Polycirrus Grube, 1850

Carrerette, Orlemir & Nogueira, João Miguel De Matos, 2013, Four new species of Polycirrus Grube, 1850 (Polychaeta: Terebellidae) from Campos Basin, southeastern Brazil, Zootaxa 3626 (1), pp. 146-172 : 148-149

Genus Polycirrus Grube, 1850

Type species: Polycirrus medusa Grube, 1850 , by original designation.

Diagnosis. Branchiae absent. Both prostomial parts forming thick crests on dorsal part of upper lip, usually with lateral expansions; distal part of prostomium frequently extending along dorsal surface of upper lip until near anterior border. At least two types of buccal tentacles, long tentacles distally or subdistally expanded, short tentacles uniformly cylindrical or tapering to fine tips. Peristomium forming lips, sometimes extending dorsally and forming complete annelation; upper lip expanded, usually circular and folded into three lobes, lower lip developed, ciliated and grooved, extending posteriorly from mouth for variable extension. Notopodia starting from segment 3, with distally winged or pinnate notochaetae, both types sometimes present on same notopodium. Neuropodia frequently only present after notopodia terminate, neurochaetae as types 1 or 2 uncini sensu Glasby and Glasby (2006) (Hutchings & Glasby 1986; Hutchings & Avery 2003; Glasby & Glasby 2006).

Remarks. Since the original description (Grube 1850), Polycirrus has had a problematic taxonomic history, including several genera which were synonymized with it over time. These synonymized genera are Anisocirrus Gravier, 1905 , Aphlebina Claparède, 1864 , Apneuma Quatrefages, 1866 , Cyaxares Kinberg, 1866 , Dejoces Schmarda, 1861 , Ereutho Malmgren, 1867 , Leucariste Malmgren, 1866 , Litancyra Hutchings, 1977 , Torquea Leidy, 1855 , and Pseudoampharete Hartmann-Schröder, 1960 (Hessle 1917; Holthe 1986a; Hutchings & Glasby 1986; Glasby & Glasby 2006).

Hutchings and Glasby (1986) expanded the generic definition to include species with notopodia beginning on segments 2 or 3 (Hutching & Glasby 1986; Glasby & Glasby 2006). In addition, the authors discussed the problems in counting the anterior segments of some taxa. However, according to Nogueira et al. (2010), in all polycirrines, notopodia, if present, start from segment 3, and those taxa diagnosed as having notopodia from a different segment are due to miscountings of anterior segments. Nogueira et al. (2010) also indicated that polycirrines are remarkably conservative with regard to their anterior end and in all taxa of this subfamily the basal part of prostomium may terminate laterally or extend ventrally and terminate between mid-ventral glandular shields on segments 1 and 2; the upper lip is large, nearly circular, while the lower lip is button-like, frequently covered by mid-ventral glandular shield on segment 1; segment 1 is well developed at least ventrally, with large mid-ventral glandular shield; segment 2 is always distinctly narrower than other segments, constricting the body posteriorly to the mouth; a midventral glandular shield may be present on segment 2, or fused to segment 1; a mid-ventral groove extends from segments 2–3; and notopodia, if present, begin from segment 3. The miscounting of anterior segments, which have caused some authors to consider notopodia as beginning on segments 2 or 4 (Hessle 1917; Holthe 1986b; Hutchings & Glasby 1986) is probably due to the peristomium and segment 1 either extending dorsally or not.

In the present paper we have reconsidered our interpretation of the lower lip and segment 1, and considered the large midventral shield posterior to mouth as the lower lip, instead of segment 1, as discussed in more details by Nogueira et al. (in press).

Glasby and Glasby (2006), through a morphometric analysis, recognized two types of uncini in Polycirrus . Type 1 uncini sensu Glasby and Glasby (2006) are distinctly longer than high, with a flat base, short triangular heel directed posteriorly, short back, with short to inconspicuous dorsal button placed closer to main fang base than to tip of elongated prow. Type 2 uncini are about as long as high and also have an almost straight base and elongate prow, but the heel is elongate, directed downwards, and the back is also elongate, while the dorsal button is similar to that of type 1 uncini, short to inconspicuous, situated near base of main fang (see also Nogueira et al. 2010). Moreover, our SEMs show that type 1 uncini are embedded in neuropodia like those of the other subfamilies of Terebellidae , only the main fang and the crest extending off the integument, the remaining uncinial parts being internal ( Figs 6 C–G; 8F–G), while type 2 uncini are more exposed, with only the anterior third to half of the prow covered by thin epithelium, while part of the base is visible, sitting on top of neuropodial pinnules ( Fig. 10 D, F–I).

Glasby and Glasby (2006) found a correlation between the morphology of uncini and other characters traditionally considered important in the taxonomy of the group, especially the last segment with notopodia and the presence of pinnate notochaetae. According to them, the species with type 1 uncini can be divided into two groups, 1A and 1B, depending on the position of the last pair of notopodia, if up to segment 20, or posterior to it, respectively. On the other hand, all species with type 2 uncini have the last pair of notopodia on segment 20 or before that, and they are divided into groups 2A and 2B by bearing or lacking pinnate notochaetae, respectively, in the posterior row.

Nine species of Polycirrus have been recorded from the Brazilian coast, P. abrolhensis Garraffoni & Costa, 2003, P. clavatus (Kinberg, 1866) , P. cf. coccineus (Grube, 1870) , P. hamiltoni Benham, 1921 , P. paivai Garraffoni & Costa, 2003, P. plumosus (Wollebaek, 1912) , P. tenuisetis Langerhans, 1881 , and two informally described, Polycirrus sp. sensu Alves (2008) and Polycirrus sp. A sensu Blankensteyn (1988). In Tables 1–2 species described in the present study are compared with the most similar congeners belonging to the same groups sensu Glasby and Glasby (2006), and all species recorded from Brazil, regardless of the group they belong to, and if they were formally described or not.

Figures

FIGURE 6. Polycirrus papillosus sp. nov. Photos A – C, E from holotype (MZUSP 1216); photos D, F – G from paratype 10 (MZUSP 1244). A, notochaetae from anterior notopodium; B, close up view of the tips of two notochaetae from anterior row (winged); C – E, uncini, anterior neuropodium; F – G, uncini, posterior neuropodia; arrow points to dorsal button. Scale bars: A – C = 20 μm; D, G = 5 μm; E = 10 μm; F = 2 μm.

FIGURE 10. Polycirrus habitats sp. nov. Photos A – D, F from holotype (MZUSP 1221); photos E, G – I from paratype 1 (MZUSP 1246). A – B, tips of pinnate notochaetae; C – D, F – I, uncini, posterior neuropodia; E, notochaetae, anterior notopodium. Scale bars: A, C = 20 μm; B, D, F = 10 μm; E, G – I = 10 µm.