Cassideus scalariconus, Dumitrica & Zügel, 2003

Dumitrica, Paulian & Zügel, Peter, 2003, Lower Tithonian mono- and dicyrtid Nassellaria (Radiolaria) from the Solnhofen area (southern Germany), Geodiversitas 25 (1), pp. 5-72 : 42-43

Cassideus scalariconus n. sp. ( Fig. 21 G-I)

HOLOTYPE. — Photo No. 57120, 57121; stub Mue 22/19; Musée de Géologie , Lausanne, No. 74398 ( Fig. 21G, H ). ETYMOLOGY. — From the Latin scalae: scale; and conus: cone.

MATERIAL EXAMINED. — 12 illustrated specimens from the type horizon (sample Mue 22) and others not illustrated.

DIMENSIONS ( IN µM). — Total length 150, length of apical horn 25, length of ventral horn 25-30, total width 195-215 (av. 205), width of cephalis 25-35 (av. 30), of the thorax above the thoracic skirt 130-135 (av. 132).

DESCRIPTION

Conical to hat-shaped test. Cephalis small, perforate, undistinguished externally from thorax. Apical horn directed obliquely upward, curved in ventral direction. Ventral horn straight, directed obliquely upward. Both horns three-bladed proximally, rapidly tapering to a circular crosssection. Apical horn slightly longer than ventral horn. Thorax wide-conical, its proximal part with four to six pore rows, without circumferential ridges. Main part of thorax scalariform, usually with five circumferential ridges separated by concave areas with two rows of alternate pores. Circumferential depressional bars separating the two transverse rows of pores in each concave area are circumferential ridges on the interior surface, resulting in a zigzag outline. Pores wide, rounded hexagonal, alternate, separated by thin intervening bars. Thoracic skirt horizontal or slightly subhorizontal with four to five transverse rows of pores. Pores alternate or partly in square pattern, decreasing in size distally. Internally the boundary between the conical part of thorax and the skirt marked by a thick composite circular rim which can be interpreted as a lumbar septal partition.

REMARKS

This new species differs from C. biannulatus n. sp. by having a conical thorax, shorter horns, and by the high number and distribution of circumferential ridges. Its thorax is morphologically closer to C. riedeli in having a great number of transverse ridges but differs in that the ridges are very uniformly distributed.

Figures

FIG. 21. — A-D, L, Cassideus biannulatus n. sp.; A, B, holotype, left lateral and basal views; C, D, L, paratypes; C, right lateral view; D, latero-apical view; L, basal view of initial spicule showing the absence of dorsal spine; E, F, Cassideus deweveri n. sp.; E, holotype, left lateral view; F, paratype, right lateral view; G-I, Cassideus scalariconus n. sp.; G, H, holotype, right lateral and basal views; I, paratype, left lateral view; J, K, Cuniculiformis sp., fragment, basal and left lateral views. Scale bars: A-K, 30 µm; L, 10 µm.