Iolanthe Beddard, 1886

Acanthoniscus Sars, 1879: 434 (preoccupied).— Bovallius 1886: 16.

Iolanthe Beddard, 1886a: 104 .— Beddard 1886b: 15.— Wolff 1962:33.— Menzies & Schultz 1968: 166.— Menzies & George 1972: 118.

Jolanthe .— Menzies 1962a:177.— Menzies 1962b: 83 (incorrect subsequent spelling).

Acanthaspidia Stebbing, 1893: 378 [replacement name for Acanthoniscus Sars, 1879].— Vanhöffen 1914: 537.— Menzies 1962a: 177.— Menzies 1962b: 83.— Wolff 1962: 34.— Birstein 1963: 20.— Menzies & Schultz 1968: 155.— Kussakin 1988: 156.— Brandt 1991: 208.— Timm et al. 2013: 239.

Paracanthaspidia Menzies & Schultz, 1968: 161 (synononymised by Brandt, 1991).

Exacanthaspidia Menzies & Schultz, 1968: 171 (synononymised by Brandt, 1991).

Type species: Iolanthe acanthonotus Beddard, 1886 (by monotypy).

Remarks. Sars (1879) erected the genus Acanthoniscus Sars, 1879 for the species Acanthoniscus typhlops Sars, 1879, collected from the Norwegian Sea, its type species by monotypy. Beddard (1886a) erected the genus Iolanthe Beddard, 1886a for a single new species, Iolanthe acanthonotus Beddard, 1886a, collected from south of Kerguelen Island. Beddard (1886b) erected a second genus Ianthopsis Beddard, 1886b for Ianthe bovallii Studer, 1884 . Beddard (1886b) remarked on the close resemblance of this new genus to Acanthoniscus . Bovallius (1886) realised that Acanthoniscus was preoccupied, a junior homonym of Acanthoniscus Kinahan, 1859 ( Isopoda: Oniscidea), and although he remarked that it should be replaced with another name, he did not propose one. Stebbing (1893) proposed the replacement name Acanthaspidia Stebbing, 1893 for Acanthoniscus . Iolanthe was first synonymised with the younger name Acanthaspidia by Hansen (1916), while Nordenstam (1933) instead synonymised Iolanthe with Ianthopsis . Menzies (1962a) established the family Acanthaspidiidae Menzies, 1962a, recognising Iolanthe (mispelled as Jolanthe) and Acanthaspidia as separate genera, a view that was continued by Menzies & Schultz (1968) and Menzies & George (1972), with both studies including descriptions of Iolanthe and describing new species. Menzies & Schultz (1968) erected two new genera, Paracanthaspidia Menzies & Schultz, 1968 and Exacanthaspidia, Menzies & Schultz, 1968 both synononymised by Brandt (1991).

In her revision of the Acanthaspiidae, Brandt (1991) recognised only two genera of the family Acanthaspidia and Ianthopsis, synonymising the older Iolanthe once again with Acanthaspidia, including the type species of Iolanthe, I. acanthonotus . Following the Principle of Priority (ICZN 1999: Article 23.1) the older name Iolanthe has priority over Acanthaspidia, not the other way around. The conditions required for reversal of precedence (ICZN 1999: Article 23.9) are not met.

We conclude that Iolanthe is the senior synonym of Acanthaspidia and is the valid name in accordance with ICZN Articles 23.1 and 23.9. To our knowledge the condition of Article 23.9.1.2 does not apply— Iolanthe has been used as a valid name since 1899 by at least Menzies (1962a, b), Menzies & Schultz (1968) and Menzies & George (1972) —and the conditions of Article 23.9.1.2 are not met— Acanthaspidia has been used by fewer than ten authors in fewer than 25 papers over the immediately preceding period of 50 years.

Iolanthe is femine.

Species included. Iolanthe acanthonotus Beddard, 1886a, I. bifurcata (Menzies, 1962), I. bifurcatoides (Vasina & Kussakin, 1982), I. curtispinosa (Vasina & Kussakin, 1982), I. decorata Hansen, 1895, I. drygalskii (Vanhöffen, 1914), I. hanseni (Birstein, 1963), I. iolanthoidea (Vasina & Kussakin, 1982), I. laevis (Chardy 1975), I. longiramosa (Vasina & Kussakin, 1982), I. matsi (Timm et al. 2013), I. mucronata (Menzies & Schultz, 1968), I. namibia (Brandt, 2001), I. natalensis (Kensley 1977), I. neonotus Menzies & George, 1972, I. pleuronotus Menzies & Schultz, 1968, I. porrecta (Menzies & Schultz, 1968), I. rostrata (Menzies & Schultz, 1968), I. sulcatacornia (Menzies & Schultz, 1968), I. typhlops (Sars, 1879) .