Ischnochiton cf. rissoi ( Payraudeau, 1826 )

Dell’Angelo, Bruno, Schwabe, Enrico, Gori, Sandro, Sosso, Maurizio & Bonfitto, Antonio, 2014, Chitons (Mollusca, Polyplacophora) from São Tomé and Príncipe Islands, African Invertebrates 55 (2), pp. 171-200 : 176

Ischnochiton cf. rissoi ( Payraudeau, 1826)

Figs 2I–K

Chiton rissoi: Payraudeau 1826: 87 , pl. 3, figs 4–5.

Ischnochiton (I.) rissoi: Kaas & Van Belle 1990: 78 , fig. 32; Dell’Angelo & Smriglio 1999: 100, pls 29–31, figs 40–48. Syntype:MNHN 6109 (not seen). Type locality: France, Bonifacio , Corse (41°23'10"N 09°09'31"E).

Material examined: ST06: 1 specimen, length 1.3 mm ( BD 107 ) .

Distribution: São Tomé Island.

Comparison and remarks: The single available specimen shares with Ischnochiton rissoi a similar tegmental sculpture and dorsal girdle scales. I. rissoi varies considerably in size and sculpture ( Carmona Zalvide & García 1999; Dell’Angelo & Smriglio 1999). The sculpture of the specimen examined is similar to the “forma 4” described by Carmona Zalvide and García (1999), from the Gibraltar area. The minute size of the specimen and the fact that the nominal species has so far not been reported from the African Atlantic coast, led us to the tentative identification. I. rissoi is typically Mediterranean, and recorded from the Atlantic only in the vicinity of Gibraltar. Records from the Canary Islands ( Shuttleworth 1853; Bergenhayn 1931) as well as the Selvagens and Azores Islands ( Bergenhayn 1931) require confirmation.

Figures

Fig. 2. (A–D) Leptochiton denhartogi Strack, 2003, São Tomé Island, ST03, intermediate valve: (A–B) dorsal and frontal views, (C–D) detail of the sculpture of the tegmentum, close-ups of granules with aesthetes in different views; (E–H) Leptochiton sp., São Tomé Island, ST11, tail valve: (E–F) dorsal and lateral views, (G–H) detail of the sculpture of antemucronal and postmucronal areas, respectively; (I–K) Ischnochiton cf. rissoi (Payraudeau, 1826), São Tomé Island, specimen from ST06: (I) dorsal view, (J) dorsal girdle scales, (K) detail of the intermediate and tail valves; (L–Q) Ischnochiton sp., SãoTomé Island, specimen from ST06:(L–M) dorsal and lateral views,(N) detail of thehead and the first intermediate valves, (O–P) detail of the sculpture of central and lateral areas, respectively, (Q) dorsal girdle scales.Scale bars = 1 mm (B); 800 μm (I); 600 μm (A); 500 μm (E); 400 μm (L, M); 300 μm (F, K); 200 μm (N); 100 μm (J); 60 μm (G, H); 50 μm (D); 40 μm (C); 30 μm (P); 20 μm (O, Q).