Have a personal or library account? Click to login
Successful establishment of the Asian cyclopoid copepod Thermocyclops taihokuensis in Ukrainian waters Cover

Successful establishment of the Asian cyclopoid copepod Thermocyclops taihokuensis in Ukrainian waters

Oceanological and Hydrobiological Studies
AHEAD OF PRINT
By: Maria Hołyńska,  Leonid Svetlichny,  Łukasz Sługocki and  Larysa Samchyshyna  
Open Access
|Feb 2026

Figures & Tables

Figure 1

Map showing the presumed native range (dashed line) and published occurrence records (white circles with years – see Introduction) assumed to be outside the range of T. taihokuensis. Dates of the species discovery were taken from Monchenko (2008); Dela Paz et al. (2016a, 2016b); Zhikharev et al. (2020); Lazareva (2022); Lazareva et al. (2022); Maiphae et al. (2023); Lazareva and Sabitova (2024); Sługocki and Hołyńska (2024). The new Ukrainian records from Kyiv and its surroundings are shown in the satellite insets. Sampling sites: (A) Pond of the Bucha River, (B) Sovki pond of the Sovki River, (C) pond of the Syrets River, (D) pond of the Borshchahivka River. Blue lines indicate the local river network.
Map showing the presumed native range (dashed line) and published occurrence records (white circles with years – see Introduction) assumed to be outside the range of T. taihokuensis. Dates of the species discovery were taken from Monchenko (2008); Dela Paz et al. (2016a, 2016b); Zhikharev et al. (2020); Lazareva (2022); Lazareva et al. (2022); Maiphae et al. (2023); Lazareva and Sabitova (2024); Sługocki and Hołyńska (2024). The new Ukrainian records from Kyiv and its surroundings are shown in the satellite insets. Sampling sites: (A) Pond of the Bucha River, (B) Sovki pond of the Sovki River, (C) pond of the Syrets River, (D) pond of the Borshchahivka River. Blue lines indicate the local river network.

Figure 2

Habitus of T. taihokuensis (Harada, 1931) collected in a pond of the Bucha River on 15 August 2020 (A) and on 21 June 2025 (B), and T. oithonoides collected in the Dnieper River on 21 June 2025 (C).
Habitus of T. taihokuensis (Harada, 1931) collected in a pond of the Bucha River on 15 August 2020 (A) and on 21 June 2025 (B), and T. oithonoides collected in the Dnieper River on 21 June 2025 (C).

Figure 3

Diagnostic characters of T. taihokuensis (Harada, 1931), female (Nyvky pond, Kyiv, Ukraine). (A) Pediger 5, genital double-somite and urosomites 3 and 4 (ventral view)—arrow shows posteriorly curved lateral arm of the seminal receptacle. (B) Anal somite and caudal rami with caudal setae coded by Roman numerals in the text (ventral view), setulation of the caudal setae is shown only on one side of the rami—arrow shows the spinules along the posterior margin of the anal somite. (C,D). Antenna: (C) coxobasipodite (posterior view); (D) coxobasipodite and first endopodite (anterior view). (E) Leg 3 intercoxal sclerite (posterior view)—arrow shows hairs. (F,G). Leg 4: (F) protopodite, first exopodite and first endopodite (posterior view)—arrows show the morphological features (intercoxal sclerite with short hairs; coxopodite seta with plumose setulation; medial expansion of the basipodite with a row of spinules and with acute tip distally) distinguishing the species from T. oithonoides; (G) third endopodite, homonomous setulation of setae is shown only on proximal section of the lateral seta. Scale bars show 50 μm. A–B show ♀-1[MIZ CRU 001316], C–D show ♀-4 [MIZ CRU 001319], and E–G show ♀-2 [MIZ CRU 001317].
Diagnostic characters of T. taihokuensis (Harada, 1931), female (Nyvky pond, Kyiv, Ukraine). (A) Pediger 5, genital double-somite and urosomites 3 and 4 (ventral view)—arrow shows posteriorly curved lateral arm of the seminal receptacle. (B) Anal somite and caudal rami with caudal setae coded by Roman numerals in the text (ventral view), setulation of the caudal setae is shown only on one side of the rami—arrow shows the spinules along the posterior margin of the anal somite. (C,D). Antenna: (C) coxobasipodite (posterior view); (D) coxobasipodite and first endopodite (anterior view). (E) Leg 3 intercoxal sclerite (posterior view)—arrow shows hairs. (F,G). Leg 4: (F) protopodite, first exopodite and first endopodite (posterior view)—arrows show the morphological features (intercoxal sclerite with short hairs; coxopodite seta with plumose setulation; medial expansion of the basipodite with a row of spinules and with acute tip distally) distinguishing the species from T. oithonoides; (G) third endopodite, homonomous setulation of setae is shown only on proximal section of the lateral seta. Scale bars show 50 μm. A–B show ♀-1[MIZ CRU 001316], C–D show ♀-4 [MIZ CRU 001319], and E–G show ♀-2 [MIZ CRU 001317].

Figure 4

Photos of the diagnostic characters in Thermocyclops species. (A) Genital double-somite with seminal receptacle (shown by arrow) in T. taihokuensis. (B,C) Anal somite and caudal rami with caudal setae, note the difference in the site of the insertion of the lateral caudal (II) seta on the caudal ramus between (B) T. taihokuensis and (C) T. oithonoides. (D,E). Leg 4, note the difference in the proportional length of the inner apical spine (indicated by arrows) in relation to the length of the segment between (D) T. taihokuensis; and (E) T. oithonoides.
Photos of the diagnostic characters in Thermocyclops species. (A) Genital double-somite with seminal receptacle (shown by arrow) in T. taihokuensis. (B,C) Anal somite and caudal rami with caudal setae, note the difference in the site of the insertion of the lateral caudal (II) seta on the caudal ramus between (B) T. taihokuensis and (C) T. oithonoides. (D,E). Leg 4, note the difference in the proportional length of the inner apical spine (indicated by arrows) in relation to the length of the segment between (D) T. taihokuensis; and (E) T. oithonoides.

Sampling sites, coordinates, and collection details for T_ taihokuensis and T_ oithonoides examined in this study

SpeciesDate(s)Type of waterArea of water body (ha)Water temp. (°C)Sampling siteCoordinatesCollector(s)
T. taihokuensis15.08.2020;21.06.2025Pond75.821–23Bucha River catchment area near Kyiv (Ukraine)50° 28′ 18.1″ N 30° 06′ 50.6″ EL. Svetlichny
11.10.2020Pond3.712Sovki River catchment area, Kyiv (Ukraine)50° 24′ 26.9″ N 30° 28′ 54.1″ EL. Svetlichny
04.04.2021Pond0.99Syrets River catchment area in Nyvky Park, Kyiv (Ukraine)50° 27′ 38.2″ N 30° 24′ 38.0″ EL. Svetlichny
05.06.2025Pond0.919Syrets River catchment area in Nyvky Park, Kyiv (Ukraine)50° 27′ 38.2″ N 30° 24′ 38.0″ EL. Svetlichny
21.06.2025Pond7.421‘Velyke Ozero’ of the Borshchahivka River catchment area, Kyiv (Ukraine)50° 26′ 06.7″ N 30° 20′ 48.6″ EL. Svetlichny
T. oithonoides21.06.2025River-22Dnieper River, riverbed, Kyiv (Ukraine)50° 26′ 37.6″ N 30° 33′ 27.4″ EL. Svetlichny
16.08.2006Lake2170-Lake Wigry (Poland)54° 02′ 12″ N 23° 05′ 54″ EG. Wyngaard;M. Hołyńska
16.08.2006Lake101.9-Lake Białe Wigierskie (Poland)54° 01′ 56.9″ N 23° 05′ 33.9″ EG. Wyngaard;M. Hołyńska
22.06.2010Lake116-Lake Storbørja (Norway)60° 05′ 38.5″ N 11° 54′ 21.2″ EI. Dimante-Deimantovica

Morphometric characteristics and abundance of Thermocyclops species in the right-bank tributaries of the Dnieper River and its main riverbed in the Kyiv region

ParametersT. taihokuensisT. oithonoides
BuchaSovkiSyretsBorshchahivkaDnieper River
15.08.202021.06.202511.10.202004.04.202105.06.202521.06.202521.06.2025
Total body length, mm0.970 ± 0.079 (10)1.058 ± 0.076 (10)1.054 ± 0.038 (13)1.088 ± 0.047 (12)1.125 ± 0.054 (13)1.079 ± 0.038 (13)0.727 ± 0.043 (10)
Length of urosome/total body length ratio0.408 ± 0.009 (10)0.381 ± 0.024 (10)-0.38-0.40 (4)--0.439 ± 0.012 (10)
Urosome width/prosome width ratio0.390 ± 0.009 (10)0.398 ± 0.024 (10)-0.37-0.42 (4)--0.304 ± 0.009 (10)
Total abundance of copepodids and adults, ind. m−3.5624.31828.61236.84333.312592.6428.57.2
DOI: https://doi.org/10.26881/oahs-2026.1.01 | Journal eISSN: 1897-3191 | Journal ISSN: 1730-413X
Journal RSS Feed
Language: English
Submitted on: Oct 28, 2025
|
Accepted on: Dec 8, 2025
|
Published on: Feb 13, 2026
Published by: University of Gdańsk
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year
Keywords:
Crustacea,
Europe,
invasive species,
non-indigenous species,
rivers,
ponds
Related subjects:
Chemistry,
Chemistry, other,
Geosciences,
Geosciences, other,
Life sciences,
Life sciences, other

© 2026 Maria Hołyńska, Leonid Svetlichny, Łukasz Sługocki, Larysa Samchyshyna, published by University of Gdańsk
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

AHEAD OF PRINT