and ventral
lobes of the collar are present in Spirobranchus, Pyrgopolon (ten Hove 1970, 1973 fig. 35, as Sclerostyla),
Pomatoceros (termed lappets: Thomas 1940 pl. I fig. 5) and Pomatoleios. According to ten Hove (1973), they
are not found in Ditrupa, Hydroides, Ficopomatus, Pomatostegus, Serpula, and Vermiliopsis. Thomas (1940:
9, 39) hypothesizes a possible sensory function, since a nerve is seen to enter each tonguelet.
Collar segment. In almost all Sabellida, the first chaetiger is the collar segment lacking neuropodial
uncini and bearing only notopodial chaetae (termed collar chaetae). It appears that uncini are secondarily lost
in the collar segment, the biramous condition being original in Polychaeta and Oligochaeta. Mainly because
the first chaetiger in Ditrupa bears both chaetae and uncini, ten Hove & Smith (1990: 103) argue that it is not
the collar segment, but actually the second segment. Secondary loss of collar chaetae has been reported to
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