Microstomum laurae Atherton & Jondelius 2018, sp. nov

Autor: Atherton, Sarah, Jondelius, Ulf
Rok vydání: 2018
Předmět:
DOI: 10.5281/zenodo.5991921
Popis: Microstomum laurae sp. nov. urn:lsid:zoobank.org:act:49378 EBE- 7046-49D3- BC 3 C-DD 783580A90E Fig. 1 Diagnosis Strap-shaped Microstomum with body length of 760 ��m (two vegetative zooids) and rounded anterior and posterior ends. Posterior rim with approximately twenty adhesive papillae. Paired red eyespots 43 ��m long and located in the lateral margins at level of the brain. Rhabdites concentrated in the anterior end above the pharynx. Nematocysts present. Preoral gut extending anterior to brain. Reproductive system unknown. GenBank accession number for partial COI sequence MF 185712 -3. Etymology This species is dedicated to Laura R. Atherton, mother of the first author. Material examined Holotype SWEDEN: vegetative specimen, Str��mstad, Salt��, 58��52���29��� N, 11��08���41��� E, 10 cm, 17 Jun. 2016, marine, eulittoral sand, S. Atherton leg. (SMNH-Type-8903, Genbank accession MF 185712). Additional material SWEDEN: vegetative specimen, Str��mstad, Salt��, 58��52���41��� N, 11��06���56��� E, 10 cm, 19 Jun. 2016, marine, eulittoral sand, S. Atherton leg. (SMNH-Type-8904, Genbank accession MF 185713). Description Microstomum with a total body length of 760 ��m and two vegetative zooids. Body strap-shaped with very slight constrictions between zooids and at the level of the ciliary pits. Ratio of body width:length 1: 5 in slightly compressed animal. Anterior and posterior ends rounded. Ciliary pits very small and shallow (Fig. 1 A), below eyespots, 185 ��m from anterior. Paired red eyespots approximately 43 ��m long and present in the lateral margins of the body level with brain (Fig. 1 A ��� B). Many small (max. diameter 10 ��m) orange lipid droplets derived from food scattered across body, heavily concentrated around pharynx and anterior end (Fig. 1 A ��� B). Body otherwise colorless or reflective of intestine. Epidermis uniformly covered with cilia. Nematocysts present. Rhabdite bundles, 20���30 ��m long, scattered about the body, particularly concentrated in the anterior end above the pharynx (Fig. 1 B). Approximately twenty adhesive papillae, 8���10 ��m long, on the rim of the posterior end (Fig. 1 C). Mouth slit-like and 55 ��m long. Pharynx encompassing the second fifth of the body. Preoral gut extending well anterior to brain. Intestine evenly filled with orange droplets. Reproductive system unknown. Remarks Eight of the currently recognized Microstomum species (M. bioculatum Faubel, 1984, M. gabriellae Marcus, 1950, M. giganteum Hallez, 1878, M. groenlandicum Levinsen, 1879, M. lineare ��rsted, 1843, M. melanophthalmum Steinbock, 1933, M. par��dii Graff, 1913 and M. spiriferum Westblad, 1953) possess pigmented eyespots. The eyespots of M. melanophthalmum and M. par��dii are black with distinct lenses, while the eyespots of M. laurae sp. nov. are red. The eyespots in M. bioculatum, M. gabriellae, M. giganteum, M. lineare and M. melanophthalmum are situated far in the front of the animal, whereas they are level with the brain in M. laurae sp. nov. Finally, the eyespot of M. groenlandicum is unpaired, red and located medially above the brain. Microstomum laurae sp. nov. is most similar to M. spiriferum, being alike in general body size and shape as well as their small ciliary pits and large bundles of rhabdites. However, M. spiriferum can be differentiated based on the dorsal richly yellowish pigment cells and absence of adhesive papillae (Westblad 1953). M. laurae sp. nov., on the other hand, is colorless or sometimes colored by its gut contents; there are no pigment cells apart from the eyespots, and it possesses a distinct line of adhesive tubes along the posterior rim. Though both species are found on the Swedish west coast, M. spiriferum was described from sublittoral habitats between 15 and 60 m depth, while M. laurae sp. nov. was collected from eulittoral sand at around 10 cm depth.
Published as part of Atherton, Sarah & Jondelius, Ulf, 2018, Microstomum (Platyhelminthes, Macrostomorpha, Microstomidae) from the Swedish west coast: two new species and a population description, pp. 1-18 in European Journal of Taxonomy 398 on pages 4-6, DOI: 10.5852/ejt.2018.398, http://zenodo.org/record/1160484
{"references":["Marcus E. 1950. Turbellaria Brasileiros. Boletins da Facultade de Filosofia Ciencias e Letras Zoologia 17: 5 - 191.","Von Graff L. 1913. Turbellaria II. Rhabdocoelida. Das Tierreich, eine Zusammenstellung und Kennzeichnung der rezenten Tierformen 35, Verlag Friedlander und Sohn, Berlin.","Westblad E. 1953. Marine Macrostomida (Turbellaria) from Scandinavia and England. Arkiv for Zoologi 4: 391 - 408."]}
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