Leptoplax unica ( Nierstrasz, 1905 )

Sirenko, B. I., 2024, Molluscs of the genus Leptoplax (Mollusca: Polyplacophora) from Spratly Islands, South China Sea, Ruthenica, Russian Malacological Journal (Stockholm, Sweden: 1987) 34 (1), pp. 7-14 : 8

Leptoplax unica ( Nierstrasz, 1905)

( Figs 1-4 )

Acanthochites (Notoplax) unicus Nierstrasz, 1905: 62 , pl. 1 fig. 20, pl. 4, figs 115–117, pl. 5, fig. 118.

Leptoplax unica – Schwabe, 2006: 104, figs 1D, 6G-L, 8-10).

Type material. Holotype, ZMA 1899.05.07.

Type locality. Indone sia, 6°32’32’S, 120°25’34’’E, 8–10 m.

Material examined. South China Sea, Spratly Islands, 8°48’27’’N, 113°56’04’’E, 30 m, SCUBA, on old corals, 1 spm. ZIN 2572 , BL 18 mm, 25.05.2019, leg. B. Sirenko.

Distribution. Indonesia, Papua New Guinea and Spratly Islands, 2– 30 m.

Remarks. It is a rarely collected species, with a total of 6 known specimens. The specimen studied here is the first found in the Spratly Islands. This specimen, as well as the type specimen from Indonesia and the specimen studied by Schwabe [2006] from New Guinea, has a large number of slits on the tail valve. Its slit formula is 5/1/9. It has 11 gills on each side arrange from valve V to valve VII. The radula of this specimen is 3.0 mm long with 32 transverse rows of mature teeth. Ventral spicules are flattened with one or two oblique, irregular riblets which arranged on a lower side of the spicule.

Figures

FIG. 1. Leptoplax unica, South China Sea, Spratly Islands (ZIN 2572), BL 18.0 mm. РИС. 1. Leptoplax unica, Южно-Китайское море, острова Спратли (ZIN 2572) BL 18,0 мм.

FIG. 2. Leptoplax unica, ZIN 2572. A. Head valve, dorsal view.B. Valve II, dorsal view. C. Valve V, dorsal view.D. Valve VIII, dorsal view. E. Valve IV, ventral view. F.Valve V, tegmentum sculpture in pleurolateral area. G. Valve V, frontal view. H. Valve VIII, lateral view. I. Valve VIII, from behind. РИС. 2. Leptoplax unica, ZIN 2572. A. Головной Щиток, вид сверху. B. Щиток II, вид сверху. C. Щиток V, вид сверху. D. Щиток VIII, вид сверху. E. Щиток IV, вид сниЗу. F.Щиток V, скульптура тегментума на ролатеральном поле. G. Щиток V, вид спереди. H. Щиток VIII, вид сбоку. I. Щиток VIII, вид сЗади.