Leptochiton ferreirai Sirenko & Sellanes, 2016, sp. nov.

Leptochiton ferreirai sp. nov.

(Figs 15–17)

LSID [urn:lsid:zoobank.org:act:DA338971-2C33-42A1-B16A-8FD3B9718C84]

Type material. Holotype (MNHNCL 400189) now disarticulated consisting of SEM stub of valves I, IV, V, part of perinotum and radula, mount of part of perinotum and radula and vial with other valves.

Type locality. Off Chile, 46.55216°S, 75.34852°W, 460 m.

Etymology. Named in honor of the late Dr. Antonio J. Ferreira, from the Department of Invertebrate Zoology of the California Academy of Sciences, who made a major contribution to the knowledge of polyplacophorans.

Material examined. Holotype BL—5.0 mm, Off Chile, 46.55216°S, 75.34852°W, 460 m depth. RV Melville, st. INSPIRE, AGT-1_594, 0 6.03.2010.

Distribution. Only known from the type locality.

Diagnosis. Animal small. Valves moderately elevated, rounded, not beaked. Lateral areas not raised. Tail valve with mucro anterior. Central areas with about 28 almost longitudinal vague rows of weakly raised, oval granules. Each granule with one megalaesthete and four, rarely two, micraesthetes. Dorsal scales wide, obtusely pointed, with 9–11 distinct ribs. Radula with numerous transverse rows of very small teeth. Central teeth narrow, first lateral teeth narrow and long, major lateral teeth with long tridentate cusp. Seven gills per side.

Description. 5.0 x 2.4 mm. Shell elongate-oval, moderately elevated (elevation ratio in valve V 0.35). Valves thin, rounded, not beaked. Color of tegmentum white.

Head valve semicircular, wider than tail valve. Intermediate valves broadly rectangular, short and wide, anterior and posterior margins nearly straight, not beaked, lateral margins rounded. Lateral areas not raised. Tail valve broken with anterior mucro.

Tegmentum sculptured with weakly raised oval granules arranged in almost longitudinal vague rows in central area of intermediate valves and quincuncially in other areas. Each granule has one megalaesthete and four (rarely two) micraesthetes. Aesthete pores very small and roughly equal in size.

Articulamentum weakly developed, apophyses small and widely separated.

Girdle very narrow, covered with wide and obtusely pointed dorsal scales (39– 48 x 29 –32 µm) with 9–11 distinct ribs. Those near valves longer (65 x 26 µm). Sutural needles (143 x 13 µm), long and smooth. Marginal spicules elongate with 6 distinct ribs arranged around the spicule. Ventral scales in central part sharply pointed, smooth (56 x 16 µm).

Radula 1.7 mm long with about 140 transverse rows of mature very small teeth. Central teeth narrow, first lateral teeth elongated, major lateral teeth with long tridentate cusp, central denticle largest, side denticles arranged on different height.

Seven gills per side arranged from end of valve VI to anus.

Remarks. Leptochiton ferreirai sp. nov. is similar to L. linseae Sirenko, 2015, but differs by having 9–11 ribs on dorsal scales (vs. 16–17 in L. linseae), five (rarely three) aesthete pores in each aesthete group (always three in L. linseae). The new species is also similar to L. compostellanum Carmona Zalvide & Urgorri, 1999 and L. sanmatiensis Güller, Liuzzi & Zelaya, 2015, but differs from them by having 9–11 ribs in dorsal scales (14–15 ribs in L. sanmatiensis and 15–20 ribs in L. compostellanum) and the shape of the cusp of the major lateral teeth of radula with side denticles arranged at a different level (side denticles arranged in equal level in L. sanmatiensis and L. compostellanum. Moreover L. ferreirai sp. nov. differs from L. sanmatiensis by having the tail valve narrower than the head valve (head and tail valve of equal width in L. sanmatiensis). Leptochiton ferreirai sp. nov. differs from L. peruvianus in having 5 aesthete pores in each aesthete group (vs. 7 in L. peruvianus) and 7 gills arranged from valve VI to anus (vs. 11 gills arranged from valve V to anus).