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Pandey, Vikas
- A New Record of Nerita nigrita Röding, 1798 (Mollusca:Gastropoda:Neritidae) from India
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Authors
Affiliations
1 Department of Ocean Studies and Marine Biology, Pondicherry University, Brookshabad Campus, Port Blair 744 112, IN
1 Department of Ocean Studies and Marine Biology, Pondicherry University, Brookshabad Campus, Port Blair 744 112, IN
Source
Current Science, Vol 116, No 5 (2019), Pagination: 828-831Abstract
Many members of the family Neritidae display polymorphism as their shells can be highly variable in colour, which has sometimes led to confusion in the identification of closely related species. One such confusion in the taxonomic identification of two Nerita spp. currently exists in India. According to the literature and identification keys available, Nerita nigrita does not exist in the country (has not been reported), but the reason is that this species has thus far been misidentified as Nerita maxima. The key difference between these two species can be observed in their shell spire – N. nigrita consists a slightly elevated spire with distinguishable protoconch, whereas N. maxima has a depressed spire with indistinct protoconch. Other identification characters which separate these two species, such as shell texture, operculum structure and outer lips are also described. The present study reports N. nigrita as a new record from the Indian coast.Keywords
Identification Characters, Nerita nigrita, Nerita maxima, Polymorphism.Full Text
References
- Eichhorst, T. E., Neritidae of the World, Vol. 1, Conch Books, Hackenheim, Germany, 2016, p. 694.
- Tan, S. K. and Clements, R., Taxonomy and distribution of the Neritidae (Mollusca: Gastropoda) in Singapore. Zool. Stud., 2008, 47(4), 481–494.
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- Metamorphic evolution of mafic granulites from Tiyara area, Makrohar granulite belt, Singrauli district, Madhya Pradesh, India
Abstract Views :129 |
PDF Views:74
Authors
Affiliations
1 Department of Civil Engineering, Indian Institute of Technology (BHU), Varanasi 221 005, India, IN
1 Department of Civil Engineering, Indian Institute of Technology (BHU), Varanasi 221 005, India, IN
Source
Current Science, Vol 123, No 11 (2022), Pagination: 1334-1340Abstract
The mafic granulite rocks from the Makrohar Granulite Belt of the Chotanagpur Granite Gneissic complex (CGGC) have been studied with reference to their petrography, mineral chemistry and pressure–temperature (P–T) conditions of metamorphism. The common mineral assemblage observed within different thin sections is orthopyroxene–clinopyroxene–hornblende–plagioclase–biotite–quartz. The average P–T condition of the mafic granulites in the study area suggests a peak of metamorphism at 799° ± 40°C/6.3 ± 0.9 kbar. However, the peak P–T estimate obtained from the conventional two-pyroxene thermobarometer is 5.83–6.47 kbar and 887° ± 62°C at a fixed pressure of 6 kbar, followed by post-peak P–T conditions of metamorphism at 590°–693°C/2.1–2.4 kbarKeywords
Mafic granulites, metamorphic rocks, mineral assemblage, pressure, temperature.Full Text
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