Spinisinella zagorseki, Martino, Emanuela Di & Taylor, Paul D, 2012

Martino, Emanuela Di & Taylor, Paul D, 2012, Pyrisinellidae, a new family of anascan cheilostome bryozoans, Zootaxa 3534, pp. 1-20 : 6-8

Spinisinella zagorseki n. sp.

( Figs 9–12 ; Table 2)

Material examined. Holotype: NMP O- 6751, Cretaceous, Cenomanian or Turonian, Kaňk, Bohemian Basin, Czech Republic.

Etymology. Named for Kamil Zágoršek (Národní Museum, Prague) in recognition of his significant contribution to the study of bryozoans.

Description. Colony encrusting, multiserial, unilaminar. Autozooids small, distinct, separated by deep furrows, oval, slightly longer than wide (mean L/W = 1.14). Gymnocyst narrow, separated from the extensive cryptocyst by a thin salient mural rim forming together with distal rim of opesia a pear-shaped border around the cryptocyst and opesia, highest distally. Cryptocyst deep, shelf-like, flat and finely granular. Opesia trifoliate, longer than wide, a pair of rounded downwards directed denticles separating the larger, distal semielliptical part from the shallower proximal part with a straight or barely convex edge ( Fig. 12 ). Four oral spine bases located distolaterally of the opesia (mean D = 10 µm). Ovicell spinose, ooecium represented by two pairs of spine bases (mean D = 15 µm) arranged in a line parallel to the proximal-distal axis of the zooids, the proximal pair positioned close to the distal oral spine bases of the maternal zooid; a depression on the proximal gymnocyst of the distal zooid is delimited by the pair of spine bases and the straight proximal edge of the mural rim of the distal zooid ( Fig. 12 ). Avicularia and ancestrula not observed.

Remarks. This species is immediately distinguishable from other species of pyrisinellids in having a spinose ovicell represented by two pairs of spine bases. The spine bases in living colonies are inferred to have borne basally articulated spines bent towards the median axis of the ovicell to form a cage-like structure. The embryo would have been accommodated in the space between the depression on the proximal gymnocyst of the distal zooid and the overarching spines. Given their close proximity to the ovicell, it is possible that the distalmost pair of oral spines of the maternal zooid also contributed to the ovicell roof. If so, the brood chamber was constructed, unusually, by spines from both the maternal and distal zooids.

Distribution. Cenomanian or Turonian? (Late Cretaceous) of the Bohemian Basin, Czech Republic.

N (colonies, zooids) Mean SD Range Zooid length 1, 8 201 22 159–230 Zooid width 1, 8 176 15 154–197 Orifice length 1, 8 65 4 55–69 Orifice width 1, 8 57 8 51–63 Cryptocyst length 1, 8 83 12 61–96 Cryptocyst width 1, 8 130 10 113–143

N, Number of colonies and number of zooids measured; SD, standard deviation.

Figures

FIGURES 9 − 12. Spinisinella zagorseki n. sp., NMP O- 6751, holotype, Cretaceous, Cenomanian or Turonian, Kaňk, Czech Republic. 9. view of colony, scale bar = 200 µm; 10. ovicellate and non-ovicellate autozooids, scale bar = 100 µm; 11. close-up of two autozooids, scale bar = 100 µm; 12. close-up of spinose ovicell, scale bar = 20 µm.