Research Article |
Corresponding author: Vladimir E. Gokhman ( vegokhman@hotmail.com ) Academic editor: Denilce Meneses Lopes
© 2023 Vladimir E. Gokhman.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Gokhman VE (2023) Chromosomes of the genus Arge Schrank, 1802 (Hymenoptera, Argidae): new data and review. Comparative Cytogenetics 17: 327-333. https://doi.org/10.3897/compcytogen.17.115485
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Results of the chromosome study of 12 sawfly species of the genus Arge Schrank, 1802 are reviewed, including new data on the karyotypes of A. ciliaris (Linnaeus, 1767) and A. enodis (Linnaeus, 1767) with n = 10. Moreover, the same chromosome number, n = 10, is found in A. ustulata (Linnaeus, 1758), for which n = 8 was previously reported. In addition, n = 8 is confirmed in A. gracilicornis (Klug, 1814). The results of the morphometric analysis of chromosome sets of these four species are given. In the genus Arge, haploid chromosome numbers of n = 8, 10, 11 and 13 were found. Among these sawflies, n = 8 appeared to be the most frequent chromosome number, followed by n = 10. The known data of the chromosome study of these insects are summarized and discussed in the light of phylogeny and taxonomy of the genus Arge.
Chromosome morphometry, karyotypes, sawflies
Arge Schrank, 1802 is the most speciose genus of the family Argidae, which is, in turn, the second largest group of its kind among sawflies (Symphyta) (
Adult female sawflies of the genus Arge were collected by the author in the wild, mostly on the flowers of umbelliferous plants (Apiaceae) in Ozhigovo, Moscow, Russia (55°28'N, 36°52'E) in 2022–2023 (Table
Relative lengths (RLs) and centromeric indices (CIs) of chromosomes of four Arge species (mean ± SD).
Chromosome no. | A. gracilicornis | A. enodis | A. ciliaris | A. ustulata | ||||
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RL | CI | RL | CI | RL | CI | RL | CI | |
1 | 27.07 ± 1.32 | 41.80 ± 3.88 | 15.04 ± 0.87 | 40.68 ± 3.37 | 23.22 ± 0.92 | 42.08 ± 4.00 | 25.98 ± 1.34 | 43.66 ± 4.35 |
2 | 13.59 ± 0.54 | 44.52 ± 4.10 | 12.68 ± 0.88 | 41.10 ± 4.45 | 13.23 ± 2.13 | 41.45 ± 4.31 | 14.49 ± 0.82 | 40.81 ± 4.23 |
3 | 12.31 ± 0.60 | 46.94 ± 1.76 | 11.39 ± 0.58 | 41.32 ± 4.80 | 10.41 ± 0.34 | 42.60 ± 3.77 | 11.18 ± 0.41 | 43.49 ± 3.31 |
4 | 11.67 ± 0.46 | 45.37 ± 4.19 | 10.66 ± 0.35 | 40.03 ± 4.48 | 9.25 ± 0.54 | 34.34 ± 3.35 | 10.52 ± 0.47 | 45.44 ± 3.72 |
5 | 10.38 ± 0.64 | 42.80 ± 3.12 | 9.56 ± 0.47 | 37.81 ± 4.78 | 8.48 ± 0.45 | 38.79 ± 2.98 | 9.14 ± 0.36 | 42.41 ± 4.13 |
6 | 9.82 ± 0.69 | 42.64 ± 3.94 | 9.22 ± 0.47 | 37.46 ± 4.63 | 8.28 ± 0.51 | 37.20 ± 4.64 | 7.12 ± 0.57 | 41.96 ± 4.93 |
7 | 9.08 ± 0.48 | 46.40 ± 2.75 | 8.67 ± 0.47 | 41.74 ± 3.48 | 7.57 ± 0.49 | 38.67 ± 3.96 | 6.03 ± 0.27 | 43.26 ± 4.69 |
8 | 6.08 ± 0.33 | 0 | 8.06 ± 0.36 | 38.74 ± 4.05 | 7.09 ± 0.50 | 36.38 ± 4.83 | 5.48 ± 0.33 | 42.58 ± 3.96 |
9 | – | – | 7.56 ± 0.31 | 44.31 ± 3.40 | 6.49 ± 0.54 | 41.01 ± 3.70 | 5.25 ± 0.35 | 43.86 ± 3.70 |
10 | – | – | 7.16 ± 0.37 | 39.28 ± 4.79 | 5.98 ± 0.42 | 43.79 ± 3.09 | 4.81 ± 0.40 | 44.45 ± 4.91 |
Chromosomal preparations were obtained from embryos forming inside the developing eggs, generally following the protocols used by
Haploid mitotic divisions were studied and photographed using an optic microscope Zeiss Axioskop 40 FL fitted with a digital camera Axiocam 208 color (Carl Zeiss, Germany). To produce illustrations, the resulting images were handled with image processing programs ZEN version 3.0 (blue edition) and GIMP version 2.10. Chromosomes were measured on ten metaphase plates of all studied species using KaryoType software version 2.0 and then classified according to the guidelines provided by
Arge gracilicornis (Klug, 1814) (n = 8). Seventeen embryos obtained from four females were examined. Most chromosomes are metacentric/submetacentric, but the shortest one is an acrocentric (Fig.
Species | n(2n) | Chromosomal formula, n | Region | Reference |
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A. ciliaris (Linnaeus, 1767) | 10 | 3M + 7M/SM | European Russia | Present paper |
A. clavicornis (Fabricius, 1781) | 8 | 8M† | Eastern Canada |
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A. cyanocrocea (Förster, 1771) | 11 | 6M + 5SM | Eastern Germany |
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A. enodis (Linnaeus, 1767) | 10 | 2M + 8M/SM | European Russia | Present paper |
A. gracilicornis (Klug, 1814) | 8 | 7M + 1ST | Eastern Germany |
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8 | 7M + 1A | European Russia | Present paper | |
A. jonasi (Kirby, 1882) | 10 | 5M + 5M/SM† | Japan |
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A. melanochra (Gmelin, 1790) | 10 | 5M + 5SM | Eastern Germany |
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A. nigripes (Retzius, 1783) | 13 | 4M + 4M/SM + 5ST/A† | Eastern Germany |
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A. nigronodosa (Motschulsky, 1860) | 8 | 4M + 3M/SM + 1A† | Japan |
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A. pagana (Panzer, 1798) | (16) | 7M + 1M/SM | Eastern Germany |
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A. pectoralis (Leach, 1817) | 8 | 8M†‡ | Eastern Canada |
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A. ustulata (Linnaeus, 1758) | 8(16) | ? | Scotland, UK |
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10 | 8M + 2M/SM | European Russia | Present paper |
Haploid karyograms of Arge species A A. gracilicornis B A. enodis C A. ciliaris D A. ustulata. Scale bar: 10 μm.
A. enodis (Linnaeus, 1767) (n = 10). Two embryos obtained from a single female were examined. All chromosomes are obviously biarmed, either metacentric or submetacentric (Fig.
A. ciliaris (Linnaeus, 1767) (n = 10). Ten embryos, also obtained from a single female, were examined. As in the previous species, all chromosomes are clearly biarmed, either metacentric or submetacentric (Fig.
A. ustulata (Linnaeus, 1758) (n = 10). Seven embryos obtained from four females were studied. The karyotype generally resembles that of A. ciliaris (Fig.
Up to now, karyotypes of 12 members of the genus Arge have been studied. In these sawflies, haploid chromosome numbers of n = 8, 10, 11 and 13 were found (Table
Given the relatively high karyotypic diversity of the genus Arge, it is difficult to understand what the initial karyotype for the group might look like. Judging from the most frequent chromosome numbers, the ancestral n value could be close to 8 or 10. Both these numbers fall within range of putative initial values for the superfamily Tenthredinoidea and Argidae in particular, i.e., n = 7 to 10 (
Nevertheless, I believe that karyotype analysis can be successfully used in further taxonomic and phylogenetic studies of the genus Arge due to its high chromosomal diversity. Our results together with published karyotypic data collectively suggest that chromosome sets of most species of this group can be easily distinguished without a detailed morphometric analysis. On the other hand, this kind of analysis can be important at least in some cases, which can be judged from an example of A. ciliaris and A. ustulata (see above). This situation is generally similar to the pattern observed in other studied sawfly families, e.g., Tenthredinidae (
The author is very grateful to Sergey A. Basov (Zoological Institute, Russian Academy of Sciences) for identifying the studied specimens and providing useful information on classification and phylogeny of the genus Arge. The present study was supported by the Russian Science Foundation (grant no. 23-24-00068).
Vladimir E. Gokhman https://orcid.org/0000-0001-9909-7559