The bloodfeeding leech genus Placobdella is dominated by North American diversity, with only a single nominal species known from Central America and one from the Palearctic region. This is likely due to considerable underestimation of Palearctic biodiversity, but investigations into potential hidden diversity are lacking. To shed light on this, the present study introduces new data for specimens initially identified as Placobdella costata from Ukraine (close to the type locality),

Phreodrilidae is a small family uniting about 50 species of minute freshwater clitellate annelids inhabiting mainly the Southern hemisphere. Other than the male and spermathecal genitalia, their internal organization is poorly known. Here, we present results of our study of the ovaries and oogenesis in Insulodrilus bifidus, a phreodrilid from Western Australia using light and electron microscopy. The ovaries are paired and located in segment XII. They are inconspicuous and composed of several (10–12) spherical germ‐line cysts loosely interconnected by flattened somatic cells. The cysts usually comprise 32 germ cells and each cell is connected via a cytoplasmic bridge (ring canal) to the central cytoplasmic mass (the cytophore). In ovaries, germ cells in a given cyst develop in full synchrony. However, there is no synchrony among cysts, so there is a developmental gradient of cysts (from oogonial to early meiotic) along the longitudinal ovary axis. Within the cysts that are located in the distal end of the ovary the synchrony is finally lost and interconnected cells diversify into two morphologically distinct categories: an oocyte and 31 nurse cells. Such cysts detach from the ovaries and further development occurs within the body cavity. The oocyte gathers nutrients, mainly in form of yolk spheres, whereas nurse cells grow slightly and do not gather yolk. Organelles such as ribosomes, mitochondria and endoplasmic reticulum pass freely through the ring canals and are present within the cytophore, which suggests cytoplasmic transfer towards the oocyte. The formation of female germ‐line cysts equipped with cytophore and cells differentiated into oocyte and nurse cells matches the general pattern of oogenesis found in clitellates. In details, the ovary organization and oogenesis found in I. bifidus resembles the situation described in some representatives of Naidinae and Enchytraeidae.

No abstract

Acanthobdellida gnaw into the sides of salmonid fishes in frigid Arctic lakes and rivers, latching on with fearsome facial hooks. Sister to leeches, they are an ancient lineage with two described species. Unfortunately, Acanthobdellida are rarely collected, leading to a paucity of literature despite their unique morphology. Populations range from Eurasia to Alaska (USA), but few specimens of Acanthobdella peledina are represented in molecular studies, and no molecular data exist for Paracanthobdella livanowi, making their taxonomic position difficult to assess. We use phylogenetics and morphology to determine whether allopatric populations of A. peledina are distinct species and assess the current classification scheme used for Acanthobdellida. We produce a new suborder, Acanthobdelliformes, to match the taxonomy within Hirudinea. Scanning electron micrographs indicate species-level differences in the anterior sucker and facial hooks; molecular phylogenetics mirrors this divergence between species. We assign both species to the family Acanthobdellidae and abandon the family Paracanthobdellidae. Alaskan and European A. peledina populations are morphologically similar, but appear phylogenetically divergent. Our data strongly suggest that members of the order Acanthobdellida diverged relatively recently in their ancient history, but based on genetic distance, this divergence appears to pre-date the most recent cycles of glaciation.

Herein, we describe a new species of turtle blood-feeding leech, Placobdella nabeulensis sp. nov. from Palearctic North Africa (Tunisia and Algeria). The new species is described based on detailed morphological analyses using light and scanning electron microscopes. Apart from the detailed morphology of the atrium, morphological features alone do not sufficiently separate the species from congeners due to the absence of distinct diagnostic characters. Therefore, we turned to molecular data to better distinguish this new species from other members of the genus and establish a basis for its genetic separation. Four DNA fragments were successfully amplified, including mitochondrial COI and 12s rDNA, as well as nuclear 28S rDNA and histone H3. We then provided the molecular descriptor of the taxon, based on redundant diagnostic nucleotide combinations in DNA sequence alignment within the Folmer region. Results of the phylogenetic analysis and species delimitation methods (ABGD, ASAP, and bPTP) based on the COI locus support the species rank of the Tunisian-Algerian Placobdella. The new species is most closely related to the European species Placobdella costata (Fr. Müller, 1846) and the present study indicates that Placobdella nabeulensis sp. nov. has likely been confused with the European counterpart in several previous studies.