Crocodia species in northern argentinean forests: distribution range and potential distribution

Abstract

This study aims to present a revision of Crocodia Link (Peltigeraceae, Lobarioideae) in northern Argentinean forests, to estimate its distribution range and potential geographic distribution in the region and to determine main factors affecting its distribution. Crocodia is a cosmopolitan genus with its highest diversity in the southern hemisphere in tropical and temperate regions. It is characterized by a foliose thallus, with green algae photobiont and internal cephalodia with cyanobacteria, yellow medulla, yellow pseudocyphellae on the lower surface, pedicellate and usually pubescent or verrucose apothecia, fusiform-ellipsoid, brown, and usually 3-septate ascospores, colorless bacilliform conidia, and triterpenoids as characteristic chemical components. A total of 114 specimens of CTES herbarium were studied, together with additional type specimens. Morphological and anatomical analyses were carried out using standard stereoscopic and compound light microscopes. Measurements were made with ImageJ software. Lichen substances were identified with spots tests. Based on occurrence data of material studied together with localities available in literature from northern Argentina and adjacent regions of bordering countries potential distribution was modeled with Maxent version 3.3.k. Cllimatic and topographic variables of WorldClim and Envirem were used and jackknife test was used to measure their importance. As a result, three species were identified from northern Argentinean forests: C. arvidssonii, C. aurata, and C. clathrata. Their distribution range is extended: C. arvidssonii is recorded for the first time for Argentina; C. aurata for Corrientes, Misiones, and Salta provinces; and C. clathrata for Corrientes and Jujuy provinces. Species potential distribution models have shown that highest suitable areas are mostly coincident with the Yungas Province (northwestern Argentina), and the Paranaense Province (northeastern region), both dominated by subtropical rainforests. Most relevant environmental variables affecting these species distribution are SAGA-GIS topographic wetness index (C. arvidsonii), elevation (C. aurata), and mean monthly potential evapotranspiration of driest quarter (C. clathrata).