Unidistelopora krauseae (Voigt & Schneemilch, 1986)

Ostrovsky, Andrew N. & Taylor, Paul D., 2005, Brood chambers constructed from spines in fossil and Recent cheilostome bryozoans, Zoological Journal of the Linnean Society 144 (3), pp. 317-361 : 325

UNIDISTELOPORA KRAUSEAE

(VOIGT & SCHNEEMILCH, 1986)

( FIGS 5A, B , 21D , 24P )

Material: VC 11025, Cretaceous, Lower Campanian , Grube Allemania, Höver, near Hannover, Germany . VC T 10580, Lower Campanian , Grube Alsen, Lägerdorf, near Hamburg, Germany . VC T 10581, Lower Campanian , Grube Breitenburg, Germany .

Description: Non-brooding zooids of this uniserial species have 24–25 mural spine bases, compared with 20– 21 in ovicellate zooids. Distal spine bases, particularly the four ‘oral’ spine bases, are slightly larger than the others.

Ovicell roofs were constructed of 18–19 spines whose bases are arranged atop a low semicircular ridge and raised above the concave ovicell floor formed by the proximal gymnocyst of the distal brooding zooid ( Figs 5A, B , 21D , 24P ). The diameter of ovicell spine bases is markedly smaller than that of mural spine bases, especially the nearby oral spine bases of the maternal zooid. In all cases observed, the distal, median ovicell spine bases are located on the mural rim of the distal zooid where mural spines were absent. The two most proximal spine bases are placed very close to the distal edge of the maternal zooid. Ovicell spine bases are closely spaced, with the distance between adjacent bases usually less than spine base diameter, except in the distal part of the ovicell where the spine bases are sparser and spaced further apart.

Remarks: All spines in the species of Distelopora and Unidistelopora described above were basally articulated, as indicated by the double ring structure seen in some of the spine bases ( Figs 4C , 5B ; Ostrovsky & Taylor, 2004). This is also supported by the fact that no spines are preserved in situ. In the majority of the ovicellate zooids of Distelopora spp. and Unidistelopora krauseae , the proximal part of the mural rim of the distal zooid lacks mural spines in the zone where ovicell spine bases adjoin it. Thus, the mural spine bases and distalmost, median ovicell spine bases often (always in the case of U. krauseae ) form a continuous line, and the distalmost ovicell spine bases are positioned where the most proximal mural spine bases are normally located in the nonbrooding zooids ( Figs 4A, C , 5A, B , 24P ). However, the ‘missing’ proximal mural spines do develop when the ovicell spine bases are separated from the mural rim, and also in intramural reparative buds formed within the distal zooid.

Figures

Figure 4. A, Distelopora langi Ostrovsky & Taylor, fragment of a colony, with two broken ovicells showing ovicell spine bases in a gently curved arch; medial spine bases are adjacent to the proximal edge of the mural rim of the distal zooid. Lower Cenomanian, Cambridge, England, NHM D23111. B-D, Distelopora spinifera Ostrovsky & Taylor; Lower Cenomanian, Cambridge, England. B, part of a colony, showing spine bases of three ovicells; NHM D21651. C, ovicell spine bases arranged in a semicircle, the medial spines adjacent to the proximal edge of the mural rim of the distal zooid; NHM D21667. D, poorly preserved ovicell in which the medial spine bases are some distance from the mural rim of the distal zooid; NHM D21897. Scale bars: A, B = 100 Mm; C, D = 25 Mm.

Figure 5. A, B, Unidistelopora krauseae (Voigt & Schneemilch), Lower Campanian, northern Germany, VC T10580. A, maternal zooid with ovicell and intramural bud. B, ovicell spine bases arranged in a semicircle along a ridge on the proximal gymnocyst of the distal zooid. C-F, Gilbertopora larwoodi Ostrovsky & Taylor, Lower Cenomanian, Cambridge, England. C, complete ovicell of two flattened spines; NHM D23297. D, complete ovicell viewed from the side, showing a lateral foramen; NHM D23298. E, complete ovicell in proximal view, showing the main opening of the ovicell; NHM D23298. F, complete ovicell in distal view, showing the distal opening; NHM D23298. Scale bars: A = 100 Mm; B-F = 50 Mm.

Figure 21. Schematic diagrams of brood chambers in Tendridae (A, B) and Calloporidae (C-E) in longitudinal and transverse section, showing maternal and distal zooids (fossil spinose ovicells reconstructed). A, Tendra zostericola. B, Heteroecium sp. C, Distelopora bipilata and D. langi. D, Distelopora spinifera, Unidistelopora krauseae. E, Gilbertopora larwoodi.

Figure 24. Schematic diagrams showing the shape of the mural rim and positioning of ovicell spine bases in frontal aspect; number of spines in Stichomicropora is approximate. Note that variable species may appear more than once. A, Stichomicropora sp. 1. B, S. oceani. C, Stichomicropora sp. 6. D, Stichomicropora sp. 1, S. sicksi and S. sulcata. E, S. oceani, Stichomicropora sp. 3, and Stichomicropora sp. 5. F, Stichomicropora sp. 6 and S. baccata. G, Stichomicropora spp. 1, 2 and 4, S. sicksi, S. sulcata, S. erecta, S. biconstricta, S. cf. clathrata and S. punctilla. H, S. marginula, Stichomicropora sp. 3; I, Distelopora bipilata and D. langi. J, Stichomicropora spp. 6 and 7, S. baccata, S. subquadrata, Monoporella spp. 1 and 2, M. prisca, M. nodulifera, and M. exculpta. K, Gilbertopora larwoodi or Wilbertopora mutabilis. L, Distelopora bipilata. M, Monoporella multilamellosa and M.? vincentownensis. N,?Thoracopora sp. and Craticulacella schneemilchae. O, Leptocheilopora tenuilabrosa, Leptocheilopora sp. 1, and Leptocheilopora sp. 2. P, Distelopora spinifera and Unidistelopora krauseae. R, Macropora spp.