Eucytherura batalaria Michael 1995, n.sp.

Eucytherura batalaria n.sp.

Fig. 4 A-D

" Eucytherura batalaria" Downing, 1985 *: 448, pI. 19, figs 19,20.- Ayress, 1988 * (in part), p. 582, pI. 20, figs 1 -4.

Etymology. Latin, a warship armed with battering ram. Referring to the resemblance of the anterior marginal spme to a battering ram.

Type material and dimensions. Holotype, OS 14080, adult right valve, length 0.35 mm, height 0.20 mm. Paratypes: OS 14081, adult left valve, length 0.35 mm, height 0.20 mm, Site 209, core 2, section 2, interval 75 -80 cm, Early Pleistocene, Zone NN 19; OS 14082, adult left valve, length 0.28 mm, height 0.18 mm, Site 207A, core1, section4, interval 8 -17 cm, Early Pliocene, ZoneNN NN13.

Type locality and horizon. 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. A subtriangular to subovate species of Eucytherura with a long marginal spine at mid-height anteriorly, lacking tubercles or ridges dorsally and a narrow anterior marginal rim. Primarily and secondarily reticulate.

Description. Small, subtriangular to subovate in lateral view. Anterior margin bluntly convex, weakly rimmed with three prominent denticles: the uppermost at midheight longest, the lower two projecting downward. Posterior margin very short with a prominent spine at ventral and dorsal angle. Dorsal margin weakly convex usually interrupted by short spines, one prominent just behind mid-length. Ventral margin gently convex with very weak oral incurvature. Thin-shelled and weakly inflated. Tuberculate ventrally: sub-central tubercle subhemispherical bearing horizontal ridge; posterior tubercle longitudinally elongate bearing a row of at least three prominent spines. Ventro-lateral ridge extends from anteroventral margin below ventral tubercles. Lateral surface covered with polygonal primary and secondary reticulation; primary muri have slightly raised conjunctions, primary fossae subdivided usually into three secondary fossae over most of the valve surface but more numerous towards the valve periphery. Microreticulate anteroventrally and on the posteroventral periphery. Internal surface with clusters of 4 to 5 perforations. Other internal features as for genus.

Comparisons. The close similarity of this species to Eucytherura downingae (Coles & Whatley) clearly indicates a close relationship with that species. Eucytherura batalaria can be distinguished by its lack of a posterodorsal tubercle or ridge, its very weakly developed anterior rim and more rugose ornament.

Distribution. Found so far only in the south-west Pacific region, viz: Early Miocene of DSDP Site 593; Middle Miocene and Pleistocene of DSDP Site 209; Middle Miocene of DSDP Site 56; Middle to Late Miocene of DSDP Site 592; Pliocene of DSDP Sites 207A and 208; Late Pleistocene of cores Z2108, Sonne 36 -61 and 1-86/6GC3; Recent (coretop) of OSI core 12 -87/13GCI0.