Andreas Schmidt-Rhaesa

Six specimens of Nephasoma constricticervix are reported from the Guinea Basin from 5141–5171 m depth, collected during the Diva II expedition. This species was reported earlier from this region as “unpublished record”. Most characteristic are the long introvert hooks (up to 123 µm in our specimens), which decrease in size posteriorly and a constriction between introvert and trunk. An SEM investigation of the hooks shows their fine structure and the presence of papillae associated with the hooks.

Digestive systems with two openings, mouth and anus, dominate the animal kingdom, but systems with only one opening, so-called sac-shaped digestive systems, are present in a number of taxa. Sac-shaped digestive systems are regarded to have preceded through-guts evolutionarily, and they do so during individual development, as the gastrula stage with one opening, the blastopore, always precedes the origination of a second opening. Sac-shaped digestive tracts occur predominantly in taxa with a basal position in the tree of life, but can also evolve secondarily. They occur in a variety of forms, including hard structures for food uptake, muscular regions (pharynx) or strong branching. In several taxa, anus-like structures are known, but their existence may be a functional trait rather than a reminiscence or preadaptation of a “real” anus. This review includes a closer look at the digestive system of Ctenophora, Cnidaria, Xenoturbellida, Acoelomorpha, Platyhelminthes, Gnathostomulida and Micrognathozoa.

Free-living flatworms, also known as turbellarians, are abundant and key components of aquatic habitats. They play vital roles in food webs and contribute to ecosystem health. However, our understanding of their diversity remains limited, even from comparably well-studied regions of Europe. In this work, we summarise the available records on aquatic turbellarians from Hamburg, Germany, provide new records based on material obtained during exploratory collecting, and place selected species in a molecular phylogenetic context. We sampled four localities in Hamburg, two urban and two suburban, and three other localities in Germany and Switzerland, collecting submerged vegetation, litter, and mosses. Prior to our investigation, Hamburg had documented 26 species of aquatic turbellarians. Our collections have led to the first recorded instances of Stenostomum gotlandense and Castrella alba in Germany, along with four new species for Hamburg: Macrostomum rostratum, Microdalyellia schmidtii, Krumbachia hiemalis, and Polycelis tenuis. Additionally, we provide updated information for five species previously recorded from Hamburg: S. leucops, Prorhynchus stagnalis, Microdalyellia armigera, Gyratrix hermaphroditus, and Planaria torva. The phylogenetic analysis revealed cryptic diversity within S. grande and S. leucops, with S. grande comprising two distinct clades (Brazil and Japan + Germany), and S. leucops consisting of four clades (Sweden + Germany, two from Finland, and Brazil). One of the Finnish clades, S. leucops aquariorum, is both morphologically and molecularly distinct, and we recognise it as a valid species, now S. aquariorum. Future research is needed to further clarify the relationships of the remaining clades of these two species, particularly with material from their type localities in the United States. Among rhabdocoel microturbellarians, we identified cryptic diversity within Castrella truncata (with European and North American lineages) and Microdalyellia armigera (encompassing Finnish and Spanish lineages). We also provided the first molecular evidence supporting the monophyly of Krumbachia following the sequencing of K. hiemalis. Conversely, species of Bothromesostoma were found to be nested within a clade containing species of Mesostoma, leading us to propose synonymising these genera. Overall, our study underscores the rich biodiversity potential of urban and suburban ecosystems for detecting freshwater turbellarian species, while highlighting the need for further research in Hamburg and across Germany to clarify species distributions. Moreover, molecular phylogenetic analyses have uncovered cryptic diversity in several species of catenulids and rhabdocoels, emphasizing the importance of future efforts to describe potential new species.

To date, only eight species of marine tardigrades have been recorded from the Southern Ocean. A total of 1210 tardigrade specimens were collected during various marine expeditions with R/V POLARSTERN: ANDEEP-1, ANDEEP-2, ANDEEP-3 and ANDEEP-SYSTCO. The sampled tardigrades belong to five families (Batillipedidae, Coronarctidae, Halechiniscidae, Styraconyxidae and Echiniscoididae), seven genera (Batillipes, Coronarctus, Moebjergarctus, Angursa, Styraconyx, Tholoarctus, Isoechiniscoides) and 15 species (Batillipes wyedeleinorum, Coronarctus dissimilis, Coronarctus tenellus, Coronarctus cf. tenellus, Moebjergarctus clarionclippertonensis, Angursa sp., A. abyssalis, A. antarctica, A. capsula, A. lanceolata, A. lingua, Styraconyx qivitoq, S. takeshii, Tholoarctus oleseni, Isoechiniscoides aff. sifae sp. can.). For the genera Batillipes, Coronarctus, Moebjergarctus, Tholoarctus and Isoechiniscoides, these new distribution data are the southernmost records and first reports from the Southern Ocean. Furthermore, the genera Styraconyx, Batillipes and Isoechiniscoides are reported from the abyssal zone for the first time. These new findings significantly expand our previous knowledge of both geographic and bathymetric distribution of marine Tardigrada.

Twenty-two marine species of Dalytyphloplanida from Cuba, Panama, and Lanzarote are presented, sixteen of which are new to science. Five known species are recorded from Cuba: Kytorhynchus microstylus, Ceratopera paragracilis, Trigonostomum armatum, T. franki, and T. vanmecheleni. Neokytorhynchus pacificus is recorded for the first time in the Atlantic (Lanzarote). For one species, a new genus is erected to be included in a new family. A new genus and thirteen new species from Cuba and three new species from Panama are described. The new species are mainly distinguished from their congeners by the specific morphology of the copulatory structures. The new taxa are discussed in the context of a new phylogenetic analysis of Dalytyphloplanida. This analysis includes sequences of 238 species, 14 of which were sequenced for the first time. The phylogenetic analysis and the detailed morphology suggest that K. microstylus may constitute a complex of cryptic species. The internal phylogenetic relationships of Trigonostomum and Promesostoma were separately analysed to include new sequence data of the mitochondrial cox1 gene. These genera are shown to consist of several diagnosable clades, concurring with the results of early morphological studies of these taxa. Morphological and molecular data support the notion that Trigonostomum sinensis is a junior synonym of T. vanmecheleni, and we therefore propose their synonymisation. A new family is erected, Schockaertiidae fam. n., to include a monophyletic clade of neodalyellids with a pharynx rosulatus and a copulatory bulb devoid of hard structures (Schockaertia aprostatica gen. n. sp. n. and Einarella argillophyla). We propose a new classification into families of Thalassotyphloplanida, which envolves elevating the status of Adenorhynchinae to family level (Adenorhynchidae status novus). All previously recognised thalassotyphloplanid families are recovered as monophyletic (Kytorhynchidae, Byrsophlebidae, Promesostomidae, and Trigonostomidae). No support was found for the previously described subfamilies, except Paramesostominae, and we, therefore, propose to suppress these taxa.

We report here a specimen of the horsehair worm (Gordiida, Nematomorpha) Spinochordodes bacescui (Căpuşe, 1965) found in a patient´s urine. This is the first record of this species from Serbia and the sixth gordiid species known in Serbia. It is discussed that there is no evidence that gordiids are parasites of humans. Instead, gordiids parasitize terrestrial insects, which release their mature gordiid parasite into water and may thereby also use containers in human surroundings. Pseudoparasites, such as Spinochordodes bacescui, do not pose a threat to human health nor are they a serious public health issue.

The nematode phylum Nematomorpha contains organisms which are also known as horsehair worms or Gordian worms. We report here a male specimen of Gordian worm from a horse farm in Balıkesir province, Turkey. The body of the specimen was brown in color and the length was about 38 cm. After fixed in ethyl alcohol (80%) scanning electron microscopic (SEM) observations were carried out. Based on macroscopic and SEM findings the specimen was identified as Gordius sp.. As merely little data is available on these organisms in Turkey, our finding will contribute to the existing knowledge in terms of the local diversity of this taxon.

Summary: We report a female Chordodes anthophorus from a Giant Asian Mantis (Hierodula membranacea) for the first time from Iran. Scanning electron microscopy (SEM) was used to describe the characters and substructures precisely. We demonstrate characteristic cuticular patterns for Chordodes anthophorus. The presence of five types of areoles including simple, tubercle, crowned and circumcluster areoles and also crowned areoles with long fi laments which is a common feature in females, confi rm our investigation.