Hidden areas of endemism: Small units in the South-eastern Neotropics

Abstract

This study aimed to establish if the Lower R ıo de la Plata Basin (LRPB) wetlands can be considered a biogeographic unit. The species of this area were compiled and segregated according to the habitat, selecting only 87 endemic taxa restricted to the LRPB and linked to wetlands. Distributional data of species obtained from the literature, web databases, biological collections, and field trips were georeferenced. The areas of endemism were established as those areas where the distribution of two or more taxa overlaps in groups of rivers' sections with geographic continuity and were tested with a cluster analysis. This congruence is due to ecological, geomorphological, and historical factors. Four areas of endemism were found: a broad area that comprises the whole study area (Riverine district), which is divided into three nested smaller areas (Paraguay-Paran a Flooding Valleys, Uruguay Basin, and Paran a Delta subdistricts). Then, we analysed 170 taxa distributions to evaluate the relationship between the study area and the neighbouring biogeographic units. According to the results, the study area belongs to the Paran a biogeographic province. Some areas of endemism are hidden inside broader areas and are hardly detected with the currently used biogeographic grid-methods. We propose to combine the information about ecological requirements of each taxon with its georeferenced records to estimate their areas of distribution as a primary step for searching areas of endemism in intracontinental studies.

Biogeographic regionalization of the Neotropical region: New map and shapefile

“…The map is based on the modifi ed shapefi les of the ecoregions of Olson et al (2001) and the provinces of Löwenberg-Neto (2014), Morrone et al (2017), Apodaca et al (2019), Colli-Silva et al (2019) and Arana et al (2021. To facilitate future biogeographic analyses, we provide a vector fi le (shapefi le; .shp extension).…”

“…The Neotropical region comprises the tropical areas of South America, Central America, southern and central Mexico, and the Antilles (Morrone 2018). In the most recent biogeographic regionalization analyses, 57 provinces have been recognized (Morrone 2014, 2018, 2020, Martínez et al 2017, Apodaca et al 2019, Colli-Silva et al 2019, Arana et al 2021.…”

“…To unify the different evolutionary biogeographic and ecoregional schemes into a single system, as done for Argentina (Arana et al 2017(Arana et al , 2021 and Mexico (Morrone et al 2017), we consider that the boundaries of the ecoregions combining climatic, geological, and biotic criteria with evolutionary units (areas of endemism) are appropriate. Thus, we provide herein a map of the biogeographic provinces of the Neotropical region (following Löwenberg-Neto 2014, Morrone 2014, 2017, 2018, 2020, Martínez et al 2017, Apodaca et al 2019, Colli-Silva et al 2019, Arana et al 2021, based on the ecoregions recognized by Olson et al (2001), and the corresponding shapefi le.…”

Diagnostics of new species of Neotropical Tischeriidae (Lepidoptera), with the first record of Coptotriche Walshingham from South America

“…Terminalia australis, or palo amarillo, is a southern South American tree species. It forms part of the communities typical of gallery forests and riverine scrub forests along the Paraná and Uruguay rivers and their tributaries, adapted to periodical floods (Apodaca et al 2019). We expect this tischeriid species to also occur in Brazil, Paraguay, and Uruguay.…”

First records of Chrysocyon brachyurus (Illiger, 1815) (Mammalia, Carnivora) in the Gualeguay Department, Entre Ríos Province, Argentina

“…This river and its many tributary streams are surrounded by wide, seasonally flooded plains, where there are several lagoons and oxbow lakes (Ormazábal et al 2005;Margasin et al 2020). Given this fluvial complexity, the area shows a diverse range of environments, which is reflected in the flora, fauna, and the diversity of the landscape (Bó and Malvárez 1999;Madanes et al 2010;Apodaca et al 2019). The main vegetal formation in our study area is the temperate grassland, with the grass genera Axonopus, Paspalum, Digitaria, Schizachtrium, and Bothriochloa (Poaceae) dominating (Bilenca and Miñarro 2004;Matteucci 2012) corn crops, and cattle ranching.…”