New and rare species of microturbellarians of the genus Opisthocystis Sekera, 1911 (Plathelminthes, Kalyptorhynchia, Polycystididae) from lake Baikal

Cover Page

Cite item

Full Text

Open Access Open Access
Restricted Access Access granted
Restricted Access Subscription Access

Abstract

Descriptions of four new species of the genus Opisthocystis Sekera, 1911 are given: Opisthocystis zaytsevae Krivorotkin et Timoshkin sp. n., Opisthocystis strictostylus Krivorotkin et Timoshkin sp. n., Opisthocystis sekeri Krivorotkin et Timoshkin sp. n. and Opisthocystis tenuistylus Krivorotkin et Timoshkin sp. n., all of them endemic to Lake Baikal. The former three species were found in the coastal zone of the lake: O. zaytsevae: in the shallow waters of Bolshoy Ushkany Island; O. strictostylus: in the shallow waters of Ayaya Bay (northern basin) and opposite the village of Khuzhir (Olkhon Island, Maloye More Strait); O. sekeri: in the shallow waters of Onokochanskaya Bay (northern basin); O. tenuistylus was found on the underwater Akademichesky Ridge at a depth of about 350 m. Illustrated descriptions, differential diagnoses, brief information on their distribution and ecology are provided for all new species. New extensive information on the morphology and zoogeography of three rare and poorly studied endemic Baikal species of the same genus is provided: Opisthocystis multifidus (Nasonov, 1935), Opisthocystis octopropagostylus Lukhnev et Timoshkin, 2014, and Opisthocystis cf. umylinae Timoshkin, 2010. Brief illustrated descriptions and generalized information on their distribution are provided for all species. Revision of the taxonomic status of five Baikal species is proposed: Opisthocystis bilobatus Nasonov, 1935, Opisthocystis bicurvatus Nasonov, 1935 Opisthocystis campanulatus Nasonov, 1935, Opisthocystis irregularis Nasonov, 1935 and Opisthocystis trifida Nasonov, 1935. These species were described very briefly, and the drawings were very schematic. Based on the poor descriptions and schematic drawings, their reliable identification is impossible. In this regard, we are compelled to assign the status of nomen nudum to the above species of N. V. Nasonov.

Full Text

Restricted Access

About the authors

R. S. Krivorotkin

Limnological Institute, Russian Academy of Sciences

Author for correspondence.
Email: roman_bio@mail.ru
Russian Federation, st. Ulaanbaatar, 3, Irkutsk, 664033

O. A. Timoshkin

Limnological Institute, Russian Academy of Sciences

Email: roman_bio@mail.ru
Russian Federation, st. Ulaanbaatar, 3, Irkutsk, 664033

References

  1. Евдонин Л. А., 1977. Хоботковые ресничные черви Kalyptorhynchia фауны СССР и сопредельных стран. Фауна СССР. Турбеллярии. Т. 1. № 1. Л.: Наука. 400 с.
  2. Зайцева Е. П., Кривороткин Р. С., Тимошкин О. А., 2022. Новые виды микроскопических псаммофильных турбеллярий родов Coulterella, Cohenella и Linella (Plathelminthes, Kalyptorhynchia, Rhynchokarlingiidae) из озера Байкал // Зоологический журнал. Т. 101. № 12. С. 1323–1336.
  3. Зайцева Е. П., Тимошкин О. А., Гуцол М. В., Лухнев А. Г., 2012. Новые, редкие и малоизученные виды родов Opisthocystis и Gyratrix (Plathelminthes, Turbellaria, Kalyptorhychia) из озера Байкал // Зоологический журнал. T. 91. № 6. С. 648–656.
  4. Кривороткин Р. С., Зайцева Е. П., Тимошкин О. А., 2023. Первые сведения о фауне микротурбеллярий (Plathelminthes, Rhabditophora) Богучанского водохранилища р. Ангара. 1. Хоботковые ресничные черви (Kalyptorhynchia) байкальского происхождения с описанием трех новых видов семейства Rhynchokarlingiidae // Зоологический журнал. Т. 102. № 9. С. 980–999.
  5. Международный кодекс зоологической номенклатуры: Принят Междунар. союзом биол. наук: Вступает в силу с 1 янв. 2000 г.: Рус. пер. авторизован Междунар. комис. по зоол. номенклатуре / [пер. И. М. Кержнера]; Рос. акад. наук, Зоол. ин-т, Рос. ком. по зоол. номенклатуре, Междунар. комис. по зоол. номенклатуре. Изд. четвертое, второе, испр. изд. рус. пер. Москва: Товарищество научных изданий. КМК. 223 с.
  6. Сибирякова О. А., 1929. К фауне Turbellaria Rhabdo-coelida реки Ангары // Русский Гидробиологический журнал. Т. 8. № 8–9. С. 237–350.
  7. Тимошкин О. А., Зайцева Е. П., Гуцол М. В., 2009. Новые виды микроскопических псаммофильных турбеллярий рода Opisthocystis (Plathelminthes, Turbellaria, Kalyptorhynchia) из озера Байкал // Зоологический журнал. Т. 88. № 4. С. 398–413.
  8. Тимошкин О. А., Зайцева Е. П., Гуцол М. В., Тереза Е. П., 2010–2011. Новые и малоизученные виды рода Opisthocystis Sekera, 1911 (Plathelminthes, Turbellaria, Kalyptorhynchia: Polycystididae) из озера Байкал с предварительными данными об их кариотипах и “Оn Set Logger” сведениями о придонной температуре воды мелководной зоны Южного Байкала // Аннотированный список фауны озера Байкал и его водосборного бассейна. Новосибирск: Наука, Сибирское отделение. Т. II. Водоемы и водотоки Восточной Сибири и Северной Монголии. Кн. 2. С. 1105–1164.
  9. Тимошкин О. А., Попова О. В., Лухнев А. Г., Зайцева Е. П., 2014. Фауна и особенности распределения микротурбеллярий заплесковой зоны озера Байкал с описанием новых видов рода Opisthocystis (Plathelminthes, Turbellaria, Kalyptorhynchia) // Зоологический журнал Т. 93. № 3. С. 412–425.
  10. Karling T. G., 1956. Morphologisch-histologische Untersuchungen an den männlichen Atrialorganen der Kalyptorhynchia (Turbellaria) // Arkiv för Zoologi. V. 9. P. 187–277.
  11. Karling T. G., 1963. Die Turbellarien ostfennoskandiens. V. Neorhabdocoela. 3. Kalyptorhynchia // Fauna Fenica. V. 17. P. 5–59.
  12. Nasonov N. V., 1935. Ueber den Heliotropismus der Turbellaria rhabdocoelida des Baikalsees // Труды лаборатории экспериментальной зоологии и морфологии животных АН СССР. Т. 4. С. 195– 204.
  13. Tyler S., Schilling S., Hooge M., Bush L. F., (comp.) 2006– 2024. Turbellarian taxonomic database. Version 2.2: http://turbellaria.umaine.edu/. Дата обновления: 19.11.2024.

Supplementary files

Supplementary Files
Action
1. JATS XML
Download
2. Fig. 1. Scheme of measurement and structure of stylet sections of opisthocystis using the example of stylet of Opisthocystis zaytsevae Krivorotkin et Timoshkin sp. n.: A – stylet; B – funnel-shaped section of stylet, top view; C – proximal part of stylet.

Download (1MB)
Indexing metadata
3. Fig. 2. Schemes of the arrangement of some internal organs in the holotypes of new species: A – Opisthocystis zaytsevae Krivorotkin et Timoshkin sp. n., B – Opisthocystis strictostylus Krivorotkin et Timoshkin sp. n. Scale 400 µm.

Download (1MB)
Indexing metadata
4. Fig 3. Opisthocystis zaytsevae Krivorotkin et Timoshkin sp. n., stylets: A – holotype, B – paratype No. 1, C – paratype No. 2, D – paratype No. 4, E – paratype No. 6, F – paratype No. 10, G – paratype No. 12, H – paratype No. 15, I – paratype No. 18. Scale 100 µm.

Download (1MB)
Indexing metadata
5. Fig. 4. Opisthocystis zaytsevae Krivorotkin et Timoshkin sp. n., stylets: A – holotype, B – paratype No. 4, C – paratype No. 5, D – paratype No. 6, E – paratype No. 11. Scale 100 µm.

Download (6MB)
Indexing metadata
6. Fig. 5. Opisthocystis zaytsevae Krivorotkin et Timoshkin sp. n., distal tips of stylets: A – holotype, B – paratype #2, C – paratype #3, D – paratype #4, E – paratype #5, F – paratype #6, G – paratype #13, H – paratype #15, I – paratype #20. Scale bar 25 µm.

Download (13MB)
Indexing metadata
7. Fig. 6. Opisthocystis strictostylus Krivorotkin et Timoshkin sp. n., stylets: A – holotype, B – paratype No. 7, C – paratype No. 8, D – paratype No. 1, E – paratype No. 2, F – paratype No. 9, G – paratype No. 10, H – paratype No. 11. Scale 100 µm.

Download (2MB)
Indexing metadata
8. Fig 7. Opisthocystis strictostylus Krivorotkin et Timoshkin sp. n., deformed stilettos: a – paratype No. 14, b – paratype No. 3, c – paratype No. 6, D – paratype No. 12, E – paratype No. 4, F – paratype No. 5, G – paratype No. 13. Scale 100 microns.

Download (2MB)
Indexing metadata
9. Fig 8. Opisthocystis strictostylus Krivorotkin et Timoshkin sp. n., stilettos: A – holotype, B – paratype No. 1, c – paratype No. 2, D – paratype No. 7, E – paratype No. 8, f – paratype No. 9. Scale 100 microns.

Download (6MB)
Indexing metadata
10. Fig 9. Opisthocystis sekeri Krivorotkin et Timoshkin sp. n., holotype: A – arrangement of organs; B, C – stylet; D–F – distal tip of the stylet. Scale, microns: A – 400; B – 65; C – 100; D–F – 10.

Download (3MB)
Indexing metadata
11. Fig 10. Opisthocystis tenuistylus Krivorotkin et Timoshkin sp. n., organ layout (A), stilettos (B–E) and their distal ends (F, G): A, B, D, F is the holotype; C, E, G is the paratype. Scale, microns: A – 400; B, C – 200; D, E – 100; F, G – 10.

Download (3MB)
Indexing metadata
12. Fig 11. Opisthocystis multifidus (Nasonov, 1935), organ layout (A), stilettos (B–F) and their distal ends (G, H): A – specimen No. 13; B – specimen No. 1; C – specimen No. 2; D – specimen No. 3; E, H – individual No. 7; F, G – individual No. 8. Scale, microns: A – 400; B–F – 100; G, H – 20.

Download (2MB)
Indexing metadata
13. Fig 12. Opisthocystis multifidus (Nasonov, 1935), stilettos: A – specimen No. 4, B – specimen No. 5, C – specimen No. 6, D – specimen No. 9, E – specimen No. 10, F – specimen No. 11, G – specimen No. 12. The scale is 100 microns.

Download (2MB)
Indexing metadata
14. Fig 13. Opisthocystis multifidus (Nasonov, 1935), stilettos: A – specimen No. 1, B – specimen No. 3, C – specimen No. 4, D – specimen No. 9. Scale 50 microns.

Download (6MB)
Indexing metadata
15. Fig 14. Opisthocystis multifidus (Nasonov, 1935), distal section of stilettos (A–C, E–H) and microstructural features of the cocoon surface (D): A – specimen No. 3, B, C – specimen No. 5, D – specimen No. 13, E, F – specimen No. 9, G, H – individual No. 7; on A, B, E–H, the arrows show the processes, on C– the arrow shows the outlet located at the base of the processes. The scale is 20 microns.

Download (5MB)
Indexing metadata
16. Fig 15. Opisthocystis octopropagostylus Lukhnev et Timoshkin, 2014, stilettos (A–I) and their distal ends (J, K): A – specimen No. 1, B – specimen No. 2, C – specimen No. 3, D – specimen No. 4, E – specimen No. 5, F – individual No. 6, G – individual No. 8, H – individual No. 9, I – individual No. 11, J – individual No. 7, K – individual No. 10. The scale is 100 microns.

Download (3MB)
Indexing metadata
17. Fig 16. Opisthocystis cf. umylinae Timoshkin, 2010, stilettos (A–J) and their distal ends (K–O): A, K – specimen No. 1; B, L – specimen No. 2; C, M – specimen No. 3; D – specimen No. 4; E, N – individual No. 5; F – individual No. 6; G – individual No. 7; H, O – individual No. 8; I – individual No. 9; J – individual No. 10. Scale, microns: A–J – 100; K–O – 20.

Download (2MB)
Indexing metadata
18. Fig 17. Opisthocystis cf. umylinae Timoshkin, 2010, stilettos (A–C, E, F) and granular vesicle (D): A – specimen No. 1; B – specimen No. 2; C, D – specimen No. 5; E – specimen No. 8; F – specimen No. 10. The scale is 50 microns.

Download (11MB)
Indexing metadata
19. Fig 18. Opisthocystis cf. umylinae Timoshkin, 2010, distal end of stilettos (A–F) and cocoon surface structure (G, H): A – specimen No. 1; B – specimen No. 2; C – specimen No. 5; D, E – specimen No. 8; F – specimen No. 10; G, H – individual No. 6. Scale 20 microns.

Download (10MB)
Indexing metadata
20. Fig 19. Distal ends of the stilettos of Opisthocystis bilobatus nasonov, 1935 (a), Opisthocystis multifidus (Nasonov, 1935) (B), Opisthocystis irregularis nasonov, 1935 (c), Opisthocystis campanulatus nasonov, 1935 (D), according to: nasonov, 1935. There is no scale in the original.

Download (521KB)
Indexing metadata

Copyright (c) 2025 Russian Academy of Sciences