A new obligate groundwater species of Asellus (Isopoda, Asellidae) from Iran

Abstract

With only 43 described stygobionts and only two isopod species the obligate groundwater fauna of Iran, a vast country with over 10% of limestone surface, is inadequately known. Here, we report the discovery of Asellus ismailsezarii sp. nov. from Zagros mountains, the first eyeless and depigmented asellid isopod from Iran. The new species is morphologically similar to Asellus monticola Birstein, 1932, but it is eyeless and fully depigmented, has a slightly curved pereopod IV and does not bear any setae on proximal margins of exopodite of pleopods IV and V. Species phylogenetic relationships using original and datamined mitochondrial DNA and nuclear rDNA, and estimation of molecular divergences with other Asellus species, suggest that A. ismailsezarii sp. nov. is sister to a larger clade that also contains the European A. aquaticus species complex. Surface populations of Asellus have colonized groundwater at multiple occasions and localities, both in Europe and Asia, giving rise to species and subspecies that have evolved troglomorphisms, such as depigmentation and loss of eyes. Of the 37 formally described species and subspecies of Asellus, 15 are from groundwater, including A. ismailsezarii sp. nov. We predict that many more obligate groundwater Asellus taxa are yet to be discovered in Asia.

Progress in the discovery of isopods (Crustacea: Peracarida)—is the description rate slowing down?

“…For recently described isopod species, shelf life varied between 0 years ( Monticelli Cardoso, Bastos-Pereira & Lopes Ferreira, 2022 ) and 54 years ( Williams, Boyko & Marin, 2020 ) with an overall tendency toward the lower range of the spectrum. For example, Malek-Hosseini et al (2022) described a new groundwater species from Iran within three years of sampling, additionally using molecular data to corroborate its species status. In contrast, the material from which the first bopyrid isopod species from hydrothermal vents was described was collected 21 to 10 years before its taxonomic description ( Kato et al, 2022 ).…”

A New Locality for the Blind Loach, Eidinemacheilus smithi (Teleostei: Nemacheilidae) in Iranian Zagros: A Morpho-Molecular Approach

“…Recently, we described a new obligate groundwater species of asellid crustacean from the Ganow spring, about a kilometer east of Tuveh [33], and a new species of troglobiont gastropod from this aquifer is awaiting description. These findings suggest that increased field efforts will continue to reveal more troglobiont species inhabiting this big aquifer.…”

A new stygobiotic species of the genus Proasellus (Crustacea: Isopoda: Asellidae) from South Dagestan, Russia

“…It is widely distributed in groundwaters of Europe, southern coast of Minor Asia, and the Caucasus (Capderrey et al, 2013;Morvan et al, 2013;Palatov, Sokolova, 2021). The eastern border of this genus' range apparantely passes through the Caucasian Isthmus: it has not been found so far neither in Iran and Central Asia, nor in the Kura basin in eastern Transcaucasia (Turbanov et al, 2016;Malek-Hosseini et al, 2022). The most eastern species are known for the Terek basin within North Ossetia.…”