Reptoclausa radwanskii, Hara & Taylor, 2009

Hara, Urszula & Taylor, Paul D., 2009, Cyclostome bryozoans from the Kimmeridgian (Upper Jurassic) of Poland, Geodiversitas 31 (3), pp. 555-575 : 566

Reptoclausa radwanskii n. sp. ( Fig. 7 )

Bryozoan colony – Radwańska & Radwański 2003: 87, pl. 1, fig. 3a, b.

DIAGNOSIS. — Reptoclausa with unilamellar, to multilamellar colonies, stellatetodiscoidalorirregular in outline shape, surfacewith finetransverse wrinkling; autozooidal ridges narrow, long, arranged radially interspersed with kenozooidal areas forming wedge-shaped to elongate longitudinal furrows, shorterthan theautozooecial ridges; gonozooids subpyriform in shape.

HOLOTYPE. — UW ARMaBy 007, colony figured here as Figure 7 A-C, A. Radwański collection, encrusting shell of brachiopod Sellithyris .

PARATYPES. — UW ARMaBy 008-009, other colonies on same Sellithyris shell as holotype, including that shown in Figure 7D, A . Radwański collection. NHM BZ 5522, Skorków Lumachelle, Małogoszcz Quarry ( Fig. 7E, F ).

TYPE HORIZON. — Lower Kimmeridgian.

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

ETYMOLOGY. — Namedfor Professor Andrzej Radwański, Universityof Warsaw, inrecognitionof his contributions to the palaeontologyof the Holy Cross Mts, inparticular that of Małogoszcz quarry, and who also collected some of the studied specimens of this new species.

MEASUREMENTS. — Longitudinalaperturaldiameter = 0.20-0.24 mm; transverseaperturaldiameter (top of ridge) = 0.12-0.15 mm; transverseapertural measurement (sideof ridge) = 0.07-0.09 mm; transverseperistome measurement (top of ridge) = 0.18-0.21 mm; transverse peristomemeasurement (sideof ridge) = 0.15-0.18 mm; autozooidal frontal wall length = 0.48-0.62 mm; autozooidal frontal wall width = 0.18-0.24 mm; total gonozooidal frontal wall length = 0.72 mm; gonozooidal width = 0.45-0.66 mm.

OCCURRENCE. — Lower Kimmeridgian, Małogoszcz Quarry, Holy Cross Mts, Poland.

DESCRIPTION

Colonies encrusting, sheet-like, up to 30 mm in diameter, stellate to discoidal or irregular inoutline shape, commonly unilamellar but rarely multilamellar, surface with fine transverse wrinkles. Autozooids arranged in narrow radiating ridges 5-12 mm long and 1.2-2.4 mm wide, forming lobes at growing edge, ridges about 2 mm apart, separated by slightly depressed areas occupied by kenozooids. Zooidal boundaries poorly defined on colony surface. Growing edge 0.18-0.3 mm wide. Early astogeny unknown.

Autozooids very slightly salient, two to four rows of larger zooids occupying ridge crest, zooidal size gradually decreasing down ridge flanks. Apertures subcircular to somewhat longitudinally elongate, with thin peristomes, often occluded by terminal diaphragms.

Gonozooid abraded in only known example ( Fig. 7C ), more or less pyriform in shape, slightly longer than wide, ooeciopore destroyed.

Kenozooids featureless, clearly seen only at growing edge, wherethey form buds narrowerthan those of the autozooids, and in worn specimens where they appear as longitudinal striations.

REMARKS

Only a few species exist of Reptoclausa , an Aalenian- Aptiangenuscharacterised byhavingridges containingautozooidsseparatedby furrowswith kenozooids. Thenewspeciesdescribedhere fromthe Lower Kimmeridgian fills the Upper Jurassic gap in the range of the genus. Reptoclausaporcata Taylor, 1980 , fromthe Aalenian (Lower Inferior Oolite) of the Cotswolds, England, shows some similarities with R. radwanskii n. sp. butdiffers in havingwider aperturesand much longer gonozooids. Another species, R. hagenowi (Sharpe, 1854) , fromthe Aptian Sponge Gravel of Oxfordshire, England,differsfrom R.radwanskii n.sp. inhavingmoresinuousanddiscontinuousautozooidal ridges.Newridgesin R. hagenowi arisebybifurcation of established ridges (see Pitt & Taylor 1990: 82) and their pattern is not as regular as in R. radwanskii n. sp. Autozooidalaperturesin R.radwanskii n. sp. are largerandnottransverseasin R. hagenowi . Reptoclausa neocomiensis described from the Upper Hauterivian (see Hillmer 1971), differsfrom R. radwanskii n. sp. in having longer and wider autozooids which are hexagonal in shape in comparison with the longitudinally elongate autozooids of R. radwanskii n. sp. Autozooidalridges are shorterin R. neocomiensis and the gonozooid is much longer and narrower.

Like Reptoclausaporcata (see Taylor 1980), the new Polish species R. radwanskii n. sp. may have been associated with living host brachiopods because bryozoan growth can be found to terminate at growth lines on the brachiopod shell, suggesting that growth of both the bryozoan and brachiopod werechecked simultaneously (see also Radwański & Radwańska 2003: 85-88).

Figures

FIG. 7. — Reptoclausa radwanskii n. sp., Lower Kimmeridgian, Małogoszcz Quarry, Holy Cross Mts, Poland: A-C, holotype, UW ARMaBy 007; A, edge of colony overgrowing brachiopod shell (visible bottom right);B, two autozooidal ridges forming convex lobes at colony growing edge and separated by kenozooidal troughs of lower profile; C, cavity left by destroyed gonozooid (arrowed); D, paratype, UW ARMaBy 008, autozooids; E, F, NHM BZ 5522; E, part of colony showing autozooidal ridges and striate kenozooidal areas between; F, autozooids showing large variation in aperture size according to position on ridge. Scale bars: A, B, E, 1 mm; C, 500 μm; D, F, 200 μm.