Research Article |
Corresponding author: Valentina Proviz ( proviz@lin.irk.ru ) Academic editor: Veronika Golygina
© 2015 Valentina Proviz.
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:
Proviz V (2015) Comparative analysis of karyotypes of Chironomus solitus Linevich & Erbaeva, 1971 and Chironomus anthracinus Zetterstedt, 1860 (Diptera, Chironomidae) from East Siberia. Comparative Cytogenetics 9(2): 237-248. https://doi.org/10.3897/CompCytogen.v9i2.4702
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A comparative chromosome banding analysis of Chironomus solitus Linevich & Erbaeva, 1971 and Chironomus anthracinus Zetterstedt, 1860 from East Siberia (Lakes Baikal, Gusinoe, Arakhley and Irkutsk Reservoir) showed close similarity of banding sequences. Ch. solitus differs from Ch. anthracinus in one species-specific sequence of arm B. Arms C (43%) and D (30%) had inversion banding sequences previously reported in Ch. anthracinus The similarity of karyotypic features of Ch. solitus and Ch. anthracinus in combination with morphological features of larvae provide evidence in favour of including Ch. solitus in the C. anthracinus group of sibling species long with Ch. reservatus Shobanov, 1997.
Karyotype, banding sequences, inversion, Chironomus solitus , Chironomus anthracinus
Chironomus solitus Linevich & Erbaeva, 1971 and Chironomus anthracinus Zetterstedt, 1860 are abundant chironomid species (Diptera: Chironomidae), inhabiting the silty bottoms of various water bodies in Pribaikalye and Zabaikalye. Ch. solitus was first registered in the Irkutsk Reservoir as well as in the Angara River, Bratsk, Ust-Ilimsk water reservoirs (
Ch. solitus and Ch. anthracinus live in the single type water environments (lakes, water reservoirs), and are characterized by similar larval morphology in the features used in the distinction of Chironomus species, which makes their differentiation complicated. Thus, accurate identification of these species requires analysis of their karyotypes, rather than only external larval morphology. Until recently, the Ch. solitus karyotype had only been examined in one population from the Irkutsk Reservoir. The first data were reported by
The present work is aimed at comparative analysis of Ch. solitus and Ch. anthracinus karyotypes from the largest lakes of East Siberia, Baikal, Gusinoe, Arakhley and Irkutsk Reservoir, and determination of cytogenetic features for their identification.
Fourth instar larvae of Ch. solitus were collected in January 1992 in the Irkutsk Reservoir (depth 3 m, 52 larvae), and in June 2008 in Lake Baikal opposite the Bolshye Koty Settlement (depth 6 m, 12 larvae). Ch. anthracinus were collected in May 2013 in Lake Gusinoe (10–22 m, 65 larvae), and in March 2014 in Lake Arakhley (10–17 m, 78 larvae). Larvae were fixed in a 3:1 mixture of 96% ethanol and glacial acetic acid. Karyological preparations were made using the ethyl-orcein method (
Both species have a light yellow (from the dorsal part) cephalic capsule, including the frontal sclerite. Abdominal segment VIII bears two pairs of long ventral appendages; lateral appendages on segment VII are absent (bathophilus type after:
Karyotypes of Ch. solitus (Fig.
Karyotype of Chironomus solitus. h’solA1.1, p’solB1.1 ets.–genotypic combinations of banding sequences in chromosomal arms; N – nucleolus; BR – Balbiani Ring, p – puff, arrows show centromeric bands.
Arms A of Ch. anthracinus and Ch. solitus are monomorphic with a single identical banding sequence h’antA1=h’solA1 (Fig.
Arms B of Ch. anthracinus and Ch. solitus are monomorphic with banding sequences h’antB1 (Fig.
h’antB1 25s-24i 18c-16b 22b-21a 23l-24h 18d-20n 23k-d 15m-16a 22c-23c 15l-12v C
p’solB1 25s-24i 18c-16b 18d 24h-23l 21a-22b 19a-20n 23k-d 15m-16a 22c-23c 15l-12v C
Homozygous banding sequences in the arms A and B of Chironomus anthracinus and Chironomus solitus. a h’antA1.1 b h’solA1.1 c h’antB1.1 d p’solB1.1. Numbers and small letters under chromosome arm correspond to banding sequences, brackets near chromosome arms show inversions.
In addition to the inversion, Ch. solitus differs from Ch. anthracinus by the presence of a puff in the region 17. The banding sequence h’antB2 (
h’antB2 25s-24i 18c-17a 23l 21a-22b 16b 24h 18d 19a-20n 23k-d 15m-16a 22c-23c 15l-12v C
Arm C of Ch. anthracinus is monomorphic, with a single banding sequence h’antC1 (Fig.
h’antC1= h’solC2 1a-2c 2d-6b 11c-8a 15ed 15c-11d 6gh 17a-16a 7d-a 6f-c 17b-22g C
p’solC1=p’antC2 1a-2C 15de 8a-11c 6b-2d 15c-11d 6gh 17a-16a 7d-a 6f-c 17b-22g C
h’antC1 sequence dominated in all of the populations studied, while p’antC2 was less common and occurred in both homo- and heterozygous states (
Banding sequences in the arm C of Chironomus anthracinus and Chironomus solitus. a homozygotes h’antC1.1. b homozygotes p’solC1.1 c heterozygous inversions p’solC1.h’solC2. Designations as in Fig.
Arm D of Ch. anthracinus is monomorphic, with one h’antD1 banding sequence (Fig.
h’antD1=h’solD1 1a-3g 14g-16e 8c-7g 5d-7f 18d-17a 8d-10a 13a-11a 14f-13b 10b-e 4a-5c 18e-24g C
p’antD2=p’solD2 1a-3g 14g-16e 5c-4a 10e-b 13b-14f 11a-13a 10a-8d 17a-18d 7f-5d 7g-8c 18e-24g C
Homozygous banding sequences in the arm D of Chironomus anthracinus and Chironomus solitus. a h’antD1.1 b and c h’solD1.1. Designations as in Fig.
Inversion heterozygote h’solD1.p’solD2 in the arm D Chironomus solitus. Designations as in Fig.
Arms E of Ch. anthracinus (Fig.
h’antE1= h’solE1 1a-3e 5a-10b 4h-3f 10c-13g C
Homozygous banding sequences in the arms E and F of Chironomus anthracinus and Chironomus solitus. a h’ant E1.1 b h’solE1.1 c h’antF1.1 d h’solF1.1.
Arms F of Ch. anthracinus (Fig.
h’antF1= h’solF1 1a-8e 9c-17d 18a-23f C
A second nucleolus in Arm F of Ch. anthracinus is a species-specific feature of Ch. anthracinus that makes it different from Ch. solitus with a single nucleolus in arm G.
Arms G of Ch. anthracinus and Ch. solitus (Figs
As a result of comparative analysis of banding patterns of Ch. solitus and Ch. anthracinus from East Siberia, the similarity of these species in morphological features of larvae as well as karyotypes was revealed. Most of the chromosomal arms, A, D, E and F, have identical banding sequences, and a similar structure of arm G. The principal distinctive features of Ch. solitus karyotype are the species-specific p’solB1 sequence and the absence of a nucleolus in arm F. Previous investigators (Belyanina 1979,
There is one more species of the genus Chironomus – Ch. reservatus Shobanov, 1997, which has close similarity of karyotypic and morphological features at all developmental instars of Ch. anthracinus (Shobanov, 1997). Based on these results, the author included the two species in the C. anthracinus group. Banding sequence p’resB1, alongside h’antB2, localised close to p’solB1, and is regarded one of the species-specific markers:
p’resB1 25s-24i 18c-16b 22b-18d 24h-23d 15m-16a 22c-23c 15l-12v C
The morphology of Ch. anthracinus and Ch. solitus imagines from East Siberia is insufficiently studied (
The results of our investigation, similarity of karyotypic features of Ch. solitus and Ch. anthracinus in combination with morphological features of larvae provide evidence in favour of their close similarity and enable us to include Ch. solitus as well as Ch. reservatus in the C. anthracinus group.
This study was supported by the State Project VI.51.1.10 “Current state, biodiversity and ecology of the shore zone of Lake Baikal” (headed by Prof O.A. Timoshkin).
The author offers sincere gratitude to N.V. Bazova, P.V. Matafonov and D.V. Matafonov who kindly provided larvae from Lakes Gusinoe and Arakhley.