Corrigendum: A revision of the trichostrongylid nematode Cooperia Ransom, 1907, from deer game: recent integrative research confirms the existence of the ancient host-specific species Cooperia ventricosa (Rudolphi, 1809).

[This corrects the article DOI: 10.3389/fvets.2024.1346417.].

A revision of the trichostrongylid nematode Cooperia Ransom, 1907, from deer game: recent integrative research confirms the existence of the ancient host-specific species Cooperia ventricosa (Rudolphi, 1809).

The trichostrongylid roundworms of the genus Cooperia, which are important in veterinary medicine, currently comprise 19 valid species that parasitize the small intestine of both free-living and domestic ruminants. Only four Cooperia spp. have been reported in Europe, namely C. oncophora, C. punctata, C. curticei and C. pectinata. In 2018-2022, 25 red deer (Cervus elaphus) and 30 sika deer (Cervus nippon) of both sexes and various ages from several remote locations in the Czech Republic were parasitologically examined. Intestinal nematodes of the genus Cooperia were found only in two northern regions. Using the globally recognized key book on trichostrongylid nematodes, they were preliminarily identified as C. pectinata. However, a molecular analysis of cox2 and ITS rDNA gene sequences revealed that Cooperia sp. parasitizing Czech deer is a separate taxon that is more closely related to C. oncophora than to C. pectinata. A subsequent morphological analysis and literature survey confirmed the independence of deer Cooperia sp., which is similar but not identical to bovid C. pectinata. Previous long-term correct identifications of bovid C. pectinata and misidentifications of deer Cooperia species were caused by a fundamental error in the key book mentioned above. Interestingly, the ancient trichostrongylid nematode Strongylus ventricosus from the type host red deer (Cervus elaphus) shot near Greifswald (Germany) was described by Rudolphi in 1809. Rudolphi's type material (one male and four females) was deposited in the Museum für Naturkunde (Berlin). Later, the ancient species S. ventricosus was taken as a synonym for various Cooperia spp. Our current re-examination of the type male indicated that there is a relatively good agreement with our new material from Czech deer regarding the most important characteristics of S. ventricosus (i.e., the shape and size of the male spicules); however, Rudolphi's type material is in rather poor condition. The suggested resurrection of the deer Cooperia sp. in this study as Cooperia ventricosa (Rudolphi, 1809) requires verification by collecting and analyzing new nematode material from the type locality near Greifswald.

Robert Price Higgins-Aspects of his life and his contributions to meiobenthic research (1932-2022).

The scientific life of Robert P. Higgins was devoted to meiofauna, microscopically small animals living in aquatic sediments from the intertidal to hadal depths worldwide. He focused on the taxonomy, life-history, and ecology of the marine taxa Kinorhyncha, Tardigrada, and Priapulida and co-discovered the phylum Loricifera. He improved the methods for studying meiofauna and contributed significantly to spreading knowledge about these animals. Aspects of his life are described and lists of his publications, taxa described, contributions to science, and honours received are provided.

Epibiontic life on intertidal Setaphyes kielensis and S. dentatus (Kinorhyncha, Pycnophyidae) from Sylt, North Sea, Germany, with a description of a new species of Trematosoma (Ciliophora, Acinetidae) and a redescription of Cothurnia buetschlii (Ciliophora, Vaginicolidae).

Specimens of two species of Kinorhyncha, Setaphyes dentatus and S. kielensis, were collected in 1988, 1998, and 2016 at two intertidal sites on the island of Sylt, North Sea, and investigated as preserved material by light microscopy and scanning electron microscopy for their epibionts. One species of Acinetidae (Suctoria), one species of Vaginicolidae (Peritrichia), and two species of bacteria were traced. The most abundant ciliate species with 705 specimens was Trematosoma husselae sp. nov. occurring with 146 specimens on a basibiont, mainly on the ventral side and here especially on segment 1. Cothurnia buetschlii was found as 14 specimens. Trematosoma husselae sp. nov. agreed with T. amphiasci and T. pusilla in the calyciform shape of the lorica and with most species in the general size of the body except for the much larger T. constricta and T. pusilla. The new species could be distinguished from T. amphiasci, T. complatana, T. constricta, T. falcata, T. ovata, and T. pusilla by the short length of its stalk and agreed with T. bocqueti and T. rotunda in this character. Cothurnia buetschlii was redescribed for the first time after the descriptions by Zelinka (1914, 1928).

A new species of Echinoderes (Kinorhyncha: Cyclorhagida: Echinoderidae) from the Argentinean continental shelf with notes on its postembryonic development and on subcuticular morphological characters unreported for Kinorhyncha.

Echinoderes goku sp. nov. is described from adult and juvenile specimens in samples collected from the Argentinean continental shelf in March 2019 during the campaign of the Motorsailer Bernardo Houssay, based on light and scanning electron microscopy studies. Echinoderes goku sp. nov. is differentiated from other species by its unique spine and tube pattern: (1) middorsal spine on segments 4, 6, and 8, (2) spine in lateroventral position on segments 69, (3) tube present in subdorsal position on segment 2, sublateral to midlateral position on segments 7 and 9, lateral accessory position on segment 8, lateroventral position on segment 5 and ventrolateral position on segment 2. Additionally, this species (4) lacks type-2 gland cell outlets and female-specific papillae or subcuticular funnel-like structures. (5) The male possesses a sublateral tube on segment 10 with a basal cylindrical reinforcement structure and three penile spines on segment 11, whereas the female lacks penile spines but reveals a lateral terminal accessory spine on segment 11 and on segment 10 lacks a subdorsal tube but possesses instead a sublateral fringe on the surface connected with a subcuticular conical structure and a basal cylindrical reinforcement structure. Among several juvenile specimens, one was captured in the process of moulting from the last juvenile stage to the female. Whereas the last juvenile stage revealed a sublateral tube on segment 10, the moulting female lacked this tube and showed a conical subcuticular structure with a basal cylindrical reinforcement structure instead. A cylindrical reinforcement structure at the base of a tube and a subcuticular conical structure have not been reported before for Kinorhyncha, and 14 selected species of Echinoderidae available for study were screened for these characters in order to get a first idea of their possible taxonomic importance. This article reports about the second species of Echinoderes from Argentinean waters.

Ageing Effects in Mounting Media of Microscope Slide Samples from Natural History Collections: A Case Study with Canada Balsam and PermountTM.

Microscope slide collections represent extremely valuable depositories of research material in a natural history, forensic, veterinary, and medical context. Unfortunately, most mounting media of these slides deteriorate over time, with the reason for this not yet understood at all. In this study, Raman spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and different types of light microscopy were used to investigate the ageing behaviour of naturally aged slides from museum collections and the experimentally aged media of Canada balsam and Permount™, representing a natural and a synthetic resin, respectively, with both being based on mixtures of various terpenes. Whereas Canada balsam clearly revealed chemical ageing processes, visible as increasing colouration, Permount™ showed physical deterioration recognisable by the increasing number of cracks, which even often impacted a mounted specimen. Noticeable changes to the chemical and physical properties of these mounting media take decades in the case of Canada balsam but just a few years in the case of Permount™. Our results question whether or not Canada balsam should really be regarded as a mounting medium that lasts for centuries, if its increasing degree of polymerisation can lead to a mount which is no longer restorable.

New record of the soft-bodied genus Franciscideres (Kinorhyncha) from Argentina, with notes on its movement and morphological variation.

Samples collected from Monte Hermoso, Buenos Aires Province, Argentina revealed the presence of specimens of the genus Franciscideres Dal Zotto et al., 2013, previously known only from Brazil. This morphotype seems to differ from the only known species, Franciscideres kalenesos Dal Zotto et al., 2013, in the following characters: (1) presence of ventrolateral tubes on segment 1, (2) introvert features, (3) each segment composed of a closed cuticular ring, (4) trunk cuticle ornamented by a secondary fringe of knob-like structures, (5) posterior margin of segment 10 ventrally terminating in two lateral and one broad triangular lobes, (6) posterior margin of segment 11 centrally terminating in four lobes (7) lateral terminal spines armed with thorn-like processes, (8) pores/sensory spots/gland cells distribution and (9) sexual dimorphism in segments 10 and 11. Because of the lack of full information about F. kalenesos from Brazil, we consider the new exemplars as Franciscideres cf. kalenesos. Additionally, we provide new information about the movement of this species using light microscopy and we compare these movements with those of other meiofaunal inhabitants.

Revision of Condyloderes (Kinorhyncha, Cyclorhagida) including description of Condyloderes shirleyi sp. nov.

The description of a new representative of the species-poor genus Condyloderes Higgins, 1969 from the Northeast Pacific (Alaska) is reported. The analyzed specimens of Condyloderes shirleyi sp. nov. showed a significant variation of numerous morphological characters, along with female-specific traits known also from other congeneric species. These findings stimulated the re-investigation of the type material of the six species of Condyloderes described so far, i.e., C. kurilensis Adrianov Maiorova, 2016, C. megastigma Sørensen, Rho Kim, 2010b, C. multispinosus (McIntyre, 1962) Higgins, 1969, C. paradoxus Higgins, 1969, C. setoensis Adrianov, Murakami Shirayama, 2002, and C. storchi Higgins, 2004 in Martorelli Higgins, 2004. Our study allowed to reveal various morphological novelties and to emend the diagnosis of these species and of the genus Condyloderes. Furthermore, our analysis led to synonymize C. megastigma with C. setoensis. The results of our investigation about the significant variation in C. shirleyi sp. nov. raise a wider question on species identity within Kinorhyncha, underscoring the necessity, if possible, to describe new species from a higher number of specimens and to concentrate on the morphological variation of the going-to-be-described species.

Echinoderes pterus sp. n. showing a geographically and bathymetrically wide distribution pattern on seamounts and on the deep-sea floor in the Arctic Ocean, Atlantic Ocean, and the Mediterranean Sea (Kinorhyncha, Cyclorhagida).

Kinorhynchs rarely show a wide distribution pattern, due to their putatively low dispersal capabilities and/or limited sampling efforts. In this study, a new kinorhynch species is described, Echinoderes pterussp. n., which shows a geographically and bathymetrically wide distribution, occurring on the Karasik Seamount and off the Svalbard Islands (Arctic Ocean), on the Sedlo Seamount (northeast Atlantic Ocean), and on the deep-sea floor off Crete and on the Anaximenes Seamount (Mediterranean Sea), at a depth range of 675-4,403 m. The new species is characterized by a combination of middorsal acicular spines on segments 4-8, laterodorsal tubes on segment 10, lateroventral tubes on segment 5, lateroventral acicular spines on segments 6-9, tufts of long hairs rising from slits in a laterodorsal position on segment 9, truncated tergal extensions on segment 11, and the absence of any type-2 gland cell outlet. The specimens belonging to the populations from the Arctic Ocean, the Sedlo Seamount, and the Mediterranean Sea show morphological variation in the thickness and length of the spines as well as in the presence/absence of ventromedial sensory spots on segment 7. The different populations are regarded as belonging to a single species because of their overlapping variable characters.

New species of Echinoderes (Kinorhyncha: Cyclorhagida) from Mediterranean seamounts and from the deep-sea floor in the Northeast Atlantic Ocean, including notes on two undescribed species.

Two new species of Echinoderes from the Eratosthenes Seamount and a deep-sea station near the Sedlo Seamount are described. Echinoderes multiporus sp. nov. from the Eratosthenes Seamount is characterized by a combination of the presence of middorsal acicular spines on segments 4, 6, and 8, ventrolateral tubes on segment 2, lateroventral tubes on segment 5, lateroventral acicular spines on segments 6-9, midlateral tubes on segment 10, and type-2 glandular cell outlets in subdorsal position on segment 2 and in laterodorsal position on segments 4-9. Echinoderes unispinosus sp. nov. from the deep-sea station differs from its congeners by the combination of middorsal acicular spine on segment 4, lateroventral acicular spines on segments 6 and 7, type-2 glandular cell outlets present in midlateral position on segment 1, in subdorsal, laterodorsal, sublateral, and ventrolateral position on segment 2, in lateral accessory position on segment 5, and in sublateral position on segment 8, and densely aligned pectinate fringe teeth of the primary pectinate fringes similar in width on segments 1-10. In addition, the morphological data of two undescribed species from the Anaximenes Seamount and a deep-sea station near the Sedlo Seamount are given. An undescribed species from the Anaximenes Seamount is morphologically similar to Echinoderes unispinosus sp. nov., but differs in the smaller trunk length, the presence of broader pectinate fringe teeth of the primary pectinate fringe on segment 1, and the absence of ventromedial sensory spots on segment 8. Another undescribed species from the deep-sea station differs from its congeners in the pattern of spines, tubes, and type-2 glandular cell outlets and length of middorsal and lateral terminal spines. New names are not given to both undescribed species in this study, because only one specimen is available for each species, and both of the specimens were damaged during the preparation.

Redescription of Cateria gerlachi (Kinorhyncha, Cyclorhagida) from Sri Lanka and of C. styx from Brazil, with notes on C. gerlachi from India and C. styx from Chile, and the ground pattern of the genus.

Cateria gerlachi is redescribed based on specimens from the west coast of Sri Lanka by light microscopical observations of 57 adult and 47 juvenile specimens and by SEM investigations of 33 adult and 10 juvenile specimens. Cateria styx from Brazil is redescribed from 33 adult and 5 juvenile specimens mounted for light microscopy (original material). The original material of C. gerlachi from India and new material of C. styx from Chile have been studied for comparison. Cateria gerlachi can be distinguished from C. styx by leaf-like cuticular hairs dorsally but not laterally on the tergal plate of segment 1 and on the midsternal plate of segments 1-2 vs scales with a posterior process on the entire tergal plate of segment 1 and on the midsternal plate of segments 1-2 in C. styx, fewer lines of leaf-like hairs of the secondary fringe on segments 2-10 in C. gerlachi, broader scales in the central part of the segments in C. gerlachi, the blunt tube on segment 5 in a lateral accessory vs a lateroventral position in C. styx, the lack of a midlateral spine on segment 11 vs its existence on segment 11 of C. styx, the lack of a protrusible dorsal organ at the border of segments 5 and 6 vs its existence in C. styx and type-5 sensory spots and gland cell outlets present on different segments and positions in the two species. We report and document for species of Cateria detailed morphological data, including variability within populations, a female and a male life-history stage, as well as moulting of an adult stage to another adult stage. In contrast to previous records, C. gerlachi occurs in sandy intertidal habitats not only deeply buried in the sediment but also at the surface.

New species of Centroderes (Kinorhyncha: Cyclorhagida) from the Northwest Atlantic Ocean, life cycle, and ground pattern of the genus.

Four new species of Centroderes are described from the Northwest Atlantic Ocean based on light microscopical observations of 153 adult and 26 juvenile specimens and on SEM investigations of 54 adult and 3 juvenile specimens. Centroderes barbanigra n. sp. and C. bonnyae n. sp. can be distinguished from all other species by the existence of a short lateroventral tube on segment 7. The latter species can be separated from the former by an acicular spine in the lateral accessory position on segment 8. The female of both C. readae n. sp. and C. spinosus possesses a female-specific, modified gland cell outlet on segments 7-9, but such an outlet is missing on segment 7 of all other species. The latter species is distinguished from the former by its robust lateroventral spine on segment 8 and by its lack of a laterodorsal sensory spot on segment 4, whereas the former species shows a midlateral sensory spot on segment 8. Centroderes drakei n. sp. agrees with the remaining American species in the possession of a laterodorsal sensory spot on segment 4; the former species can be distinguished from C. readae n. sp. by the lack of a sensory spot sublaterally on segment 1 and midlaterally on segment 8 as well as by the lack of a female-specific, modified gland cell outlet on segment 7; C. drakei n. sp. can be separated from C. barbanigra n. sp. and C. bonnyae n. sp. by its lack of a lateroventral tube on segment 7.        We report anomalies rarely noticed for Kinorhyncha, such as different developmental artifacts in several specimens and a potential tumour in one individual. Evidence is provided that species of Centroderes develop via at least two adult life history stages, but three or more adult stages exist in C. drakei n. sp.; this represents the first record of a more complicated life cycle in Kinorhyncha. This paper also contains the first report of spermatophores in cyclorhagid Kinorhyncha and in both female and male specimens. In addition, characters in the ground pattern of Centroderes are summarized.

Ultrastructure of the protonephridia of larval Rugiloricus cf. cauliculus, male Armorloricus elegans, and female Nanaloricus mysticus (Loricifera).

The protonephridial system of several Loricifera was studied by transmission electron microscopy. A larval specimen of Rugiloricus cf. cauliculus possesses two protonephridia, which are "capped" frontally by a compact mass of still undifferentiated gonadal cells. Each protonephridium consists of four monociliary terminal cells and four canal cells with a diplosome but no cilia. Because of incomplete series of sections and unsatisfactory fixation, the outleading cell(s) could not be detected. In a male specimen of Armorloricus elegans, each gonad contains two protonephridia that open into the gonadal lumen. Each protonephridium consists of two monociliary terminal cells, each forming a filter, two nonciliated canal cells, and two nephroporus cells. The protonephridial lumina of the latter cells fuse to one common lumen, which unites with the gonadal lumen. Preliminary observations on the protonephridia of a female Nanaloricus mysticus reveal a more complicated arrangement of interdigitating terminal and canal cells. One or two terminal cells form their own individual filter or four cells form a common compound filter. The cilium of the terminal cells of all species investigated are surrounded by a palisade of nine microvilli that support the filter barrier made of an extracellular matrix. An additional filter diaphragm could be traced between the pores in the cell wall of each terminal cell of A. elegans. The urogenital system of the Loricifera differs from that of the Priapulida in that the protonephridia of the former are completely integrated into the gonad, whereas the excretory organs of the latter open into the urogenital duct caudally of the gonads.

Head sensory organs of Dactylopodola baltica (Macrodasyida, Gastrotricha): a combination of transmission electron microscopical and immunocytochemical techniques.

The anterior and posterior head sensory organs of Dactylopodola baltica (Macrodasyida, Gastrotricha) were investigated by transmission electron microscopy (TEM). In addition, whole individuals were labeled with phalloidin to mark F-actin and with anti-alpha-tubulin antibodies to mark microtubuli and studied with confocal laser scanning microscopy. Immunocytochemistry reveals that the large number of ciliary processes in the anterior head sensory organ contain F-actin; no signal could be detected for alpha-tubulin. Labeling with anti-alpha-tubulin antibodies revealed that the anterior and posterior head sensory organs are innervated by a common stem of nerves from the lateral nerve cords just anterior of the dorsal brain commissure. TEM studies showed that the anterior head sensory organ is composed of one sheath cell and one sensory cell with a single branching cilium that possesses a basal inflated part and regularly arranged ciliary processes. Each ciliary process contains one central microtubule. The posterior head sensory organ consists of at least one pigmented sheath cell and several probably monociliary sensory cells. Each cilium branches into irregularly arranged ciliary processes. These characters are assumed to belong to the ground pattern of the Gastrotricha.

Ultrastructure, biology, and phylogenetic relationships of kinorhyncha.

The article summarizes current knowledge mainly about the (functional) morphology and ultrastructure, but also about the biology, development, and evolution of the Kinorhyncha. The Kinorhyncha are microscopic, bilaterally symmetrical, exclusively free-living, benthic, marine animals and ecologically part of the meiofauna. They occur throughout the world from the intertidal to the deep sea, generally in sediments but sometimes associated with plants or other animals. From adult stages 141 species are known, but 38 species have been described from juvenile stages. The trunk is arranged into 11 segments as evidenced by cuticular plates, sensory spots, setae or spines, nervous system, musculature, and subcuticular glands. The ultrastructure of several organ systems and the postembryonic development are known for very few species. Almost no data are available about the embryology and only a single gene has been sequenced for a single species. The phylogenetic relationships within Kinorhyncha are unresolved. Priapulida, Loricifera, and Kinorhyncha are grouped together as Scalidophora, but arguments are found for every possible sistergroup relationship within this taxon. The recently published Ecdysozoa hypothesis suggests a closer relationship of the Scalidophora, Nematoda, Nematomorpha, Tardigrada, Onychophora, and Arthropoda.