Hyporosopora bugajensis, 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 : 281-282

Hyporosopora bugajensis sp. nov.

Fig. 11 .

Etymology: From the type locality Bugaj in the Polish Jura.

Type material: Holotype:GIUS 8−3509−20; paratype:GIUS 8−3509−21.

Type locality: Bugaj, Polish Jura.

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

Material.— Holotype and paratype listed above.

Measurements.—FWL, 750–1388 µm; FWW, 183–250 µm; LAM, 100–166 µm; TAM, 100–150 µm; LPM, 166–200 µm; TPM, 116–233 µm; GTL, 1183 µm; GDL, 510 µm; GW, 920 µm; OL, 40 µm; 70 µm; PL, 2.5–5 µm; PW, 15–17.5 µm.

Diagnosis.— Hyporosopora with large autozooids, usually more than 1 mm long; gonozooids with small transversely elliptical brood chambers; pseudopores transverse, gull wing−shaped.

Description.—Colony encrusting, sheet−like, multiserial, bereniciform, unilamellar, surface covered by transverse growth checks ( Fig. 11A ).

Autozooids long, with flat to slightly convex frontal walls; zooidal boundaries distinct, shallowly grooved. Preserved peristomes short, tapering distally. Apertures circular to elliptical, some closed by diaphragms, irregularly arranged often forming ill−defined transverse rows. Pseudopores transversely elongate, narrow, gull wing−shaped, spaced a moderate distance apart ( Fig. 11D ).

Gonozooid preserved in the holotype only. Proximal part indistinguishable from an autozooid. Brood chamber small, inflated, broad, width nearly twice length, elliptical ( Fig. 11C ), lateral margins slightly indented by autozooidal apertures. Roof densely pseudoporous. Ooeciopore terminal, transversely elliptical, much smaller than an autozooidal aperture. Ooeciostome short, upright.

Remarks.—This new species of Hyporosopora species has the longest autozooids, averaging 1113 µm, of all the bereniciform cyclostomes described in the present paper. The gonozooid is small for Hyporosopora and more transversely elliptical than the type species H. typica or H. tenera ( Reuss, 1867) in which it more clearly resembles an equilateral triangle. Transversely elongate pseudopores, as seen in the new species, are rare in cyclostomes and have not been recorded previously from any species of Hyporosopora . The gull wing−shaped pseudopores of H. bugajensis most closely resemble those seen in the unifoliate erect species Diastopora lamourouxi Milne Edwards, 1838 . These pseudopores are sufficiently unusual that we have no hesitation in assigning an infertile colony to H. bugajensis as a paratype.

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

Figures

Fig. 11. Plagioeciid cyclostome bryozoan Hyporosopora bugajensis sp. nov. from the Middle Jurassic ore−bearing clays of the Polish Jura, holotype, GIUS 8−3509−20. A. Colony view. B. Autozooids. C. Partly crushed gonozooid. D. Pseudopores. Scale bars: 300 µm (A), 100 µm (B, C), 20 µm (D). BSE SEM images of uncoated specimens.