Chemical Secretion Use Varies Among Species but Lacks a Straightforward Relationship With Other Defenses in Neotropical Opiliones

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  Chemical Secretion Use Varies Among Species but Lacks a Straightforward Relationship With Other Defenses in Neotropical Opiliones ABSTRACT Chemical secretion deployment is a widespread defensive strategy in arthropods, typically aimed at surviving encounters with predators. However, the ecological forces shaping variation in its use across species remain unclear. We quantified chemical secretion behavior in 11 sympatric species of Prionostemma within the understudied arachnid order Opiliones. We surveyed species in two distinct forests in Costa Rica and tested their secretion propensity when stimulated, and whether these differences correlate with interspecific variation in morphology, leg-loss levels, or social behavior. We found that species varied in their tendency to release chemical secretions, forming a continuous gradient from taxa that rarely secreted to those that secreted in nearly all encounters. However, this variation was not explained by body size or leg loss. Spec...

A Decade of Change: Trends in Scorpion Richness, Abundance, and Community Structure in Central Algerian Sahara

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A Decade of Change: Trends in Scorpion Richness, Abundance, and Community Structure in Central Algerian Sahara

Abstract

Understanding long-term temporal dynamics of desert arthropod communities is essential for evaluating ecosystem responses to environmental variability. This study investigates decadal changes (2014–2024) in species richness, abundance, diversity, and assemblage composition of scorpions in the central Algerian Sahara. Annual species abundance data were analyzed using diversity indices and multivariate approaches. Temporal turnover in species composition was assessed using Bray–Curtis dissimilarity, linear regression, and SIMPER analysis to identify species contributing to assemblage change. Species richness increased substantially over the study period, rising from four species in 2014 to eleven species in 2024, but this rise likely reflects improved taxonomic knowledge and more complete inventories rather than a recent ecological colonization. In contrast, total abundance showed strong interannual variability without a clear temporal trend, indicating a decoupling between richness and overall population size. Diversity indices increased progressively, with higher Shannon and Simpson values in later years, reflecting reduced dominance and greater evenness, although both indices reached minimum values in 2019. Temporal β-diversity revealed moderate interannual turnover (mean dissimilarity = 0.22) and a non-significant decline through time, suggesting gradual assemblage reorganization. SIMPER analysis indicated that temporal change was mainly driven by shifts in dominance, particularly the decline of Androctonus amoreuxi and changes in secondary species such as Buthacus samiae and Lissothus chaambi. Overall, scorpion assemblages exhibited increasing richness and diversity with moderate turnover, driven primarily by changes in species dominance rather than widespread species replacement.

Sadine, S. E., Zebsa, R., Bensakhri, Z., Souilem, Z., Rouari, L., Houhamdi, M., & Lira, A. F. (2026). A Decade of Change: Trends in Scorpion Richness, Abundance, and Community Structure in Central Algerian Sahara. Diversity, 18(7), 420. https://doi.org/10.3390/d18070420