Chitons (Mollusca, Polyplacophora) from São Tomé and Príncipe Islands Author Dell’Angelo, Bruno Museo di Zoologia, Via Selmi 3, 40126 Bologna, Italy bruno.dellangelo@chitons.it Author Schwabe, Enrico Bavarian State Collection of Zoology, Münchhausenstrasse 21, 81247 München, Germany enrico.schwabe@zsm.mwn.de Author Gori, Sandro Via Sernesi 7, 57123 Livorno, Italy; Author Sosso, Maurizio Via Bengasi 4, 16153 Genova, Italy Author Bonfitto, Antonio Dipartimento di Scienze Biologiche, Geologiche e Ambientali (BiGeA), Via Selmi 3, 40126 Bologna, Italy; antonio.bonfitto@unibo.it text African Invertebrates 2014 2014-07-16 55 2 171 200 journal article 58582 10.5281/zenodo.7680891 0eaabf0d-5f07-4d53-aad2-9372ccac3303 2305-2562 7680891 B5CAA0D6-6F90-4311-899F-210544BFDCFF Rhyssoplax canariensis (d’Orbigny, 1839) Figs 9F–N Chiton canariensis : d’Orbigny 1839: 99 , pl. 7, figs 18–19; Gray 1854: 19; MacAndrew 1856: 117 ; Nierstrasz 1906: 515 ; Thiele 1909: 6; Lamy 1907: 151 ; Bergenhayn 1931: 18 , pl. 1, figs 30–33, pl. 3, fig. 66; Nickles 1950: 14 , fig. 3; Sourie 1954: 239 , 299; Marche-Marchad 1958: 11; Leloup 1968 a : 28; Sabelli & Spada 1970: 6 ; Fischer 1978: 43 ; Altimira & Ros 1979: 9 ; Bernard 1984: 122 , pl. 63; Poppe & Goto 1991: 60 , pl. 1, fig. 12; Slieker 2000: 32 , pl. 4, figs 39, 39a; Ardovini & Cossignani 2004: 18 , figs p. 58. Type material: NHMUK 1854.9.28.152, 3 Syntypes ( Figs 9H–J ). Type locality: Canary Islands . Chiton ( Lophurus ) canariensis : Shuttleworth 1853: 205 . Chiton ( Gymnoplax ) canariensis : Dautzenberg 1910: 108 ; 1912: 80. Chiton ( Rhyssoplax ) canariensis : Van Belle 1984 a : 101 , pl. 3; Strack 1987: 181 ; Gerber et al . 1989: 22 ; Kaas 1991: 94; Kaas et al . 2006: 156 , fig. 57 (chresonymy and synonymy); Rolán 2011: 50, figs 4I–T. Chiton lyratus Sowerby 1840 a : fig. 126 ( nom. nud .); 1840 b : 293; Reeve 1847 : pl. xviii, species 110; Pilsbry 1893: 184, pl. 31, figs 35–36; Nierstrasz 1906: 515 ; Tomlin & Shackleford 1915: 269; Fernandes & Rolán 1993: 33. Type material: NHMUK 1979176, 2 Syntypes ( Figs 9F–G ). Type locality: unknown (Prince Island, West Africa, fide Reeve 1847 ). Material examined: ST01: 2 specimens in alcohol, maximum length 11 mm ( ZSM Mol-20080400); ST02: 5 specimens , maximum length 20 mm ( Figs 9L, 9N ) ( BD 119 A); ST03: 38 specimens , maximum length 22 mm ( Figs 9K, 9M ) ( BD 119 B); ST03: 1 specimen in alcohol, length 21 mm ( ZSM Mol- 20071398 ), and 81 valves (14 head, maximum width 5 mm , 54 intermediate, maximum width 8 mm , and 13 tail, maximum width 4.2 mm ) ( BD 119 C, ER ); ST05 : 6 specimens , maximum length 13 mm ( BD 119 D); ST07: 3 specimens , maximum length 26 mm ( BD 119 E); ST09: 8 specimens in alcohol, maximum length 15 mm ( ZSM Mol-20040494); ST09: 3 specimens in alcohol, maximum length 14 mm ( ZSM Mol-20040503); ST10: 7 specimens in alcohol, maximum length 15 mm ( ZSM Mol-20034143); ST10: 1 specimen in alcohol, length 6 mm ( ZSM Mol-20034149); ST11: 10 valves (3 head, maximum width 3.5 mm , and 7 intermediate, maximum width 3.5 mm ) ( BD 119 F); PR 01: 5 specimens , maximum length 19 mm ( BD 119 G); PR 02: 2 specimens , maximum length 18.5 mm ( BD 119 H); PR 03: 1 specimen , maximum length 16 mm ( BD 119 I); PR 04: 1 specimen in alcohol, length 26 mm ( BD 119 J); PR 06: 11 specimens in alcohol, maximum length 21 mm ( ZSM Mol-20040208); PR 07: 9 intermediate valves, maximum width 7.2 mm ( BD 119 K) . Fig. 6. (A–F) Lepidochitona rolani Kaas & Strack, 1986 , São Tomé and Príncipe Islands: (A) complete specimen from ST06, (B–D) PR07, intermediate valve, (B–C) dorsal and frontal views, (D) detail of the sculpture, (E–F) ST11, tail valve, (E) dorsal view, (F) detail of the sculpture; (G–L) Acanthochitona crinita ( Pennant, 1777 ) , São Tomé Island, ST03, intermediate valve: (G–I) dorsal, lateral and frontal views, (J) detail of the sculpture, (K–L) detail of granules in different views. Scale bars = 1 mm (A, B, E); 800 μm (G, I); 600 μm (H); 200 μm (F); 100 μm (D, J); 80 μm (L); 60 μm (K). Distribution: Rhyssoplax canariensis is a common subtidal species, reported from the Canary Islands and western Africa, from Morocco to Angola ( Kaas et al . 2006 ), and the São Tomé and Príncipe Islands. It does not occur in the Cape Verde and Madeira archipelagos except for one report from Porto Santo, Madeira, as a Pleistocene fossil ( Gerber et al . 1989 ). Comparison and remarks: Chiton lyratus is considered a synonym of Rhyssoplax canariensis , as already reported by Pilsbry (1893: 184). Syntypes of both taxa are illustrated ( Figs 9F–G, 9H–J ). The examination of the 100 valves found gives a slit formula of 8–9 / 1 / 10–13 vs. 8 / 1 / 7–11, reported by Kaas et al . (2006) , which can be considered to be within the range of acceptable variation for a common and widely-distributed species. Only one intermediate valve with 2 slits on the right side was found, out of a total of 70 intermediate valves checked. A unique head valve from ST03 has a shell scar due to injury, which caused the development of a new insertion plate under the older one in the articulamentum.