Xenobrochus australis Cooper, 1981

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

Xenobrochus australis Cooper, 1981

( Fig. 6A–D )

This micromorphic short-looped species, the second representative of the family Dyscoliidae , is noted for the first time from the Norfolk Ridge. It was collected on three seamounts ( Tables 1, 2) during the Norfolk 1 and 2 cruises and has a depth range of 200 to 967 m ( Fig. 14 ). Like D. johannisdavisi , X. australis was originally described from the Indian Ocean ( Cooper 1981).

Laurin (1997) recorded two other species of Xenobrochus from the New Caledonian region ― X. africanus ( Cooper, 1973b) and X. indianensis ( Cooper, 1973b) . The material from the Norfolk Ridge differs from X. africanus in the outline of the loop and the presence of a narrow median fold on the transverse band ( Fig. 6C, D ), which is absent in X. africanus ( Cooper 1973b, 1983; Hiller 1986). In turn, X. indianensis can be distinguished from the studied specimens by the more incurved beak with a partly concealed symphytium and distinct cardinal process ( Cooper 1973b, 1983).

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.