Choneplax indica Odhner, 1919

Schwabe, Enrico, 2004, The Polyplacophora (Mollusca) collected during the First International Marine Biodiversity Workshop for Rodrigues (western Indian Ocean), with the description of a new species, Journal of Natural History 38 (23), pp. 3143-3173 : 3160-3163

Choneplax indica Odhner, 1919

( figures 11–13 , 17D ) Choneplax indicus Odhner, 1919: 40 ; pl. 3, figures 44, 45; Ashby, 1928: 92; 1931: 53;

Bergenhayn, 1931: 3, pl. 1, figures 5–9 ; Winckworth, 1933: 319; Kaas and Van

Belle, 1980: 63; 1998: 95; Leloup, 1981a: 19; Kaas, 1985a: 331, 339; 1986: 20,

figures 62–72; Slieker, 2000: 50, pl. 13, figure 32; Sirenko, 2003: 33, 35, figure 1I .

Type. Holotype ( SMNH 1324 , indicated as syntype).

Type locality. Tamatave , Madagascar .

Material examined. 7 spms, 3.2 6 1.8 mm, ca 9.9 6 2.5 mm (curled) (pd), 3 6 1.2 mm, 2.7 6 1.2 mm, 4.7 6 1.9 mm, ca 5.7 6 1.9 mm (curled), ca 6 6 1.7 mm (curled): RDS 35, Grande Baie, 21.5 m, leg. N. Bruce; 3 spms, 5.7 6 1.6 mm, 5.9 6 1.8 mm, ca 6.3 6 2.1 mm (curled): RDS 32, Grand Pate´, 17.5 m, leg. N. Bruce; 1 spm, ca 10.3 6 3.3 mm (curled): RDS 31, Grand Pate´, 13–15 m, leg. N. Bruce.

Description

Animal elongate and nearly worm-like ( figure 17D ). Tegmentum finely granulated all over, except for smooth jugal area ( figure 11A–D ). The perinotum is densely covered with fine spicules and large tufts of longer needles.

Tegmentum. Head valve with very large, all-over granulated tegmentum. Granules arranged in quincunx ( figure 11A ). In intermediate valves granules arranged in longitudinal lines in pleurolateral areas and end without overlapping along the smooth (sculptured by numerous fine pores), wedge-shaped jugum ( figure 11B, C ). Mucro of tail valve is situated terminally, not elevated and inconspicuous ( figure 11D ). Postmucronal area lacking and ‘antemucronal area’ sculptured like intermediate valves, but the jugum is less wedge-shaped. Macroaesthetes of granules are situated posteriorly and surrounded by five microaesthetes ( figure 11C ).

Articulamentum. White, very thin and fragile. Slit formula: 3/0/0, slits in head valve very short. Slit rays visible in head valve only. Apophyses of intermediate valves rather large and triangular, and directed laterally, those of tail valve much shorter and closer to each other.

Perinotum. Rather wide, dorsally densely covered with small (62–72.5 6 13.8–15 M m), elongate, longitudinally ribbed spicules ( figure 12A, B, E ). Among them, larger (154.6–245.5 6 16.4–20 M m), flat, straight and longitudinally ribbed spicules may be found (often arranged in groups) ( figure 12A, B ). They are longer than the needles, which are arranged in the 18–20 tufts in groups of about 15 per tuft, which measure 163.6–216.7 6 36.4–43.6 M m ( figure 12A ). Along the margin, there are short spicules (40.9 6 10.2 M m), which are distinctly ribbed in their upper part ( figure 13B ). Ventrally, the girdle shows long, sharp-pointed, flat, smooth scales, 44.6–58.2 6 7.8 M m in size ( figure 13C, D ).

Radula. The disarticulated specimen has 38 rows of teeth, of which 27 are mineralized. Central tooth very short and stout, with a single, forward-projected blade and a transversal slit above the sharp-keeled shaft. First lateral tooth large and covers nearly completely the central one. Posteriorly it extends sidewards, whereas it is upward directed in the anterior portion ( figure 11E, F ). Major lateral tooth has a long shaft that is deeply grooved laterally. Head of the major lateral tooth tricuspid, with the denticles of nearly the same size. It is supported

by a slender, long spatulate uncinal tooth, which has a spoon-like, forwarddirected blade ( figure 11E ).

Ctenidia . The wet preserved holotype (flattened, valves I, VzVIII missing; 9.7 6 2.7 mm) has 11 merobranchial and abanal ctenidia on the right side. Those from left side are inchoate.

Figures

FIG. 11. Choneplax indica Odhner, 1919. (A) Dorsal view of head valve; (B) dorsal view of second valve; (C) close-up of the second valve, left pleural area, right jugal area; (D) dorsal view of the tail valve; (E) radula; (F) close-up of the central tooth. Scale bars: 500 Mm (A, D); 1 mm (B); 50Mm (C); 100 Mm (E); 20 Mm (F).

FIG. 12. Choneplax indica Odhner, 1919. (A) Dorsal girdle elements along the valve margin in situ; (B) dorsal girdle tuft; (C, D, F) isolated spicules from dorsal girdle tufts; (E) isolated dorsal girdle spicules from mid-girdle. Scale bars: 100Mm (A, C–F); 200 Mm (B).

FIG. 13. Choneplax indica Odhner, 1919. (A) Isolated dorsal girdle spicule from valve margin; (B) isolated dorsal girdle spicule from margin; (C, D) ventral girdle scales in situ. Scale bars: 50 Mm (A, C, D); 20Mm (B).

FIG. 17. (A) Parachiton hylkiae mauricejayi Schwabe, 2002, complete animal, posteriorlateral view (length: 7 mm); (B) Callochiton deshayesi Thiele, 1909, complete animal, dorso-lateral view (length: 2.5 mm); (C) Callistochiton barnardi Leloup, 1981, complete animal (now partly disarticulated), dorsal view (length: 4.2 mm); (D) Choneplax indica Odhner, 1919, complete animal, dorso-lateral view (length: 5.7 mm); (E) Cryptoconchus oliveri n. sp., paratype, complete specimen, dorsal view (length: 15.6 mm); (F) Onithochiton maillardi (Deshayes, 1863), complete specimen, dorsal view (length: 15.7 mm); (G, H) Lucilina indica (Leloup, 1981): (G) complete specimen, dorsal view (length: 5.8 mm); (H) holotype, partly dissected specimen, dorsal view (length: 8 mm).

FIG. 5. Callistochiton barnardi Leloup, 1981. (A) Dorsal view of head valve; (B) dorsal view of second valve; (C) dorsal view of tail valve; (D) lateral view of tail valve; (E) radula; (F) radula, close-up of central tooth. Scale bars: 1 mm (A–C); 500Mm (D); 100 Mm (E); 50 Mm (F).

FIG. 6. Callistochiton barnardi Leloup, 1981. (A) Dorsal girdle scales in situ; (B) dorsal girdle scales, margin; (C, E) dorsal-marginal view of girdle, close-up of the tips of clapper; (D) dorsal-marginal view of girdle to show needle in situ; (F) ventral girdle scales in situ. Scale bars: 100 Mm (A, B); 25 Mm (C); 50 Mm (D–F).

FIG. 7. Lucilina indica (Leloup, 1981). (A) Dorsal view of head valve; (B) dorsal view of second valve; (C) dorsal view of tail valve; (D) lateral view of tail valve; (E) close-up of postmucronal area to show the lenses of macroaesthetes; (F) radula. Scale bars: 1 mm (A–C); 500Mm (D); 20Mm (E); 100 Mm (F).

FIG. 8. Lucilina indica (Leloup, 1981). (A) Close-up of central tooth of radula; (B) dorsal girdle spicules, in situ; (C) dorsal-marginal girdle, flattened marginal spicules in situ; (D) dorsal girdle scales in situ, close-up; (E) ventral girdle scales in situ; (F) ventral girdle scales, close-up to show the scale sculpture. Scale bars: 50Mm (A, C, E, F); 10 Mm (B); 20 Mm (D).

FIG. 9. Onithochiton maillardi (Deshayes, 1863). (A) Dorsal view of head valve; (B) detail of head valve, to show the lense of macroaesthetes; (C) dorsal view of the second valve; (D) dorsal view of tail valve; (E) lateral view of the tail valve; (F) dorsal girdle elements in situ. Scale bars: 1 mm (A, C, D); 30 Mm (B); 500 Mm (E); 200Mm (F).

FIG. 1. Parachiton hylkiae mauricejayi Schwabe, 2002. (A) Piece of head valve, dorsal view; (B) close-up of head valve, to show the granules of the radial ribs and the arrangement of the aesthetes; (C) left half of the second valve, dorsal view; (D) close-up of the longitudinal ribs of the pleural area to show the arrangement of the aesthetes; (E) second valve, ventral view of the right half to show the pores of the articulamentum; (F) tail valve, dorsal view. Scale bars: 1 mm (A, C, F); 20 Mm (B); 100 Mm (D); 500 Mm (F).