Answers are grounded in this paper and cite their sources.
A new freshwater bivalve species, Pseudohyria (Matsumotoina) somanai n. sp. from the Early Cretaceous Sao Khua Formation of northeastern Thailand is described. The new species possesses the unique characters of subgenus Matsumotoina, including smooth hinge teeth and submedian pseudocardinal teeth, but it differs from the preceding sole species, Pseudohyria (Matsumotoina) matsumotoi Yang, 1979, from Korea in the number of pseudocardinal teeth, number of posterior ribs and shell shape. The new species is interpreted as a river species, and the dominant species among the bivalve assemblage in the type stratum. The temporal distribution of this subgenus is limited to the Late Barremian Formations of Japan and Korea, thus we suggest a Late Barremian age for the Sao Khua Formation.
No takes yet. Share an insight, caveat, or question.
Tumpeesuwan et al. (2010) studied this question.