Microeciella kuklinskii, 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 : 274

Microeciella kuklinskii sp. nov.

Fig. 4.

Etymology: In honour of Dr. Piotr Kukliński, a bryozoan ecologist from the Institute of Oceanology, Polish Academy of Sciences, Sopot.

Type material: Holotype: GIUS 8−3509−10; paratypes: GIUS 8−3509− 11–12.

Type locality: Bugaj , Polish Jura, Poland .

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

Material.—The holotype and two paratypes listed above.

Measurements.—FWL, 1000–1371 µm; FWW, 250–333 µm; LAM, 125–200 µm; TAM, 125–150 µm; LPM, 166–266 µm; TPM, 183–233 µm; GTL, 2040 µm; GDL, 735 µm; GW, 815 µm; OL, 65 µm; OW, 65 µm; PL, 20–23 µm; PW, 15–18 µm.

Diagnosis.— Microeciella with ovoidal or heart−shaped brood chamber, strongly subterminal ooeciopore; autozooids large, frontal walls more than 250 µm wide; pseudopores large; teardrop−shaped pseudopores; nanozooids occasionally present.

Description.—Colony encrusting, multiserial, unilamellar, bereniciform.

Autozooids large, elongate, with flat proximal and convex distal frontal wall; zooidal boundaries distinct. Preserved peristomes short, tapering distally. Apertures subcircular to longitudinally elongate. Pseudopores moderately spaced, large, teardrop−shaped, pointed distally ( Fig. 4A 4).

Nanozooids occur sporadically over the colony surface only in one paratype (GIUS 8−3509−12), often in close proximity to autozooidal apertures ( Fig. 4B); peristomes short, upright; apertures circular to subcircular in outline, c. 70 µm long by 63 µm wide.

Gonozooids uncommon, with flat to slightly convex frontal walls, proximally indistinguishable from autozooids. Brood chamber ovoidal or heart−shaped, only slightly wider than long, accentuated by two small lobes distally ( Fig. 3B ), roof densely pseudoporous, similar in convexity to autozooidal frontal walls. Ooeciopore subterminal, located well below distal edge of brood chamber, circular in outline, much smaller than an autozooid aperture.

Remarks.—Although only one colony preserves a gonozooid, the overall morphology of this species of Microeciella is sufficiently distinct to justify the creation of a new species. Two paratype colonies (GIUS 8−3509−11–12) without gonozooids are included in this species on the basis of their similar autozooid and pseudopore characteristics. It is worth noting that nanozooids, polymorphs occurring rarely in Jurassic bryozoans, have never been detected previously in the genus Microeciella . Their scattered occurrence on the colony surface is reminiscent of the extant cyclostome Plagioecia sarniensis . Silén and Harmelin (1974) interpreted such patterns of “occasional nanozooid” development as due to irregularities of the substratum disturbing the normal growth of the colony and resulting in narrowing of the space available such that a normal autozooid could not be budded.

Stratigraphic and geographic range.—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.