Biodiversity of vertebrates in Argentina: patterns of richness, endemism and conservation status.

Optimising conservation efforts requires an accurate record of the extant species as well as their geographic distributions. Nevertheless, most current conservation strategies start from an incomplete biodiversity inventory. Argentina has an extraordinary diversity of species, however, until now an updated inventory of its fauna has not been carried out. In this context, the main objective of this work is to present the results of the first national inventory of vertebrate species. Experts from each major vertebrate taxonomic group assembled and compiled its respective inventory. The information gathered included taxonomic rank, conservation status, endemism and geographic distribution. Species richness and representativeness were calculated for each taxonomic group, distinguishing between native, endemic and exotic, for each Argentinian province. Our results show Argentina harbours 3,303 species: 574 marine fish, 561 freshwater fish, 177 amphibians, 450 reptiles, 1,113 birds, and 428 mammals. Native species constitute 98.1% of the total taxa. The results achieved were spatially represented showing a pattern of higher richness from north to south and from east to west. Species considered as threatened account for 17.8% and 15.2% are endemic. There are five Extinct species. These results provide key information on developing strategies and public policies at the national and provincial levels and constitute a tool for the management and conservation of biodiversity.

Resource partitioning in a snake assemblage from east-central Argentina.

Two dimensions of the ecological niche (diet and habitat) of a snake assemblage from an endemic rich area in east-central Argentina, the Sierras de Ventania mountain chain, were analyzed. Field data collection was performed in 15-week study periods between 2010 and 2014. Snakes were hand-captured using transect surveys. Field observations on diet were analyzed together with stomach content data from museum specimens. Our results supported the partitioning of the snake assemblage by both habitat use and diet into at least three functional groups: species restricted to microhabitats under rocks and with a diet composed exclusively of ants (Epictia australis); species found mostly in stream microhabitats and feeding mainly upon anurans (Erythrolamprus poecilogyrus and Lygophis elegantissimus); and species found mostly in grassland microhabitats, with specialized diets of terrestrial prey items (Philodryas patagoniensis and Bothrops alternatus). Consistent with previous work, diet was more important than habitat in explaining ecological niche partitioning of this snake assemblage. Our results showed that high overlap values of microhabitat use were compensated by low overlap values of the trophic niche dimension, thus matching the traditional complementary niches hypothesis.

First Natural Endocranial Cast of a Fossil Snake (Cretaceous of Patagonia, Argentina).

In this study, we describe a natural endocranial cast included in a partially preserved medium-sized skull of the Upper Cretaceous South American snake Dinilysia patagonica. The endocast is composed of sedimentary filling of the cranial cavity in which the posterior brain, the vessels, the cranial nerves, and the inner ear surrounded by delicate semicircular canals, are represented. It is simple in form, with little differentiation between the three main areas (Forebrain, Midbrain, and Hindbrain), and without flexures. The nervous system is well preserved. The posterior brain surface is smooth, except for two small prominences that make up the cerebellum. A large inner ear is preserved on the right side; it consists of a voluminous central mass, the vestibule, which occupies most of the space defined by the three semicircular canals. In particular, the lateral semicircular canal is very close to the vestibule. This characteristic, in combination with the medium to large body size of Dinilysia, its large skull and dorsally exposed orbits, and vertebrae bearing a rather high neural spine on a depressed neural arch, suggests that this snake would have had a semifossorial lifestyle. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:9-20, 2018. © 2017 Wiley Periodicals, Inc.