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Corresponding author: Vladimir A. Lukhtanov ( lukhtanov@mail.ru ) Academic editor: Valentina G. Kuznetsova
© 2019 Vladimir A. Lukhtanov, Konstantin A. Efetov, Alexander V. Dantchenko.
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Citation:
Lukhtanov VA, Efetov KA, Dantchenko AV (2019) Karyotype reinvestigation does not confirm the presence of two cryptic species and interspecific hybridization in the Polyommatus (Agrodiaetus) damocles complex in the Crimea (Lepidoptera, Lycaenidae). Comparative Cytogenetics 13(3): 311-319. https://doi.org/10.3897/CompCytogen.v13i3.46777
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The karyotype of the blue butterflies from the Angarskiy Pass (Crimea), previously attributed to Polyommatus (Agrodiaetus) poseidon (Herrich-Schäffer, 1851), was re-examined. In all 19 studied individuals, we found the haploid chromosome number n = 26, including 7 pairs of relatively large and 19 pairs of relatively small chromosomes. According to the chromosome number and karyotype structure, the studied population does not differ from P. (A.) damocles krymaeus (Sheljuzhko, 1928) from the eastern part of the Crimean Mountains. This result does not confirm the previously formulated hypotheses, according to which (1) two morphologically similar but karyologically different species, P. (A.) poseidon and P. (A.) damocles krymaeus, occur sympatrically in the Crimea and (2) there is hybridization between these taxa on the Angarskiy Pass. Thus, only three species of the subgenus Agrodiaetus Hübner, 1822 have been reliably established for the Crimea: P. (A.) damone pljushtchi Lukhtanov & Budashkin, 1993, P. (A.) damocles krymaeus (Sheljuzhko, 1928) and P. (A.) ripartii budashkini Kolev & de Prins, 1995.
Biodiversity, chromosome, hybrids, meiosis, karyosystematics, taxonomy
The subgenus Agrodiaetus Hübner, 1822 of the genus Polyommatus Latreille, 1804 is a diverse and taxonomically difficult group of blue butterflies of the subtribe Polyommatina (
Karyotypes of the Crimean Agrodiaetus were studied by
Since these chromosomal morphs (n = 26 and n = 19) were reported to inhabit in sympatry, it could be assumed that they belong to different species. This is a plausible assumption given that (1) the distribution areas of P. (A.) damocles and P. (A.) poseidon overlap in Turkey (
To test the hypotheses about the two karyomorphs and interspecific hybridization, we re-examined the karyotypes of the blues from the same population (Crimea, the Angarskiy Pass) that was previously studied by
Adult males were collected by K. A. Efetov on the Angarskiy Pass of the Crimean Mountains exactly in the same place where in 1993 (erroneously cited by Kandul as "1992") the Kandul’s material (
Testes were extracted from the butterfly abdomens and fixed in a mixture of glacial acetic acid and 96% ethyl alcohol (1 : 3). The fixed material was stored at + 4°C for 5–6 months. The testes were stained with 2% orcein acetic acid for 8–30 days as previously described (
Butterflies of the P. (A.) damocles species complex have a single generation in the Crimea (
Summing up the analysis of the samples collected on the Angarskiy Pass, 26 bivalents were found in all studied individuals in all cells at the stages of MI and diakinesis, and 26 chromosomes at the stage of MII. The karyotype at these stages is sharply asymmetric and includes 7 relatively large and 19 relatively small bivalents. Diploid chromosome number 2n = 52 was found in spermatogonial mitosis and atypical meiosis. No variation in the chromosome number was observed. Therefore, we do not confirm the numbers n = 25 and n = 27 reported for this population by
Karyotype in male mitosis and meiosis of Polyommatus (Agrodiaetus) damocles krymaeus from the Angarskiy Pass (Crimea). Numbers from 1 to 7 show the largest chromosome pairs in mitosis and the largest bivalents in meiosis. 1 metaphase of spermatogonial mitosis, 2n = 52 2 early anaphase of spermatogonial mitosis, 2n = 52 3 diakinesis, n = 26 4 MI, n = 26. Scale bar: 10 μm.
Chromosome numbers found in P. (A.) damocles krymaeus (Crimea, the Angarskiy Pass).
Code of specimen | Dates of collection | Chromosome number | Quantity and type of studied cells |
---|---|---|---|
1997-A | 25.07.1997 | n = 26 | 27 MI |
1997-B | 26.07.1997 | n = 26 | 1 MI |
1997-C | 26.07.1997 | n = 26 | 2 MI |
1997-D | 31.07.1997 | n = 26 | 1 MI |
1998-1 | 2.07.1998 | n = 26 | 4 MI |
1998-2 | 2.07.1998 | n = 26 | 1 MI |
1998-4 | 12.07.1998 | n = 26 | 7 MI |
1998-4 | 12.07.1998 | n = 26 | 2 MII |
1998-4 | 12.07.1998 | 2n = 52 | 2 atypical divisions |
1998-4 | 12.07.1998 | 2n = 52 | 2 mitotic metaphases |
1998-5 | 14.07.1998 | n = 26 | 13 MI |
1998-6 | 14.07.1998 | n = 26 | 20 MI |
1998-6 | 14.07.1998 | n = 26 | 20 MII |
1998-7 | 15.07.1998 | n = 26 | 2 MI |
1998-8 | 15.07.1998 | n = 26 | 9 MI |
1998-9 | 15.07.1998 | n = 26 | 16 MI |
1998-11 | 15.07.1998 | n = 26 | 8 MI |
1998-11 | 15.07.1998 | n = 26 | 2 diakinetic cells |
1998-12 | 15.07.1998 | n = 26 | 7 MI |
1998-13 | 15.07.1998 | n = 26 | 4 MI |
1998-14 | 21.07.1998 | n = 26 | 4 MI |
1998-51 | 23.07.1998 | n = 26 | 5 MI |
1998-54 | 23.07.1998 | n = 26 | 7 MI |
1998-55 | 23.07.1998 | n = 26 | 9 MI |
1998-55 | 23.07.1998 | n = 26 | 4 MII |
Analyzing the information at our disposal, as well as butterflies collected by K. A. Efetov on the Angarskiy Pass in 1993 (Kandul’s material, cited by him as “1992”) and 1997–1998 (our material), we conclude that, most likely, there are no blue butterflies of the subgenus Agrodiaetus with the karyotype n = 19 in the Crimea. Our conclusion is based on the following:
1) the presence of the karyomorph n = 19 is not confirmed by several studies, all 19 individuals studied from the Angarskiy Pass have n = 26;
2) males of P. (A.) poseidon and P. (A.) damocles are not identical in their appearance. Males of P. (A.) damocles have a darker blue coloration, and their veins on the wing upperside possess black scales (
Additionally, our data do not confirm the conclusion (
3) the conclusion about hybridization between the two putative chromosomal races was based on the analysis of the metaphase plates of insufficient quality (see:
In the end, we assume that the karyomorph n = 19 from the Angarskiy Pass does not actually exist and is an artifact, although it is rather difficult to explain the possible origin of this error. It cannot be excluded that it resulted from an accidental mix-up between the chromosomal preparations (but not between the butterfly samples) of P. (A.) poseidon from Turkey (n = 19) and P. (A.) damocles krymaeus from the Crimea (n = 26), since they were processed in parallel (see
In terms of the chromosome number and karyotype structure, the studied population found on the Angarskiy Pass is the same as that from the eastern Crimea (Sudak region) (Figs
We thank Pavel Bogdanov (State Darvin Museum, Moscow) for important information on ecology P. (A.) damocles crymaeus and Yuri Budashkin for hospitality and help during the field studies in the Crimea. We thank Snejana Grozeva and Vladimir Gokhman for comments on the manuscript. The financial support for this study was provided by the grant no. 19-14-00202 from the Russian Science Foundation to the Zoological Institute of the Russian Academy of Sciences. The work was partially performed using equipment of the ‘Chromas’ Core Facility and the Centre for Molecular and Cell Technologies of St. Petersburg State University.