Proboscinopora, Pitt and Taylor, 1990

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

Proboscinopora ? sp.

Fig. 2C .

Material.—One poorly preserved colony GIUS 8−3509−7.

Measurements.—FWL, 500–800 µm; FWW, 200–300 µm;

LAM, 120–200 µm; TAM, 83–120 µm; LPM, 183–266 µm; TPM, 133–200 µm; PL, 15–20 µm; PW, 2.5–3.8 µm.

Description.—Colony encrusting with narrow oligoserial, ribbon−like branches. Generally up to 2–3 autozooids across the width of the branches which are slightly convex, low, and bifurcate irregularly at variable angles ( Fig. 2C 1 ). Autozooids are elongate, have circular or longitudinally elliptical apertures, variably spaced and short preserved peristomes. Frontal walls are ornamented by very narrow, slit−like pseudopores elongated parallel to growth direction ( Fig. 2C 2 ).

Remarks.—Colony−form agrees with the genus Proboscinopora , introduced by Pitt and Taylor (1990) for Proboscina − like colonies lacking basal gonozooids (it is possible that peristomial gonozooids were developed but were lost when the peristomes broke off). However, the fragmentary nature of the single colony described here precludes its unequivocal identification as Proboscinopora as it may alternatively be an infertile colony of Oncousoecia (see Taylor and Zatoń 2008) which has a very similar colony−from. The distinctive slit−like pseudopores while typical of many stomatoporids can also be found in species of Microeciella (family Oncousoeciidae ) and Multisparsa (family Multisparsidae ) (see below and Taylor 2009).

Stratigraphic and geographic range.—Middle Bathonian of Bugaj, Polish Jura.

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.