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The stone crayfish is a native European freshwater species with significant population declines caused by anthropogenic pressure onto its habitats, climate change and spreading of non-indigenous invasive crayfish and their pathogens (e.g., Aphanomyces astaci). We present the first record of an Austropotamobius torrentium population in a small stream from the southern lowlands of Romania, in an area without limestone or karst, known as a typical stone crayfish habitat in this country. No additional populations were found in the neighbouring streams. The mtDNA analysis based on sequencing a short fragment of the cytochrome c oxidase subunit I (COI) gene revealed that specimens from this newly discovered population belongs to the most widespread phylogroup of A. torrentium (CSE) and share the same haplotype as the specimens found in Croatia. Unfortunately, this crayfish population has disappeared most likely because of the crayfish plague since pathogen A. astaci was isolated from moribund crayfish. Our study highlights the vulnerability of isolated relic populations in the face of outside stressors.

The cuticle is the interface between an animal and its environment; thus, it has a special importance. In Arthropods, the cuticle is not uniform, having numerous formations, which is also the case of epigeic terrestrial isopods. Our study presents data on cuticle surface morphology, obtained with a scanning electron microscope, of an endemic terrestrial isopod species, Trachelipus trilobatus. Here we present SEM images of some external morphological features of this species, which were previously described only at the light microscope. Although T. trilobatus was frequently encountered in caves, the aspect of its cuticle is characteristic for an epigeic isopod, presenting numerous micro-scales, spines, and tricorn sensilla, which are considered hygroreceptors. This fact proves that originally T. trilobatus is an epigeic species, which secondarily adapted to karst areas with caves. Nevertheless, it regularly leaves the caves and the limestone cracks and emerges on the soil surface. Therefore, T. trilobatus is able to receive information about environmental humidity, especially on the soil surface, which, when unfavorable, causes the species retreat into caves or cracks. Climatic fluctuations from the glacial periods could direct T. trilobatus to this environment and way of life, modifying its morphology, but not its cuticle. [ABSTRACT FROM AUTHOR]