We report on a new species of Stenasellus Dollfus, 1897 (Isopoda, Stenasellidae) from groundwater of Iran. Stenasellus stygopersicus Jugovic, Malek-Hosseini & Issartel sp. nov. inhabits the Chah Kabootari Cave that is adjacent to the Tashan Cave, the type locality of the first recorded species of Stenasellidae from Iran, Stenasellus tashanicus Khalaji-Pirbalouty, Fatemi, Malek-Hosseini & Kuntner, 2018. Both caves are fed by sulfidic groundwater and belong to the Tashan-Chah Kabootari species-rich aquifer on the Zagros Mountains. Both species are characterized by a large body size (≥ 20 mm), a female-biased sexual size dimorphism, and a distinct black-pigmented Bellonci’s organ. Stenasellus stygopersicus differs from S. tashanicus by a short and wide protopodite of pleopod I, setae set essentially along the apical margin of pleopod I exopodite, the subequal length and width of the male pleopod II protopodite, and deeply bilobed endopodites of pleopods III–V. Molecular evidence suggests that while Stenasellus stygopersicus is sister to S. tashanicus, the species are genetically distinguishable, with divergence time estimates ranging from 23 to 39.8 Ma.

The genus Chaetogaster belongs to the subfamily Naidinae (Naididae); it includes mostly species of small size and is diverse and abundant in surface coarse sediments in streams. The aim of the present study is to initiate an inventory of lineages (=species) of Chaetogaster in Switzerland. We used 135 specimens collected at 6 sites in 4 streams of 4 cantons. We sequenced the cytochrome c oxidase (COI) gene from all specimens and ITS2 and rDNA 28S from all or several specimens of each lineage that was delimited using COI data, and preserved, for morphological identifications, the anterior part of almost all sequenced specimens. We were able to delimit, based on the calculation of genetic distances and analyses of single-locus data, one lineage for Chaetogaster diaphanus (Gruithuisen, 1828), three within Chaetogaster diastrophus (Gruithuisen, 1828), one for Chaetogaster langi Brestcher, 1896, one for Chaetogaster setosus Svetlov, 1925, and three unidentified Chaetogaster spp. Two lineages of Chaetogaster spp. could correspond to a new morphological group, but this should be confirmed in more specimens. We proposed a new identification key of the nominal species and described the three C. diastrophus lineages and two Chaetogaster spp. as new species. The prospects of the present work are to complete the data of the molecular diversity of this genus in Switzerland and to describe the newly found Chaetogaster species on a molecular/morphological basis.

Hydrological exchanges between rivers and groundwater are essential for many ecosystem processes: identifying their location requires a set of physical, chemical and biological indicators. Here, we describe Schellencandona rhodanensis sp. n. (Ostracoda, Candoninae), a species highly sensitive to hydrologic exchanges in river sediment. The new species is close to Schellencandona triquetra (Klie, 1936), but mainly differs in the shapes of the female genital lobe and the male hemipenis. The species is described from the Rhône River watershed, where it occurs in at least five tributaries. It is a stygobite species (i.e. a groundwater specialist), occurring in both the main channel and associated wetlands, with a maximum abundance at depth of about 1 m below the sediment surface. While S. triquetra is collected in a wide range of groundwater habitats, S. rhodanensis sp. n. is mostly restricted to river interstitial habitats fed by groundwater. It can be used as a biological indicator of interstitial habitat stability and to locate groundwater upwellings in river bed sediment.

We describe five new species of the genus Schellencandona Meisch, 1996 (Ostracoda, Candoninae) collected in the southern French Alps. Four of these species, S. danielopoli sp. nov., S. capderreyae sp. nov., S. mercantourensis sp. nov., and S. claretae sp. nov., are related to S. simililampadis (Danielopol, 1978), a species previously described from southern France. The fifth species, S. malardi sp. nov., is related to the species of Schellencandona present in the Northern Alps. These five new species were collected in the interstitial habitats of rivers, generally deep inside the bedsediment (i.e., at a depth of about 90 cm into the sediment), and show some morphological characteristics linked to a specialisation to live in groundwater (e.g., long aethetascs, large oocytes). Schellencandona danielopoli and S. claretae have a large geographic distribution and a wide altitudinal range. Schellencandona mercantourensis is present at high elevation in two different rivers. The last two species, S. capderreyae and S. malardi, occur at low-elevation sites in a single river. They can be considered vulnerable to future climatic changes in the Mediterranean region.

At continental to global scales, energy‐related predictors relate positively to regional species richness, often explaining much of its variation in different ecosystems. However, the influence of energy on local species richness (LSR) has received much less attention. In aquatic ecosystems, LSR is predicted to increase with increasing catchment terrestrial productivity. Greater food resources resulting from increased terrestrial subsidies of nutrients and organic matter to the stream can support more individuals, thereby enabling more species to attain viable local populations, a hypothesis known as the more‐individuals hypothesis (MIH). We used generalized linear models and variance partitioning to quantify the unique and shared effects of nine local predictors and nine catchment predictors on LSR of hyporheic communities sampled at 228 sites in tropical New Caledonia streams. We found that productivity proxies, including the proportions of peridotite and bare soil in the catchment, and the normalized difference vegetation index (NDVI), correlated strongly with proxies of sediment metabolism (dissolved oxygen and pH), which in turn accounted for much of the variation in LSR. However, the positive relationship between LSR and catchment productivity, and the resulting dominance of shared effects of local and catchment predictors, were largely driven by fast‐growing taxa. Their richness and abundance increased monotonically with increasing catchment productivity. The LSR of slow‐growing taxa was largely explained by local predictors, and it showed a weak, hump‐shaped relationship to catchment productivity. The additional food resources from more productive catchments could either not be assimilated by slow‐growing taxa or were monopolized by fast‐growing taxa. Hence, other processes than those underlying the MIH, including the competitive ability of taxa to acquire available resources, likely play a role in controlling the species‐energy relationship in hyporheic invertebrate communities.

The genus Chaetogaster belongs to the subfamily Naidinae (Naididae), includes mostly species of small size and is diverse and abundant in surface coarse sediments in streams. The aim of the present study is to initiate an inventory of lineages of Chaetogaster in Switzerland. We used 135 specimens collected at six sites in four streams of four cantons. We sequenced the cytochrome c oxidase (COI) gene from all specimens and ITS2 and rDNA 28S from all or several specimens of each lineage delimited using COI data and preserved a voucher of almost all sequenced specimens. We could delimit one lineage (=species) for Chaetogaster diaphanus (Gruithuisen, 1828), three within Chaetogaster diastrophus (Gruithuisen, 1828), one for Chaetogaster langi Brestcher, 1896, one for Chaetogaster setosus Svetlov, 1925 and three unidentified Chaetogaster spp. Two lineages of Chaetogaster spp. could correspond to a new morphological group, but this should be confirmed on more specimens. We described the three C. diastrophus lineages and two Chaetogaster spp. as new species for science. The prospects of the present work are to complete the data of the molecular diversity of this genus in Switzerland and to describe on a molecular/morphological basis the new Chaetogaster species that we will probably find.