Flagelligorgia, Cairns, Stephen D. & Cordeiro, Ralf T. S., 2017

Cairns, Stephen D. & Cordeiro, Ralf T. S., 2017, A new genus and species of golden coral (Anthozoa, Octocorallia, Chrysogorgiidae) from the Northwest Atlantic, ZooKeys 668, pp. 1-10 : 1-2

Flagelligorgia gen. n.

Type species.

Flagelligorgia gracilis , here designated. Gender: feminine.

Diagnosis.

Colonies unbranched (flagelliform), loosely coiled, attached by a holdfast; axis composed of undulating concentric layers (Figs 1 C–E, 2D). Polyps arranged biserially. Body wall and coenenchymal scales elongate, smooth scales. Polyps lack an operculum.

Remarks.

Until 1956 ( Bayer 1956) the Chrysogorgiidae had been divided into three subfamilies, one being the Lepidogorgiinae Versluys, 1902, consisting of genera with an unbranched colony and lacking polyp opercula. However, the subfamily classification has been ignored for decades and is not supported by molecular evidence. Nonetheless, it is incumbent to compare Flagelligorgia to the four other unbranched chrysogorgiid genera. Helicogorgia Bayer, 1981, known only from the east coast of Africa at 66-775 m depth range, is unbranched but has its polyps arranged in a multiserial fashion on one side of the stem, a naked track displayed on the opposite side. Furthermore, its body wall scales are irregular plates and its coenenchymal scales are spindles. For all of these reasons Helicogorgia is easily distinguished from Flagelligorgia . Based on sequencing of three genes, Pante et al. (2012) indicate that Helicogorgia might constitute a family on its own, as sister to the Chrysogorgiidae . Helicogorgia was revised by Williams (1992), recognizing four species in the African coast.

Chalcogorgia Bayer, 1949, known only from its type locality off northwestern Cuba at 708 m depth, is also unbranched and has biserially arranged polyps, like Flagelligorgia , but differs in having eight triangular opercular scales on each polyp, and body wall scales shaped as irregularly shaped platelets. According to Pante et al. (2012: 8), based on "very limited data," Chalcogorgia was suggested to ally with Helicogorgia , and thus also outside of the MCC.

Distichogorgia Bayer, 1979, known only from the Blake Plateau off Florida at 814 m depth, is unbranched and has biserially arranged polyps, but differs in having unique body wall scales consisting of two fans of longitudinally arranged, blade-like scales, one on each side of the polyp, interspersed with tiny pointed sclerites, similar to its coenenchymals. Pante et al. (2012) did not report sequencing data for this genus, but based on its biserially polyps, they suggested an affinity with Helicogorgia and Chalcogorgia in a family separate from the Chrysogorgiidae .

Perhaps most similar to Flagelligorgia is the genus Radicipes Stearns, 1883, consisting of 9-10 species (see Cordeiro et al., in press), which occurs worldwide at depths of 241-3580 m. Radicipes is unbranched but differs from Flagelligorgia in having uniserially arranged polyps, and a body wall and coenenchymal sclerites that are rod-shaped to compressed rod-shaped. Furthermore, chrysogorgiids (MCC), including Radicipes , are characterized by having an axis formed by non-undulated (smooth) concentric layers ( Bayer 1956), which is not the case for Flagelligorgia . Based on molecular evidence Pante et al. (2012) placed Radicipes firmly in the Chrysogorgiidae clade (MCC), as the sister genus to Chrysogorgia . Lacking molecular evidence for Flagelligorgia (all specimens are quite old), it is not possible at this time to determine if it is allied with Radicipes in the Chrysogorgiidae (based on similarity of body wall sclerites) or the other cluster of genera including Helicogorgia , Chalcogorgia and Distichogorgia (based on polyp arrangement), which may constitute an as yet undescribed family.

Distribution.

Off Southeastern United States from North Carolina to Florida, 196-567 m depths.

Etymology.

The name is a combination of flagellum (Latin for small whip) and gorgia (a common octocoral suffix and once the name of the order Gorgonacea , the name derived from the mythical female monster, the Gorgon), in reference to the flagelliform nature of the colony.