Leptochiton cf. opiparus (Iredale & Hull, 1925)

Sirenko, Boris, 2020, New Zealand and Australian species of the genus Leptochiton (Mollusca Polyplacophora), Zootaxa 4851 (3), pp. 401-449 : 426-427

Leptochiton cf. opiparus (Iredale & Hull, 1925)

( Figures 32–35 , 44A, B )

Material examined. New Zealand, Kermadec Islands , NNE of Herald Islets, Raoul Island, 29°12.00’S, 177°49.30’W, R / V Acheron , stn 1973312, 1188– 1225 m, 1 spm, BL 16 mm ( NMNZ M 222132 ), 05.04.1973 .

Remarks. This specimen from Kermadec Islands belongs to the group of Leptochiton belknapi as characterized by Sirenko (2015). The sculpture and shape of the valves of the present specimen are very similar to the description of L. opiparus given by Iredale & Hull (1925). The current identification is tentative as a conclusive decision will only be possible after a detailed study of the nominal species. The present specimen has 13 gills on both sides. The whole tegmentum is sculptured with small quincuncially arranged granules. Each granule has five aesthetes. The dorsal girdle scales show several very weak riblets. The radula has a broad central tooth and a unidentate cusp of the major lateral tooth with a very small rudiment of an inner denticle. The specimen differs from L. belknapi by having five aesthetes in each granule (vs. three in L. belknapi ), several very weak riblets at the dorsal girdle scales (vs. 1–3 distinct ribs in L. belknapi ).

The specimen from Kermadec is similar to L. sigwartae Sirenko, 2015 and L. mutschkeae Sirenko, 2015 (both from off Chile) but differs from L. sigwartae by having a convex anterior margin of intermediate valve (vs. concave in L. sigwartae ), wide dorsal girdle scales with several very weak riblets (narrow scales with two distinct ribs in L. sigwartae ), the head valve wider than the tail valve (vs. head valve narrower than tail valve in L. sigwartae ).

The Kermadec specimen differs from L. mutschkeae by having a major lateral tooth with a big, unicuspid head with a very small rudiment of an inner denticle (vs. without rudiment at inner edge in L. mutschkeae ), several very weak riblets in dorsal girdle scales (vs. 2 ribs in L. mutschkeae ).

Figures

FIGURE 32. Leptochiton cf. opiparus, New Zealand, Kermadec Islands, NNE of Herald Islets, Raoul Island, BL 16 mm, (NMNZ M 222132). A. Valve I, dorsal view; B. Valve V, dorsal view; C. Valve VIII, dorsal view; D. Valve V, tegmentum sculpture in central area; E. Valve V, rostral view; F. Valve VIII, lateral view.

FIGURE 33. Leptochiton cf. opiparus, New Zealand, Kermadec Islands, NNE of Herald Islets, Raoul Island, BL 16 mm, (NMNZ M 222132), A. Dorsal and ventral scales; B. Dorsal scales; C. Dorsal scales near suture; D. Marginal needle, dorsal and ventral scales.

FIGURE 34. Leptochiton cf. opiparus, New Zealand, Kermadec Islands, NNE of Herald Islets, Raoul Island, BL 16 mm, (NMNZ M 222132). A. Central portion of radula from anterior part; B. Central and first lateral tooth of radula.

FIGURE 35. Leptochiton cf. opiparus, New Zealand, Kermadec Islands, NNE of Herald Islets, Raoul Island, BL 16 mm, (NMNZ M 222132). A. Sutural needle; B, C. Dorsal scales; D. Marginal needle; E. Ventral scale from mid-girdle; F. Central and first lateral teeth; G. Head of major lateral tooth; H. Aesthete group in central area. Scale bar 100 μm (A–G).

FIGURE 44. Images of species of genus Leptochiton from New Zealand and Australia: A, B. L. cf. opiparus, New Zealand, Kermadec Islands, R/V Acheron, stn 1973312, 1188-1225 m, BL 16 mm, (NMNZ M 222132); C, D. L. marshalli n. sp., holotype, New Zealand, Three Kings Islands, Tasman Bay, Great Island, 6 m, BL 10.0 mm, (NMNZ M 117376); E, F. L. subantarcticus, New Zealand, Head of Pegasus Canyon, Pegasus Bay, 446 m, mud, BL 5.5 mm, (NMNZ M 152576); G, H. L. cf. laurae, New Zealand, South Island, SSE of Kaikoura, R/V James Cook, stn 1986020, 927–995 m, BL 10.5 mm, (NMNZ M 319764).