Anil Bhandari
Paleontological Research 8 (3), 181-197, (1 October 2004) https://doi.org/10.2517/prpsj.8.181
KEYWORDS: Stigmatocythere, Cenozoic, evolutionary lineages, Ostracode, western India
Stigmatocythere Siddiqui is an important ostracode genus and occurs profoundly in sediments of marginal marine to shallow inner neritic origin in the Cenozoic succession of western India. Its species have short stratigraphic ranges and wide geographic distribution, which makes them good markers and helps in finer subdivision of the Cenozoic strata. Nineteen species including one new species Stigmatocythere (Bhatiacythere) khoslai have been recognized from Lower Eocene to Middle Miocene sediments of western India. Of these, Stigmatocythere (S.) obliqua Siddiqui is restricted to the upper part of the Lower Eocene. Stigmatocythere (S.) lumaria Siddiqui morphotype A and S. (S.) portentum Siddiqui are restricted to the upper part of the Middle Eocene (Bartonian) and Stigmatocythere (S.) lumaria Siddiqui morphotype B to the Upper Eocene. Stigmatocythere (Bhatiacythere) khariensis Khosla and Pant is restricted to the Lower Oligocene, while S. (S.) bermotiensis Khosla and Pant ranges from Lower Oligocene to Upper Oligocene and Stigmatocythere (S.) reticulata Khosla and Pant from Oligocene to Lower Miocene (middle part of Aquitanian). Stigmatocythere (S.) khoslai sp. nov. ranges from Aquitanian to lowermost Burdigalian, S. (S.) chaasraensis Guha ranges from uppermost Lower Oligocene to Lower Miocene (middle Burdigalian), and S. (B.) reversa Khosla, S. (S.) quilonensis Khosla and Nagori range from Aquitanian to middle Burdigalian, while S. (S.) latebrosa Lyubimova and Guha, S. (B.) spinosa Khosla and Nagori and S. (B.) interrupta Khosla and Nagori are confined to the Lower Miocene (lower to middle Burdigalian). S. (B.) rete Khosla and Nagori and S. (B.) arcuata Khosla and Nagori are confined to middle Burdigalian and S. (S.) multicostata Khosla and Nagori ranges from middle to upper Burdigalian. S. (S.) colini Bhandari is confined to the lowermost Middle Miocene and S. (S.) keeni Bhandari ranges up to the top of the Middle Miocene. The above species of the genus Stigmatocythere belong to five evolutionary lineages. They are: 1- Stigmatocythere (S.) obliqua – S. (S.) portentum, 2- S. (S.) reticulata – S. (S.) latebrosa – S. (S.) multicostata – S. (S.) keeni, 3- S. (S.) bermotiensis – S. (S.) quilonensis – S. (S.) chaasraensis, 4- S. (B.) khariensis – S. (B.) khoslai – S. (B.) reversa – S. (B.) rete – S. (B.) arcuata, 5- Stigmatocythere (B.) reversa – S. (B.) interrupta. These lineages are briefly discussed here.