Poculinapora, 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 : 65-66

Genus Poculinapora n. gen.

TYPE SPECIES. — Poculinapora poculigera n. gen., n. sp. ETYMOLOGY. — From the Latin poculum: cup ; and Napora .

RANGE. — Tithonian so far as known.

DIAGNOSIS. — Dicyrtid nassellarians with a small cephalis and a large subglobular thorax. Cephalis with a well developed hollow apical horn. Apical tube subaxial between the two blades aligned with the primary lateral spines of the initial skeleton. Thorax with a large circular or triangular aperture and three threebladed feet, one blade external, two blades lateral. Thoracic velum usually present.

REMARKS

Except for the hollow apical horn, the morphology and structure of the cephalis, thorax and feet of this new genus are similar to those of the genus Napora . In fact, this genus could be defined as Napora with hollow apical horn. Four new species ( P. marsupiala n. gen., n. sp., P. poculigera n. gen., n. sp., P. spathulipes n. gen., n. sp., and P. tripartita n. gen., n. sp.), all of them from the very rich sample Mue 22, are assigned to this genus. A fifth species, Napora espinosa Hull, 1997 , also Tithonian in age, shows very clearly the same character along the ventral groove ( Hull 1997:pl.45, fig. 19) ( Fig. 32A ) and should be assigned to this new genus. All these five species have a rather similar globular thorax and a well distinct cephalis.

Before discussing the hollow structure of the apical horn one should mention that the three blades and grooves of the apical horn of Napora are generally aligned approximately with the three feet. Accordingly, there are two blades, herein called lateral, aligned with the two feet representing prolongations of the primary lateral spines of the initial spicule, one blade, herein called dorsal, aligned with the dorsal spine and foot, one ventral groove opposite to the dorsal foot, on the direction of the ventral spine, and two latero-dorsal grooves between the dorsal and lateral blades.

In four species ( Poculinapora espinosa n. comb., P. marsupiala n. gen., n. sp., P. poculigera n. gen., n. sp., and P. spathulipes n. gen., n. sp.) ( Fig. 32A , C-F) the tube of the apical horn is certainly situated along the ventral groove which is closed in the ventral part. It represents the prolongation of the cephalic pore open in this area in front of the apical horn. In P. tripartita n. gen., n. sp. the tube would seem to be axial, at least on the distal portion. Because this position is difficult to explain it seems that in this case the axis of the horn (prolongation of the apical spine) is strongly displaced dorsally.

The tube is a simple hollow in P. marsupiala n. gen., n. sp., P. spathulipes n. gen., n. sp., and P. espinosa n. comb. In P. tripartita n. gen., n. sp. and some specimens of P. poculigera n. gen., n. sp. the tube, or at least its distal end, seems to be subdivided by some septa or bars radiating from the axis.

The genus Poculinapora n. gen. undoubtedly derived from a species of Napora by developing a tube along the ventral groove. A species susceptible to be such an ancestor could be Napora pacifica that is the most frequent species of Napora at this stratigraphic level and that has the thorax and feet rather similar to those of Poculinapora n. gen., and an apical horn with a rather variable distal part.

Figures

FIG. 32. — Apical horns of Poculinapora n. gen.; A, P. espinosa n. comb., right lateral view; B, P. tripartita n. gen., n. sp., holotype, right lateral view; C, E, P. spathulipes n. gen., n. sp., holotype and paratype in left lateral and right lateral views respectively; D, P. poculigera n. gen., n. sp., paratype, left lateral view; F, P. marsupiala n. gen., n. sp., paratype, left lateral view. All arrows point to the opening of the tube along the apical horn. Scale bar: 0.1 mm.