Microeciella magnopora, Zatoń & Taylor, 2009

Zatoń, Michał & Taylor, Paul D., 2009, Middle Jurassic cyclostome bryozoans from the Polish Jura, Acta Palaeontologica Polonica 54 (2), pp. 267-288 : 276-277

Microeciella magnopora sp. nov.

Fig. 7 .

Etymology: In reference to the unusually large size of the ooeciopore.

Type material: Holotype:GIUS 8−3509−15; paratype: GIUS 8−3509−2.

Type locality: Bugaj , Polish Jura, Poland .

Type horizon: Middle Bathonian ( Tulites subcontractus or Morrisiceras morrisi Zone ), Jurassic.

Material.— Holotype and paratype listed above.

Measurements.—FWL, 850–1150 µm; FWW, 250–275 µm; LAM, 100–125 µm; TAM, 100–125 µm; LPM, 125–200 µm; TPM, 150–175 µm; GTL, 1250–1625 µm; GDL, 550–725 µm; GW, 512–625 µm; OL, 150 µm; OW, 162 µm; PL, 15–16.5 µm; PW, 1.6–3.3 µm.

Diagnosis.— Microeciella with gonozooids having equidimensional, ovoidal or heart−shaped brood chambers with a large ooeciopore about the same size as an autozooidal aperture; autozooids large, frontal walls more than 250 µm wide; pseudopores narrow, slit−like.

Description.—Colony encrusting, sheet−like, multiserial, bereniciform. Early astogenetic stages preserved but ancestrula not visible.

Autozooids large, elongate, widening distally towards apertures, with rather flat frontal wall but with distinct boundaries. Peristomes short, upright, tapering distally. Apertures circular to subcircular, some closed by terminal diaphragms. Pseudopores closely−spaced, narrow, slit−like, longitudinally elongate ( Fig. 7A 4).

Gonozooids uncommon. Proximal frontal wall indistinguishable from that of an autozooid. Brood chamber ovoidal or heart−shaped, V−shaped at its proximal end, slightly longer than wide, bulbous, roof densely pseudoporous ( Fig. 7A 3 ). Ooeciopore, preserved in only one gonozooid, subterminal, circular in outline, large, similar in size to an autozooidal aperture ( Fig. 7A 3 ).

Remarks.—Although the gonozooids in the paratype specimen are roofless, without the distinctive large ooeciopore being visible, the general shape of the brood chambers is similar to the holotype, as are the autozooids and pseudopores. Therefore, we place the two specimens in the same new species, M. magnopora .

No other species of Microeciella have such a large ooeciopore as that of M. magnopora , in which it is approximately the same size as the autozooidal apertures. Neglecting ooeciopore size, the closest resemblance among the Polish species of Microeciella described in this study is with M. kuklinskii which has autozooids of about the same size and a similarly−shaped brood chamber. However, the pseudopores of the two species are quite different, those of M. kuklinskii being broad and teardrop shaped, contrasting with the narrow, slit−like pseudopores of M. magnopora .

Stratigraphic and geographic range.—Middle Bathonian of Bugaj, Polish Jura.

Figures

Fig. 7. Oncousoeciid cyclostome bryozoan Microeciella magnopora sp. nov. from the Middle Jurassic ore−bearing clays of the Polish Jura. A. Holotype, GIUS 8−3509−15, Bugaj, Middle Bathonian. A1, general view of the preserved colony; A2, autozooids; A3, close−up of the gonozooid with the ooeciopore (arrowed); A4, pseudopores. B. Paratype, GIUS 8−3509−2, Bugaj, Middle Bathonian. B1, autozooids and two roofless gonozooids; B2, close−up of the gonozooids. Scale bars 100 µm (A1, A2, A3, B1, B2), 20 µm (A4). BSE SEM images of uncoated specimens.

Fig. 3. Oncousoeciid cyclostome bryozoan Microeciella annae sp. nov. from the Middle Jurassic ore−bearing clays of the Polish Jura. Holotype, GIUS 8−3509−8, Kawodrza Górna, Lower Bathonian. A. General colony view. B. Three gonozooids, one of which is aborted (arrow). C. Close−up of ooeciopore (arrow) and autozooids. D. Pseudopores. Scale bars 1000 µm (A), 100 µm (B), 100 µm (C), 20 µm (D). BSE SEM images of uncoated specimens.