The chromosome-level genome of Mesobuthus martensii provides insights into its evolution and the diversity of venom peptides

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  The chromosome-level genome of Mesobuthus martensii provides insights into its evolution and the diversity of venom peptides Abstract Mesobuthus martensii , the source species of the traditional Chinese medicine “Quanxie”, has long been utilized for its therapeutic properties. Venom peptides are recognized as the major active molecular basis of these pharmacological activities. Despite this, their development as therapeutic agents remains poorly explored. In this study, we performed an integrated multi-omics investigation to systematically explore the venom peptides of Mesobuthus martensii . We generated a chromosome-level genome assembly of Mesobuthus martensii using third-generation sequencing technologies, yielding a genome size of 1.08 Gb with a contig N50 of 46.46 Mb. Integrated genomic and transcriptomic analyses led to the identification of 51 putative novel venom peptide candidates. From the broader venom peptide set, five lysine- and arginine-rich candidates were select...

Testing the Limits of Morphology: A Comprehensive Morphometric Study of the Sister Lineages Lasiocyano Galleti-Lima, Hamilton, Borges and Guadanucci, 2023 and Lasiodora C. L. Koch, 1850 (Theraphosidae, Mygalomorphae)

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Testing the Limits of Morphology: A Comprehensive Morphometric Study of the Sister Lineages Lasiocyano Galleti-Lima, Hamilton, Borges and Guadanucci, 2023 and Lasiodora C. L. Koch, 1850 (Theraphosidae, Mygalomorphae)

ABSTRACT

Morphological conservatism and homoplasy pose significant challenges for the systematics of mygalomorph spiders, limiting the number of reliable morphological characters available for species identification, particularly in Theraphosidae. Closely related taxa frequently display high phenotypic similarity, which limits the resolution of morphology-based approaches. In this study, we conducted the most extensive morphometric analysis to date within Theraphosidae, with the objective of explicitly testing how much morphological information is retained within the Lasiocyano sazimai and Lasiodora lineage. We applied a morphometric framework combining linear morphometry and geometric morphometry, including multivariate statistics, discriminant analyses, and cross-validation, to evaluate interspecific differentiation in this group. Although some analyses recovered statistically significant differences among taxa, extensive morphological overlap, high intraspecific variation, and pronounced overfitting in cross-validated classifications consistently reduced the discriminatory power of the methods. As a result, none of the approaches provided reliable diagnostic separation between Lasiocyano sazimai and Lasiodora species. Our results indicate that morphology alone reaches clear limits of resolution within this lineage. The only characters that remained consistently informative for distinguishing the genera were the presence of stridulatory setae in Lasiodora and the distinctive blue-purplish setae of Lasiocyano. By explicitly testing the limits of morphometric and morphological inference in a morphologically conservative group, this study helps clarify the actual scope and limitations of morphology-based systematics in Theraphosidae.

Marquezin-Gomes, A. G., Galleti-Lima, A., A. Morales, M. J., & L. Guadanucci, J. P. (2026). Testing the Limits of Morphology: A Comprehensive Morphometric Study of the Sister Lineages Lasiocyano Galleti-Lima, Hamilton, Borges and Guadanucci, 2023 and Lasiodora C. L. Koch, 1850 (Theraphosidae, Mygalomorphae). Journal of Morphology, 287(4), e70123. https://doi.org/10.1002/jmor.70123