Hidden diversity in plain sight: four new species of Nemesia (Araneae: Mygalomorphae) from the Córdoba Province of Spain

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  Hidden diversity in plain sight: four new species of Nemesia (Araneae: Mygalomorphae) from the Córdoba Province of Spain Abstract A taxonomic revision of the species of Nemesia Audouin, 1826, distributed in the vicinity of Córdoba City, southern Spain, is presented. Four new species are described: Nemesia morana sp. nov. (female), N. kodama sp. nov. (male and female), N. rosae sp. nov. (male and female), and N. tamajoni sp. nov. (male and female). These species are distinguished by distinct morphological characters, including the shape of the spermathecae, palpal bulbs, and spinnerets, as well as by burrow architecture. Fieldwork was conducted across two of the three major habitat types in the region—the humid, forested mountains of Sierra Morena and the croplands and riparian forests of the Guadalquivir Valley—while the third, the “campiña”, which is mainly composed of agricultural landscapes, remains poorly explored. Sampling methods included pitfall trapping and the direct e...

Latitude Matters: A Global Perspective on Climate-Driven Demographic Responses in Tarantulas

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Latitude Matters: A Global Perspective on Climate-Driven Demographic Responses in Tarantulas


ABSTRACT

Aim

To investigate how past climate change has shaped the genetic diversity and demographic responses (changes in population size and structure inferred from genetic data) of tarantulas across latitudes, and to test whether climate–demography relationships vary with latitude.

Location

Global; spanning tropical to temperate regions.

Taxon

Tarantulas (family Theraphosidae).

Methods

We compiled mitochondrial cytochrome oxidase I (COI) sequences for 50 tarantula species worldwide, including newly generated sequences, to estimate nucleotide diversity (π) and Tajima's D as indicators of genetic diversity and population demographic history. Ecological niche models (ENMs) were constructed under present-day and Last Glacial Maximum (LGM) climatic conditions to quantify changes in habitat suitability since the LGM. Using generalised linear models (GLMs), we tested associations between latitude, habitat suitability change and genetic metrics.

Results

Pairwise correlations among latitude, habitat suitability change and genetic metrics showed no significant associations. However, GLMs revealed a significant interaction: the effect of habitat suitability change on Tajima's D was strongly positive at high latitudes but negative or negligible at low latitudes. This indicates that demographic responses to past climate change varied latitudinally. Several high-latitude species showed genetic signatures of demographic expansion and range increase since the LGM.

Main Conclusions

Our results support the hypothesis that species at higher latitudes experience stronger demographic fluctuations due to historical climate change, aligning with Darwin's predictions. Moreover, patterns of demographic growth in temperate taxa suggest that some species may benefit from recent warming, consistent with Janzen's climatic variability hypothesis. These findings demonstrate that climate-driven genetic and demographic responses in tarantulas are probably shaped by latitude, highlighting the importance of integrating population genetics with ecological niche modelling to understand species' resilience under climate change.

Biswas, A., & Karanth, P. Latitude Matters: A Global Perspective on Climate-Driven Demographic Responses in Tarantulas. Journal of Biogeography, e70055. https://doi.org/10.1111/jbi.70055