South American Transition Zone Research Articles

Arthrobrachus crassicornis sp. nov (Coleoptera: Melyridae), a new species from the South American Transition Zone in Argentina

Arthrobrachus Solier, 1849 is a genus of Melyridae distributed in the southern cone of South America, with twenty valid species. A new species of the genus was recognized in the study of collection material. Artrobrachus crassicornis sp. nov. is described from Argentina and distributed in the South American Transition Zone.

Richness and endemism in Chusquea subg. Swallenochloa (Poaceae), a Neotropical subgenus adapted to temperate conditions

Chusquea subg. Swallenochloa comprises 52 species distributed in five biogeographical areas (Mexican Transition Zone, Brazilian subregion, South American Transition Zone, Chacoan subregion, and Andean region). Species of the subgenus grow from almost sea level in the Andean region to almost 4000 m in the northern South American Transition Zone (SATZ) and are often common or dominant elements of the vegetation. In this study, three questions related to species richness, endemism, and risk category of Chusquea subg. Swallenochloa were addressed. Analyses were based on the geo-referenced occurrence data of these 52 species, using different methods and software programs. Results indicate that the Chacoan subregion and SATZ had the highest richness with 16 and 15 species, respectively. The area of highest endemism was found in the Brazilian subregion. The AOO and EOO methods provided strongly differing estimations of conservation status.

Diversity and distribution of andean tubers: an agrogeographic analysis

Andean tubers are a group of basic plants in the security and food sovereignty of Andean community for thousands of years. The conservation of the infra and interspecific diversity of these plants is a strategy for environmental adaptation rooted in the high-Andean cultural identity. Solanum tuberosum, Oxalis tuberosa, Tropaeolum tuberosum and Ullucus tuberosus, have in common that they develop edible modified stems with a wide variety of shapes, colors, and flavors, and these are cultivated in the Andean countries. The high diversity of Andean tuberous species is heterogeneously distributed and concentrated in micro-centers of diversification distributed in South American countries. The aim of this work was to determine the general distribution pattern of the four mentioned species and their agrogeographic nodes. With the coordinates of presence of these four species, registered in the GBIF platform (Global Biodiversity Information Facility), biogeographical methods were applied to model the individual traces that show the distribution pattern of each species and through the intersection of these, a generalized trace that makes visible the distribution patterns of Andean tubers, as well as their agro-geographical nodes. The greatest diversity of the four species is concentrated in these intersections, favoring domestication scenarios. Some micro-centers of diversity identified, correspond to those defined in the investigations of morphological or molecular characterizations. The main nodes were found in Peru and Ecuador between the biogeographic provinces of Puno, in the South American Transition Zone and the Yungas, from the southern Brazilian domain. The study of the geographical distribution patterns of cultivated plants allows to identify the patterns of plant exchange of the human groups involved in their management. The study of the geographical distribution patterns of cultivated plants allows to identify the patterns of plant exchange of the human groups involved in their management.

Revision of the South American stiletto fly genera Entesia Oldroyd and Melanothereva Malloch, with the description of a new genus (Therevidae: Agapophytinae)

The South American members of the stiletto fly subfamily Agapophytinae (Diptera: Therevidae) occur in the South American Transition Zone, predominantly in Chile and southwestern Argentina. The four agapophytine genera described from this region are Entesia Oldroyd, 1968; Melanothereva Malloch 1932; Pachyrrhiza Philippi, 1865; and more recently, Sigalopella Irwin & Winterton, 2020. Here we revise Melanothereva and Entesia and describe the new monotypic genus Pachylopella. Keys to South American Agapophytinae genera and species of Melanothereva and Entesia are provided. 

Taxonomic revision of Aegognathus Leuthner, 1883 (Coleoptera: Lucanidae)

ABSTRACT Aegognathus Leuthner, 1883 (Coleoptera: Lucanidae) is revised and redefined. With this revision, the genus is now composed by Andean species only. The Brazilian species, Aegognathus spitzi Ohaus, 1929 and Aegognathus caledoniaensis Grossi, Racca-Filho and Vaz-de-Mello, 2003, are both transferred to the genus Leptinopterus Hope, 1838 with which they share many characteristics. Aegognathus iridicolor Luederwaldt, 1935 is synonymised with Leptinopterus spitzi (Ohaus, 1929), syn. nov. A known distribution map is provided, showing that the nine species are distributed along the South American Transition Zone, six of them associated with the South Brazilian Biogeographic Dominion, and the remaining three with the Pacific Dominion. Distribution data reflects the high conservation value of all Aegognathus species as they are distributed in the Tropical Andes, one of the most important biodiversity hotspots.

The smallest area shaped a big problem: a revision of the placement of the Ventania sky island in the biogeography of South America

AbstractThe placement of the southern border of the Neotropical region, called the Subtropical Line, is a long-lasting point of discussion. Its most debatable section runs around the Pampean province, where an isolated mountain system called Ventania has Andean connections surrounded by Neotropical biota. To answer where to place the Subtropical Line, a thorough revision of the biogeography of Ventania is needed. Thus, we characterized Ventania as an area of endemism and conducted a similitude analysis to compare it with surrounding systems using stenoic taxa. Then we compiled the disjunct distributions in Ventania and the phylogenetic information of its endemic taxa to know with which other areas it is related. We also compared the biogeographic differences with Tandilia, the nearest mountain system. We found that Ventania is a small but well-defined area of endemism mostly related to the Andean and South American Transition Zone (SATZ) provinces. Relatedness with the Pampean province is less than had been thought. We suggest that Ventania is a SATZ sky island province, and the smallest continental province of the world. The Subtropical Line should therefore be placed in the southern border of the Pampean province, with Ventania as a SATZ island inside the Neotropical region.

<p><strong>Biogeographic origins and floristic affinities of the bryophytes of the Tota-Bijagual-Mamapacha complex in the Páramos of Boyacá, Colombia</strong></p>

Páramos are Neotropical high-elevation isolated ecosystems in the Andes. These areas are inhabited by many distinct plant species, such as bryophytes, which provide environmental services including the storage and regulation of surface and groundwater; however, the diversity and biogeographic affinities of bryophytes are still unknown. We used phytogeographic analysis and biogeographic regionalization approaches to determine the biogeographic origins and floristic affinities of this flora in the Tota-Bijagual-Mamapacha (TBM) páramos complex. We found 219 species of bryophytes, 145 mosses, and 75 liverworts. These species are mainly of Neotropical origin, although we also found relationships with Ethiopian, Nearctic, Australian, Antarctic, Palearctic and Oriental regions. According to Morrone (2014), the TBM is located in the South American Transition Zone, the Páramo province, and the Páramos de la cordillera Oriental biogeographic district. The TBM had important floristic relationships with the South Brazilian subregion and the Magdalena province. We found no endemic species to the TBM complex, but identified several endemic species for the Andean páramos.

Liogenys Guérin-Méneville, 1831 (Coleoptera: Scarabaeidae: Melolonthinae) from the southern South American Transition Zone and boundaries: taxonomic overview with four new species.

The biodiversity of Liogenys Guérin-Méneville, 1831 (Coleoptera: Scarabaeidae: Melolonthinae: Diplotaxini) from the southern South American Transition Zone and boundaries is presented. Four new species are described: L. brachyclypeata Cherman, new species; L. lucialmeidae Cherman, new species; L. martinezi Cherman, new species; and L. maxillaricuspis Cherman, new species. The synonymy of L. flaveola Moser, 1924 (= L. kadleci Frey, 1970) is proposed. Lectotypes are designated for L. flavida Moser, 1918; L. pallidicornis Blanchard, 1851 (currently L. xanthocera Harold, 1869); and L. rufoflava Moser, 1918. Redescriptions are provided for all the species mentioned above plus L. calcarata Frey, 1970 and L. kunzteni Moser, 1921, as well as an identification key and updated geographical distributions to all species in the region. All species are present in the Monte province, except of L. kuntzeni (Andean provinces of Chile). Liogenys flavida and L. rufoflava have the broadest distribution, the latter here expanded to Paraguay and Chile.

Do mayflies (Ephemeroptera) support a biogeographic transition zone in South America?

AbstractAimSouth America is considered a biologically hybrid continent. To the south, the Patagonian region harbours a unique biota strongly related to other southern continents. To the northern portion, tropical and subtropical areas from the Neotropical region show a more complex taxocoenosis related to the Nearctic and Afro‐Oriental regions. The South American Transition Zone (STZ) has been proposed to belong simultaneously to both regions. This work aimed to test the validity of STZ in the light of the distributions of an ancient freshwater taxon.LocationSouth America.TaxonEphemeroptera.MethodsWe compiled a dataset including all mayfly species having at least one record in South America (8,268 records for 661 species). By using the Network Analysis Method (NAM), we analysed the validity and delimitation of the STZ.ResultsThe distributions of Ephemeroptera give rise to groups of cohesively sympatric species with a clear distinction between Patagonian and Neotropical regions. Although some degree of overlap occurs between them, the overlapping area does not match the STZ to a significant extent. The units of co‐occurring species recovered show that Neotropical groups mainly occupy the STZ.Main conclusionsAlmost the entire provinces of Puna, Desert and Paramo are not supported as part of the STZ by mayfly distribution. The transition zone between Patagonian and Neotropical mayfly fauna involves Southern Puna and high Andes (south to 17° S latitude), Monte province, and a narrow portion of Patagonian steppe with Chubut River being the southern limit.

<p><strong>A new subspecies<em> </em>of <em>Jodina rhombifolia</em> (Santalales: Cervantesiaceae), with taxonomical considerations</strong></p>

The monotypic genus Jodina is endemic from central to south-eastern South America, where it grows from southern Bolivia and Brazil, Uruguay, to northern and central Argentina. The only species included in the genus is Jodina rhombifolia, a small hemiparasitic tree about 4–8 m high that is characteristic of the chacoan environments of the Neotropical region and Monte from the South American transition zone. As part of the floristic updates in the Neotropical and Andean regions of South America, the nomenclature of taxa related to Jodina rhombifolia was re-examined. Owing to the morphological and anatomical differences observed, and the well-delimited geographical distribution patterns that suggest the existence of two distinguishable subspecific entities, a new subspecies of Jodina rhombifolia is proposed here. Two lectotypes are designated and the nomenclature is clarified. An identification key, complete descriptions of the taxa and geographical distribution of the subspecies are also provided.

Does nomenclatural stability justify para/polyphyletic taxa? A phylogenetic classification in the xeric clade Pitcairnioideae (Bromeliaceae)

The genera Deuterocohnia, Dyckia, and Encholirium are recognized as the xeric clade Pitcairnioideae. More than 220 xeric species of this group occur in South America in the Andean region, the Chacoan subregion, and the South American Transition Zone. The species recently and rapidly diversified, and such phylogenetic relationships are difficult. This clade is well-supported in phylogenetic analyses, but despite the monophyly of this group of xeric species, the analyses have demonstrated the paraphyly or polyphyly of genera in the xeric clade. However, most of these studies suffer with partial resolution, limited taxon sampling or incorrect homology statements. To investigate this group, we conducted the most comprehensive phylogenetic analysis of the xeric clade to date using parsimony criteria with morphological and molecular datasets, including plastid and nuclear genomes concatenated for the first time, to establish a suitable classification. A total of 133 accessions were included that corresponded to 109 taxa. The dataset included 70 morphological characters and ∼6 kb of sequence data from the plastid and nuclear genomes. Phylogenetic analyses were conducted using equal and implied weighting. The analysis resulted in a well-supported cladistic hypothesis and demonstrated the three genera as currently circumscribed are not supported as monophyletic. Based on the results we propose a new classification that reflects the evolutionary relationships, a new circumscription for Dyckia is proposed that includes the species belonging to Deuterocohnia and Encholirium. For this circumscription, 41 combinations were made for Dyckia.

An extraordinary new genus and species of Pseudachorutinae (Collembola: Neanuridae) from Colombia.

A new genus of springtail, Sernatropiella gen. nov., from Cundinamarca province, Colombia, was found at an altitude close to 3.000 m above sea level. It is the largest Neanuridae known in the Northern part of the South American Transition Zone. It is characterized by the presence of a strong hypertrichosis, five eyes per side, very small moruliform postantennal organ and a long buccal beak. Mouth parts very thin and slender. Body with paratergal areas different from other Pseudachorutinae of the region. Thorax and abdominal segments I and II with pre- and post-segmental tergites with setae, and most remarkable is the presence of pseudocelli on head, thorax and abdomen of the type species Sernatropiella pinzonae gen. et sp. nov. A new combination for Neotropiella malkini Arlé, 1981 as Sernatropiella malkini (Arlé, 1981) comb. nov. is given and is considered as a member of the new genus.

The Patagonian Steppe biogeographic province: Andean region or South American transition zone?

AbstractAmerica comprises three biogeographic regions: Nearctic, Neotropical and Andean. In between them, two transition zones (TZ) have been proposed: Mexican and South American. The biogeographic provinces belonging to a TZ have no predominance of biotic elements pertaining to each of its bordering regions. Regarding the Andean region, one of its provinces, the Patagonian Steppe, presents a mixture of different biogeographic elements, which are typical of transition zones. Because of this, we assessed whether the Patagonian Steppe belongs to the Andean region or whether it forms the southernmost part of the South American TZ. We gathered phylogenetic information from 177 taxa that inhabit the Patagonian Steppe and established to which biogeographic element they belong. We followed the criterion that an area can be considered as part of a region when at least 70% of its biota has the same origin, that is belongs to the same biogeographic element. In contrast, when the biota of an area presents a similar percentage of its different biogeographic elements, it could be considered as belonging to a transition zone. We found that the Patagonian Steppe presents a similar proportion of genera of Andean as well as neotropical origin. Therefore, we propose that this province should be included in the South American transition zone. Moreover, inclusion of the Patagonian Steppe as part of this TZ will make it the largest TZ of America, encompassing most of the arid lands of South America.

Map and shapefile of the biogeographic provinces of Argentina.

We provide a map of the 15 biogeographic provinces of Argentina based on the ecoregions recognized for the country, combining climatic, geological and biotic criteria. Argentinean provinces belong to the Neotropical region (Yungas, Paraná Forest, Araucaria Forest, Chaco and Pampean provinces), the South American transition zone (Puna, Monte, Comechingones and Cuyan High Andean provinces) and the Andean region (Patagonian, Maule, Valdivian Forest, Magellanic Forest, Falkland Islands and Magellanic Moorland provinces). In order to facilitate future biogeographic analyses, we provide a file of this biogeographical regionalisation in vector format using the World Geodetic Survey 1984.

The evolutionary history of Senna ser. Aphyllae (Leguminosae–Caesalpinioideae), an endemic clade of southern South America

In the legume genus Senna, series Aphyllae includes seven species of leafless shrubs and subshrubs from arid, semiarid and xerophilous areas of three different biogeographic subregions in southern South America. In this study, we investigated the evolutionary history of Aphyllae in a molecular phylogenetic framework. We reconstructed phylogenetic relationships among Aphyllae species based on DNA sequence data of four plastid (rpS16, rpL16, matK, trnL-F) and one nuclear (ITS) region from 23 accessions, analyzed with parsimony, Bayesian and maximum likelihood methods. We inferred the evolutionary and biogeographic history estimating divergence times and reconstructing ancestral character states and ancestral areas of distribution. Series Aphyllae was found to be monophyletic, and the taxa formed two main clades: Clade A gathering S. aphylla var. aphylla, S. crassiramea, S. rigidicaulis and S. spiniflora; and Clade B grouping S. acanthoclada, S. aphylla var. divaricata, S. aphylla var. pendula and S. pachyrrhiza. The morphologically complex S. aphylla appears thus polyphyletic. Molecular dating and ancestral area reconstructions suggest that the Aphyllae clade started to diversify in the South American Transition Zone in the Late Pliocene. Based on these results, we hypothesize that this diversification occurred during the last period of Andean uplift with the aridification in South America. The ancestral character state reconstructions suggest that, in addition to the loss of leaves in adult plants, series Aphyllae evolved various morphological features, such as fastigiate, thickened or decumbent–subdecumbent branches during the colonization and establishment in different arid and semiarid lands in South America.

Distribution of the xeric clade species of Pitcairnioideae (Bromeliaceae) in South America: a perspective based on areas of endemism

AbstractAimThe main goals were to assess the distributional concordance among taxa of the xeric clade of Pitcairnioideae (Bromeliaceae) to establish biogeographical units (i.e. endemic areas), and to use the results to identify conservation priorities.LocationGeographical data were analysed between parallels −1° and −47° S and meridians 35°6′ and 80°1′ W, which includes the Andean region, the Chacoan subregion and the South American Transition Zone, and three global hotspots (Atlantic Forest, Cerrado and Tropical Andes).MethodsTwo methods were employed, parsimony analysis of endemicity (PAE) and endemicity analysis (EA), to search for the biogeographical congruence between endemic areas for 220 species. Two grid cell sizes (2° and 3°) and three criteria were employed to delimit the areas of endemism.ResultsThe results of the PAE demonstrated eight candidate areas of endemism when applying a grid cell size of 2° and six areas of endemism with 3°. The EA optimization method, using a grid size of 2°, recovered six (consensus 75%) and four (consensus 5%) areas, and a size of 3° recovered eight (consensus 75%) and three (consensus 5%) areas. Based on consistent results of the three combined criteria and the congruence of areas of endemism, we delimited three biogeographical areas of endemism for the clade in the Chacoan subregion of South America. The following areas in Brazil were delimited: (1) south‐eastern Minas Gerais, (2) north‐eastern Minas Gerais, and (3) north‐eastern Goiás.Main conclusionsEndemic species with congruent occurrence patterns were identified to propose primary biogeographical homologies and to highlight areas that should be prioritized for conservation of species in the xeric clade of Pitcairnioideae. Furthermore, we suggest that evolutionary and historical processes (adaptive radiation; glacial and interglacial period in the Quaternary), as well as ecological factors, could have induced the high diversification rates for this clade in South America.

Distributional patterns of living ungulates (Mammalia: Cetartiodactyla and Perissodactyla) of the Neotropical region, the South American transition zone and Andean region

To recognize the distributional patterns of living ungulates in the Neotropical region, the South American transition zone, and Andean region using the panbiogeographical method of track analysis, and to attempt to correlate these patterns with geological history. The distribution of 24 species of living ungulates (in the families Camelidae, Cervidae, Tapiridae and Tayassuidae) was studied by the panbiogeographical method of track analysis. It was performed using distributional data acquired from literature and databases of scientific institutions. Individual tracks were obtained for each species by plotting locality records on maps and connecting them by minimum-spanning trees. Generalized tracks were determined from the spatial overlap between individual tracks, indicating a common history. The intersection between generalized tracks defined a biogeographic node, implying that these locations are biogeographic composites resulting from different ancestral biotas coming into spatial contact, possibly at different geologic times. The superposition of the 24 individual tracks resulted in five generalized tracks (GTs): GT1, Mesoamerican/Choco (composed of Mazama pandora, Mazama temama, Odoicoileus virginianus and Tapirus bairdii); GT2, Northern Andes (Mazama rufina, Pudu mephistophiles and Tapirus pinchaque); GT3, Central Andes (Hippocamelus antisensis, Lama guanicoe, Mazama chunyi and Vicugna vicugna); GT4, Chilean Patagonia (Hippocamelus bisulcus and Pudu puda); and GT5, Chaco/Central west Brazil (Blastocerus dichotomus, Catagonus wagneri and Ozotocerus bezoarticus). The biogeographic node was found in the Northwestern Colombia. The geological events such as tectonism and volcanism that occurred through the Neogene and mainly in the Pleistocene caused fragmentation, diversification and endemism of biota. The biogeographic node in Colombia occurred within a zone of convergence. This node emphasized the complexity of the area and it contains biotic elements with different origins, which represent a special condition for the establishment of priority conservation areas.

Biogeography and areas of endemism of Prepops Reuter (Heteroptera: Miridae).

The Miridae (Hemiptera: Heteroptera) are one of the most species rich families of insects, with about 11 100 described species. Mirinae is the largest subfamily and its endemism becomes evident at the tribal level and below. Mirines of the tribe Restheniini are found throughout America, with most of the diversity confined to the Neotropics. Prepops Reuter is the largest genus in Restheniini with 198 described species and its geographi- cal range is similar to that of the tribe. The study of the distribution and areas of endemism in Miridae are scarce and non-existent for Prepops. We analyzed all the geographic records of Prepops (707 records for 181 species) in order to identify diversity patterns and areas of endemism, using network analysis. Locality data were assigned using museum specimens and geographic records in the literature. Additionally we used spatial data to propose habitat preferences and geoclimatic variables important for each group of co-occurring species. The results indicate high species richness in subtropical regions, while the tropical belt and high latitudes appear impover- ished. The Neotropical region contains 86% of the species, and the Nearctic about 11 % (but with larger species ranges); the Andean region is sparingly represented. Twenty-three areas of endemism (and two diads), formed by 2 or more endemic species, are distributed in the Nearctic (3), Mexican Transition Zone and Caribbean sub- region (5), South American Transition Zone and Amazonian, Chacoan and Paranaense subregions (15). Overlap between some of the areas indicates regions with high species richness and complex history. The lack of records from the Andean region (except for P. nigrus in Southern Patagonia) and dominance of strictly Neotropical spe- cies (86 %) supports the hypothesis of a Neotropical origin for the tribe Restheniini. The general arrangement of the units of co-occurrence of Prepops species shows a close correlation with known biogeographic regions and subregions. Broad physiographic characteristics most commonly associated with Prepops geographical records are, in order of importance: broad leaf forests (wet and dry), grasslands and xeric habitats.

Biogeographical relationships and new regionalisation of high-altitude grasslands and woodlands of the central Pampean Ranges (Argentina), based on vascular plants and vertebrates

Evolutionary biogeography aims to provide a hierarchical system of biotic regionalisation for areas of the Earth that correspond to natural areas related by their common evolutionary history. In this context, the central Pampean Ranges of Argentina, formed by the mountain systems of Córdoba and San Luis, are immersed in the Chacoan dominion; however, higher-altitude environments of these mountains, namely highland grasslands and tabaquillo forests, have relationships with the Andean region and other Neotropical areas that are different from the Chacoan dominion, which would indicate that the current classification would not be natural. To clarify their biogeographic relationships, a track analysis of the distribution of the biota of vertebrates and vascular plants of the highland grasslands and tabaquillo forests of central Pampean Argentinian Ranges was conducted. The obtained distributional patterns suggest that the area under study has diverse geobiotic origins, both Andean and Neotropical, indicating that, in this area, an interaction of biota with different evolutionary origins occurs; so, its status as a biogeographic province is proposed, belonging to the South American transition zone.

Andean region: a shapefile of Morrone's (2015) biogeographical regionalisation.

Morrone's (2015) biogeographic regionalisation of the Andean region is based on the distributional ranges of terrestrial plants and animals. It is the most comprehensive and methodologically supported biogeographical scheme for the region to date. The Andean region comprises one transition zone (the South American transition zone), three subregions (Central Chilean, Subantarctic and Patagonian) and 15 provinces (Morrone, 2015).