Thecidellina Thomson, 1915

Bitner, Maria Aleksandra, 2008, New data on the recent brachiopods from the Fiji and Wallis and Futuna islands, South-West Pacific, Zoosystema 30 (2), pp. 419-461 : 451

Genus Thecidellina Thomson, 1915

TYPE SPECIES. — Thecidium barretti Davidson, 1864 by original designation ( Thomson 1915: 462).

Thecidellina maxilla ( Hedley, 1899) ( Fig. 19 A-C)

Thecidea maxilla Hedley, 1899: 508-510 , fig. 57.

Thecidellina maxilla – Dall 1920: 283. — Thomson 1927: 140. — Cooper 1954: 317, pl. 81, figs 1-10. — Zezina 1985: 208. — Laurin 1997: 453, 454, fig. 40a, b. — Lee & Robinson 2003: 350-352, figs 28-35. — Bitner 2007: 498, 499, fig. 3a-h.

Thecidellina cf. T. maxilla – Cooper 1964: 1118, pl. 301, figs 15, 16, 18, 19.

MATERIAL EXAMINED. — Wallis. MUSORSTOM 7, stn DW 604, 1 ventral valve.

Fiji. MUSORSTOM 10, Bligh Water, stn DW 1333, 1 complete specimen, 4 dorsal valves.

BORDAU 1, Lau Ridge, stn DW 1463, 1 ventral valve.

DEPTH RANGE. — 200- 420 m.

MEASUREMENTS. — Length 6.0 mm, width 4.3 mm.

REMARKS

Thecidella maxilla is widely distributed in the Pacific Ocean ( Thomson 1927; Cooper 1954; Pajaud 1970; Laurin 1997; Lee & Robinson 2003; Bitner 2007). This is a small species that reaches 6 mm of length in the investigated material. The interarea is triangular with distinct transverse growth lines and no trace of a pseudodeltidium. No septum is observed in the ventral valve. The dorsal valve is subcircular with long median septum. The rim is strongly tuberculate.

Thecidella maxilla is a shallow water species ( Lee & Robinson 2003). The material from Fiji, collected at the depth of 200-420 m is dead and might have been redeposited from shallower water.

The specimens of Thecidellina sp. from the Miocene of Fiji, illustrated by Cooper (1978) are very close to T. maxilla .

Figures

FIG. 19. — A-C, Thecidellina maxilla (Hedley, 1899), Fiji; A, dorsal view of complete specimen (MNHN BRA-3120), Bligh Water; MUSORSTOM 10, stn DW 1333, 200-215 m;B, inner view of dorsal valve (MNHN BRA-3121),Bligh Water, MUSORSTOM 10, stn DW 1333, 200-215 m; C, inner view of ventral valve (MNHN BRA-3122), Lau Ridge, BORDAU 1, stn DW 1463, 300-400 m; D, E, Megerlia truncata (Linnaeus, 1767), Wallis and Futuna, ventral and dorsal views of complete specimen (MNHN BRA-3061), MUSORSTOM 7, stn DW 525, 500-600 m. All SEM. Scale bars: A, 1 mm; B-E, 2 mm.