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Corresponding author: Natalia Golub ( nvgolub@mail.ru ) Academic editor: Vladimir Lukhtanov
© 2014 Natalia Golub, Valentina Kuznetsova, Roman Rakitov.
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:
Golub N, Kuznetsova V, Rakitov R (2014) First karyotype data on the family Myerslopiidae (Hemiptera, Auchenorrhyncha, Cicadomorpha). Comparative Cytogenetics 8(4): 293-300. https://doi.org/10.3897/CompCytogen.v8i4.8813
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In the first cytogenetic study of the recently proposed family Myerslopiidae the male karyotype of Mapuchea chilensis (Nielson, 1996) was analyzed using conventional chromosome staining, AgNOR- and C-bandings, and fluorescence in situ hybridization (FISH) with 18S rDNA and (TTAGG)n telomeric probes. A karyotype of 2n = 16 + XY, NOR on a medium-sized pair of autosomes, subterminal location of C-heterochromatin, and presence of (TTAGG)n telomeric sequence were determined. Additionally, the male internal reproductive system was studied.
Karyotype, NOR, C-heterochromatin, rDNA, TTAGG telomeric sequence, Mapuchea chilensis , Myerslopiidae , Hemiptera , Auchenorrhyncha , Cicadomorpha , Membracoidea
The family Myerslopiidae includes three recent genera of cicadomorphan Auchenorrhyncha with 19 species in New Zealand and temperate Chile (
Four adult males of M. chilensis were collected by the third author in Chile, P.N. Puyehue, Anticura (40.6667°S, 72.1742°W) on 15–17 January 2014 from leaf litter between creeping stems of Hydrangea serratifolia (Hooker & Arnott, 1833). Specimens were fixed in 3:1 fixative (96% ethanol: glacial acetic acid) and stored at +4°C. Testes were dissected in a drop of 45% acetic acid and squashed. The cover slip was removed using dry ice. Chromosome staining techniques used were as follows: the Feulgen-Giemsa method (
The classification of cicadomorphan Auchenorrhyncha accepted in this paper follows
In adult M. chilensis males, the reproductive system consisted of a pair of testes, pair of seminal vesicles, and pair of accessory glands (Fig.
Male reproductive system of Mapuchea chilensis. t.f. testicular follicles (4 and 6 in different testes); v.d. vasa differentia s.v. seminal vesicle; a.g. accessory gland; c.d.e. common ejaculatory duct.
Male karyotype of Mapuchea chilensis. a metaphase I, n = 8AA + XY b diakinesis, largest bivalent with two chiasmata c diplotene, 5 bivalents with two chiasmata each d metaphase II with the largest chromosome in the center of a ring formed by autosomes. Note chromatin associations between non-homological chromosomes e metaphase I showing associations between bivalents f anaphase II with lagging chromosomes (arrows) g diplotene (C-banding) showing terminal C-bands in chromosomes h early prophase (NOR-banding) showing argyrophilic granules associated with autosomes i–k diplotenes (i, j) and mitotic metaphase (k) after FISH with rDNA-probe (green signals) and (TTAGG)n telomeric probe (red signals). rDNA sites are located on a medium-sized pair of autosomes. Bar = 10µm.
M. chilensis showed a karyotype of 2n = 16 + XY. At MI, 8 bivalents of autosomes and an XY-pair were present (Fig.
After C-banding, the majority of bivalents showed C-blocks at the ends of chromosomes (Fig.
The number of testicular follicles is generally characteristic of an insect species, although variation between the two testes of the same male has occasionally been reported (
Among Cicadellidae, chromosome numbers in males vary from 2n = 7(6 + X) to 2n = 27(26 + X) and both X(0) and XY sex chromosome systems occur, the latter being found only occasionally (
Therefore, in both the karyotype and the number of follicles, M. chilensis falls within the spectrum of variation observed in Cicadellidae.
Other cytogenetic characters have so far been examined in only a few representatives of cicadomorphan Auchenorrhyncha and thus do not inform on the relationships of Myerslopiidae. M. chilensis was found to have small subterminal C-blocks, the pattern described, with the exception of large blocks in Philaenus italosignus Drosopoulos & Remane, 2000 (Cercopoidea: Aphrophoridae) (
In M. chilensis, rDNA loci were detected by FISH on one of the medium-sized pairs of autosomes, this location being confirmed by AgNOR-staining, which suggested presence of a single autosomal NOR (per haploid set). The latter technique has previously been used to demonstrate variation in the number and position of NORs in four genera of Cercopoidea (
The telomeric sequence (TTAGG)n, identified in M. chilensis, is known to be characteristic of the majority of insect groups and is considered to be ancestral for Insecta (
The study was supported by the Russian Foundation for Basic Research grants 14-04-01051 (NG and VK) and 13-04-01839 (RR) and the programs of the Presidium of the Russian Academy of Sciences “Gene Pools and Genetic Diversity” and “Origin of the Biosphere and Evolution of Geo-biological Systems” (NG and VK). We thank Dr. B. Anokhin (Zoological Institute RAS, St. Petersburg) for technical assistance with FISH and Dr. D. Shcherbakov (Paleontological Institute RAS, Moscow) for having organized the research trip to Chile during which the specimens of M. chilensis had been collected.