Notoplax sp.

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 : 191

Notoplax sp.

Figs 8G–J

Description:

Intermediate valve beaked, tegmentum a little wider than long, very reduced in the anterior portion, with anterolateral margins sinuose in the upper part, almost straight and obliquely directed in the lower one; sutural laminae very large, separated anteriorly by a wide sinus; lateral margins oblique, with a single slit. Jugum well defined, raised, smooth, separated from the latero-pleural areas. Lateral and pleural areas with similar sculpture of irregularly rounded pustules.

Material examined: ST03: 1 intermediate valve, width 2.8 mm (BD 121).

Distribution: São Tomé Island.

Comparison and remarks: The reduced tegmentum, the very large insertion plates, the pustulose sculpture of the lateropleural areas, and the well defined and narrow jugum support our tentative assignment of this unique intermediate valve to the genus Notoplax , as redefined by Gowlett-Holmes (1991).

Our tentative assignment of this valve to Notoplax greatly extends the distribution of the genus, considered to be restricted to Australia and New Zealand by GowlettHolmes (1991), but already widened to Japanese waters by Saito (1995, 1997, 2005 for Notoplax hilgendorfi Thiele, 1909 ), and Saito (1998, 2004 for Notoplax sp. ), and to South Vietnam by Sirenko (2012 for Notoplax sp. ).

Some species with a similar wing-shaped tegmentum, to date attributed to Acanthochitona , are known, e.g. A. rhodea (Pilsbry, 1893) from the Caribbean coasts of Costa Rica, Panama and Colombia, and A. mastalleri Strack, 1989 from the Red Sea, Oman and Kenya. However, both have a different tegmental layout ( Lyons 1988: fig. 12; Strack 1989: pl. 19, fig. 2).

This valve may belong to an undescribed species, but additional material is needed to give a complete description of the species.

Figures

Fig. 8. (A–F) Craspedochiton productus (Carpenter in Pilsbry, 1892) from South Africa (NSMT-Mo 72867), specimen disarticulated:(A–B) head valve,width 11.2 mm, dorsal and ventral views, (C–D) intermediate valve, width 13.1 mm, dorsal and ventral views, (E–F) tail valve, width 9.1 mm, dorsal and ventral views; (G–J) Notoplax sp., São Tomé Island, ST03, intermediate valve: (G–I) dorsal, frontal, and ventral views, (J) detail of the sculpture. Scale bars = 800 μm (G); 600 μm (H); 500 μm (I); 80 μm (J).