Porphyrocrinus Gislen 1925

Porphyrocrinus Gislén, 1925

Diagnosis. Aboral cup at least slightly conical, usually taller than wide; pairs or triplets of brachials joined by ligamentary articulation proximally; up to 5 articulations between ligamentary articulations distally; several to many proximal columnals thin and discoidal with synostosial or syzygial articulations; usually with a pair or more middle or distal columnals joined by cryptosynarthry characterized by an interior synarthry reflecting an earlier ontogenetic stage surrounded by secondary syzygial crenulae.

Type species. Porphyrocrinus verrucosus Gislén, 1925.

Other included species. Monachocrinus incrassatus Gislén, 1933; Porphyrocrinus thalassae Roux, 1977; Porphyrocrinus daniellalevyae n. sp.; † Porphyrocrinus fossilis Roux and Montenat, 1977 (Upper Miocene).

Distribution. Tropical western Atlantic, northeastern and southern Atlantic, tropical western Pacific, southwestern Indian, off Tasmania. Depth range: 218 to at least 5,205 m (possibly 5,240 m).

Remarks. Messing (2007) treated P. polyarthra A.M. Clark, 1973, from the southwestern Indian Ocean in 400 m, as a synonym of P. verrucosus, although the limits of the latter remain uncertain. The holotype of P. verrucosus was collected in 345 m in Indonesia, and other material attributed to this species was taken in 218–400 m in the western Pacific (Messing 2007, Tunnicliffe et al. 2015). Specimens treated as Porphyrocrinus aff. verrucosus have been photographed or videotaped off New Caledonia in 616 m (Bourseau et al. 1991) (as Porphyrocrinus sp. in Améziane 2007), off Queensland, Australia,(~ 218–400 m), and northern Sulawesi, Indonesia, in 500–505 m (Tunnicliffe et al. 2015). P. daniellalevyae n. sp. from the tropical western Atlantic occurs over a similar depth range: (400?) 582 – 616 m. By contrast, P. thalassae Roux 1977, from the NE Atlantic occurs in 1,700–2,750 m (Roux 1985), and P. incrassatus from the NE and Central Atlantic occurs in 1,300–2,400 (?2,780) m and possibly deeper. Eléaume et al. (2012) treated two specimens from the S Atlantic taken at depths> 5,000 m as P. cf. incrassatus. Bourseau et al. (1991) reported isolated columnals attributed to Porphyrocrinus sp. in bioclastic sediments off New Caledonia in 400–1800 m, and Améziane and Roux (2001) noted an unidentified species from seamounts off Tasmania, but gave no depth range.