Hemiparacytheridea vanharteni, Michael, 1995

Ayress, M. A., Whatley, R., Downing, S. E. & Millson, K. J., 1995, Cainozoic and from Recent Deep Sea Cytherurid Ostracoda the South Western Pacific and Eastern Indian Oceans, Part Cytherurinae, Records of the Australian Museum 47 (2), pp. 203-223 : 220

Hemiparacytheridea vanharteni n.sp.

Fig. 5 M-O

" Eucytherura sp. I" Ayress, 1988 *: 589; pI. 20, figs 13 -15. " Eucytherura sp. 4" Coles, 1989*, pI. 18, fig. 5.

Etymology. For Professor Dick van Harten in recognition of his work on deep-sea Ostracoda.

Type material and dimensions. Holotype, OS 14582, adult right valve, length 0.30 mm, height 0.17 mm. Paratype, OS 14583, adult left valve, length 0.30 mm, height 0.16 mm, Site 253, core 1, section 4, interval 13-19 cm, Pleistocene.

Type locality and level. Lord Howe Rise, present day water depth 1428 m, DSDP Site 209, core 2, section 6, interval 75-80 cm, Early Pleistocene, Zone NN 19 .

Diagnosis. Hemiparacytheridea with long caudal process, mid-ventral, bitubercular alar process and low pyramidal posterodorsal tubercle. Arcuate ridge behind centre, essentially smooth elsewhere. Normal pores are large with stellate external openings.

Description. Small, elongate sub-triangular in lateral view. Anterior margin bluntly convex, asymmetrical, extremity below mid-height and weakly rimmed. Posterior margin acuminate produced into a long caudal process dorsally. Dorsal margin straight, interrupted by low, subtriangular tubercle just behind mid-length; weak hinge ear anteriorly in right valve. Ventral margin weakly biconvex Thin-shelled; well inflated posteroventrally, rather compressed elsewhere. Large posteroventral longitudinally extended swelling with weak terminal spine, joined to subcentral hemisperical tubercle by low sub-horizontal ridge, together forming a bitubercular alar process midventrally. Low arcuate ridge behind centre and a second ridge extends close to margin anterodorsally, remainder of lateral surface smooth. Normal pores well scattered, external openings large and stellate. Internal features as for genus.

Comparisons. This is a distinctive species by virtue of its weak inflation and smooth external surface. It is somewhat similar to Hemiparacytheridea leopardina ( Ruan & Hao, 1988) but is more elongate and lacks the dorsal tubercle and reticulation of that species.

Distribution. Widely distributed but usually rare: Early Pleistocene of DSDP Site 209, Queensland Plateau; Pleistocene of DSDP Site 253, Ninetyeast Ridge; Recent (coretop) of OSI core 12- 87/13GC10; Recent and Lower Oligocene of central Norih Atlantic (Van Harten pers. comm. 1985 and Coles, 1989 respectively). The species has also been found recently at DSDP Guyot Site 171, central Pacific Ocean (Boomer, pers. comm. 1993).