Phylogenetic relationships among spiny pocket mice (Heteromys) inferred from mitochondrial and nuclear sequence data

Cranial variation across spiny pocket mice (Heteromys, Liomys) in new phylogenetic and taxonomic perspectives

Spiny pocket mice are usually divided into two genera, Heteromys and Liomys, and more recently the latter have been subsumed into the former, leaving subfamily Heteromyinae with one genus. However, this arrangement conveys false equivalency among heteromyines, and does not represent the great morphological, molecular, and ecological diversity in this subfamily. To address this, geometric morphometric methods were used to explore interspecific cranial variation in this subfamily, which were then evaluated in the context of recent phylogenetic and taxonomic findings. The dataset consisted of 65 landmarks on the crania of 328 adult voucher specimens (15 species, 114 localities). Allometry and habitat adaptation are potential explanations for some of the variation patterns. Morphometric clustering among some distant relatives suggests convergent adaptation to similar habitats. These results support recent taxonomic proposals for the subfamily based on molecular phylogenies, in which the three to four main lineages are assigned generic status. We summarize the evidence and describe their scaled cranial shape variation. These lineages consist of Heteromys as traditionally defined (i.e., not including Liomys) while the traditionally defined Liomys would be divided into the genera Schaeferia (S. adspersus + S. salvini), Liomys sensu stricto (L. irroratus), and potentially a fourth (new) undescribed/undiagnosed genus for L. pictus + L. spectabilis. The implications of the present study are that scaled cranial shape variation patterns align better with this modified taxonomy than earlier ones. Our results confirm the usefulness of geometric morphometrics in providing taxonomic insights in taxa that appear cryptic using traditional distance-based measurements.

Updated list of the mammals of Costa Rica, with notes on recent taxonomic changes

Although Costa Rica occupies a mere 0.03% of the Earths land area, it nevertheless has recorded within its borders approximately 5% of the global diversity of mammals, thus making it one of the worlds megadiverse countries. Over the past ten years, 22 species have been added to the countrys inventory, bringing the total number known as here documented to 271; Chiroptera account for ten of these, having grown to 124 from 114; rodents have increased by eight species, from 47 to 55, with the caveat that we include three invasive species of Muridae that have gone feral. In contrast, the number of orders has decreased by one, by Artiodactyla incorporating the former Cetacea. Notes are provided for all taxonomic novelties since the last update. Since the first taxonomic compendium of the mammals of Costa Rica in 1869, the number of known species has grown by approximately 1.22 species year-1 (R2 = 0.96). Since 1983 however, this growth rate has been 1.64 species year-1 (R2 = 0.98). Despite this strong growth, an asymptote in the number of known species has not been reached. Conservation remains a primary need: over 60% of the countrys mammal species show population trends that are decreasing (13%), unknown (37%), or not assessed (11%), based on IUCN criteria. These analyses suggest that much remains to be known regarding the number of mammal species living in Costa Rica, but also that much more remains to be done to safeguard Costa Ricas exceptional biodiversity heritage.

Evolutionary relationships and climatic niche evolution in the genus Handleyomys (Sigmodontinae: Oryzomyini)

Mesoamerica is considered a biodiversity hot spot with levels of endemism and species diversity likely underestimated. Unfortunately, the region continues to experience some of the highest deforestation rates in the world. For mammals, the evolutionary relationships of many endemic taxa are controversial, as it is the case for members of the genus Handleyomys. Estimation of a time-calibrated hypothesis for the evolution of these six genera (Euryoryzomys, Handleyomys, Hylaeamys, Nephelomys, Oecomys and Transandinomys) supported a monophyletic Handleyomys sensu lato. Based on their distinctive morphology and the amount of inter-generic genetic divergence, Handleyomys sensu stricto, H. alfaroi, the H. chapmani, and the H. melanotis species groups warrant recognition as separate genera. In addition, species delimitation documents the existence of cryptic species-level lineages within H. alfaroi and H. rostratus. Cryptic lineages within H. rostratus exhibited significant niche differentiation, but this was not the pattern among species-level clades within H. alfaroi. Similarly, age-range correlations revealed that niche evolution within Handleyomys is not correlated with evolutionary time, instead, ancestral climate tolerance reconstructions show niche disparities at specific diversification events within the chapmani and melanotis species groups, while the climatic niche of the rest of species of Handleyomys tended to be conservative.