Tonicia fremblyana, KAAS, 1957

Ibáñez, Christian M, Eernisse, Douglas J, Méndez, Marco A, Valladares, Moises, Sellanes, Javier, Sirenko, Boris I & Pardo-Gandarillas, M Cecilia, 2019, Phylogeny, divergence times and species delimitation of Tonicia (Polyplacophora: Chitonidae) from the eastern Pacific Ocean, Zoological Journal of the Linnean Society 186 (4), pp. 915-933 : 925-926

TONICIA FREMBLYANA KAAS, 1957

( FIG. 4 )

Chiton lineolatus Frembly, 1827: 204 , suppl. pl. 17, fig. 8, non Chiton lineolatus de Blainville, 1825 .

Tonicia elegans f. lineolata ; Leloup, 1956: 75, figs 44–46 (bibliography).

Tonicia fremblyana Kaas, 1957: 84 (nom. nov.pro Chiton lineolatus Frembly, 1827 , non de Blainville, 1825.

Type material repository: British Museum of Natural History ( BMNH) .

Type locality: Valparaiso, Chile .

Description of T. fremblyana

Medium-sized body, ≤ 40 mm in length ( Table 2); oval, with low elevation (dorsal elevation 0.24). Valves subcarinated, with side slopes weakly convex. Tegmentum brown coloured, closely and finely marked with numerous undulating, concentric brown lines. Sometimes parts of some or all valves are dark brown. Head valve semi-circular; posterior margin widely V-shaped; tegmentum with small granules. Ocelli small, black and with random distribution. Intermediate valves with wavy anterior margin that somewhat slants towards the more-or-less rounded side margin. Posterior margin weakly concave at both sides of the blunt apex. Lateral areas slightly raised; sculptured like the head valve. Central area with several short, bent, narrow grooves on both sides of the smooth jugum. Rare small granules in pleural areas. Tail valve less than semi-circular; slightly smaller than the head valve. Front margin strongly convex. Antemedian mucro slightly raised (ratio of the length of the postmucronal area to the length of the antemucronal area is 1.9). Hind slope slightly concave near the mucro, then straight. Antemucronal area sculptured like central areas; postmucronal area like head valve. Articulamentum whitish; sutural laminae very wide and short, inequilaterally triangular. Sinus narrow and has a short, dentate (eight to ten teeth) jugal plate. Slit formula 8/1/9. Slits shallow and slit rays finely indicated. Teeth short, deeply pectinated. Girdle moderately wide (ratio of the width of valve V to the width of the girdle near the valve 2.7–3.2), leathery. Naked to the eye; dorsally, bears small, sharply pointed spicules implanted in the cuticula without any particular order. Marginal spicules small, round-topped; ventral part of the girdle covered with radiating rows of subquadrangular scales. Radula of a specimen with a body length of 12 mm is 6.4 mm long and has 39 transverse rows of mature teeth. Narrow central tooth with a long blade; major lateral teeth with unicuspid head. Gills spanning from valve II to valve VIII; 37 on each side of a specimen with body length of 12 mm.

Remarks

Tonicia fremblyana is very similar in colour to T. swainsoni , but differs from the latter in having short, bent ribs near the jugum (vs. longitudinal ribs in T. swainsoni ). The head valve, lateral areas and postmucronal area have small, rare granules (vs. having radiating ribs in T. swainsoni ). Tonicia fremblyana differs from other Tonicia species by having a few short, narrow grooves on both sides of the jugum. Additionally, it has undulating, concentric lines on the tegmentum of intermediate valves and it has a short antemucronal area.

Distribution: Tonicia fremblyana is found from Ancón ( Peru, ~ 11°S) to central Chile (Pichilemu, ~ 34°S).

Figures

Figure 4. Pictures oflive specimens ofTonicia.A,Tonicia chilensis (southern ecotype), Huinay (~41°S).B, Tonicia calbucensis (southern ecotype), Huinay (~41°S). C, Tonicia chilensis, Ventanas (~33°S). D, Tonicia disjuncta, Los Vilos (~32°S). E, Tonicia calbucensis (northern ecotype), Coquimbo (~29°S). F, Tonicia fremblyana, Arica (~18°S). G, Tonicia forbesii, Baja California (~24°N). H, Tonicia lebruni, Punta Arenas (~53°S). I, Tonicia disjuncta, Huinay (~41°S).