Acanthochitona discrepans ( Brown, 1827 )

Acanthochitona discrepans ( Brown, 1827) View in CoL

Chiton discrepans Brown, 1827 , pl. 35, fig. 20; Brown 1844, p. 65, pl. 21, fig. 20; Wood 1872 /1874, p. 95, pl. 4, fig. 27; Reid 1890, p. 261, tab. 3.

Acanthochitona discrepans View in CoL ; Kaas 1985a, p. 598, figs 59–75; Vončina et al. 2023, p. 9 View Cited Treatment , figs 1C, 4B, 5–6.

non Chiton discrepans ; Sowerby II 1840 a, p. 2 [in synonymy of C. crinitus (non Pennant)] et mult. auct.

Remarks. Kaas (1985a) provided an accurate analysis of the taxonomic history of the three European species of Acanthochitona currently accepted at the time, i.e. A. fascicularis ( Linnaeus, 1767) , A. crinita ( Pennant, 1777) and A. discrepans ( Brown, 1827) , discussing also their various interpretations in the past. Before, A. fascicularis was reported mainly as A. communis Risso, 1826 , or A. discrepans ( non Brown), and so all the references reported as A. discrepans from Italian localities (and from few other Mediterranean localities) are attributable to A. fascicularis in our conception (see above). Some reports of A. discrepans from the English Pliocene (Coralline Crag, Sutton) could be related to the true A. discrepans , a species still living at present along the British coast (Kaas 1985a; Vončina et al. 2023).

Acanthochitona discrepans is very similar to A. crinita , with the main differences concerning the number, size and arrangement of aesthetes on tegmental granules, and especially the girdle formations ( Vončina et al. 2023), not appreciable in single valves only. Even the description and the figure provided by Wood (1872 /1874) do not permit a certain specific attribution; so, we report A. discrepans in this appendix which groups together species whose fossil findings are not correctly attributable.

“ Chiton ” octovalvis Woodward, 1833

( Fig. 153A View FIGURE 153 )

Chiton octovalvis? Woodward S., 1830, p. 23 .

Chiton octovalvis ; Parkinson 1811, p. 49, pl. 5, fig. 5; Woodward S., 1833, p. 44; Lyell 1839, p. 330; Wood 1872 –1874, p. 95; Woodward H.B. 1881, p. 48; Van Belle 1981, p. 54; Puchalski et al. 2008 (database: chiton fossil records).

Chiton grignonensis ... octovalvis ?; Parkinson 1822, p. 199; Parkinson 1833, p. 203.

Chiton sp. ( octovalvis ); Woodward S.P. 1864, p. 119.

Remarks. Woodward (1833) reports Chiton octovalvis referring to Parkinson (1811: 44 “ Org. Rem. iii, t.5, f.5 ” Ibid. ( Thorpe) One valve only ”), but Parkinson only note the finding of several separated valves at Grignon, near Paris (by Lamarck 1802) and figure a complete species from Grignon (reproduced here, Fig. 153A View FIGURE 153 ), confirming the opinion of Lamarck, as to the number of its valves, which are eight [ Lamarck (1802) described Chiton grinionensis from the Eocene of Grignon (Paris Basin) as: “ Chiton ( Grinionensis) octovalvis ?”]. Later authors still considered Chiton octovalvis as a valid taxon, until Wood (1872 –1874) observation that the species (“a single valve from Thorpe”) was not present in any known collection. This taxon should be, therefore, considered a species inquirenda.

“ Chiton ” angulosus S. Wood, 1842

Chiton angulosus S. Wood, 1842, p. 460 ; Bronn 1848, p. 291; de Rochebrune 1882, p. 70; Van Belle 1981, p. 20; Puchalski et al. 2008 (database: chiton fossil records).

Remarks. This species is reported by Wood (1842) from the Pliocene English Crag, without description. It has to be considered as a nomen nudum.

“ Chiton ” tenuisculptus S. Wood, 1842

Chiton tenuisculptus S. Wood, 1842, p. 460 ; Bronn 1848, p. 292; de Rochebrune 1882, p. 70; Van Belle 1981, p. 75; Puchalski et al. 2008 (database: chiton fossil records).

Remarks. This species is reported by Wood (1842) from the Pliocene English Crag, without description. It has to be considered as a nomen nudum.

“ Chiton ” subapenninus (Cantraine MS) de Ryckholt, 1845

Chiton subapenninus (Cantraine MS) de Ryckholt, 1845, p. 38 ; Bronn 1848, p. 292; Van Belle 1981, p. 74; Puchalski et al. 2008 (database: chiton fossil records).

Chiton subappeninus (sic); Baily 1859, p. 334; Baily 1860a, p. 92, 94; Baily 1860b, p. 44; Baily 1860c, p. 171.

Remarks. This species is reported for the first time by de Ryckholt (1845), from the “Upper Tertiary” ( Italy), and afterwards by Baily (1859; 1860a; 1860b; 1860c) that considered it conspecific with Chiton miocenicus (Michelotti) . This species is only mentioned in the literature without description. It is not reported by Cantraine (1835), and has to be considered a nomen nudum.