New data on karyotypes of lace bugs (Tingidae, Cimicomorpha, Hemiptera) with analysis of the 18S rDNA clusters distribution

Abstract

The karyotypes of 10 species from 9 genera of the family Tingidae (Hemiptera, Heteroptera, Cimicomorpha) are described and illustrated for the first time. These species are: Agramma atricapillum (Spinola, 1837), Catoplatus carthusianus (Goeze, 1778), Dictyla platyoma (Fieber, 1861), Lasiacantha hermani Vásárhelyi, 1977, Oncochila simplex (Herrich-Schaeffer, 1830), Tingis (Neolasiotropis) pilosa Hummel, 1825, and T. (Tropidocheila) reticulata Herrich-Schaeffer, 1835, all with 2n = 12A + XY, as well as Acalypta marginata (Wolff, 1804), Derephysia (Paraderephysia) longispina Golub, 1974, and Dictyonota strichnocera Fieber, 1844, all with 2n = 12A + X(0). Moreover, genera Catoplatus Spinola, 1837, Derephysia Spinola, 1837, and Oncochila (Herrich-Schaeffer, 1830) were explored cytogenetically for the first time. Much as all other hitherto studied lace bugs, the species studied here have 12 autosomes but differ in their sex chromosome systems. The ribosomal clusters were localized on male meiotic cells of all ten species already mentioned and, additionally, in Acalypta carinata Panzer, 1806 known to have 2n = 12A + X (Grozeva and Nokkala 2001) by fluorescence in situ hybridization (FISH) using a PCR amplified 18S rDNA fragment as a probe. In all cases, rDNA loci were located interstitially on a pair of autosomes. Furthermore, two species possessed some additional rDNA clusters. Thus, Acalypta marginata showed clearly defined interstitial clusters on one more pair of autosomes, whereas Derephysia longispina had a terminal cluster on the X-chromosome. FISH performed with the telomeric (TTAGG)n probe did not reveal labelling in chromosomes of any species studied. Hence, the results obtained provide additional evidence for the karyotype conservatism, at least regarding the number of autosomes, for variation in chromosomal distribution of rDNA loci between species and for the lack of the ancestral insect telomeric sequence TTAGG in lace bugs. Preliminary taxonomic comments are made basing on some cytogenetic evidence.