Fossil Thalamoporellidae (Bryozoa) from Paleogene-Neogene sediments of western Kachchh, Gujarat, India
Author
Sonar, Mohan A.
Department of Geology, Government Institute of Science, Aurangabad, Maharashtra, India.
Author
Pawar, Ravi V.
Department of Geology, Government Institute of Science, Aurangabad, Maharashtra, India.
Author
Wayal, Dyaneshwar V.
Department of Geology, Government Institute of Science, Aurangabad, Maharashtra, India.
text
Zootaxa
2022
2022-02-25
5104
2
251
274
journal article
20446
10.11646/zootaxa.5104.2.5
dc85c0df-79ee-4aab-b21d-2df3a61d8ac0
1175-5326
6280839
DE993A29-98B4-4DA0-85CF-9B8D4868A454
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.
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.
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.