Dyscolia johannisdavisi (Alcock, 1894)

Bitner, Maria Aleksandra, 2009, Recent Brachiopoda from the Norfolk Ridge, New Caledonia, with description of four new species, Zootaxa 2235, pp. 1-39 : 11

Dyscolia johannisdavisi (Alcock, 1894)

( Fig. 6 E, F)

This rare species was represented only by a single dorsal valve from Éponge seamount ( Tables 1, 2) at 707– 777 m ( Fig. 14 ) ( Norfolk 2 cruise). This constitutes the first record from the Norfolk Ridge. Dyscolia johannisdavisi is one of the largest extant brachiopods ― the present valve is 52.7 mm long. In addition to its characteristic large size, the lateral and anterior valve margins are strongly incurved ( Fig. 6 F) and the loop is very short.

Dyscolia johannisdavisi was considered to be restricted to the Indian Ocean ( Helmcke 1940; Muir-Wood 1959; Cooper 1983; Hiller 1986, 1994; Zezina 1994) until Laurin (1997) recognized it in the area of New Caledonia and the Chesterfield Islands.

Figures

FIGURE 14. Depth ranges of particular brachiopod species collected during the Norfolk 1 and Norfolk 2 cruises to the Norfolk Ridge, New Caledonia.

FIGURE 6. A – D, Xenobrochus australis Cooper, 1981, Norfolk Ridge, Norfolk 2 Stn DW 2081, 500 – 505 m, SEM; A, dorsal view of complete specimen, MNHN BRA- 3139, B – D, inner view of dorsal valve, enlargement (C) and oblique (D) views of posterior part to show details of brachial skeleton, MNHN BRA- 3140. E, F, Dyscolia johannisdavisi (Alcock, 1894), Norfolk Ridge, Norfolk 2 Stn DW 2086, 707 – 777 m, outer and inner views of dorsal valve, brachidium not preserved, MNHN BRA- 3141. G-J, Kanakythyris pachyrhynchos Laurin, 1997, Norfolk Ridge; G – I, dorsal, lateral and anterior views of complete specimen, Norfolk 2 Stn DW 2092, 320 – 345 m, MNHN BRA- 3142; J, SEM micrograph of dorsal interior to show cardinalia and brachidium, Norfolk 2 Stn DW 2136, 402 – 410 m, MNHN BRA- 3143. K – M, Stenosarina crosnieri (Cooper, 1983), Norfolk Ridge, Norfolk 2 Stn DW 2069, 795 – 852 m; K, L, dorsal and lateral views of complete specimen, MNHN BRA- 3144; M, SEM micrograph of dorsal interior to show brachial skeleton, MNHN BRA- 3145.