Named by Dumitrica, Gorican & Matsuoka.

Diagnosis: Eucyrtidiellum with stout apical horn and strong longitudinal abdominal costae separated by 2-4 longitudinal rows of pores.

Original description: Test composed of three segments. Cephalis smooth, poreless, incorporated into a long, stout, pointed apical horn, circular in cross-section throughout length. Sutural pore situated in the proximal part of the cephalis. Thorax larger, trapezoidal in outline, with a regular mesh work of polygonal pore frames. Abdomen in&64258;ated, porous, ornamented with 7-9 strong, continuous vertical costae visible laterally. Pores on abdomen circular; number of pore rows between adjacent costae may vary from two (rarely one) to four on a single specimen.

Original remarks: Eucyrtidiellum nagaiae y n. sp. differs from E. ramescens Cordey by having well-individualized costae throughout the abdomen. The wall of the abdomen is otherwise smoother, perforate but the pore frames do not form coalescent thickenings as in E. ramescens and the apical horn is shorter. The stout apical horn and the rows of intercostal pores also di&64256;erentiate this species from E. ptyctum (Riedel & San&64257;lippo).

Etymology: Named for Hiromi Nagai, Nagoya University, to honour her contribution to the knowledge of Mesozoic Radiolaria and especially of Eucyrtidiellum.

Eucyrtidiellum nagaiae was named by Gorican et al. (2006). Its type specimen is MA13547 (pl. EUC06, figs. 1a, b) and is a 3D body fossil.