Small-eared Shrews Research Articles

Cryptotis nigrescens (Eulipotyphla: Soricidae)

Abstract The blackish small-eared shrew, Cryptotis nigrescens (Allen, 1895), is a blarinine soricid that occurs in high-elevation premontane wet forest and cloud forest in the Central American countries of Costa Rica and Panama. The species is taxonomically monotypic, although it exhibits size variation that manifests as a gradual increase in size from northwest to southeast. Habitat loss is currently the greatest threat to the species’ existence, although populations in the few areas where C. nigrescens has been studied appear to be healthy, and the International Union for Conservation of Nature (IUCN) classifies it as a species whose conservation status is “Least Concern” (LC). We include a complete synonymy for the genus Cryptotis Pomel, 1848.

Two New Species of Small-Eared Shrews of the Genus Cryptotis Pomel, 1848, from the Colombian Andes (Mammalia: Eulipotyphla: Soricidae)

Two New Species of Small-Eared Shrews of the Genus Cryptotis Pomel, 1848, from the Colombian Andes (Mammalia: Eulipotyphla: Soricidae)

Geometric morphometrics clarifies the taxonomic status of semifossorial shrews (Eulipotyphla, Soricidae, Cryptotis) from Mexican cloud forests

Abstract The small-eared shrews Cryptotis mexicanus and Cryptotis obscurus (Eulipotyphla, Soricidae) are two closely related taxa from the northern Neotropics whose taxonomy is still unresolved. Here, we tested the hypothesis of three lineages (Northern, Central, and Southern) within this pair of semifossorial shrews. We photographed skulls, dentaries, and humeri from 226 museum specimens and used geometric morphometrics to evaluate sexual dimorphism, differences between lineages, and the effect of the environment on the shape of the structures. We found negligible differences between males and females, supporting previous studies of classical morphometrics in this genus. Our results also support the differentiation of semifossorial shrews into the three geographically isolated groups, where the size of the dentary and the shape of the three examined structures contribute to discrimination. We found a significant sign of the influence of the environment on the shape of the dentary but not on the skull or the humerus. We suggest that geographic isolation across climatically similar regions has contributed to the differentiation between lineages. We propose recognizing all three lineages as valid species that must be adequately described.

Predicting potential range shifts using climatic time series and niche models: A Neotropical montane shrew's case

Ecological niche models (ENMs) can forecast species' potential range shifts by transferring a model to a future climatic scenario. However, this approximation does not identify whether range shifts have occurred in species' distributional limits in the last several decades. Given ongoing anthropogenic climate change, changes in distributional limits are expected to occur (poleward and upslope for several montane species). Here, I use a climatic time series to predict potential changes in distributional limits in response to climate change over the last four decades, using the Mexican small-eared shrew (Cryptotis mexicanus), a montane cloud-forest species, as an example. I transferred the ENM (tuned to optimize complexity) to a series of thirty-year bioclimatic periods between 1979 and 2019 created with monthly precipitation and temperature data. I detected trends in suitability and bioclimatic variables using a Mann-Kendall test and identified which variables could be driving the suitability changes in distributional limits. The detected extent and direction of suitability trends do not suggest the uniform pole-ward or upslope shifts expected under warming conditions. Comparisons between suitability and variable trends suggest that precipitation, not temperature, plays a stronger role in explaining changes in climatic suitability for C. mexicanus. Where precipitation decreased, there was suitability loss, while in areas where precipitation increased, suitability gain was observed. These analyses illustrate how incorporating time-series climatic data into ENMs can aid in understanding if species are already responding to changes in climate. Here, the potential response of C. mexicanus to climate change varies across its distribution and therefore the species' range shifts may not necessarily follow expected general patterns. These findings should be verified with field data. More generally, using the valuable climatic information of the last several decades should be incorporated into studies that determine potential range shifts under recent or future climatic conditions.

A new species of small-eared shrew (Soricidae, Cryptotis) from El Triunfo Biosphere Reserve, Chiapas, Mexico

Abstract The Cryptotis goodwini species group of small-eared shrews (Eulipotyphla, Soricidae) includes at least 12 species discontinuously distributed in the cloud forests from southern Mexico to Honduras. Its taxonomy is still under study, with several species described only in the last decade. Previous genetic studies have highlighted that a population from El Triunfo Biosphere Reserve in Chiapas, Mexico, previously assigned to C. goodwini, is evolutionarily divergent from the other known species. However, the available specimens from this region have not been examined rigorously. Herein, I use morphological and biogeographic analyses to evaluate the taxonomic status of this population. The results confirm that it is an independent lineage, which I describe here as a new species endemic to Mexico. Overall, this is the largest shrew within the C. goodwini group. Its morphological and genetic distinction is probably due to long-term geographic isolation in the mountains of El Triunfo. I present what is now the first and only record of C. goodwini (sensu stricto) for Mexico. Finally, I identify some priority regions to direct field surveys on the C. goodwini species group to better understand its richness and distribution.

Microhabitat, diet, and reproductive activity of a population of the Andean shrew Cryptotis tamensis (Eulipotyphla: Soricidae)

ABSTRACT The Tamá small-eared shrew is found in the Andean cloud forests of the Cordillera Oriental of Colombia and the Tamá paramo in western Venezuela. Few aspects of its biology are known, and all information comes from its original description. In a patch of oak cloud forest, we found a relatively abundant population of the species and studied its abundance, microhabitat preference, diet composition and reproductive features, and their relationship with the rainfall seasonality of the study area. The fieldwork was carried on for two years at altitudinal intervals from 2402 to 2627 m.a.s.l. We caught 44 shrews in microhabitats with dense vegetation cover, abundant litter and fallen trees; their abundance changed significantly through time, varying along with the precipitation of the month before the capture. We found seven groups of arthropods in their diet, the composition of which did not differ significantly between sexes, reproductive stages or seasons. These shrews have a specialised diet, with ants as the most important item. Reproductive males are distinguished externally by the presence of hypertrophic subcutaneous lateral glands. We found adult reproductive males and non-reproductive males throughout the duration of the study, and their abundance did not vary significantly with precipitation. In contrast, we did not capture females in the driest months of the years, and although adult non-reproductive females were also found, we found a significant relationship between the abundance of reproductive females and precipitation. Consequently, adult reproductive males would be a permanent reproductive resource for the females, which appear to adjust their reproductive activity during the rainy seasons.

Taxonomy and conservation of the critically endangered shrew Cryptotis nelsoni (Eulipotyphla: Soricidae), endemic to Los Tuxtlas, Veracruz, México

Abstract The Nelson’s small-eared shrew (Cryptotis nelsoni) is a mammal at high risk of extinction and endemic to the cloud forest in the mountains of Los Tuxtlas, an isolated volcanic field in eastern México. It is a little-known species that remained unrecorded for over a century. However, recent works have increased the number of museum specimens and tissue samples of C. nelsoni, which we studied here to improve our knowledge of their taxonomy and conservation status. We compared the morphology and DNA barcode sequences of C. nelsoni against its three most closely related species. We also evaluated the possible effect of anthropogenic climate change on this mountain species according to three general circulation models and two scenarios proposed for the year 2050. The results showed that the skull and postcranial variables could easily discriminate C. nelsoni from the other species in terms of body size, to which some distinctive qualitative characteristics related to the width of the snout and the curvature of the humerus also contribute. DNA barcoding also helped identify the shrew species accurately, with a genetic distance of more than 6% from its closest species. The morphological and genetic characteristics highlight the evolutionary distinctiveness of C. nelsoni. Unfortunately, warmer extremes and higher rainfall than today could pose a severe threat to the survival of this shrew for decades to come, even in the most optimistic scenarios.

First record of the Northern Ecuadorian Shrew, Cryptotis niausa Moreno Cárdenas & Albuja, 2014 (Eulipotyphla, Soricidae), in Colombia

In Colombia, seven species of small-eared shrews of the genus Cryptotis Pomel, 1848 have been reported, and five of them endemic to the country. Here, we present the first confirmed record from Colombia of Cryptotis niausa Moreno Cárdenas & Albuja, 2014, a species that was previously known from only nine localities in Ecuador. The Colombian record comes from the Departamento de Nariño, in extreme southwestern Colombia, and it is supported by morphology and cytochrome-b gene evidence. This record increases to eight the number of species of Cryptotis from Colombia.

Mitogenome and phylogenetic analyses support rapid diversification among species groups of small-eared shrews genus Cryptotis (Mammalia: Eulipotyphla: Soricidae).

The small-eared shrew genus Cryptotis is the third largest in the family Soricidae and occurs in North, Central, and northern South America. In Mexico and Central and South America, most species inhabit geographically isolated moist, montane habitats at middle and high elevations in a typical sky-island pattern. The 49 recognized species have been partitioned into as many as six species groups based on morphological and molecular phylogenetic studies. The relationships among these species groups are poorly resolved, and their evolutionary histories, including migration patterns and locomotor adaptations, remain unclear. Herein, we provide a new phylogeny incorporating complete mitochondrial genomes (mitogenomes) and supermatrix approach. We compared different evolutionary scenarios using approximately unbiased (AU), Kishino-Hasegawa (KH), and Shimodaira-Hasegawa (SH) statistical tests. The phylogenetic hypothesis based on mitogenomes revealed novel relationships supporting a basal position for the Cryptotis parvus-group in the genus, and a close relationship between C. gracilis and one clade of the C. thomasi-group. The former relationship is consistent with the least derived humerus morphology and northern distribution of the species. The latter relationship implies multiple migrations between Central and South America. The lack of fine resolution for the species group relationships may be due partly to the lack of taxon sampling. In contrast, multi-approach analyses suggest that the unresolved relationships may be a result of rapid diversification during the early stages of Cryptotis evolution.

Broadening the distribution of the microendemic shrew Cryptotis phillipsii (Eulipotyphla, Soricidae)

The Phillips´ small-eared shrew, Cryptotis phillipsii (Schaldach, 1966), is geographically restricted to a small patches of montane cloud forests from southern Oaxaca, Mexico.  Distributional records and specimens of C. phillipsii are relatively scarce, so it still remains as poorly-known species.  Here, we provide 2 new localities based on the analyses of specimens that remained unidentified in a museum.  We analyzed 5 specimens from 2 localities along the Sierra Madre del Sur biogeographic province, southwestern Oaxaca, which were collected in 1-liter pitfall traps.  We determined the taxonomic identity of the specimens using specialized literature and by comparison with other shrew species potentially inhabiting the region.  The external and cranial morphology allowed us to determine that these 2 specimens belong to the species Cryptotis phillipsii.  These records extend the known distribution of C. phillipsii by about ca.60 km west and provide additional information about their habitat preferences.  The records presented here extend the range of C. phillipsii and corroborate predictions of maps of current potential distributions suggesting the existence of suitable conditions for the species in the region.  We urge continuing support and funding for fieldwork and the updating of scientific collections in order to accomplish the urgent task of completing the inventory of species and overcome the lack of distributional information.

Altitudinal, latitudinal and longitudinal responses of cloud forest species to Quaternary glaciations in the northern Neotropics

AbstractThe glaciations of the Quaternary caused changes in the geographical distributions of species associated with tropical montane cloud forests. The most obvious effect of the glacial conditions was the downward displacement of cloud forest species, thus giving opportunities for population connectivity in the lowlands. Considerable attention has been paid to these altitudinal changes, but latitudinal and longitudinal movements remain poorly understood in the northern Neotropics. Here, I use ecological niche modelling to generate palaeodistributions of small-eared shrews (Mammalia: Soricidae) closely associated with cloud forests in the mountain systems of Mexico and then retrodict their range shifts during the Last Glacial Maximum (LGM), one of the coldest periods of the Quaternary. The results suggest that cloud forest species not only migrated downwards in response to global cooling and dryness but also migrated latitudinally and longitudinally onto those slopes that maintained moist conditions (other slopes remained unsuitable during the LGM), thus revealing a hitherto unknown route for postglacial colonization of cloud forest species. This scenario of past distributional change probably had genetic and demographic implications and has repercussions for the identification of areas of refugia and postglacial colonization routes of cloud forest species.

First record of shrews (Eulipotyphla, Soricidae) in the Sierra de Otontepec, an isolated mountain in Veracruz, Mexico

Knowledge of the diversity and distribution of mammals in tropical and subtropical regions remains incomplete. This is especially true for many small species inhabiting remote areas with limited access. Here we present the first record of small-eared shrews (Soricidae, Cryptotis ) from the Sierra de Otontepec, Mexico, an isolated mountain in the Gulf Coastal Plain that has remained poorly explored (Figure 1). We conducted a short-term survey in the Sierra de Otontepec using pitfall and Sherman traps during August 2016. Taxonomic identification was based on morphological and molecular analyses (Appendix 1). We collected six shrew specimens from the cloud forests in the Sierra de Otontepec (Figure 2). Morphological and molecular characterization indicated that all specimens collected were small-eared shrews belonging to the Cryptotis mexicanus species group (Table 1, Figure 3), a clade which is closely associated with cloud forests. Based on the morphological and molecular evidence, we refer to this population from the Sierra de Otontepec as C. mexicanus , Our results corroborate the importance of continued fieldwork in remote tropical areas. Overall, this finding offers relevant information that could be used to better understand the evolution and biogeographic history of this species group and its habitat.

New records of a critically endangered shrew from Mexican cloud forests (Soricidae, Cryptotis nelsoni) and prospects for future field research.

The Nelson´s small-eared shrew, Cryptotis nelsoni (Merriam, 1895), is a critically endangered species, endemic to cloud forests in Los Tuxtlas, a mountain range along the Gulf of Mexico coast. This species is only known from the type locality and its surroundings. Here we present new records that extend its distribution approximately 7 km southeast of the type locality and report more specimens near to the type locality. We also identified climatically suitable areas for C. nelsoni using ecological niche modelling and investigated the sampling bias to identify poorly sampled areas in Los Tuxtlas. We suggest that the scarcity of records in other areas with suitable climatic conditions throughout Los Tuxtlas is a consequence of incomplete surveys. We strongly highlight the importance of continuing surveying this critically endangered shrew using more efficient sampling techniques to better understand its current distribution and conservation status. Despite all known localities occurring inside Los Tuxtlas Biosphere Reserve, deforestation and climate change still pose current and future threats to this species.

Patterns of morphological and ecological similarities of small-eared shrews (Soricidae, Cryptotis) in tropical montane cloud forests from Mesoamerica

It has been proposed that high morphological similarity between closely related species of small-eared shrews resulted from a recent divergence and intermittent population connectivity, presumably due to Pleistocene climatic fluctuations and associated changes in forest habitat distribution. Here we examined the morphological variation of two sister species of small-eared shrews inhabiting cloud forests from Mexico, Cryptotis obscurus and C. mexicanus. We then used ecological niche modelling to provide compelling evidence for current environmental barriers for population connectivity, and for detecting divergent ecological niches between candidate species. Our results indicated that the species boundaries in this clade should be subject to change. High morphological similarity suggested that populations of C. obscurus and C. mexicanus located west of the Isthmus of Tehuantepec, a major geographic barrier for montane species, are conspecific. Niche divergence between these two putative species was not supported indicating niche conservatism across the evolutionary history of these small-eared shrews. In addition, several barriers seem to play a main role for current lineage divergence between populations within this clade. The population located east of the Isthmus, previously referred to C. mexicanus, might prove to represent a new species based on morphological distinction and current geographic isolation. We have highlighted that estimating species’ potential distributions provides insights to evaluating the effect of geographic barriers on lineage divergence and making stronger inferences when delimiting species.

A new species of small-eared shrew of the genus Cryptotis (Mammalia, Eulipotyphla, Soricidae) from the northernmost Peruvian Andes.

The northernmost Peruvian Andes, a unique biogeographic region characterized by the confluence of multiple distinct ecosystems (i.e. Amazon basin, Pacific rainforest, the Sechura Desert, the northern and central Andes), is the southernmost geographic range limit of the South American shrews representing the genus Cryptotis. In the northernmost Peruvian Andes, two poorly known species have traditionally been reported (C. peruviensis and C. equatoris). Our study, based on molecular and morphologic traits, confirms the presence of C. peruviensis but also the occurrence of C. montivaga, based on specimens erroneously assigned to C. equatoris. Moreover, a new species of Cryptotis from the páramo and montane forests of the Tabaconas Namballe National Sanctuary near the Ecuadorian border is also described. It is a member of the thomasi group and is distinguished from other South American shrews by a unique set of morphological characters, including large body size, comparatively short tail, simple ectoloph of M3, and large PM4 post protocrista.

Molecular systematics and biodiversity of the Cryptotis mexicanus group (Eulipotyphla: Soricidae): two new species from Honduras supported

Small-eared shrews of the genus Cryptotis (Mammalia: Eulipotyphla: Soricidae) are widespread in the northern Neotropics. Systematic studies of these shrews over the past two decades have revealed previously undocumented morphological and species diversity, resulting in a quadrupling of the number of recognized species. Unfortunately, a small proportion of the species in the genus have been included in molecular phylogenetic studies, and evolutionary relationships within the genus are incompletely known. Traditionally, species have been assigned to four or five morphologically defined ‘species groups’, but tests of the monophyly of some of these groups show weak support and relationships amongst species groups remain somewhat speculative. The largest species group is the C. mexicanus group inhabiting Mexico and northern Central America. We studied sequences from mitochondrial cytochrome-b and 16S genes, as well as nuclear ApoB and BRCA1 genes from 22 species of Cryptotis, including 15 species in the C. mexicanus group. Our combined analysis shows that the C. goldmani subgroup is very weakly supported as monophyletic; however, the C. mexicanus group as a whole is not monophyletic. Our molecular phylogenetic analyses confirm the distinctiveness of two newly described species (C. celaque and C. mccarthyi) from isolated highlands of western Honduras and illustrate their relationship with other species formerly considered part of a widespread C. goodwini.

A hundred years later: new record of the rare Cryptotis tamensis (Soricidae: Mammalia) from Tama National Natural Park, Colombia

Here we present the most recent record of the Tama Small-eared Shrew for Colombia as a contribution to this poor-known species in the country. The record of the Tama Small-eared Shrew is located within the Tama NNP, Herran and Toledo municipalities, Norte de Santander department, Colombia on the border with Venezuela. The park presents an altitudinal range between 350 and 3.450 masl, and covers approximately 48.000 ha mostly composed of large areas of paramo, montane forest and tropical forest.

A new species of small-eared shrew in the Cryptotis thomasi species group from Costa Rica (Mammalia: Eulipotyphla: Soricidae)

We describe a new species of small-eared shrew, genus Cryptotis Pomel, 1848 (Eulipotyphla: Soricidae), from near the community of Monteverde in the Tilaran highlands of northwestern Costa Rica. The new species is immediately distinguished from all other Costa Rican shrews its large size and long tail. Morphologically, it belongs to the Cryptotis thomasi group of small-eared shrews, a clade that is more typically distributed in the Andes Cordillera and other highland regions of northern South America. The new Costa Rican species and the Panamanian endemic Cryptotis endersi Setzer, 1950 are the only two members of this species group known to occur in Central America. Like most other members of the C. thomasi group for which the postcranial skeleton has been studied, the new species tends be more ambulatory (rather than semi-fossorial) when compared with other members of the genus. Our survey efforts over several decades failed to locate a population of the new species, and we discuss its conservation status in light of its limited potential distribution in the Tilaran highlands and the significant climatic change that has been documented in the Monteverde region during the past four decades.

A new species of small-eared shrew of the genus Cryptotis Pomel, 1848 (Mammalia, Eulipotyphla, Soricidae) from the easternmost mountains of the Venezuelan Andes

The presence of shrews of the genus Cryptotis in the most northern spur of the eastern branch of the Venezuelan Andes was initially known by two specimens collected in the Macizo de Guaramacal. Both specimens were initially assigned to C. thomasi and subsequently to C. meridensis. Posteriorly, additional specimens were collected in several localities of the Cordillera de Mérida, from the Páramo la Cristalina up to the Sierra de Barbacoas. These samples are not referable to C. thomasi, C. meridensis or another Colombian or Venezuelan species, but on the contrary represent an undescribed species, belonging to the C. thomasi species group. The new species is distinguished by a unique set of morphological characters; among the most remarkable features are the lateral displacement of the foramen of the posterior edge of the tympanic process of the petromastoid, a large fourth unicuspid, visible in lateral view of the skull, and a tricuspulate lower incisor. After the recognition of this species, the number of small-eared shrews of the genus Cryptotis increases to 43, 16 of which occur in South America.

Morphological Variation among Broad-Clawed Shrews (Mammalia: Eulipotyphla: Soricidae:CryptotisPomel, 1848) from Highlands of Western Honduras, with Descriptions of Three New Cryptic Species

ABSTRACT Broad-clawed shrews of the Cryptotis goldmani group (Mammalia: Eulipotyphla: Soricidae) are discontinuously distributed in temperate highlands from southern Tamaulipas, Mexico, to Honduras. The group represents a clade within the small-eared shrews (genus Cryptotis Pomel, 1848) that is characterized by modifications of the forelimb, including broadened fore-feet, elongated and broadened fore-claws, and a massive humerus with enlarged processes. Two species of C. goldmani group shrews have been recorded previously from Honduras: C. magnimanus Woodman and Timm, 1999, is endemic to the Cordillera de Montecillos, and C. goodwini Jackson, 1933, which also occurs in the Sierra Madre of southern Guatemala, has been recorded from three isolated highland regions with remnant forest in western Honduras. Morphological and morphometrical analyses of variation in the skull and postcranial skeleton within and among the three Honduran populations of C. goodwini reveal that each represents a distinct species of ...