Ecological "Windows of opportunity" influence biofilm prokaryotic diversity differently in glacial and non-glacial Alpine streams.

In glacier-fed streams, the Windows of Opportunity (WOs) are periods of mild environmental conditions supporting the seasonal development of benthic microorganisms. WOs have been defined based on changes in biofilm biomass, but the responses of microbial diversity to WOs in Alpine streams have been overlooked. A two year (2017-2018) metabarcoding of epilithic and epipsammic biofilm prokaryotes was conducted in Alpine streams fed by glaciers (kryal), rock glaciers (rock glacial), or groundwater/precipitation (krenal) in two catchments of the Central-Eastern European Alps (Italy), aiming at testing the hypothesis that: 1) environmental WOs enhance not only the biomass but also the α-diversity of the prokaryotic biofilm in all stream types, 2) diversity and phenology of prokaryotic biofilm are mainly influenced by the physical habitat in glacial streams, and by water chemistry in the other two stream types. The study confirmed kryal and krenal streams as endmembers of epilithic and sediment prokaryotic α- and ß-diversity, with rock glacial streams sharing a large proportion of taxa with the two other stream types. Alpha-diversity appeared to respond to ecological WOs, but, contrary to expectations, seasonality was less pronounced in the turbid kryal than in the clear streams. This was attributed to the small size of the glaciers feeding the studied kryal streams, whose discharge dynamics were those typical of the late phase of deglaciation. Prokaryotic α-diversity of non-glacial streams tended to be higher in early summer than in early autumn. Our findings, while confirming that high altitude streams are heavily threatened by climate change, underscore the still neglected role of rock glacier runoffs as climate refugia for the most stenothermic benthic aquatic microorganism. This advocates the need to define and test strategies for protecting these ecosystems for preserving, restoring, and connecting cold Alpine aquatic biodiversity in the context of the progressing global warming.

Disentangling cryptic species in Parastenocarididae (Copepoda: Harpacticoida) with an integrative approach: the case of Stammericaris similior sp. nov. and Stammericaris destillans Bruno & Cottarelli 2017.

Stammericaris similior sp. nov. is described combining light microscopy, scanning electron microscopy, and genetic barcoding. The new species was collected from rimstone pools in Scrivilleri Cave, a cave in Sicily with so far unexplored microcrustacean fauna. The new species is particularly interesting because it is morphologically very similar to Stammericaris destillans, an epikarstic parastenocaridid endemic to a different Sicilian cave; however, the phylogenetic analysis based on the mitochondrial COI gene of sixteen parastenocaridids shows that these two Stammericaris are two distinct species, with an uncorrected p-distance of 22.9, and the sequences of Stammericaris similior sp. nov. cluster together in a well-supported monophyletic clade, with two different haplotypes. To our knowledge, the presence of different species of almost identical morphology had not been recorded before for the genus Stammericaris. The integrated molecular and morphological analysis, the latter conducted with the support of SEM, allows disentangling the affinities of the new species and identifying a few distinctive characters: the males of the new species are characterized by the caudal rami shorter than the anal somite; the morphology of the P3, which is thin and slightly arched, with three proximal spinules on exp-1; the peculiar structure of the P4 enp; the P4 basis ornamented with two spinules of different length, the one closest to the endopod being the shortest one, and a half-moon shaped lamella. The new species differs from S. destillans for its larger size, the presence of: three spinules, instead of two, on the P3 exp-1; the half-moon shaped lamella on the P4 basis; a row of spinules along the inner margin of P4 exp-1. We also provide data on the ecology and distribution of the new species, a list of the other copepod species collected, and a dichotomic key for the males of all species presently assigned to the genus.

The genus Stammericaris Jakobi (Copepoda: Harpacticoida: Parastenocarididae) in the Nearctic subregion: description of Stammericaris remotaepatriae sp. nov., proposal of Stammericaris palmerae (Reid 1992) comb. nov., and remarks on other North American Parastenocarididae.

We describe a new harpacticoid, Stammericaris remotaepatriae sp. nov., collected from the hyporheic habitat of a stream in Nantucket, MA, USA. The new species is characterized by the size of the caudal rami of both sexes, which are shorter than the anal somite, by the morphology and armature of the P3 and, mainly, by the P4 endopod of males, represented by a curved plate with a strongly bifid tip, the distal proximal outgrowth of the distal margin spiniform and denticled, the proximal outgrowth missing. The study of the new species allowed us to review the systematic position of Parastenocaris palmerae Reid, 1992, which we transferred to Stammericaris Jakobi, 1972 as Stammericaris palmerae (Reid, 1992) comb. nov., based mainly on the structure of the male P4 endopod complex and the setation of the caudal rami. We also discussed the taxonomic position and affinities of Parastenocaris trichelata Reid, 1955, suggesting that this species is related to the two former ones for a set of diagnostic features, but can not be attributed to the genus due to the peculiar morphology of the male P4 endopod complex; P. trichelata is therefore considered species inquirenda. We also discussed Parastenocaris sp. 1 and Parastenocaris sp. 3, two taxa only partially described and drawn in Strayer (1988). In fact, Parastenocaris sp. 1 can be related to Stammericaris and might represent a third species of the genus in the Nearctic region. Remarkably, the structure of the male P4 endopod of Parastenocaris sp. 3 is typical of Proserpinicaris Jakobi, 1972; this hypothetical assignment of the species to Proserpinicaris, if confirmed, would be of relevant taxonomic and biogeographic value. Finally, we provide an updated distribution map of the genus Stammericaris and brief remarks on the faunistic and ecological characteristics of the taxa presented and discussed in this paper.

Interesting interstitial Paramesochridae (Copepoda: Harpacticoida): Maliithipon wellsi gen. et sp. nov. from the Philippines, M. aberrans (Mielke, 1984) comb. nov. from Panama, and M. cf. aberrans (Mielke, 1984) from the Azores.

We propose and describe a new genus of interstitial Paramesochridae, Maliithipon gen. nov., to accommodate three species. Maliithipon wellsi sp. nov., type species of the genus, is described based on specimens collected in two sandy beaches in Isla Verde, the Philippines. Apodopsyllus aberrans Mielke, 1984a described from Panama, is allocated to the herein erected genus as Maliithipon aberrans (Mielke, 1984a) comb. nov. Maliithipon cf. aberrans is described, based on specimens collected in the Azores and previously identified as Apodopsyllus aberrans. The new genus is characterized by several distinct morphological features: mandible with uniramous, 2-segmented palp and gnathobase with thin and pointed teeth; maxillule with reduced armature, lacking endopod and exopod; maxilla large, with three syncoxal endites and endopod with reduced setal number; P5 very reduced in both sexes; caudal rami with six setae, two of which (setae III and VI) transformed; pseudoperculum well-developed, with four-lobed distal margin. The new genus is included in the subfamily Paramesochrinae Lang, 1944 and in the genus-group Scottopsyllus (sensu Huys, 1987). It has strong affinities with Leptopsyllus (Leptopsyllus) platyspinosus Mielke, 1984b and Wellsopsyllus (Intermediopsyllus) smirnovi (Kunz, 1992), which are considered as species inquirendae in this paper. Some remarks on the ecology and geonemy of the three studied species are provided. We also list the accompanying Paramesochridae obtained from the two new collecting sites of the genus, and all the genera of Paramesochridae recorded from other sites in the Philippines during the same survey.

Ecosystem shifts in Alpine streams under glacier retreat and rock glacier thaw: A review.

This review provides a detailed synthesis of the effects of glacier retreat and permafrost thaw on stream ecosystems in the European Alps. As a working framework, we present a conceptual model developed from an integration of current knowledge and understanding of the habitat and ecological shifts in Alpine streams caused by deglaciation. In our work, we depict how climate change and the loss of cryosphere trigger complex cascading effects on Alpine hydrology, as the main water sources shift from snow and glaciers to rock glaciers, groundwater, and precipitation. The associated changes in habitat conditions, such as channel stability, turbidity, temperature, nutrient loadings, and concentrations of legacy pollutants and trace elements are identified. These changes are followed by complex ecological shifts in the stream communities (microbial community, primary producers, invertebrates) and food webs, with a predicted loss of biotic diversity. Corresponding increases in taxa abundances, biomass, functional diversity, and in the complexity of food webs, are predicted to occur in the upper reaches of Alpine catchments in response to ameliorating climatic and habitat conditions. Finally, current knowledge gaps are highlighted as a basis for framing future research agendas. In particular, we call for an improved understanding of permafrost influence on Alpine headwaters, including the ecology of rock-glacier fed streams, as these streams are likely to become increasingly important for water supply in many glacier-free Alpine valleys in the near future.

Morphological and molecular analyses of epikarstic Parastenocarididae (Copepoda: Harpacticoida) from two Sicilian caves, with description of a new Stammericaris.

We describe Stammericaris destillans sp. nov., and re-describe Stammericaris trinacriae (Pesce, Galassi and Cottarelli 1988) based on new material. The two species were collected from epikarstic drips and pools on the floor of two different caves: a karstic (Molara Cave) and a gypsum (Entella Cave) cave, respectively, both located in Sicily, Italy. We also report the presence of previously undescribed structures for Stammericaris amyclaea (Cottarelli 1969) and Stammericaris orcina (Chappuis 1938). Phylogenetic analyses of the mitochondrial COI and ribosomal 18S genes attributed the new species to Stammericaris Jakobi 1972, therefore the structure of the male P4 endopod of S. destillans is interpreted as an autapomorphy; other morphological features (structure of male antennule and P3, of female P3; inner ornamentation of P1 basis, armature of caudal rami and shape and armature of P5 of both sexes) correspond to those typical of the genus. Hence, we slithgly amended the generic diagnosis. [zoobank.org:pub:4CC84A0C-C511-4388-9728-41647E58097A].

River bank burrowing by invasive crayfish: Spatial distribution, biophysical controls and biogeomorphic significance.

Invasive species generate significant global environmental and economic costs and represent a particularly potent threat to freshwater systems. The biogeomorphic impacts of invasive aquatic and riparian species on river processes and landforms remain largely unquantified, but have the potential to generate significant sediment management issues within invaded catchments. Several species of invasive (non-native) crayfish are known to burrow into river banks and visual evidence of river bank damage is generating public concern and media attention. Despite this, there is a paucity of understanding of burrow distribution, biophysical controls and the potential significance of this problem beyond a small number of local studies at heavily impacted sites. This paper presents the first multi-catchment analysis of this phenomenon, combining existing data on biophysical river properties and invasive crayfish observations with purpose-designed field surveys across 103 river reaches to derive key trends. Crayfish burrows were observed on the majority of reaches, but burrowing tended to be patchy in spatial distribution, concentrated in a small proportion (<10%) of the length of rivers surveyed. Burrow distribution was better explained by local bank biophysical properties than by reach-scale properties, and burrowed banks were more likely to be characterised by cohesive bank material, steeper bank profiles with large areas of bare bank face, often on outer bend locations. Burrow excavation alone has delivered a considerable amount of sediment to invaded river systems in the surveyed sites (3tkm(-1) impacted bank) and this represents a minimum contribution and certainly an underestimate of the absolute yield (submerged burrows were not recorded). Furthermore, burrowing was associated with bank profiles that were either actively eroding or exposed to fluvial action and/or mass failure processes, providing the first quantitative evidence that invasive crayfish may cause or accelerate river bank instability and erosion in invaded catchments beyond the scale of individual burrows.