Acanthogorgia spinosa Hiles, 1899 (Fig. 5) Acanthogorgia spinosa Hiles, 1899: 198; Grasshoff, 1999: 22; 2000: 42. Material: RMNH Coel. 38766, one colony, Koninklijke Shell Exploratie en produktie laboratorium, sta. T1211, off Bahrain, coll. A.J. Keij, 1966. Remarks. According to Grasshoff (1999: 20) the present material belongs to the Acanthogorgia breviflora –group, including species characterised by having small polyps less than 1 mm tall, tips of polyp wall sclerites protruding, tentacle bases with a conspicuous crown of spines, and coenenchyme with thornstars. He included five New Caledonian species in this group: A. breviflora Whitelegge, 1897, A. ildibaha Grasshoff, 1999, A. spinosa Hiles, 1899, A. turgida Nutting, 1911, and A. dofleini var. spinosa Aurivillius, 1931. Of these only A. spinosa has a colony form alike the present material, a tangled three dimensional network. The sclerites of the present Bahrain specimen (Fig. 5) are also similar to those of A. spinosa (Grasshoff 1999: Fig. 26; Grasshoff 2000: Fig. 69). Grasshoff (2000: 45) put A. ildibaha Grasshoff, 1999 in another group of Acanthogorgia species, the newly formed isoxya -group. This group differs from the breviflora -group in lacking thornstars. Indeed, the Red Sea specimen identified by Grasshoff in 2000 as A. ildibaha lacks thornstars (Grasshoff 2000: Fig. 77) but the 1999 holotype specimen from New Caledonia has them (Grasshoff 1999: Fig. 26). According to us Grasshoff actually had two different species, and the A. ildibaha specimen from the Red Sea should be described as a new species. Dr. Phil Alderslade (Honorary Fellow, Commonwealth Scientific and Industrial Research Organisation, Hobart, Australia) drew our attention to some discrepancies in Grasshoff’s 1999 paper. In the abstract of this publication A. ildibaha is not mentioned while A. acrosoma n. sp. is, but the latter species is nowhere described in the publication. Maybe Grasshoff changed the species name from acrosoma to ildibaha in his 1999 publication but forgot to do so in the abstract, or he forgot to change the species name ildibaha into acrosoma in the description and captions of the figures. It is plausible these errors also caused the wrong identification of the Red Sea specimen.

Published as part of Namin, Samimi & Ofwegen, Van, 2009, Some shallow water octocorals (Coelenterata: Anthozoa) of the Persian Gulf, pp. 1-52 in Zootaxa 2058 on page 9, DOI: 10.5281/zenodo.186743