Records of the land planarian Polycladus gayi (Tricladida,Geoplanidae) preying on black snails Macrocyclis peruvianus (Gastropoda,Macrocyclidae)

Polycladus gayi is a colourful and easily recognizable land planarian native to the temperate to cold rainforests of the west coast of southern South America, in Chile and Argentina; however, its ecology is poorly understood. Here, we describe the first records of P. gayi preying on a black snail Macrocyclis peruvianus in the wild. Two events were recorded, the first in a healthy forest in Llancahue Alto, Panguipulli, Chile, during the austral summer of 2023, and the second in a mature evergreen forest in the coastal range of La Union, Chile. These records expand our knowledge of the feeding habits and behaviour of P. gayi and add M. peruvianus to its prey list.     

Leaf growth rate and nitrogen content determine respiratory costs during leaf expansion in grapevines

Respiration processes are well recognized as fundamental for the plant carbon balance, but little attention has been paid to the relationships among respiration rates, environment and genetic variability. This can be of particular interest to understand the differences in net carbon balances in crops as grapevines. Night respiration (R_n) and its associated growth (R_g) and maintenance (R_m) components were evaluated during leaf expansion in two grapevine cultivars (Tempranillo cv. and Garnacha cv.) that differ in their plant growth pattern and carbon balance. Simultaneously, leaf traits as leaf mass area, nitrogen (N) and carbon (C) content were evaluated in order to relate to the respiratory processes and the leaf growth. The results showed the differences in respiration rates associated with the leaf expansion pattern. Tempranillo developed leaves with higher leaf area and lower dry weight per leaf unit than Garnacha. Although differences between cultivars were observed in terms of growth costs in expanding leaves, the maintenance costs were similar for both cultivars. Also, a significant linear regression was found between respiration rates and N content in expanding and mature leaves. The results indicate that differences in structure and nitrogen content of expanding leaves may lead to respiratory differences between cultivars. These results also demonstrate the importance of respiratory cost components in carbon balance calculations in grapevines.