Macandrevia, King, 1859

Bitner, Maria Aleksandra & Romanin, Marco, 2017, Recent brachiopods from the South China Sea, NW Pacific, Zootaxa 4306 (2), pp. 287-290 : 289

Macandrevia sp. ( Fig. 1 C–G)

Material examined. DongSha 2014 cruise, stn CP 4123, 21°36’N, 118°16’E, depth 1612–1665 m, one specimen.

Measurements. Length 13.3 mm, width 10.8 mm, thickness 6.1 mm.

Description. Shell of medium size, thin, elongate oval with greatest width at mid-valve, ventribiconvex. Shell surface smooth, ornamented only by numerous growth lines. Lateral commissures straight, anterior commissure rectimarginate. Hinge line short, curved. Beak ridges rounded, beak short, suberect. Foramen subcircular, permesothyrid, deltidial plates minute.

Ventral valve interior with small hooked teeth supported by strong dental plates united by a callus closely applied to the valve floor ( Fig. 1 E, F). Dorsal valve interior with high inner socket ridges. Hinge plates attached directly to the valve floor ( Fig. 1 G). No median septum. Loop not preserved.

Remarks. The genus Macandrevia is readily recognized by its characteristic permesothyrid foramen, well developed dental plates, and hinge plates extending directly to the valve floor without a median septum. This is the first record of this genus from the West Pacific but the limited material precludes assignment at species level. In size the specimen is close to the northern Atlantic species, Macandrevia novangliae Cooper, 1977 and M. tenera (Jeffreys, 1876) ( Cooper 1973b, 1981) as well as to M. emigi Bitner & Logan, 2016 from the Indian Ocean ( Bitner & Logan 2016). The specimen differs from M. novangliae in possessing rudimentary deltidial plates ( Cooper 1981) and from M. emigi by its elongate oval outline ( Bitner & Logan 2016).

Figures

FIGURE 1. A – B. Terebratulina japonica (Sowerby, 1846), dorsal views of complete specimens, stn DW 4125, 305 – 306 m, SEM, MNHN IB- 2013 - 640. C – G. Macandrevia sp., one complete specimen, stn CP 4123, 1612 – 1665 m, MNHN IB- 2013 - 641. C – D. Dorsal and lateral views of complete specimen. E – F. Ventral valve of the same specimen, posterior part of interior and tilted view to show strong dental plates, SEM. G. Interior view of dorsal valve to show cardinalia, SEM. H – R. Nipponithyris afra Cooper, 1973, stn CP 4130, 795 – 822 m. H – M. Dorsal, lateral and anterior views of two complete specimens, MNHN BI- 2013 - 642. N – O. Posterior part of ventral valve interior and tilted view to show swollen bases and grooves to accommodate inner socket ridges, SEM, MNHN BI- 2013 - 643. P. Interior of dorsal valve, partly broken loop visible, SEM, MNHN BI- 2013 - 644. Q – R. Posterior part of dorsal valve interior and enlargement to show details of strongly thickened cardinalia, SEM MNHN BI- 2013 - 645.