Connexochiton solomonicus, Sirenko, 2021

Sirenko, Boris, 2021, Composition of the genus Connexochiton Kaas, 1979 (Mollusca: Polyplacophora Ischnochitonidae), Zootaxa 4950 (1), pp. 83-102 : 95-97

publication ID	https://doi.org/ 10.11646/zootaxa.4950.1.4
publication LSID	lsid:zoobank.org:pub:5277A7B7-8AFC-4BC0-976D-B63C74963FC8
DOI	https://doi.org/10.5281/zenodo.4643436
persistent identifier	https://treatment.plazi.org/id/038987E3-FF9D-FFA9-FF30-FC99FA5B4621
treatment provided by	Plazi
scientific name	Connexochiton solomonicus
status	sp. nov.

Treatment

Connexochiton solomonicus View in CoL n. sp.

( Figs. 12–14 View FIGURE 12 View FIGURE 13 View FIGURE 14 )

Type material. Holotype (MNHN-IM-2007-17458) ( BL 3.5 mm) now disarticulated, consisting of SEM stub of valves I, II, V, VIII, part of perinotum and radula, mount of part of perinotum and radula and vial with other valves.

Type locality. Solomon Islands 7°54.8’S 156°52.6’E, 537–590 m (SALOMON 2, stn DW2265, 04.11.2004, leg. P. Bouchet, A. Waren, S. Samadi) GoogleMaps .

Etymology. Named after Solomon Islands.

Distribution. Known only from the type locality.

Diagnosis. All intermediate valves are subcarinate and of different lengths: valve II and valve III are longer than others, width of valve IV is 2.5 times greater than its length. Valves sculptured by convex triangular granules arranged in quincunx and forming a lacy pattern. Each granule with 11 pores of aesthetes. Pores of megalaesthetes 6 µm in diameter. Mucro of tail valve anterior. Dorsal scales wide, bent, imbricating, sculptured with large globular spherules with rough surface texture, arranged in quincunx pattern, diameter of spherules diminishes towards proximal edge. Central teeth of radula narrow, elongated, major lateral teeth with unidentate sickle-shaped cusps, base of cusp almost as long as denticle.

Description. Small size, BL 3.5 mm, back subcarinated in all intermediate valves, dorsal elevation rather low (0.34) in valve V, valves not beaked, color of tegmentum white.

Head valve semicircular, posterior margin widely V-shaped and noticeably larger than tail valve. Intermediate valves trapezoidal, valves II and III longer than others, lateral areas narrow and strongly raised. There is a shallow groove between the central and lateral areas of intermediate valves and anterior and posterior areas of the tail valve. Tail valve with anterior mucro, anterior margin straight, antemucronal and postmucronal slope straight.

Tegmentum evenly sculptured by convex triangular granules arranged in quincuncial lacy-like pattern. Granules in central areas not overlapping each other. Each granule with 11 pores of aesthetes. Pores of megalaesthetes 6 µm in diameter, pores of micraesthetes about 2–3 µm in width.

Articulamentum thin, apophyses short, roundish to trapezoidal, connected by short jugal plate, slit formula 12/1/8, slits short, slit rays indistinct, teeth blunt.

Girdle of moderate width, covered with wide, bent, imbricating scales 70 x 80 µm, sculptured with large, globular spherules with rough surface texture arranged in quincunx pattern, closer to each other than in other species of Connexochiton , diameter of spherules diminishes towards proximal edge. Marginal scales sharply pointed 100 x 30 μm, with 5–6 longitudinal ribs on dorsal side. Two rows of ventral scales near margin; scales 50 x 18 µm with two short ribs, other ventral scales rectangular and smooth 40 x 15 µm.

Seven gills arranged from valve V to valve VII on each side.

Radula 1.0 mm long with 72 transverse rows of mature teeth, central tooth narrow, elongated, major lateral teeth with unidentate sickle-shaped cusps, base of cusp is almost the same length as denticle.

Remarks. Connexochiton solomonicus n. sp. differs from other species of the genus by having globular spherules arranged in quincunx pattern on dorsal scales and in that the diameter of the spherules diminishes towards the proximal edge. This species differs from other species of the genus except C. kermadeci by having intermediate valves of different lengths. In Connexochiton solomonicus , the base of the cusp of the major lateral tooth has almost the same length as the denticle. However, the base of the cusp is much shorter than the denticle in C. kermadeci .