Vertebrate taxa with entirely unisexual populations are composed of females that reproduce without fertilization and are generally of hybrid origin. At least 23 vertebrate families have unisexual lineages. Within squamate reptiles, >40 uniparental species have been described from five major lineages: acrodont iguanians, Gekkota, Serpentes, Scincomorpha, and Varanidae. Pleurodont iguanians include >1100 species, all of which have gonochoristic reproduction. Here we report the discovery of a new unisexual lizard from the liolaemid genus Liolaemus, a species-rich (∼260 species) clade distributed over most of southern South American. The new species, Liolaemus parthenos, is the only known all-female triploid pleurodont iguanian. The structural chromosome heteromorphisms of the karyotypes support the hypothesis that L. parthenos is the product of a hybrid origin. Based on morphology, the new species is assignable to the L. boulengeri group (sensu Abdala, 2007), and phylogenetic analyses of mitochondrial DNA in... Los taxones de vertebrados con poblaciones totalmente unisexuales se componen de hembras que se reproducen sin fecundación y son generalmente de origen híbrido. Al menos 23 familias de vertebrados tienen linajes unisexuales. Dentro de los reptiles escamosos, se han descrito >40 especies uniparentales pertenecientes a cinco grandes linajes: iguanios acrodontes, Gekkota, Serpentes, Scincomorpha y Varanidae. Los iguanios pleurodontes incluyen >1100 especies, las cuales todas tienen reproducción gonocórica. Aquí presentamos el descubrimiento de un nuevo lagarto unisexual del género Liolaemus, clado con gran riqueza especifica (∼260 especies) distribuido en casi todo el sur de América del Sur. La nueva especie, Liolaemus parthenos, es la única conocida con hembras triploides entre los iguanios pleurodontes. Los heteromorfismos cromosómicos estructurales de sus cariotipos apoyan la hipótesis de que L. parthenos es producto de un origen híbrido. Basado en la morfología, la nueva especie es asignable al grupo de ...

Linnean shortfalls, or the discrepancy between formally described species and the number of existing species, imply noteworthy biodiversity conservation constraints. The case of Argentinian reptiles is unique in this context. The genus Liolaemus represents ~60% of the Argentine reptile fauna and has a current species description rate of 3.25 spp./year, leading to a significant increase in the number of known species. Filling Linnean shortfalls within this genus has revealed an extraordinary recent evolutionary radiation that strongly modifies the spatial accumulation patterns of richness and endemism, mainly in the Patagonian steppe and Monte ecoregions of Argentina. Thus, while 40 years ago none of the studied species was considered endemic at the ecoregional level, today the genus represents an essential element to define the southernmost terrestrial ecoregions of the world. Furthermore, the remarkable decrease in the average extent of occurrence (EOO) of Liolaemus species implies an increased extinction risk in light of threats caused by humans. Based on the thresholds for the IUCN Red List B1 criteria, and 11 well-studied clades of Liolaemus, we show that, while in 1980 87% of the described species would not qualify as threatened based on EOO, today 80% of the species have an EOO smaller than 20 000 km2. Therefore, they may qualify as threatened based on the B1 EOO thresholds, which demonstrates the importance of the recent increase of knowledge regarding the taxonomy, systematics and genetics of the group.

The South American lizard genus Liolaemus comprises > 260 species, of which > 60 are recognized as members of the Liolaemus montanus group, distributed throughout the Andes in central Peru, Bolivia, Chile and central Argentina. Despite its great morphological diversity and complex taxonomic history, a robust phylogenetic estimate is still lacking for this group. Here, we study the morphological and molecular diversity of the L. montanus group and present the most complete quantitative phylogenetic hypothesis for the group to date. Our phylogeny includes 103 terminal taxa, of which 91 are members of the L. montanus group (58 are assigned to available species and 33 are of uncertain taxonomic status). Our matrix includes 306 morphological and ecological characters and 3057 molecular characters. Morphological characters include 48 continuous and 258 discrete characters, of which 70% (216) are new to the literature. The molecular characters represent five mitochondrial markers. We performed three analyses: a morphology-only matrix, a molecular-only matrix and a matrix including both morphological and molecular characters (total evidence hypothesis). Our total evidence hypothesis recovered the L. montanus group as monophyletic and included ≥ 12 major clades, revealing an unexpectedly complex phylogeny.

El género Liolaemus presenta una gran diversidad entre los tetrápodos actuales, al punto de corresponder al segundo género con mayor número de especies válidas descritas del infraorden Iguania. En este trabajo, se describe una nueva especie de lagartija arenícola perteneciente al subgénero Eulaemus, grupo de Liolaemus montanus, procedente de las lomas costeras de Quilca, La Chira y Ocoña, todos en la provincia de Camaná, departamento de Arequipa, Perú. Para determinar el estatus taxonómico de esta nueva especie, analizamos los caracteres morfológicos, moleculares y geográficos. Los caracteres morfológicos permitieron la caracterización y diagnóstico de la nueva especie, los moleculares fueron utilizados para realizar una inferencia bayesiana y los geográficos para determinar potenciales áreas de distribución. Este reptil se diferencia de las otras especies del grupo Liolaemus montanus en su tamaño pequeño a mediano, su conjunto de caracteres morfológicos, folidosis y patrón de coloración: es la única especie del género donde los machos tienen un patrón de manchas laterales de forma redondeada con borde oscuro e interior verde desde las axilas hasta la mitad del cuerpo. Del mismo modo, los resultados filogenéticos moleculares realizados con el gen Cyt-b indican que no tiene relación directa con las especies fenéticamente similares descritas para el grupo. Sin embargo, existe una relación con poblaciones geográficamente cercanas que permanecen taxonómicamente innominadas. Finalmente, se determinó que esta lagartija tiene un endemismo muy marcado y sus poblaciones son poco abundantes.

Within the Liolaemus boulengeri group or ‘patch’ group, there is a monophyletic clade named Liolaemus fitzingerii group.This clade is composed of large Liolaemus individuals, mostly psammophilus, oviparous and mainly insectivorous, dis-tributed from central Río Negro and Neuquén to the south of Santa Cruz in Argentine Patagonia. We make a taxonomicand phylogenetic revision of the L. fitzingerii clade, describe two new species of the group, compare these results withphylogenetic hypotheses from the literature, and discuss the geographic distribution of species of the L. fitzingerii clade.The new species described here inhabit central and central-eastern Chubut Province, Argentina. These new species areeasily distinguished from the other species of the L. fitzingerii group by a combination of morphological characters. Thephylogenetic analyses support the description of these new species, because they are not closely related to the species withwhich they were previously confused. According to a new phylogenetic analysis of the L. fitzingerii clade, one of the newspecies, L. camarones sp. nov., has a relatively basal position within the group, whereas the other new species, L. shehuensp. nov., is sister taxon of L. chehuachekenk. With these two new species, the L. fitzingerii clade is now composed of nine species, all of which are distributed in Argentine Patagonia.