Jellyfish blooms have become increasingly frequent, but we still don’much about these organisms. New morphological data and a phylogenetic analysis have enabled the redescription of a recently discovered species (Pelagia benovici) from the Mediterranean Sea. This jellyfish is moved to a new genus within Pelagiidae named Mawia. Mawia benovici, comb., nov. is a sister taxon to Sanderia malayensis. Photograph: Mawia benovici, sp. nov., Piran, Slovenia, by Tihomir Makovec.

Xiphinema species are an important group of plant-parasitic nematodes with a high number of species and distributed almost worldwide. The aim of this work is to describe two new species of Xiphinema (X. macrodora, sp. nov. and X. oleae, sp. nov.) using an integrative approach (morphologically, morphometrically and molecularly). This study expands the biodiversity and morphological traits of this genus. Image: line drawing of the female lip region of Xiphinema macrodora, sp. nov.

Two spider species new to science have been discovered in the Western Italian Alps, one of the most important biodiversity hot spot in Europe. The new species belong to a group of cave dwelling spiders (Pimoa) represented so far in Europe by two species only. According to the molecular analysis, these spider species originated as a result of dramatic climatic change occurring in Europe between 13 and 1 million years ago. Photograph: Pimoa graphitica, sp. nov., by Francesco Tomasinelli.

High-mountain regions are known to harbour considerable biodiversity, although it is not all well known, especially in world’s largest mountain range, the Himalayas. Intensive field surveys of limnic molluscs resulted in the discovery of a species that can be clearly distinguished from all other sphaeriid bivalve species with oriental biogeographical affinity occurring in Nepal. Our findings highlight the importance of studies of the freshwater biodiversity at high-altitude ecosystems. Images: line drawings of left – Pisidium alexeii, sp. nov. and right – P. prasongi.

Morphology and distribution of body scales are fundamental in the classification and evolution of Entomobryidae. Molecular phylogeny clustered the new genus Lepidodens, having pointed scales on dens, with Entomobryinae rather than Seirinae. This study clearly undermines the traditional separation of Entomobryinae and Seirinae/Lepidocyrtinae, and demonstrate that dental scales could occur in all entomobryid subfamilies containing scaled taxa. Photographs: scales in Lepidodens similis, gen. and sp. nov.

The description here of two new shark tapeworms belonging to the genus Calliobothrium suggests that diversity in this genus has been underreported and that species exhibit tighter host-specificity than once thought. Molecular phylogenetic analyses of species of Calliobothrium and the closely related genus Symcallio provide insight into the evolution of diagnostic morphological features. Comparison of this phylogeny with that of their hosts, sharks of the genus Mustelus, reveals interesting host association patterns. Image: line drawing of Calliobothrium cisloi, sp. nov. scolex.

Antarctica is an ice-dominated continent and all its terrestrial and freshwater habitats are fragmented, which leads eventually to speciation. Acutuncus antarcticus is the most common Antarctic tardigrade, and morphological and molecular analyses elucidated its genetic diversity and distribution. All analysed specimens were morphologically indistinguishable and presented the same 18S rRNA sequence, while cytochrome c oxidase subunit I analysis showed higher variability. Acutuncus antarcticus can still be considered a pan-Antarctic species, although there is the potential for future speciation events. Photograph: Acutuncus antarcticus, from Crater Cirque, Victoria Land, Antarctica.