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Issue: Vol. 5325 No. 3: 9 Aug. 2023
Type: Article
Published: 2023-08-09
DOI: 10.11646/zootaxa.5325.3.2
Page range: 342-358
Abstract views: 174
PDF downloaded: 18

Clarification of the diagnosis of the genus Loxosoma s.l. (Entoprocta; Loxosomatidae) based on morphological and molecular data

Faculty of Biology; Moscow State University; Moscow 119991; Russia. Biological Faculty; Shenzhen MSU-BIT University; Shenzhen; 518172 China
Faculty of Biology; Moscow State University; Moscow 119991; Russia. Biological Faculty; Shenzhen MSU-BIT University; Shenzhen; 518172 China
Bryozoa Entoprocta Kamptozoa taxonomy morphology phylogeny 28S 18S new combination

Abstract

Loxosomatidae are solitary entoprocts associated with various types of invertebrate hosts. Two genera are distinguished in the family Loxosomatidae, Loxosomella and Loxosoma, that have clear morphological differences in the attachment structures. Loxosoma attaches to the substratum by a muscular sucking pedal disk, which allows moving. Both kidneys and adults are thought to have a pedal disc throughout their lives. In August 2021, several specimens of loxosomatids were found in the White Sea at a depth of 30–70 m on a polychaete Laonice sp. (Spionidae), which were investigated using light and electron microscopy as well as molecular phylogenetic analysis. These loxosomatids were identified as Loxosomella aripes Nielsen, although a stalk of large buds of the specimens from the White Sea terminate with a pedal disc typical of Loxosoma. Molecular phylogenetic analysis of two markers [28S rRNA (~380bp) and 18S rRNA (in three parts totaling ~1850bp)] confirms the affinity of the species to Loxosoma s.l. and does not confirm monophyly of the genera Loxosoma and Loxosomella, indicating that the entire system of loxosomatids requires revision. Here, we redescribe the species Loxosomella aripes as Loxosoma s.l. aripes. The diagnosis of the genus Loxosoma s.l. is supplemented with the observation that the structure of the attachment organ can change after anchoring to the substrate. A list of species currently assigned to Loxosomella that may in fact belong to the genus Loxosoma s.l. is also given.

 

References

  1. Altschul, S.F., Gish, W., Miller, W., Myers, E.W. & Lipman, D.J. (1990) Basic local alignment search tool. Journal of Molecular Biology, 215 (3), 403–410. https://doi.org/10.1016/S0022-2836(05)80360-2
  2. Bobin, G. & Prenant, M. (1953a) Les populations de Loxosomes du Phascolion strombi (Montagu). Archives de Zoologie Expérimentale et Générale, 90, 93–104.
  3. Bobin, G. & Prenant, M. (1953b) Sur les populations de Loxosomes des Aphrodites et des Hermiones. Bulletin de la Société zoologique de France, 78, 122–132.
  4. Bobin, G. & Prenant, M. (1953c) Sur trois Loxosomes méditerranéens. Bulletin de l'Institut Océanographique, 50 (1030), 1–9.
  5. Borisanova, A.O. (2018) Entoprocta (Kamptozoa). In: Schmidt-Rhaesa, A. (Ed.), Handbook of Zoology. Miscellaneous Invertebrates. De Gruyter, Berlin and Boston, pp. 111–162. https://doi.org/10.1515/9783110489279-006
  6. Borisanova, A.O. (2020) Two types of the tentacle structure of Entoprocta and the fine structure of the vestibular groove. Zoomorphology, 139 (4), 433–445. https://doi.org/10.1007/s00435-020-00497-y
  7. Borisanova, A.O. & Krylova, E.M. (2014) A new species of Loxosomatidae (Entoprocta, Solitaria) from the White Sea: Loxosomella unicornis sp. nov. Zootaxa, 3861 (3), 290–296. https://doi.org/10.11646/zootaxa.3861.3.6
  8. Borisanova, A.O. & Chernyshev, A.V. (2019) A new loxosomatid species from the Kuril-Kamchatka trench area: Loxosomella marcusorum sp. n., the first record of hadal Entoprocta. Progress in Oceanography, 178, 102146. https://doi.org/10.1016/j.pocean.2019.102146
  9. Borisanova. A.O., Chernyshev, A.V. & Ekimova, I.A. (2018) Deep-sea Entoprocta from the Sea of Okhotsk and the adjacent open Pacific abyssal area: new species and new taxa of host animals. Deep Sea Research Part II: Topical Studies in Oceanography, 154, 87–98. https://doi.org/10.1016/j.dsr2.2017.11.010
  10. Brien, P. (1959) Classe des Endoproctes ou Kamptozoaries. In: Grasse, P. (Ed.), Traité de Zoologie. Vol. 5. Masson et Cie, Paris, pp. 927–1007.
  11. Edgar, R.C. (2004) MUSCLE: multiple sequence alignment with high accuracy and high throughput. Nucleic Acids Research, 32 (5), 1792–1797. https://doi.org/10.1093/nar/gkh340
  12. Eggleston, D. (1965) The Loxosomatidae of the Isle of Man. Journal of Zoology, 145, 529–547.
  13. Emschermann, P. (1993) On Antarctic Entoprocta: nematocyst-like organs in a Loxosomatid, adaptive developmental strategies, host specificity and bipolar occurrence of species. Biological Bulletin, Woods Hole, 184, 153–185. https://doi.org/10.2307/1542225
  14. Franzén, Å. (1973) Some Antarctic Entoprocta with notes on morphology and taxonomy in the Entoprocta in general. Zoologica Scripta, 2, 183–195. https://doi.org/10.1111/j.1463-6409.1974.tb00751.x
  15. Fuchs, J., Iseto, T., Hirose, M., Sundberg, P. & Obst, M. (2010) The first internal molecular phylogeny of the animal phylum Entoprocta (Kamptozoa). Molecular phylogenetics and evolution, 56 (1), 370–379. https://doi.org/10.1016/j.ympev.2010.04.009
  16. Iseto, T. & Hirose, E. (2010) Comparative Morphology of the Foot Structure of Four Genera of Loxosomatidae (Entoprocta): Implications for Foot Functions and Taxonomy. Journal of Morphology, 271, 1185–1196.
  17. Ivanova, N.V., de Waard, J. & Hebert, P.D.N. (2006) An inexpensive, automation-friendly proto-col for recovering high-quality DNA. Molecular Ecology Notes, 6, 998–1002. https://doi.org/10.1111/j.1471-8286.2006.01428.x
  18. Kajihara, H., Tomioka, S., Kakui, K. & Iseto, T. (2015) Phylogenetic position of the queer, backward-bent entoproct Loxosoma axisadversum (Entoprocta: Solitaria: Loxosomatidae). Species Diversity, 20 (1), 83–88. https://doi.org/10.12782/sd.20.1.083
  19. Keferstein, W. (1862) Ueber Loxosoma singulare gen. et sp. nov., den Schmarotzer einer Annelide. Zeitschrift für Wissenschaftliche Zoologie, 12, 131–132.
  20. Konno, K. (1972) Studies on Japanese Entoprocta. I. On four new species of loxosomatides found at Fukuara, Aomori Prefecture. Science Reports of the Hirosaki University, 19, 64–78.
  21. Konno, K. (1977) Studies on Japanese Entoprocta. VII. On two new species of Loxosomatidae. Science Reports of the Hirosaki University, 1977 (24), 81–84.
  22. Marcus, E. & Marcus, E. (1968) Neue brasilianische Loxosomen. Zoologische Beiträge, 14, 203–212.
  23. Mortensen, T. (1911) A new species of Entoprocta, Loxosomella antedonis, from Northeast Greenland. Meddelelser om Grønland, 45, 399–406.
  24. Nielsen, C. (1964a) Studies on Danish Entoprocta. Ophelia, 1, 1–76. https://doi.org/10.1080/00785326.1964.10416272
  25. Nielsen, C. (1964b) Entoprocta from the Bergen area. Sarsia, 17 (1), 1–6. https://doi.org/10.1080/00364827.1964.10409535
  26. Nielsen, C. (1966) Some Loxosomatidae (Entoprocta) from the Atlantic coast of the United States. Ophelia, 3, 249–275. https://doi.org/10.1080/00785326.1966.10409645
  27. Nielsen, C. (1996) Three new species of Loxosoma (Entoprocta) from Phuket, Thailand, with a review of the genus. Zoologica Scripta, 25, 61–75. https://doi.org/10.1111/j.1463-6409.1996.tb00152.x
  28. Nielsen, C. (2010) A review of the taxa of solitary entoprocts (Loxosomatidae). Zootaxa, 2395, 45–56. https://doi.org/10.11646/zootaxa.2395.1.4
  29. Nielsen, C. & Jespersen, Å. (1997) Entoprocta. In: Harrison, F.W. & Ruppert, E.E. (Eds.), Microscopic anatomy of invertebrates. Vol. 13. Wiley-Liss, New York, pp. 13–43.
  30. Nielsen, C. & Ryland, J.S. (1961) Three new species of Entoprocta from West Norway. Sarsia, 1, 39–45. https://doi.org/10.1080/00364827.1961.10410243
  31. Osburn, R.C. (1912) The Bryozoa of the Woods Hole region. Issue 760 of Bureau of Fisheries document. US Government Printing Office, Washington, pp. 205–266. https://doi.org/10.5962/bhl.title.1325
  32. Osterburg, H.H., Allen, J.K. & Finch, C.E. (1975) The use of ammonium acetate in the precipitation of ribonucleic acid. Biochemical Journal, 147 (2), 367. https://doi.org/10.1042/bj1470367
  33. Riisgard, H.U., Nielsen, C. & Larsen, P.S. (2000) Downstream collecting in ciliary suspension feeders: the catch-up principle. Marine Ecology Progress Series, 207, 33–51. [https://www.jstor.org/stable/24863777]
  34. Stamatakis, A. (2014) RaxML version 8: a tool for phylogenetic analysis and post-analysis of large phylogenies. Bioinformatics, 30 (9), 1312–1313. https://doi.org/10.1093/bioinformatics/btu033
  35. v. Salvini-Plawen, L. (1968) Neue Formen im marinen mesopsammon: Kamptozoa und Aculifera. Annalen des Naturhistorischen Museums in Wien, 1968, 231–272.
  36. Williams, J.B. (2000) Description of two loxosomatids (Entoprocta), with emphasis on a relationship between symbiont attachment structures and host cuticle. Canadian Journal of Zoology, 78 (1), 110–120. https://doi.org/10.1139/z99-193