The taxonomy of earthworms has been riddled by instability, lack of systematically useful characters, and lax diagnoses of some genera. This has led to the use of some genera such as Allolobophora Eisen, 1874 as taxonomic wastebaskets, blurring their evolution and biogeographical history. The implementation of molecular techniques has revolutionized the systematics of the genus; however, some of its species have not been previously included in molecular phylogenetic analyses. Thus, the molecular markers COI, 16S, ND1, 12S, and 28S were sequenced for six endemic species including several taxa of Allolobophora and Aporrectodea Örely, 1885 (another related catch-all genus). Phylogenetic relationships determined by Bayesian inference and maximum likelihood analyses support the status of two of the six taxa examined (Allolobophora burgondiae Bouché, 1972 and Aporrectodea icterica Savigny, 1826) as part of Allolobophora sensu stricto and a presumed synonymy between Allolobophora and Heraclescolex Qiu and Bouché, 1998. Branch lengths and average pairwise genetic distances support the transfer of Allolobophora satchelli Bouché, 1972 to the genus Panoniona Mršić and Šapkarev, 1988 and the emergence of two new genera, Heraultia gen. nov. and Vosgesia gen. nov., endemic to France, hosting Allolobophora tiginosa Bouché, 1972 and Allolobophora zicsii Bouché, 1972, respectively. The aforementioned changes of status and the diagnosis for Heraultia and Vosgesia are presented. These results provided more evolutionarily and biogeographically coherent earthworm groups and highlighted that the Maghreb and the area around the Alps are potential key locations for the diversification of Allolobophora and several lineages of Lumbricidae.

The Iberian Peninsula and south-western France have been postulated as centres of diversification of a wide variety of endemic earthworm species and genera within the Lumbricidae family. However, the phylogenetic position and identity of some of these endemisms is still uncertain and their phylogeographic patterns totally unknown. In the present study, phylogenetic analyses were carried out with the molecular markers COI, 16S, 28S, ND1 and 12S to clarify the phylogenetic position of the Iberian endemism Iberoscolex in the lumbricid tree. In addition, phylogeographic patterns of three of its species (I. albolineatus, I. carpetanus and I. gerardoi) were studied based on the COI marker and compared with patterns of species showing similar distributions within Castellodrilus (C. ibericus and C. chitae), another Iberian endemism. Phylogenetic trees recovered all species of the genus Iberoscolex (with the exception of I. pseudorroseus) within a clade differentiated from Eiseniona where some authors had placed Iberoscolex species before. Moreover, they were clustered with some species (including the type) of Orodrilus, an Iberian-French endemism also sequenced for this study. Owing to the priority of Orodrilus, Iberoscolex should be considered a junior synonym, with all of the species formerly included within it assigned to a redefined Orodrilus. Strong population structure was observed for Iberoscolex and Castellodrilus species under study, together with a pattern of isolation by distance; however, these genera showed different patterns of genetic variability: the Castellodrilus species under study exhibit lower genetic diversity, with fewer haplotypes per population than the Iberoscolex species.

Earthworms have a crucial role in the maintenance of the biotic and abiotic soil properties, which is important for the biodiversity and productivity of terrestrial ecosystems, especially in the current scenario of climate change. Aestivation is a form of dormancy witnessed in organisms living in deserts or semiarid environments such as the ones found in the central part of the Iberian Peninsula. This work employs next-generation sequencing techniques to explore the changes in gene expression of different aestivation times (1 month and 1 year) as well as changes in gene expression upon arousal. Not surprisingly, the more the aestivation persisted the higher levels of gene downregulation were observed. Conversely, upon arousal, a quick recovery of the levels of gene expression were noted, comparable to the control. Transcriptional changes related to immune responses coming predominantly from abiotic stressors in aestivating earthworms and from biotic stressors in aroused earthworms triggered regulation of the cell fate via apoptosis. Long-term aestivation seemed to be enabled by remodeling of the extracellular matrix, activity of DNA repair mechanisms, and inhibitory neurotransmitters, which could also play a role in lifespan increase. Arousal from 1-month aestivation was on the other hand, characterized by regulation of the cell division cycle. Since aestivation is considered as an unfavorable metabolic state, aroused earthworms probably go through a damage removal process and a subsequent reparation process. This study provides the first transcriptomic investigation done on earthworms in such long aestivation times as well as arousal demonstrating the resilience and adaptability of Carpetania matritensis.

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