Johann Rudolf Rengger

Early life Johann Rudolf Rengger was born in Baden as the son of the pastor Samuel Rengger. Since his parents died early, his uncle Albrecht Rengger, then Interior Minister of the Helvetic Republic, provided his education, first at a private school, and then at the canton school of Aarau from 1805 to 1812. He later studied natural sciences and medicine in Lausanne and Tübingen. In 1817 he published the results of his research on insects under the title Physiological investigations on the animal housekeeping of Insects and thus earned on October 12 of the same year the degree of Doctor of Medicine.

The Paraguayan trip After a stay in Paris, Rengger decided, together with doctor M. Longchamp from the canton of Vaud, to undertake a research trip to South America. On May 1, 1818, they embarked in Le Havre and arrived in Buenos-Aires on July 1. Here, their attention soon turned on to the secure conditions of Paraguay. So they went up to the Entre Ríos Province, waited for eight months in Corrientes because the leader Artigas had blocked the stream traffic, and didn't reach Asunción until July 30, 1819. On their side, Rengger and Lonchamp were not allowed to cross the strictly guarded border, and had to request a special permit for each excursion. While Longchamp mostly remained in the capital, Rengger used all the permissions given for his naturalist research. Despite this scientific activity, there was a lack of contact with educated men and correspondence with foreign countries, especially with the homeland, because the dictator had all incoming and outgoing letters intercepted, so that the relatives of Rengger received only a little news of his situation. In 1825, they unexpectedly obtained an exit permit, but had only a few hours to prepare, with Longchamp packing the smaller part of his collections. On May 25, 1825, they left Paraguay, returning to Le Havre via Buenos Aires, Bahia, and Pernambuco. a cricetid rodent, the large vesper mouse: Calomys callosus (Rengger, 1830); a primate, the Azaras's capuchin: Cebus azarae (Rengger, 1830), which is a species synonym for Sapajus cay; an orb web weaving spider: Parawixia bistriata (Rengger, 1836).