Thalamoporella vinjhanensis Guha & Gopikrishna, 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 : 268-269

Thalamoporella vinjhanensis Guha & Gopikrishna, 2004

( Fig. 15 , Table 12)

Thalamoporella vinjhanensis Guha & Gopikrishna, 2004: 39 , figs 37, 38.

Material examined. GIS/B 0353–0361. Yellowish limestone at cliff section of Lakdi Nadi near Tera village , Chhasra Formation , lower Miocene (Burdigalian), 23°22’19’’ N, 68°58’10’’ E, elevation 52–56 m, 15 January 2011, DST project, New Delhi .

Description. Colony erect, bilaminar. Autozooids rectangular, parallel-sided or lateral margins weakly convex, bordered by thick, smooth, distinct boundaries ( Fig. 15A ). Orifice subrounded, the arcuate distal rim raised more than the concave proximal margin. Adoral areas narrow with no tubercles. Two opesiules adjacent to lateral walls proximal to orifice, large, rounded, mostly unequal and deeply sunken. Cryptocyst gently sloping in opesiular region, smooth, coarsely perforated ( Fig. 15B, C ). Avicularia at bifurcation of rows, variably penknife-shaped, longer than autozooids, with subacute rostrum; foramen elongate-oval, about half of avicularian length, pivots often present, cryptocyst fairly well developed proximally, sunken below autozooidal rim, smooth. Avicularium and sibling autozooid torqued toward each other ( Fig. 15C ). Ovicells not observed.

Remarks. The present material shows intracolony variation of the avicularian rostral tips, which are sometimes subacute and others rounded, but it otherwise accords with T. vinjhanensis . The species has some similarity to Thalamoporella longirostrata Maplestone, 1900 (see Soule et al. 1992, p. 53, figs 73, 74; and SEM photo, MOV P10126 from Muddy Creek, Victoria on bryozoa.net), but avicularia of T. longirostrata lack pointed pivots and are not torqued.

Figures

FIGURE 15. Thalamoporella vinjhanensis Guha & Gopikrishna, 2004 (GIS/B 0353–0361).A. General view of colony showing rectangular autozooids, orifices, equal opesiules and knife-shaped avicularia. B. General view of autozooids, orifices and equal opesiules. C. Close up of avicularia, autozooids, cryptocyst, orifices and opesiules. Scale bars: A, 500 µm; B, 500 µm; C, 200 µm.