Cassideus biannulatus, 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 : 40-42

Cassideus biannulatus n. sp. ( Fig. 21 A-D, L)

HOLOTYPE. — Photo No. 45646, 45649; stub Mue 22/16; Musée de Géologie , Lausanne, No. 74396 ( Fig. 21A, B ).

ETYMOLOGY. — From the Latin prefix bi: two; and annulatus: having rings.

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

DIMENSIONS ( IN µM). — Total length 155-180 (av. 170), total width 160-225 (av. 195), length of cephalis 25-55 (av. 40), of apical horn 25-45 (av. 35), of ventral horn 30-85 (av. 55), diametre of collar ridge 50-70 (av. 60), of proximal thoracic circumferential ridge 80- 100 (av. 90), of thorax at the boundary with thoracic skirt 85-130 (av. 110), distance between collar ridge and proximal thoracic ridge 15-25 (av. 20), and between the latter and the boundary with thoracic skirt 45-70 (av. 55).

DESCRIPTION

Conical to hat-shaped test. Cephalis small, hemispherical at the top, increasing rapidly in diametre towards the boundary with the thorax. Horns three-bladed proximally, non-bladed distally. Apical horn often distinctly curved in ventral direction in the non-bladed portion. Ventral horn straight or slightly curved upwards, variable in length but generally longer than apical horn. Boundary between cephalis and thorax not marked externally. It is above the former of the two circumferential ridges. This ridge may be rather distinct or weakly marked, partly reduced to a circumferential row of knobs. Main part of thorax high conical, commonly with a well pronounced ridge at the proximal part, separated from the former ridge by a concave belt with three to four transverse rows of alternate pores. Rarely, this ridge reduced to a circumferential shoulder. Distal part of thorax strongly flaring, forming a thoracic skirt which lies in the horizontal plane or may be undulate. Internally the boundary between high conical part and skirt marked by a thick circular rim which can be interpreted as a lumbar septal partition. Usually thorax circular in transversal section throughout, but in some specimens it may be slightly compressed laterally. Cephalic wall with small, irregularly arranged pores on the apical part and more or less regularly arranged in circumferential rows on the distal part. Thoracic pores rounded to longitudinally ovate, arranged in alternate transversal rows. On the thoracic skirt circular bars separating the transversal rows of pores often thicker than the bars separating the pores in each row. Velum absent.

REMARKS

Cassideus biannulatus n. sp. resembles very much C. riedeli and C. yoloensis . From both it differs especially by having two circumferential ridges on the thorax.

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.