Diagnosis (from Williams 1990): Long, slender and bilateral colonies. Conspicuous and non-retractile autozooids, growing in longitudinal rows along the rachis, without calyces. Numerous siphonozooids growing on the rachis, between the autozooids. Sclerites absent, only very few oval plates in the peduncle. Internal axis along the entire colony, cylindrical, sometimes quadrangular in cross-section. Strong peduncle of 1/5 of the total colony in length.
Included genera: Anthoptilum Kölliker, 1880.
Type genus: Anthoptilum.
Distribution: Cosmopolitan (North and South Atlantic, North and South Pacific, Indian and Arctic Oceans). From intertidal waters to approximately 3200 m depth (Williams 2011).
Anthoptilum Kölliker, 1880
Type species: Anthoptilum thomsoni Kölliker, 1880 (= Anthoptilum grandiflorum (Verrill, 1879)).
Valid species: Anthoptilum grandiflorum (Verrill, 1879); Anthoptilum murrayi Kölliker, 1880; Anthoptilum decipens Thomson & Henderson, 1906; Anthoptilum malayese Hickson, 1916; Anthoptilum gowlettholmesae Williams & Alderslade, 2011; Anthoptilum litophilum Williams & Alderslade, 2011.
Diagnosis: Same as the family.
Distribution: Same as the family.
Anthoptilum was created to accommodate three species: A. thomsoni, A simplex Kölliker, 1880 and A. murrayi Kölliker, 1880. No type-species was designated, and as far as we know it has never been, although A. thomsoni appears as type species of Anthoptilum in Zoobank (http://zoobank.org/NomenclaturalActs/46f88f0f-1913-4d82- 985c-d33228b00e7c). In consequence, we designate A. thomsoni Kölliker, 1880 as type-species of Anthoptilum by subsequent designation.