Reptomultisparsa sp.

Hara, Urszula & Taylor, Paul D., 2009, Cyclostome bryozoans from the Kimmeridgian (Upper Jurassic) of Poland, Geodiversitas 31 (3), pp. 555-575 : 568

Reptomultisparsa sp. ( Fig. 8 )

MATERIAL EXAMINED. — Skorków Lumachelle,Małogoszcz Quarry: NHM BZ 5523. — Wierzbica Quarry: MUZ PIG 1719.II.2.

MEASUREMENTS. — Longitudinalaperturaldiameter = 0.12- 0.16 mm; transverseaperturaldiameter = 0.10-0.12 mm; longitudinalperistomediameter = 0.22-0.28 mm; transverse peristomediameter = 0.18-0.24 mm; frontalwall length = 0.60-1.0 mm; frontalwall width = 0.18-0.22 mm; gonozooid length = 0.86 mm; gonozooid width = 0.92 mm; transverse ooeciopore width = 0.18 mm.

OCCURRENCE. — Lower Kimmeridgian, Wierzbica and Małogoszcz quarries, Holy Cross Mts, Poland.

DESCRIPTION

Colony encrusting, sheet-like, discoidal, unilamellar, growing edge bordered by a narrow basal lamina. Ancestrula and early astogeny not observed.

Autozooids long, frontalwallsalmost flat.Apertures subcircular, a little longerthan wide, widelyspaced, Peristomes indistinct, narrow, slightly tapering distally. Pseudopores longitudinally elongate, worn.

Gonozooids represented by a single example, slightly longitudinally elongate, rounded triangular in outline shape, surface flat (not inflated), crossed by transverse growth bands. Ooeciopore transversely elongate, larger than autozooidal apertures, subterminal.

REMARKS

The genus Reptomultisparsa comprisesbereniciform tubuliporines with large, longitudinally elongate gonozooids, andcommonlymultilamellar colonies.In some species, including thetype species R. incrustans , the gonozooids are several times longer than wide. However, that in the Lower Kimmeridgian species described here is almostequidimensional ( Fig. 8B ), recalling the proportions more characteristic of Microeciella and highlighting a problemcommonly encountered when trying to assign Jurassic cyclostomes to genera based on gonozooid shape.

The Polish Lower Kimmeridgianspeciesresembles R. norberti Hara &Taylor, 1996 , fromthe Oxfordian of Poland.Gonozooids inbothspecies have relatively flat frontal walls but those of R. norberti are ovoidal or fusiform in outline shape, unlike the rounded triangular gonozooids of the Lower Kimmeridgian species. Another species, R. tumida Taylor, 1980 , described from the Bathonian of England, also has a more elongate gonozooid, as well as smaller autozooids. Specific determination of the Polish Lower Kimmeridgian species is deferred in view of the scarcity of the material available.

Figures

FIG. 8. — Reptomultisparsa sp., NHM BZ 5523, Lower Kimmeridgian, Skorków Lumachelle,Małogoszcz Quarry,Holy Cross Mts,Poland:A, part of colony showing autozooids and a gonozooid; B, detail of gonozooid with ooeciopore arrowed. Scale bars: A, 1 mm; B, 500 μm.