Flabegraviera, Salazar-Vallejo, 2012

Salazar-Vallejo, Sergio I., 2012, Revision of Flabelligera Sars, 1829 (Polychaeta: Flabelligeridae) 3203, Zootaxa 3203 (1), pp. 1-64 : 41-42

Flabegraviera n. gen.

Type species: Flabelligera mundata Gravier, 1906 .

Diagnosis. Body blunt anteriorly, tapered posteriorly. Tunic thick, parchment like, including most papillae. Cephalic cage chaetae short, covered by a thick tunic, chaetae barely exposed or not exposed at all. Notopodia lateral, displaced laterally in series; neuropodia ventrolateral. Notochaetae very long, mostly uncovered by tunic, articles restricted to short, distal region; neurohooks multiarticulated or anchylosed, crest entire. Free-living.

Etymology. This genus is named by combining the first few letters of Flabelligera and the last name of the late Charles Gravier, and adding a terminal “a” for euphony. Gender feminine. Gravier made several fine contributions to polychaete taxonomy; he divided his time working with scleractinian corals and was in charge of the collections in the Paris Museum.

Remarks. Flabegraviera n. gen. is markedly different from other Flabelligera -like genera. Its unique features include a very thick, resistant tunic, very short cephalic cage chaetae, notopodia arranged in descending groups, and notochaetae with articles restricted to a short distal region.

Gravier (1907:38) noticed that notochaetae emerge at different levels although the notopodial lobes arise from about the same level: “Les points d’émergence de ces faisceaux à la surface du mucus ne sont pas alignés de chaque côté et paraissant disposes d’une manière irrégulière; mais on peut voir par transparence les points d’insertion vrais qui correspondent chacun à une éminence conique bien marquee et qui sont, eux, parfaitement alignés.” This translates as: ‘The emergence points of these chaetal fascicles in the tunic surface are not aligned on each side and are apparently arranged in a peculiar pattern; but one can see by transparency that the true chaetal insertion points correspond to a well-defined conical projection, which are, in turn, perfectly aligned.’ This pattern of unaligned chaetae reflects different orientations of the notochaetal fascicle and was illustrated by Ehlers (1913, Pl. 41, Fig. 3 ). In fact, as indicated in the key to Flabelligera -like genera, they are aligned in series of two up to chaetiger 4, with notopodia 2 lower, then notopodia 3 higher than number 4, and then in series of three to the end of the body. This is a unique pattern that might be explained because notochaetae have a defensive role; the upper ones are directed upwards, the intermediate ones are directed laterally, while the inferior ones are directed ventrally. Further, this is not a preservation artifact because living animals have the same arrangement (www.oikonos.org, www.animalsandearth.com, www.superstock.com). There are two species in Flabegraviera ; the type species seems to be restricted to shallow water on hard or mixed bottoms, with gravel or coarse sand, while the form coming from deeper water (> 350 m) has a bluish color on the tunic and neurohooks that are mainly anchylosed. These characters are described below. The diagnostic features for species are detailed in the key below.

Distribution. Restricted to the Antarctic Ocean and surrounding waters.

Figures

FIGURE 3. Flabelligera bophortica Annenkova-Chlopina, 1924, syntypes (ZIRAS-27043). A. Best syntype, lateral view. B. Same, anterior end, oblique, ventrolateral view. C. Same, head, frontal view (BS: branchial scars, Ca: caruncle, DL: dorsal lip, LL: lateral lip, PS: palp scar, VL: ventral lip). D. Same, neuropodia 4–7, oblique, ventral view showing gonopodial lobes (GL), E. Same, chaetiger 10, notochaetae (inserts: basal, medial and subdistal regions). F. Same, posterior chaetiger, neurohooks (inserts: handle articulation and crest close-up). Scale bars: A: 3.3 mm, B: 1.3 mm, C: 0.5 mm, D: 0.8 mm, E: 320 µm, F: 260 µm.