At diplotene, three bivalents showed terminal C-bands while one was euchromatic. The X chromosome showed thick C-band covering almost two thirds of the chromosome while Y was C-negative; m-chromosomes were slightly C-positive (Figs 1, 2).

All the four autosomal bivalents showed equal fluorescence with both DAPI and CMA₃ (Figs 3, 4). However, one of the medium sized autosomal bivalents showed bright CMA₃ signals at both ends, which correspond to NORs (Fig. 4). The X was positive to both DAPI/CMA₃ while Y was weak to DAPI and negative to CMA₃; m-chromosomes were DAPI bright and CMA₃ dull (Figs 5, 6).

NORs were found to be associated with both ends of a medium-sized autosomal bivalent (Figs 7, 8).

Terminal C-bands have been observed in three autosomal pairs of Elasmolomus sordidus. In Heteroptera, the terminal C-bands are of wide occurrence. This kind of C-band location has been reported in Antiteuchus mixtus (Fabricius, 1787) (Pentatomidae) by Lanzone and Souza (2006), in Dieuches uniguttatus (Thumb, 1822) and Dieuches insignis (Distant, 1918) (Rhyparochromidae) by Kaur et al. (2010). Usually, telomeric bands are absent, if interstitial blocks are present in a chromosome. This is reported in one or two chromosomes of Nezara viridula Linnaeus, 1758 (Pentatomidae) and Triatoma patagonica Del-Ponte, 1929 (Reduviidae) by Camacho et al. (1985) and Panzera et al. (1997) respectively.

One of the autosomal bivalent in Elasmolomus sordidus was found to be euchromatic. A similar condition is observed in Nezara icterica (Horvath, 1889) (Pentatomidae) by Dey and Wangdi (1990), in Dieuches coloratus Distant, 1909 (Rhyparochromidae) by Kaur et al. (2010) and in Neophysopelta schlanbuschi Ahmad & Abbas, 1987 (Largidae) by Suman et al. (2012).

The X chromosome is almost (2/3) completely C-positive and this condition has been earlier reported in Pentatomidae by Camacho et al. (1985), in Tingidae by Grozeva and Nokkala (2001) and in Nabidae by Grozeva et al. (2004), whereas, the Y chromosome, is C-negative. This condition is not uncommon in Heteroptera and has been reported previously in some species belonging to Coreidae, Pentatomidae and Tingidae (Muramoto 1980, Camacho et al. 1985, Dey and Wangdi 1990, Grozeva and Nokkala 2001).

Microchromosomes were originally described by Wilson (1905); since then they have been discovered in many heteropteran families, including Rhyparochromidae. Microchromosomes are C-positive in Elasmolomus sordidus. Similar observation have been made in Leptoglossus impictus (Stål, 1860) and Phthia picta (Drury, 1773) (Coreidae) by Bressa et al. (2005) and in Dieuches uniguttatus and Dieuches insignis (Rhyparochromidae)by Kaur et al. (2010). Microchromosomes are DAPI bright and CMA₃ dull. Similar set of observations have been previously made by Kaur et al. (2010) in Dieuches uniguttatus and Dieuches insignis (Rhyparochromidae). Information on chromatin composition of m-chromosomes is still very poor and their genetic constitution is not fully known.

The use of DNA binding fluorochromes having different base specificities allows a better characterization of heterochromatic regions in terms of their relative enrichment with AT or GC base pairs. In Heteroptera, still there is little information on heterochromatin base composition. The bright fluorescence after DAPI and CMA₃ staining observed in Elasmolomus sordidus indicates that the constitutive heterochromatic regions possess interspersed AT and GC repeats. Similar observations have been made in Edessa meditabunda (Fabricius, 1974) and Edessa rufomarginata (De Geer, 1773) (Pentatomidae) by Rebagliati et al. (2003), in Antiteuchus mixtus, Antiteuchus macraspis (Perty, 1834), Antiteuchus sepulcralis (Fabricius, 1803) (Pentatomidae) by Lanzone and Souza (2006) and in Arachnocoris trinitatus Bergroth, 1916 (Nabidae) by Kuznetsova et al. (2007).

After silver banding and fluorochrome staining, the localization of CMA₃ positive bands in NOR regions on medium sized autosomal bivalent was revealed. It was confirmed that ribosomal genes are GC rich. This correspondence of CMA₃ signals with NORs have also been reported for several true bug species at interstitial or terminal positions either on autosomes or sex chromosomes by Gonzalez-Garcia et al. (1996), Papeschi et al. (2003), Rebagliati et al. (2003), and Grozeva et al. (2004). However, NORs do not always show GC base richness as is reported in Carlisis wahlbergi Stål, 1858 (Coreidae) by Fossey and Liebenberg (1995).

A common feature of the sex chromosomes of Heteroptera is that they demonstrate bright fluorescence after both DAPI and CMA₃ during the meiotic prophase (Rebagliati et al. 2003). In the present study, the X chromosome showed fluorescence after both DAPI and CMA₃. Similar observations have been also made in Cimex emarginatus Simov, Ivanova & Schunger, 2006 by Grozeva and Nokkala (2002), Cimex lectularius (Cimicidae) by Grozeva et al. (2010), in Edessa meditabunda and Edessa rufomarginata (Pentatomidae) by Rebagliati et al. (2003), in Athaumastus haematicus (Stål, 1860), Leptoglossus impictus and Phthia picta (Coreidae), Jadera sanguinolenta (Fabricius, 1775) (Rhopalidae) by Bressa et al. (2005), in Antiteuchus mixtus, Antiteuchus macraspis and Antiteuchus sepulcralis (Pentatomidae) by Lanzone and Souza (2006). In the present study, however, the Y chromosome is C-negative, but DAPI positive and CMA₃ negative. Similar observations have been made in Triatoma vitticeps (Stål, 1859) (Reduviidae) by Severi-Aguiar et al. (2006).

The silver impregnation stains not only the NORs but also the nucleolus at specific points of some chromosomes (Castanhole et al. 2008). In the present study, NORs were found to present on terminal regions of one of medium sized autosomal pairs of Elasmolomus sordidus, like in Nysius californicus Stål, 1859 (Lygaeidae) (Souza et al. 2007), and in Arachnocoris trinitatus Bergroth, 1916 (Nabidae) (Kuznetsova et al. 2007). However, in Belostomatidae, NORs have been reported on either autosomes, on sex chromosomes or on both autosomes and sex chromosomes (Papeschi and Bidau 1985).