Ctenodrilus Claparède, 1863

Magalhães, Wagner F., Weidhase, Michael, Schulze, Anja & Bailey-Brock, Julie H., 2016, Taxonomic remarks on the genus Ctenodrilus (Annelida: Cirratulidae) including description of a new species from the Pacific Ocean, Zootaxa 4103 (4), pp. 325-343 : 327-331

Genus Ctenodrilus Claparède, 1863

Syn. Parthenope Schmidt, 1857

Type species: Parthenope serrata Schmidt, 1857 .

Diagnosis. Prostomium rounded, eyespots absent, nuchal organs shallow ciliary pits, postero-lateral, rounded; peristomium complete ring surrounding mouth; first segment complete chaetiger. Palps and branchiae absent. Body with few segments, up to 15. Chaetae thick and short, marginally smooth or serrated with variable number and size of teeth. Body with sparse cilia, concentrated on ventral region of anterior end. Digestive tract divided into three parts, anterior slender esophagus, inflated and pigmented stomach and intestine. A pair of nephridia present on peristomial region. Heart body enlarged dorsal vessel present through few anterior segments. Pygidium simple lobe, anal aperture usually dorsal. Asexual reproduction as paratomy, number of stolons variable; sexual reproduction as viviparity, protandrous or simultaneous hermaphrodites.

)

Remarks. Ctenodrilus serratus ( Schmidt, 1857) is currently considered as a valid species but type material has either been lost or never deposited. The identity of C. parvulus Scharff, 1887 and of the subspecies C. serratus limulicolus Sudzuki & Sekiguchi, 1972 is questionable ( Wilfert 1973; Westheide et al. 2003; Dean & Blake 2014) and both species lack type material. Extensive comparisons have been made between C. serratus and C. parvulus . In addition to the anatomical and histological differences, the hooks in C. parvulus were illustrated as lacking distinct teeth (see Scharff 1887; Fig. 2 ). The subspecies C. serratus limulicolus has been considered as a synonym of C. serratus but it also differs in the alleged shape of nuchal organs and very distinct characteristics of the posterior end and pygidium (as seen in Fig. 14d of Sudzuki & Sekiguchi 1972) having a ventral anus, cilia and distinct anal glands. C. paucidentatus was described as being distinct from C. serratus by the fewer number and shape of teeth on the multidentate hooks. The dentition and shape of hooks have been proved to be very variable among populations and even within an individual so the identity of C. paucidentatus is questionable based on the examination of type material. Morphology of C. serratus from the east coast of the United States and Caribbean is similar to that provided in Wilfert (1973) and Weidhase et al. (2016) ( Fig. 1 ); further details in Remarks section below.

Figures

FIGURE 1. Ctenodrilus serratus. A and B, complete specimens in lateral view from Massachusetts, USA (USNM 51480); C, complete specimen in lateral view showing multidentate hooks from Bahamas (USNM 1044811); D and E, complete specimens in dorso-lateral view from Belize (USNM 321390), D, showing five buds. (abbreviations: es, esophagus; hb, heart body; int, intestine; nep, nephridium; ph, pharynx; st, stomach).

FIGURE 2. Ctenodrilus pacificus sp. nov. A, line drawing of a complete live specimen in lateral view; B, complete specimen in lateral-ventral view showing distribution of ventral cilia; C, multidentate hooks of a single individual. (abbreviations: es, esophagus; hb, heart body; int, intestine; mo, mouth; nep, nephridium; nuO, nuchal organ; per, peristomium; ph, pharynx; pr, prostomium; py, pygidium; st, stomach; vc, ventral cilia).