Steinmanniporella Bucur, Granier & Schlagintweit, 2010

Bucur, Ioan I., Granier, Bruno & Krajewski, Marcin, 2014, Calcareous Algae, Microbial Structures And Microproblematica From Upper Jurassic-Lowermost Cretaceous Limestones Of Southern Crimea, Acta Palaeontologica Romaniae 10 (1 - 2), pp. 1-2 : 70-74

Genus Steinmanniporella Bucur, Granier & Schlagintweit, 2010

Steinmanniporella taurica ( Pcelincev, 1925) Bucur et al., 2010

Figs. 9-11

Synonymy

1925 Tetraporella taurica n. sp. – Pcelincev, p.85-86, Pl. 2, fig. 5

1965 Linoporella taurica (Pcelincev) – Praturlon, p.3-4.

1978 Tetraporella taurica Pcelincev – Bassoullet et al., p. 149-150, Pl. 17, fig. 5 (reproduction of the original illustration; considered as synonym of Linoporella capriotica )

2005 Linoporella (?) taurica Pcelincev – Barattolo & Romano, p.238

2010 Steinmanniporella taurica ( Pcelincev, 1925) nov. comb. – Bucur et al., p. 320, Fig. 1b (reproducing the specimen illustrated by Pcelincev, 1925).

Even though described in 1925, S. taurica remains a poorly studied species, as illustrated by the brief list of synonyms. The type-specimen presented by Pcelincev (1925) was collected at the Kukhu-koy locality from “oolitic- like limestones” assigned by the author to the "Lusitanian"-Lower Kimmeridgian interval. Pcelincev (1925: p. 85-86) provided the following species descripttion (translation from Bassoullet et al., 1978):

“In the Kücük- köy oolitic limestones, we frequently meet stalks and fragments of these calcified algae. About their external morphology, they are semicylindrical club-shaped with rounded end. Their maximal diameter is 3.2 mm long and their length is 14 mm. Only the external part of the stalk has been observed. In longitudinal section the internal cavity, appears, where the proper plant lives. From that cavity, primary canals crop outwards which appear, in distinct rings, on the outer part of the fossilized cylinder. When the thin outer layer has been destroyed, the concentric series of canal openings appears with a quantity no more than 30 per segment. On the whole length, the primary cylindrical canal has a constant diameter. Near the outer part of the external layer of the calcareous cylinder, each canal is divided into 4 secondary canals that are arranged on the external part of the cylinder. Small spores are situated principally at the distal end of a primary canal.”

The specimens identified by us show cylindrical, non-branched thalli (no club-shaped thalli were noticed, but based on the original description we cannot exclude the presence of such a morphology) with external diameters ranging from 1.6 to 4 mm.

The relatively large axial cavity (about 1/3 of the thallus diameter, from 0.6 to 2.4 mm) is well-defined, commonly outlined by a thin micritic rim ( Fig. 9 c, f ; Fig. 10 e ). The primary laterals show perpendicular arrangement or are slightly tilted towards the axial cavity. They have tubular shapes with rounded transverse sections and relatively constant diameter along the whole length. These laterals build-up relatively widely spaced verticils ( Fig. 9 a-d; Fig. 10 a-f; Fig. 11 h ). The number of primary laterals within a verticil varies from 38 to 45. Their length ranges from 0.25 to 0.70 mm and the diameter from 0.07 to 0.10 mm. The secondary laterals, ranging from 0.12 to 0.35 mm in length have a tubular proximal part followed by distal expansion ( Fig. 9 e ; Fig. 10 a, e, f ; Fig. 11 a-d). They are attached at the distal end of the primary laterals, each of the primary giving rise to 4 secondary laterals ( Fig. 11g, i ). The close-up view ( Fig. 11 f ) clearly illustrates the overall morphology of the primary and secondary laterals. Pcelincev (1925) noted the presence of some “spores” at the distal end of the primary laterals. However, further studies of numerous specimens have failed to confirm this feature.

Calcification consists of a sparitic calcareous sleeve (lowmagnesian calcite replacing the original aragonite) surrounding the axial cavity and extending outwards almost to the distal end of the secondary laterals. In specimens from more agitated environments with terrigenous supply the calcareous sleeve is partly eroded ( Fig. 9 f ; Fig. 10 a, b ). In some specimens that constitute the core of bacinellid oncoids ( Fig. 9 b ), the skeleton is “invaded” by such structures.

The general dimensions for this alga are included in Table 2. Despite providing a useful morphological description, Pcelincev (1925) did not present a diagnosis for this alga. Our observations identify the following diagnostic traits: Cylindrical (or possibly club-shaped), non-branched thallus with large, well-defined axial cavity. Two-orders of laterals displayed into verticils widely-spaced along the axial cavity. The primary tubular, cylindrical laterals are arranged perpendicularly or slightly-inclined with respect to the axial cavity. A bush of 4 phloiophorous secondary laterals is located at their distal end. Reproduction organs unknown, probably located within the axial cavity (endosporous).

Steinmaniporella taurica and S. kapelensis (a species identified in deposits of similar age) can be distinguished by observing the arrangement of the primary laterals (perpendicular vs. very steep) with respect to the axial cavity, as well as the inter-verticilar distance, which is smaller in the case of S. kapelensis . The general morphological features allow this species to be distinguished from other species of the genus Steinmanniporella ( Bucur et al., 2010) .

Ioan I. Bucur, Bruno Granier & Marcin Krajewski

In the study area, S. taurica was mainly identified in high energy environments (grainstones, probably bioclastic bars) associated with reef facies, as well as in reef facies with sponges, of Kimmeridgian-Tithonian age.

Associated microfossils: Salpingoporella gr. pygmaea , Griphoporella sp. ,? Clypeina /? Actinoporella sp. , “sole- noporaceans”, rivulariacean cyanobacteria, Mohlerina basiliensis, Troglotella incrustans, Coscinophragma sp., Ammobaculites sp. , Acruliammina sp. , Crescentiella morronensis , Lithocodium aggregatum , bacinellid structures.

Figures

Fig. 9 Calcareous algae (Dasycladales) from the Yalta-Ay Petri area, southern Crimea. a to f Steinmanniporella taurica (Pcelincev) in longitudinal (a, b), longitudinal, slightly oblique (c), oblique tangential (d) and oblique (e, f) sections. White square area in c is enlarged in Fig. 11f. a, sample KB-51m; b, sample KC-17b; c, sample KB38a; d, sample KC-13; e, sample KB-51L; f, sample KJ-23a. Scale bar: 0.5 mm (a to f).

Fig. 10 Calcareous algae (Dasycladales) from the Yalta-Ay Petri area, southern Crimea. a to g Steinmanniporella taurica (Pcelincev) in longitudinal-oblique (a to d, f), oblique (e) and transverse-oblique (g) sections. A, sample KJ-23a; b, sample KJ- 23b; c, sample KB-41a; d, sample KB-38a; e, sample KB-41b; f, sample KJ-23b; g, sample KC-17b. Scale bar: 0.5 mm (a to g).

Fig. 11 Calcareous algae (Dasycladales) from the Yalta-Ay Petri area, southern Crimea. a to i Steinmanniporella taurica (Pcelincev) in transverse (a, b, e), oblique (d), tangential (g) and oblique-tangential (h) sections. f represents a close-up view of the specimen in Fig. 9c (white square) showing the shape of the laterals, and i represents a close-up view of the specimen in Fig. 9 e (upper part) showing the transition from primary to secondary laterals. a, sample KM-51m; b, g, sample KB-51k; c, sample BK-41d; d, sample KB-41a; e, sample KB-51b; f, sample KB-38a; h, sample KB-41b; i, sample KB-51L. Scale bar: 0.5 mm (a to f, h); 0.25 mm (g, i).

Fig. 1 Location of the areas studied. a General sketch of the Crimean Peninsula with the main localities of its southern part. b Location of samples collected near Belogorsk (point 397). c Location of the samples collected near Yalta.