Thalamoporella kachchhensis 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 : 262

Thalamoporella kachchhensis Guha & Gopikrishna, 2004

( Fig. 10 , Table 7)

Thalamoporella kachchhensis Guha & Gopikrishna, 2004: 20 , figs 16‒19.

Material examined. GIS/B 0211–0230. Yellow limestone, Murachbann, 2 km from Walaram Teerthdham, Chhasra Formation, late lower Miocene (Burdigalian), 23 ° 30’10” N, 68 ° 52’99” E, elevation 91–93 m, 13 January 2011, DST project, New Delhi .

Description. Colony erect, bilaminar. Autozooids elongate, narrow, generally parallel-sided ( Fig. 10A ), surrounded by a thick, distinct, mural rim ( Fig. 10B ). Orifices large, elongate-oval to transversely D-shaped, distal border highly arched, raised, proximal margin concave. Adoral areas narrow, without tubercles. Conspicuous paired oval opesiules present near lateral walls of autozooids proximal to orifice, mostly of equal size, flanking a deeply sunken polypide tube ( Fig. 10C ). Cryptocyst shallow, perforated more densely in proximal half or twothirds. Avicularia at bifurcation of rows, drop–shaped, c. 75–80% of autozooidal length ( Fig. 10B, D ), with slightly raised acute symmetrical rostrum, foramen elongate-oval, more than half of avicularium length, cryptocyst granular. Ovicells not observed.

Remarks. The present species superficially resembles Thalamoporella vinjhaniensis Guha & Gopikrishna, 2004 in the shape of avicularium. However, in that species the avicularium is torqued toward the sibling zooid. Thalamoporella kachchhensis also closely resembles T. floridana (Osburn, 1914) in the shape of avicularia (see Chaney et al. 1989), however, in T. floridana avicularia are c. 65% of zooidal length, adoral tubercles are well developed and irregular, and opesiules are unequal. The present species also closely resembles T. gothica ( Busk, 1856) in the shape of the avicularium (see Chaney et al. 1989, p. 344, fig. d; Soule et al. 1999, p. 19, figs 25–28). However, T. gothica has comparatively short and wide autozooids, orifices wider than high and small or no adoral tubercles. Thalamoporella gracilata Tilbrook, Hayward & Gordon, 2001 shows some resemblance in the shape of the avicularium, but it differs from the present species in orifice shape and opesiule size.

Figures

FIGURE 10. Thalamoporella kachchhensis Guha & Gopikrishna, 2004 (GIS/B 0211). A. General view of colony showing autozooids. B. Detail of autozooids, orifices, opesiules and beaded mural rims. C. General view of colony showing orifices, opesiules and cryptocyst. D. Detail of an avicularium, orifice and opesiules. Scale bars: A, 500 µm; B, 100 µm; C, 500 µm; D, 100 µm.