Phylum Kinorhyncha

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A new species of <i>Cephalorhyncha</i> Adrianov, 1999 (Kinorhyncha: Cyclorhagida) from the Aegean Coast of Turkey

Kinorhynchs are marine, microscopic ecdysozoan animals that are found throughout the world's ocean. Cephalorhyncha flosculosa sp. nov. is described from the Aegean Coast of Turkey. Samples were collected from intertidal zones at two localities. The new species is distinguished from its congeners by having flosculi in midventral positions on segment 3-8, and by differences in its general spine and sensory spot positions. Until now, species of Cephalorhyncha were only known from the Pacific Ocean, hence, this record of the genus at the Aegean Sea not only expands its geographic distribution to Turkey, but is likely to expand it throughout the Mediterranean Sea and much of southern Europe. The new species of Cephalorhyncha represents the fifth kinorhynch species recorded from Turkey, and increases also the number of known Cephalorhyncha species to four

New mud dragons from Svalbard: three new species of Cristaphyes and the first Arctic species of Pycnophyes (Kinorhyncha: Allomalorhagida: Pycnophyidae)

Background Kinorhynchs are marine, microscopic invertebrates inhabiting the seafloors. Their segmented trunk equipped with spines and processes has inspired scientists to give them the common name “mud dragons.” Even though kinorhynchs have been known since the 19th century, less than 300 species are known to science, and it is still considered a largely understudied animal group—in particular in the Arctic, from which only 23 species are known so far. Methods Samples were collected at eight stations around Svalbard and in the fjords of Spitsbergen. Meiofauna was extracted from the sediment cores with LUDOX centrifugation method, and kinorhynchs were picked up and mounted for light- and scanning electron microscopy. Results Four new species of the kinorhynch family Pycnophyidae are described from Svalbard: Cristaphyes dordaidelosensis sp. nov., C. glaurung sp. nov., C. scatha sp. nov., and Pycnophyes ancalagon sp. nov. The new species are generally recognized by their distribution of setae along the trunk segments. Discussion After the discovery of the new species, Pycnophyidae becomes with 14 species the most diverse kinorhynch genus in the Arctic, closely followed by Echinoderidae with 13 species. So far, these are the only kinorhynch families with an Arctic distribution

Cuatro nuevas especies de Pycnophyes (Kinorhyncha: Homalorhagida) de Corea y el mar del este de China

Four new species of Pycnophyes are described from Korean waters and the East China Sea. Pycnophyes pardosi n. sp. is distinguished from other congeners by the presence of a single paradorsal seta on segments 2-8 and a pair on segment 9, combined with the presence of longitudinal cuticular thickenings on the dorsal and ventral sides of segment 10. Pycnophyes chalgap n. sp. is easily distinguished by the shape of its midsternal plate with the rounded posterior margin, extending beyond and overlapping half of the following segment. Pycnophyes cristatus n. sp. is recognized by its lack of ventromedial setae on segments 3-6 combined with the presence of pointed middorsal processes that turn progressively longer towards the posterior segments from segment 6. The process on segment 10 is conspicuously long, extending beyond the posterior margin of segment 11. Pycnophyes smaug n. sp. is distinguished by its general scarcity of setae which, with the exception of those in lateroventral positions, only appear in laterodorsal positions on segments 2 and 9 and in ventromedial position on segment 9. The description of four additional species brings the total number of valid kinorhynch species around the Korean Peninsula up to 26.Se describen cuatro nuevas especies de aguas coreanas y del este del mar de China. Pycnophyes pardosi n. sp. se distingue de las demás especies por la presencia de una única seda paradorsal en los segmentos 2-8 y un par en el segmento 9, combinado con la presencia de engrosamientos cuticulares longitudinales en el lado dorsal y ventral del segmento 10. Pycnophyes chalgap n. sp. es fácilmente distinguible por la forma de su placa medioesternal con el margen posterior redondeado, sobrepasando y solapando la mitad anterior del siguiente segmento. Pycnophyes cristatus n. sp. es reconocible por la ausencia de sedas ventromediales en los segmentos 3-6 combinado con la presencia de salientes mediodorsales puntiagudos que a partir del segmento 6 se vuelven progresivamente más largos hacia los segmentos posteriores. El saliente del segmento 10 es llamativamente largo, extendiéndose más allá del margen posterior del segmento 11. Pycnophyes smaug n. sp. se distingue por su carencia general de sedas que, aparte de las lateroventrales, solo aparecen en posición laterodorsal en los segmentos 2 y 9, y en posición ventromedial en el segmento 9. La descripción de las cuatro especies aumenta hasta 26 el número total de especies válidas de kinorrincos entorno a la península coreana

Detailed reconstruction of the musculature in <i>Limnognathia maerski</i> (Micrognathozoa) and comparison with other Gnathifera

Introduction: Limnognathia maerski is the single species of the recently described taxon, Micrognathozoa. The most conspicuous character of this animal is the complex set of jaws, which resembles an even more intricate version of the trophi of Rotifera and the jaws of Gnathostomulida. Whereas the jaws of Limnognathia maerski previously have been subject to close examinations, the related musculature and other organ systems are far less studied. Here we provide a detailed study of the body and jaw musculature of Limnognathia maerski, employing confocal laser scanning microscopy of phalloidin stained musculature as well as transmission electron microscopy (TEM). Results: This study reveals a complex body wall musculature, comprising six pairs of main longitudinal muscles and 13 pairs of trunk dorso-ventral muscles. Most longitudinal muscles span the length of the body and some fibers even branch off and continue anteriorly into the head and posteriorly into the abdomen, forming a complex musculature. The musculature of the jaw apparatus shows several pairs of striated muscles largely related to the fibularium and the main jaws. The jaw articulation and function of major and minor muscle pairs are discussed. No circular muscles or intestinal musculature have been found, but some newly discovered muscles may supply the anal opening. Conclusions: The organization in Limnognathia maerski of the longitudinal and dorso-ventral muscle bundles in a loose grid is more similar to the organization found in rotifers rather than gnathostomulids. Although the dorso-ventral musculature is probably not homologous to the circular muscles of rotifers, a similar function in body extension is suggested. Additionally, a functional comparison between the jaw musculature of Limnognathia maerski, Rotifera and Gnathostomulida, emphasizes the important role of the fibularium in Limnognathia maerski, and suggests a closer functional resemblance to the jaw organization in Rotifera.publishedVersionPeer Reviewe

A complete three-dimensional reconstruction of the myoanatomy of Loricifera:comparative morphology of an adult and a Higgins larva stage

INTRODUCTION: Loricifera is a group of small, marine animals, with undetermined phylogenetic relationships within Ecdysozoa (molting protostome animals). Despite their well-known external morphology, data on the internal anatomy of loriciferans are still incomplete. Aiming to increase the knowledge of this enigmatic phylum, we reconstruct for the first time the three-dimensional myoanatomy of loriciferans. Adult Nanaloricus sp. and the Higgins larva of Armorloricus elegans were investigated with cytochemical labeling techniques and CLSM. We discuss our findings with reference to other loriciferan species and recently established phylogenies. RESULTS: The somatic musculature of both adult and larval stages is very complex and includes several muscles arranged in three orientations: circular, transverse and longitudinal. In adult Nanaloricus sp., the introvert is characterized by a net-like muscular arrangement, which is composed of five thin circular fibers crossed by several (up to 30) thin longitudinal fibers with bifurcated anterior ends. Two sets of muscles surround the pre-pharyngeal armature: 6 buccal tube retractors arranged 3 × 2 in a conical shaped structure, and 8 mouth cone retractors. Additionally, a thick, circular muscle marks the neck region and a putative anal sphincter is the posteriormost myoanatomical feature. In the Higgins larva of A. elegans, two circular muscles are distinguished anteriorly in the introvert: a dorsal semicircular fiber and a thin ring muscle. The posteriormost region of the body is characterized by an anal sphincter and a triangular muscle. CONCLUSIONS: Based on the currently available knowledge, the myoanatomical bodyplan of adult loriciferans includes: (i) 8 mouth cone retractors, (ii) a pharynx bulb composed of transversal fibers arranged radially, (iii) circular muscles of the head and neck, (iv) internal muscles of the spinoscalids, (v) longitudinal muscles spanning all body regions, and (vi) transverse (circular) muscles in the abdomen. Concerning the Higgins larva, the muscle subsets assigned to its myoanatomical ground pattern are the (i) longitudinal retractors of the mouth cone, introvert, and abdomen, (ii) abdominal transverse muscles, and (iii) a pharynx bulb composed of transverse, radial fibers. In a comparison with phyla traditionally regarded as phylogenetically close, our data show that the overall myoanatomy of Loricifera is more similar to Kinorhyncha and Nematomorpha than to Priapulida. However, the head musculature of all these groups is very similar, which supports homology of their introverts and head morphology