Thalamoporella minuta Guha & Gopikrishnan, 2004

Sonar, Mohan A., Pawar, Ravi V. & Wayal, Dyaneshwar V., 2022, Fossil Thalamoporellidae (Bryozoa) from Paleogene-Neogene sediments of western Kachchh, Gujarat, India, Zootaxa 5104 (2), pp. 251-274 : 264

Thalamoporella minuta Guha & Gopikrishnan, 2004

( Fig. 12 , Table 9)

Thalamoporella minuta Guha & Gopikrishna, 2004: 12 , figs 6, 7.

Material examined. GIS/B 0271–0299: yellowish siltstone of Waghot cliff section and claystone of Kankawati River south of Vinjhan village , Chhasra Formation , late Lower Miocene (Burdigalian), 23°03’10’’ N, 69°00’23’’ E, elevation 25 m, 15 January 2011, DST project, New Delhi .

Description. Colony encrusting, unilaminar. Autozooids rectangular with parallel or slightly convex lateral margins, bordered by distinct, thin, slightly raised, sutured boundaries. Orifice circular to subcircular and wider than long, the arched distal margin raised, proximal margin concave ( Fig. 12A ). Adoral areas narrow without tubercles. Two subrounded, unequal opesiules close to lateral walls. Cryptocyst perforated, shallow, granular, slightly depressed in opesiular region. Avicularia small, oval, located at either right-hand or left-hand distolateral corner of orifice at bifurcation of rows, with rounded rostrum directed distolaterally ( Fig. 12B ). Ovicells not observed.

Remarks. The present material overall agrees with T. minuta Guha & Gopikrishna, 2004 except that opesiules are unequal-sized, autozooidal boundaries in some autozooids are slightly raised and avicularian crossbars are broken, thus not exhibiting the distinctive θ (theta) or figure-eight shape.

Figures

FIGURE 12. Thalamoporella minuta Guha & Gopikrishnan, 2004 (GIS/B 0271).A. General view of colony showing autozooids, orifices and avicularia. B. Close up of autozooids, orifices, unequal opesiules and an avicularium. Scale bars: A, 500 µm; B, 100 µm.