Gyrophyllum Studer, 1891

López-González, Pablo J., Drewery, Jim & Williams, Gary C., 2022, A new family for the enigmatic sea pen genus Gyrophyllum Studer, 1891 (Octocorallia, Pennatulacea), a molecular and morphological approach, European Journal of Taxonomy 847, pp. 73-103 : 84

Genus Gyrophyllum Studer, 1891

Gyrophyllum – Studer 1891: 94.

Gyrophyllum – Studer 1901: 34. — Roule 1905: 454. — Kükenthal & Broch 1911: 394. — Kükenthal 1915: 120. — Hickson 1916: 252. — Deichmann 1936: 286. — Tixier-Durivault & d’Hondt 1974a: 263; 1974b: 1420. — Williams 1995a: 316; 1995b: 128; 2011: 3.

non Bathypenna – Marion 1906: 147.

Diagnosis (modified from Williams 1995b: 128, modifications in bold)

Colonies stout and clavate, with rachis in two parts, a distal part with polyp leaves and a proximal part without them, similar to peduncle in appearance but separated from the anchoring muscular peduncle by a thickened section showing longitudinal wrinkles. Distal part of rachis with bilateral symmetry throughout.Axis extends throughout length of colony, irregularly X-shaped in cross section. Polyp leaves present, thick, fleshy, and fan-like, up to ~9 leaves per side of rachis. Autozooids up to ~50 per leaf, usually in two rows at the leaf margin. Anthocodiae retractile into low fleshy calyces with one or two distinct fleshy blunt to pointed processes (sometimes difficult to observe, eroded?). Tentacles with two types of tentacular projections: conventional pinnulae on the lateral sides of main tentacular axis, and filiform ones (numerous) along the oral side of tentacular axis. Siphonozooids present on both sides of polyp leaves between and below autozooids, and on dorsal rachis’ track, not restricted to zones or pads. Sclerites elongate, three-flanged rods in polyp leaves, rachis, and peduncle, as well as short blunt rods in the tentacle axis and autozooid body (mostly longitudinally grooved or occasionally three-flanged).

Geographical and depth distribution

Indo-West Pacific ( Madagascar, Malay Archipelago, Tasmanian Sea, New Zealand, India) and North Atlantic (Azores, Hatton and Rockall Banks, Rosemary Seamount, Bahamas); 520–2220 m depth ( Studer 1891, 1901; Deichmann 1936; Williams 1995b: 128; Williams et al. 2014; present contribution).

Type species

Gyrophyllum hirondellei Studer, 1891 (by monotypy).