Stomatopora recurva Waagen, 1867

Zatoń, Michał & Taylor, Paul D., 2009, Middle Jurassic cyclostome bryozoans from the Polish Jura, Acta Palaeontologica Polonica 54 (2), pp. 267-288 : 270

Stomatopora recurva Waagen, 1867

Fig. 2B .

1867 Stomatopora recurva sp. nov.; Waagen 1867: 647, pl. 32: 9a, b.

1867 Stomatopora dichotoma Lamouroux, 1821 ; Reuss 1867: 2 (partim), pl. 1: 3.

1867 Stomatopora bouchardi Haime, 1854 ; Reuss 1867: 2 (partim).

1867 Stomatopora dichotomoides d’Orbigny, 1850 ; Reuss 1867: 3 (partim).

1970 Stomatopora recurva Waagen, 1867 ; Walter 1970: 42, pl. 1: 5, 6.

2009 Stomatopora recurva Waagen, 1867 ; Taylor 2009: 26, figs. 2C, 3E, F.

Material.—Five fragmentary colonies GIUS 8−3509−2–6.

Measurements.— FWL, 1000–1100 µm; FWW, 600–800 µm; LPM, 200–300 µm; TPM, 250–450 µm; PW, 15–17.5 µm.

Description and remarks.—Only five fragmentary colonies, with worn and partly infilled zooids, of this uniserial species were found, all encrusting hiatus concretions. The ancestrula seems to be lacking. The branches, 600–800 µm wide, are straight or curved ( Fig. 2B 1 ), with bifurcation angles as high as 125 ° decreasing to about 87 °. Delayed separation of daughter branches may occur after bifurcation, briefly producing biserial branches ( Fig. 2B 1 ). The apertures of autozooids are spaced 1000–1100 µm apart, similar to the specimens of Stomatopora recurva from Balin ( Taylor 2009). Peristomes are preserved to a height of about 125 µm. Pseudopores are teardrop−shaped, large, 15–17.5 µm wide, bevelled and closely spaced.

The robustness of this species distinguishes it from the other Jurassic species of Stomatopora , such as S. bajocensis (d’Orbigny, 1850) , S. dichotomoides (d’Orbigny, 1850) , and S. corallina (d’Orbigny, 1850) (see Taylor 2009).

Stratigraphic and geographic range.—Uppermost Bajocian of Mokrsko and Middle Bathonian of Bugaj, Polish Jura. Stomatopora recurva is also known from the Upper Aalenian– Lower Bajocian of Germany, France and England ( Walter 1970), and uppermost Bathonian–lowermost Callovian of Balin, southern Poland ( Taylor 2009).

Figures

Fig. 2. Stomatoporid cyclostome bryozoans from the Middle Jurassic ore−bearing clays of the Polish Jura. A. Stomatopora bajocensis (d’Orbigny, 1850), Upper Bathonian, Ogrodzieniec, GIUS 8−3509−1. A1, autozooids showing high−angled bifurcations; A2, pseudopores. B. Stomatopora recurva Waagen, 1867, Middle Bathonian, Bugaj, GIUS 8−3509−2. B1, colony fragment showing early and later bifurcations; B2, pseudopores. C. Proboscinopora? sp., Middle Bathonian, Bugaj, GIUS 8−3509−7. C1, branching oligoserial colony, partly pyritised (white spots); C2, pseudopores. Scale bars: 300 µm (A1), 200 µm (B1, C1), 20 µm (A2, B2, C2). BSE SEM images of uncoated specimens.

Fig. 1. A. Map of Poland with Jurassic deposits indicated (shaded areas) after removal of the Cenozoic cover. B. Geological map of the Polish Jura area with sampled localities indicated (asterisks). Adapted from Zatoń et al. 2006.