Arachnopathes Milne Edwards, 1857

Terrana, Lucas, Bo, Marzia, Opresko, Dennis M. & Eeckhaut, Igor, 2020, Shallow-water black corals (Cnidaria: Anthozoa: Hexacorallia: Antipatharia) from SW Madagascar, Zootaxa 4826 (1), pp. 1-62 : 22-23

Genus Arachnopathes Milne Edwards, 1857

Arachnopathes was established by Milne Edwards (1857) based on the type species Antipathes ericoides Pallas, 1766 . The genus was later questioned by Brook (1889) before being synonymized with Antipathes by van Pesch (1914) and Pax & Muller (1955) ( Opresko 2006). In a more recent work, the species Arachnopathes columnaris Duchassaing, 1870 was chosen by Opresko (2006) as the type species of the genus Stylopathes . The genus Arachnopathes is characterized by branched and bushy colonies with short, straight or curved branchlets fused together into a thick mass ( Opresko 2006). The branchlets on the outer edges of the colony may be free or fused. The spines are smooth, triangular to conical to hooked upward, and can be forked.

There are currently five nominal species, of which two are known from the Indian Ocean: Arachnopathes ericoides ( Pallas, 1766) which is the type species of the genus but for which the type material is lost, and Ar. clathrata ( Pallas, 1766) for which there is no type. The remaining species, Ar. aculeata Brook, 1889 , Ar. indistincta ( van Pesch, 1914) and Ar. sibogae ( van Pesch, 1914) come from the Pacific Ocean. The latter two were originally assigned to the genus Aphanipathes , but they are now provisionally referred to Arachnopathes based on similarities in colony form and spine morphology (unpublished observations from co-author DMO). Further DNA analyses on Indian Ocean species might prove that they are related to the Stylopathidae , but based on their spine morphology, they are inferred to be closer to Antipathidae rather than Stylopathidae ( Opresko 2006) .