Fimbriosthenelais Pettibone, 1971

Barnich, Ruth & Haaren, Ton Van, 2021, Revision of Sthenelais Kinberg, 1856, Fimbriosthenelais Pettibone, 1971 and Eusthenelais McIntosh, 1876 (Polychaeta, Sigalionidae) in the Northeast Atlantic, European Journal of Taxonomy 740, pp. 138-171 : 154-155

Genus Fimbriosthenelais Pettibone, 1971 (emended)

Table 1

Fimbriosthenelais Pettibone, 1971: 25

(type species Fimbriosthenelais longipinnis Grube, 1869 ; revised by Pettibone 1971).

Diagnosis

BODY. Elongate, with numerous segments; mid-dorsum bordered by a few pairs of small ctenidia.

ELYTRA. Numerous, on segments 2, 4, 5, 7, continuing on alternate segments to 27, then on every segment to end of body. Dorsal tubercles on segments 3, 6, 8, continuing on alternate segments to 26.

PROSTOMIUM. Rounded, fused to first segment. Median antenna inserted terminally, with stout, cylindrical ceratophore with lateral auricles and tapering style. Lateral antennae fused to inner dorsal sides of tentaculophores, without ceratophore, distinctly shorter than dorsal tentacular cirri. Paired palps encircled by palpal sheath emerging ventrally to tentaculophores.

TENTACULOPHORES. With single aciculum, a pair of tentacular cirri, two bundles of capillary chaetae, L-shaped inner tentacular lobe with ciliated ridge and fused to palpal sheath, and dorsal tentacular crest.

SEGMENT 2. With first pair of elytra, biramous parapodia and buccal cirri longer than following ventral cirri. Small ctenidia on lateral lips and medial to ventral cirri in anterior segments.

SEGMENT 3. With dorsal tubercles fused to posterior sides of elytrophores of segment 2. Dorsal cirri absent.

BRANCHIAE. Cirriform, absent on anteriormost segments.

DORSAL CIRRI. Absent from all segments.

VENTRAL CIRRI. Styles with basal knob, without long basal papillae.

PARAPODIA. Biramous, each with up to three cup-shaped ctenidia dorsal to notopodia, noto- and neuropodial acicular lobes with accessory bracts and distinctly papillated stylodes. Notopodial acicular lobes nearly completely encircled by a bract covering the basis of the notochaetae. Neuropodial acicular lobes posteriorly with a large bilobed or truncate bract and anteriorly with two smaller crescent-shaped bracts.

CHAETAE. Notochaetae slender, spinous, tapering to capillary tip. Neurochaetae mostly compound falcigers and, if present, a few simple spinous chaetae; stems of compound chaetae usually with a few rows of spines distally. Neurochaetae arranged in three groups: upper group of neurochaetae within anterodorsal bract: mainly slender compound falcigers and a few simple, spinous chaetae (may be missing). Middle group of neurochaetae within posterior bract: all stout compound falcigers. Lower group of neurochaetae within anteroventral bract: all slender compound falcigers.

Remarks

The generic diagnosis of Fimbriosthenelais is emended for the presence of distinct (large) papillae on the stylodes to allow for differentiation from Sthenelais (see remarks related to S. boa above).

Based on our study, Fimbriosthenelais currently comprises two valid species in the wider NE Atlantic: F. zetlandica (McIntosh, 1876) , which is widely distributed in the area, and F. longipinnis ( Grube, 1869) , a mainly Indo-Pacific species, which is also found in the eastern parts of the Mediterranean Sea. As discussed above, we agree that F. minor ( Pruvot & Racovitza, 1895) is a junior synonym of Sthenelais boa ( Johnston, 1833) . A final decision on the validity of the genus Fimbriosthenelais would require a complete revision of all species, especially also additional species described since Pettibone’s revision (see Aungtonya & Eibye-Jacobsen 2018).