Research Article |
Corresponding author: Eduard Petitpierre ( eduard.petitpierre@uib.es ) Academic editor: Dorota Lachowska
© 2019 Eduard Petitpierre.
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:
Petitpierre E (2019) A cytogenetic analysis in two species of Cassidinae (Coleoptera, Chrysomelidae). Comparative Cytogenetics 13(3): 277-281. https://doi.org/10.3897/CompCytogen.v13i3.36581
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Two species of Cassidinae have been chromosomally analyzed, Cassida humeralis Kraatz, 1874 from France, with 2n = 18, 8 + Xyp meioformula and Anacassis fuscata (Klug, 1829) from Uruguay, with 2n = 30, 14 + Xy meioformula. The karyotype of the former is composed of similar meta/submetacentric autosomes, a small X-chromosome and a tiny y-chromosome, as many other Cassida and tribe Cassidini species, whereas that of the latter has four pairs of acro/telocentric autosomes at least and the remaining meta/submetacentrics including the X-chromosome and a tiny y-chromosome, which points out to its probable apomorphic origin by centric fissions, as found in some other species of the tribe Mesomphaliini.
Coleoptera, Chrysomelidae, Cassidinae, Cassida humeralis, Anacassis fuscata, karyotypes
The leaf beetles of subfamily Cassidinae are a very large group with some 6,000 species distributed in 43 tribes (
Two species of Cassidinae, each from two individuals, have been chromosomally surveyed: Cassida humeralis Kraatz, 1874, from Revens (Gard, France) and Anacassis fuscata (Klug, 1829) from Sauce (Canelones, Uruguay). The male adult individuals were anaesthetized with ethyl acetate before dissecting their testes with insect pins and using then the methods of chromosome treatments reported by
Cassida humeralis provided spermatogonial metaphases with 2n = 18 chromosomes, all the autosomes showing similar sizes and metacentric shapes except one pair of submetacentrics, whereas the X sex-chromosome was a clearly smaller metacentric with regard to all autosomes and the y-chromosome a tiny element (Fig.
Cassida humeralis: 1 spermatogonial metaphase with 2n = 18 meta/submetacentric chromosomes, the small X-chromosome is arrowheaded and the tiny y-chromosome pointed by an arrow 2 meiotic diakinesis with a 8 + Xyp meioformula, the Xyp is arrowheaded 3 meiotic metaphase II of X-chromosome (arrowheaded) class with nine chromosomes 4 meiotic metaphase II of y-chromosome (arrowed) class with nine chromosomes.
Anacassis fuscata had spermatogonial metaphases with 2n = 30 chromosomes of mostly medium and small sizes (Fig.
Anacassis fuscata. 5 spermatogonial metaphase with 2n = 30 chromosomes 6 spermatogonial metaphase showing at least four acro/telocentric autosome pairs indicated by arrows 7 meiotic metaphase I with a 14 + Xy meioformula 8 meiotic metaphase II of X-chromosome class with fifteen chromosomes.
The karyotype of Cassida humeralis has 2n = 18 chromosomes as in 23 (69.7%) of the 33 cytogenetically known species of the genus Cassida, and in 40 (65.6%) among the total of 61 checked species of the tribe Cassidini, including species of further fourteen genera (
The high chromosome number, 2n = 30, of Anacassis fuscata, is in agreement with others found in the Neotropical tribe Mesomphaliini (= Stolaini), whose range in numbers goes from 2n = 22 to 2n(♂) = 51, in 24 checked species of six genera, where ten species of them had diploid numbers ≥ 30 chromosomes (
Eventually, the possible most ancestral karyotype for the whole Cassidinae s. lat. subfamily, that is including the ancient subfamilies of Cassidinae s. str. (tortoise beetles) and Hispinae (leaf-mining beetles), may be that of 2n = 18 (Xyp) chromosomes, because it is prevalent in two of the three tribes with at least five or more examined species of Cassidinae s. str., and in three of the six so far checked tribes belonging to the ancient subfamily Hispinae. However, in order to secure the basal karyotype of Cassidinae s. lat., many more species, most of all in this latter group of the ancient subfamily Hispinae, would be necessary to confirm this point of view.
Mr. Bernard Bordy (Le Val-Saint-Eloi, Haute-Saône, France) and Dr. Rodrigo Ponce de León (Univ. de la República, Montevideo, Uruguay) are highly indebted for supplying samples of Cassida humeralis and for his help in capturing those of Anacassis fuscata, respectively.