Thalamoporella rhombifera 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 : 265-266

Thalamoporella rhombifera Guha & Gopikrishna, 2004

( Fig. 13 , Table 10)

Thalamoporella rhombifera Guha & Gopikrishna, 2004: 25 , figs 22, 23.

Material examined. GIS/B 0300–0325. Argillaceous limestone in Waior-Charopadi stream near Waghot, Chhasra Formation, lower Miocene (Burdigalian), 23°25’55’’ N, 68°42’40’’ E, elevation 28 m, 16 January 2011, DST project, New Delhi .

Description. Colonies erect, cylindrical, with dichotomously branching stems, circular in cross-section. Autozooids arranged in quincunx, rectangular, each separated from neighbours by thick, raised granular boundaries; arranged in series of alternating rows ( Fig. 13A ). Orifice transversely D-shaped, distally arched, proximal margin straight.Two small adoral tubercles, one on each side of orifice. Two small equal-sized opesiules, oval or subrounded, below the slanting edge of orifices away from the lateral walls of the autozooid. Frontal cryptocyst well developed, sunken below level of autozooidal margin, granular, coarsely perforated by relatively large pores ( Fig. 13B ). Avicularia at bifurcation of rows, narrowly elongate, symmetrical, almost 75% of autozooid length; torqued towards sibling zooid ( Fig. 13C, D ); rostrum tapering distally with acute tip, rounded proximally, foramen drop-shaped, c. 80% of avicularian length, the proximal part bordered by smooth cryptocyst. Ovicells not observed.

Remarks. This species has an avicularium shape similar to that in the Thalamoporella hamata – T. falcifera – T. winstonae group illustrated by Soule et al. (1999, pp. 7–11, figs 4, 5, 6a, c, 7, 8), but in these species the avicularium is torqued away from the sibling zooid.

Figures

FIGURE 13. Thalamoporella rhombifera Guha & Gopikrishna, 2004 (GIS/B 0300). A. General view of colony showing autozooids, orifices, an avicularium and adoral tubercles. B. Enlargement of autozooids, orifices, small opesiules, an avicularium and mural rims. C. Close up of an avicularium. Scale bars: A, 500 µm; B, 200 µm; C, 100 µm.