Hyporosopora radomensis, Hara & Taylor, 2009

Hara, Urszula & Taylor, Paul D., 2009, Cyclostome bryozoans from the Kimmeridgian (Upper Jurassic) of Poland, Geodiversitas 31 (3), pp. 555-575 : 569-571

Hyporosopora radomensis n. sp. ( Figs 10 ; 11 )

? Hyporosopora sp. – Taylor 1981: 868, text-fig. 3. DIAGNOSIS. — Hyporosopora with colonies unilamellar or multilamellar due to overgrowth of parent colony by marginal subcolonies; autozooids 0.52-0.84 mmlong 0.15- 0.18 mm wide, pseudopores drop-shaped; gonozooids numerous, inflated part wider than long, heart-shaped when small, boomerang-shaped when large with lobes extending well distally of ooeciopore, 0.90-1.80 mm long by 0.75-1.40 mm wide; ooeciopore terminal, very small, 0.03 mm long by 0.04-0.05 mm wide.

HOLOTYPE. — MUZ PIG 1719.II.6, figured here as Figures 10A, B , 11A.

PARATYPES. — Same locality as holotype: MUZ PIG 1719.II.3 ; NHM D59464, D59466, BZ 5512 (3), BZ 5515(2), BZ 5516, BZ5517. — Malogoszcz Quarry: NHM BZ 5520 (1), BZ 5526, BZ 5527 .

TYPE HORIZON. — Lower Kimmeridgian, Divisum Zone, Deltoideum beds .

TYPE LOCALITY. — Wierzbica Quarry, SW margin of the Holy Cross Mts, Poland.

ETYMOLOGY. — After Radom, a city close to the type locality.

MEASUREMENTS. — Longitudinalaperturaldiameter = 0.12-0.14 mm; transverseaperturaldiameter = 0.09- 0.12 mm; longitudinalperistomediameter = 0.15- 0.20 mm; transverseperistome diameter = 0.15-0.18 mm; frontal walllength = 0.52-0.84 mm; frontalwall width = 0.15-0.18 mm; gonozooid length = 0.90-1.80 mm, gonozooid width = 0.75-1.40 mm; ooeciopore length = 0.03 mm; ooeciopore width = 0.04-0.05 mm.

OCCURRENCE. — Lower Kimmeridgian, Wierzbica and Małogoszcz quarries, Holy Cross Mts, Poland. Possibly also Tithonian (Portland Limestone Formation), Dorset, England.

DESCRIPTION

Colonies encrusting, subcircular or fan-shaped, unilamellar, occasionally multilamellar, thin. Subcolonies oftendeveloped aroundmargins of parental colonies, sometimescoalescing and/or overgrowing parentcolony.Distal fringeofbasallamina extending more than 0.25 mm beyond budding zone. Ancestrula normally overgrown by later budded zooids, about 0.34 mmlong, aperture 0.06 × 0.05 mm, protoecium 0.13 mm in diameter.

Autozooidswith convex frontal walls usually well marked at colony surface, crossed by faint growth lines in many colonies. Aperturesarranged in quincunx, small, longitudinally elongate, someclosed by terminal diaphragms; preserved peristomes short. Pseudopores drop-shaped.

Gonozooids numerous, presenteven insmallcolonies, distributed unevenly, inflated part wider than long, variablein outline shape, the smaller examples being heart shaped and larger boomerang-shaped with lobes extending well distally of ooeciopore, outlines sometimes indented by autozooidal peristomes. Ooeciopore small, terminal, transversely elongate or less often subcircular.

REMARKS

This is the most common species found in our material fromthe Lower Kimmeridgianof Wierzbica and Małogoszcz quarries. Colonies are fan-shaped whensmallbut becomesubcircularwithage andmay develop numerous subcolonies along the growing edge ( Fig. 10F ). Th e boomerang shape of the most fully developed gonozooids ( Fig. 11B ) recalls two other Jurassic species of Hyporosopora : H. sauvagei ( Gregory, 1896) , fromthe Bathonian of England, and the Hyporosopora sp. of Taylor (1981), from the Tithonian Portland Stone of Dorset. However, H. radomensi s n. sp. differsfrom H. sauvagei in having smaller autozooids (e.g., frontal wall width 0.15-0.18 mm in H. radomensis n. sp. vs. 0.23 mm in H. sauvagei ) and drop shaped pseudopores, contrasting with the crescent-shaped pseudopores evident in the type of H. sauvagei (NHM B194). The un-named Portlandian Hyporosopora sp. is tentatively identified as H. radomensi s n. sp. pending restudy using SEM.

Figures

FIG. 10. — Hyporosopora radomensis n. sp., Lower Kimmeridgian, Holy Cross Mts, Poland: A, B, holotype, MUZ PIG1719.II.6, Wierzbica Quarry; A, fertile colony; B, early astogeny with protoecium arrowed; C, D, NHM D59466, Wierzbica Quarry; C, autozooids; D, growing edge showing fringe of exposed basal lamina extending distally beyond budding zone; E, NHM D59464,Wierzbica Quarry, autozooidal pseudopores; F, NHM BZ 5527, Małogoszcz Quarry, juxtaposed colonies, the lower colony developing a pair of marginal subcolonies (left). Scale bars: A, F, 1 mm; B, C, 200 μm; D, 500 μm; E, 100 μm.

FIG. 11. — Hyporosopora radomensis n. sp. showing shape and size variations in gonozooids (ooeciopores arrowed),Lower Kimmeridgian,Wierzbica Quarry,Holy Cross Mts,Poland:A, holotype, MUZ PIG 1719.II.6, small gonozooid with heart-shaped dilation; B, NHM D59464, large gonozooid with boomerang-shaped dilation. Scale bars: A, 200 μm; B, 500 μm.