Microeciella annae, 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 : 271-274

Microeciella annae sp. nov.

Fig. 3 .

Etymology: In honour of the late Anna Zatoń (1958–2002), the first author’s mother.

Type material: Holotype: GIUS 8−3509−8, colony encrusting an oyster shell; paratype:GIUS 8−3509−9, colony encrusting a hiatus concretion.

Type locality: Kawodrza Górna (“Gliński” clay−pit), Polish Jura, Poland .

Type horizon: Ore−bearing Częstochowa Clay Formation , Lower Bathonian ( Zigzagiceras zigzag Zone ), Jurassic .

Material.—Two colonies, the holotype and paratype listed above.

Measurements.—FWL, 466–800 µm; FWW, 116–150 µm; LAM, 66–83 µm; TAM, 58–75 µm; LPM, 100–116 µm; TPM, 83–108 µm; GTL, 1180 µm; GDL, 685 µm; GW, 500 µm; OL, 91 µm; OW, 100 µm; PL, 7.5–12.5 µm; PW, 5 µm.

Diagnosis.— Microeciella with ovoidal brood chambers and a terminal, subcircular ooeciopore located on a short, straight ooeciostome; autozooids small, frontal walls less than 150 µm wide; pseudopores longitudinally elongate, spindleshaped. Description.—Colony encrusting, small (holotype 8 mm in diameter), multiserial, unilamellar, discoidal, bereniciform ( Fig. 3A ). Growing edge low.

Autozooids small, elongate, flat proximally and slightly convex distally; zooidal boundaries grooved. Peristomes salient, tapering distally. Apertures subcircular to longitudinally elongate. Pseudopores narrow, teardrop to spindle−like in shape, pointed distally, sparse ( Fig. 3D ).

Gonozooids common, occurring in three generations in the holotype ( Fig. 3A ); however, all but two are crushed, and one of the remaining two is incompletely formed. Proximal frontal wall flat, indistinguishable from an autozooid. Brood chamber ovoidal, only slightly longer than wide, convex, lateral edges indented by apertures of neighbouring autozooids, roof densely pseudoporous. Ooeciopore terminal, located beyond distal edge of brood chamber, subcircular, smaller than autozooidal aperture; ooeciostome short, upright, tapering distally. Remarks.—This new species of Microeciella differs from the type species M. beliensis Taylor and Sequeiros, 1982 , as well as from other Jurassic Microeciella species including M. duofluvina ( Cuffey and Ehleiter, 1984) , M. pollostos Taylor and Wilson, 1999 , in its terminal ooeciopore and more rounded brood chamber. The terminal ooeciopore of M. annae sp. nov. is reminiscent of the Recent species M. suborbicularis ( Hincks, 1880) (see Taylor and Zatoń 2008), previously placed in Eurystrotos ( Hayward and Ryland 1985) . Microeciella sp. from the Upper Bathonian–Lower Callovian of Balin, southern Poland, has a similar ovoidal brood chamber but a subterminal ooeciopore (see Taylor 2009).

One infertile colony from the Middle Bathonian of Bugaj (GIUS 8−3509−9), which possesses a similar discoidal colony−form, autozooids and pseudopores, is provisionally assigned to Microeciella annae .

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

Figures

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.