Thinouia ventricosa is known from semi-deciduous and ombrophilous forests in the states of Paraná, Rio Grande do Sul, Santa Catarina, and São Paulo, Brazil, and from Argentina.
Thinouia ventricosa possesses a wide EOO of 306,232.35 km² and an AOO of 92.00 km², with few known locations. However, the semi-deciduous and ombrophilous forest vegetation in southeast Brazil and northeast Argentina, where the species is mostly found, is subject to continuing decline in area and quality of habitat due to anthropic pressure. Despite this, there are no data on population declines to apply other criteria, and several conservation units in Brazil and Argentina protect the species. Thus, it should be regarded as Least Concern (LC).