Clavaporania fitchorum

Clavaporania fitchorum nov. sp.

Figure 3 A–F

Etymology. The species epithet is named for Mason and Lisa Fitch, for their support of academic endeavors.

Taxonomic notes. This species is only the second recognized poraniid from the Macquarie Island region and the first from such the upper bathyal zone. O’Hara (1999) recognized “ Porania ” antarctica from 13–105 m depth. “P.” antarctica lacks the covering of spinelets on the body surface, the well-developed spines on the abactinal and marginal surface and the strongly stellate body.

Clavaporania shares a reticulate abactinal skeleton with Bathyporania, “ P. antarctica, and Poraniopsis. Large primary spines are present in all known species of Bathyporania and Poraniopsis but not in all species of “P.” antarctica. Given the more distant phylogenetic position of Poraniopsis, it is unclear if the skeleton and spines are shared plesiomorphies or derived characters in Clavaporania.

Occurrence. South of Macquarie Island, 1574–1693 m.

Description. Body shape, strongly stellate (R/r=5.4), Arms round in cross-section, disk small (Fig. 3 A). Pedicellariae not observed.

Abactinal skeleton densely reticulate, embedded in a thick, fleshy skin. Skeleton composed of larger, reticulate ossicles and smaller, secondary ossicles distributed throughout. Single papular pores. Open papular meshes absent. Abactinal and marginal spines are strongly clavate, almost mace-like, with blunt, but finely notched to irregular tips (Figs. 3 D, F). Some spine tips with one to three short, thorny tips (Figs. 3 F). Spines sit on strongly convex bosses present along reticulated network. Abactinal and lateral surface with a dense covering of spinelets, these completely cover the abactinal and lateral surfaces. Individual spinelets with one or two points; approximately five spinelets per mm. Surfaces around spine bases lacking spinelets. Fifteen short spines surrounding anal periphery. Madreporite on strongly convex plate, surrounded by short spinelets. Sulci relatively simple.

Marginal plates with one-to-one correspondence proximally, becoming offset distally. Marginal plate surface, as on the abactinal surface, covered by dense spinelets. Marginal series strongly swollen (Fig. 3 C), superomarginals and inferomarginals each with prominent spine-bearing clavate/mace-like and/or two pronged thorny tip, one or two per plate, (Fig. 3 C, D, E) identical to those on abactinal plates forming distinct periphery around actinolateral edge. Some marginal spines with a broad spearhead-like shape. Intermarginal region with single papular pore (Fig. 3 C). Marginal plates form distinct, closely articulated series separate from the abactinal reticulation.

Actinal surface composed of three plate series (Fig. 3 B). Series with largest sized plates distalmost, near contact with inferomarginal plates. Actinal plates smaller, more proximally. Plates are quadrate with rounded edges becoming smaller and more round. Actinal surface lacking large spines, but covered by widely spaced, tiny spinelets similar to those on abactinal surface (Fig. 3 B, E). Actinal and oral plates covered by skin.

Furrow spines number one or two, with a single, larger subambulacral spine, all in a transverse row with flattened and squarish to pointed tips (Fig. 3 E). Furrow spines are about half the thickness of the subambulacral spine, but all spines similar in length. Adambulacral plates rectangular in outline. Two blunt, pointed spines per oral plate directed into mouth (Fig. 3 E). Oral plate furrow spines three to four. Large blunt spine with wide, flat tip on oral plate surface.

Color in life unknown.

Material examined. Holotype, USNM 1232816, South of Macquarie island, 56º21’S, 158º28’E, 1574–1693 m, Coll. USC R/V Eltanin (1 dry spec. R=4.9, r=0.9)