© 2009 The Japan Mendel Society Cytologia 74(2): 147–152, 2009

Chromosomes and Their Meiotic Behavior in Two Species of (Heteroptera: )

Harbhajan Kaur*, Rajdeep Kaur and Vikas Suman

Department of Zoology, Punjabi University, Patiala 147 002, Punjab, India

Received March 16, 2009; accepted June 28, 2009

Summary Reduviids comprise the largest family of predaceous land Heteropterans and are charac- terized by a modal autosomal diploid number of 20 with both simple and multiple sex chromosome systems. Multiple systems are more frequent in and Stenopodainae. Microchromo- somes are invariably absent in this family. Stenopodainae have a diploid autosomal number of 20/22 (n10A/11A) plus different multiple sex chromosome systems (XnY/XnXn). In the present work the chromosome complement and course of meiosis of two species viz. notatus (2n 23 20A X1X2Y) and Sastrapada baerensprungi (2n 23 20A X1X2Y) (Stenopodainae) collected from the Punjab region of India and new to the cytogenetic world, are described.

Key words Heteroptera, Reduviidae, Stenopodainae, Oncocephalus notatus, Sastrapada baeren- sprungi, Multiple sex systems.

Reduviidae is the largest family of predaceous land Heteroptera and contains about 961 genera and 6601 species placed in 22 sub-families (Maldonada, 1990). Cytogenetic reports are available for 127 species of Reduviidae. They are characterized by a modal autosomal diploid number of 20 and both the simple and multiple sex chromosome systems. Multiple systems are more frequent in Harpactorinae and Stenopodainae than in other sub-families of this family (Poggio et al. 2007). Microchromosomes are generally absent in this family. The main contribution towards cytological knowledge of this family has been made by Mont- gomery (1901), Payne (1909, 1910, 1912), Toshioka (1933, 1936), Yoshida (1947), Muramoto (1978), Ueshima (1966, 1979) and Aguiar et al. (2006). The karyotypic evolution with special ref- erence to Stenopodainae and Harpactorinae has been reviewed by Poggio et al. (2007). Cytological information on Indian Reduviids comes from the works of Manna (1950, 1951, 1962), Banerjee (1958), Jande (1959a, b), Manna and Deb Mallick (1981), Dey and Wangdi (1988) and Satapathy and Patniak (1989). In the present paper chromosome complement and course of meiosis of two Reduviids (Stenopodainae), collected from the Punjab region of India and new to the cytogenetic world, are described.

Materials and methods Adult males of Oncocephalus notatus (Klug) and Sastrapada baerensprungi (Stal) collected from the Punjabi University campus, Patiala, using light source were dissected to take out testes which were fixed in Carnoy’s fixative. Chromosomal preparations were made by air-dried method and stained in Carbol-fuchsin (Carr and Walker, 1961).

* Corresponding author, e-mail: [email protected] 148 H. Kaur, R. Kaur and V. Suman Cytologia 74(2)

Fig. 1. a–h: Oncocephalus notatus (Klug). a: Spermatogonial Metaphase plate showing 23 elements. b: Diffuse stage. c and d: Diplotene stages. e: Metaphase-I. f: Early Anaphase-I. g: Late Anaphase-I. h: Early Metaphase-II.

Results Oncocephalus notatus (Klug) The diploid chromosomal complement of Oncocephalus notatus consists of 23 elements, which include 10 pairs of almost similar sized autosomes and 3 dot shaped sex chromosomes. The smallest 2 correspond to X1 and X2. The Y, on the other hand, is bigger is in size and is indistin- 2009 Meiotic studies in two species of Stenopodainae. 149

Fig. 2. a–b: Oncocephalus notatus (Klug). a: Late Metaphase-II. b: Telophase-II. c–h: Sastrapada baeren- sprungi (Stal). c: Spermatogonial Metaphase plate showing twenty three elements. d: Diffuse stage. e: Diplotene. f: Metaphase-I. g: Metaphase-II. h: Telophase-II. Scale Bar: 10 mm (same amplifica- tion in all the figures). guishable from the autosomes in the mitotic complement (Fig. 1a).

At Diffuse stage, a single dark heteropycnotic body representing fused X1, X2 and Y is seen (Fig. 1b). At Diplotene, autosomal bivalents become distinct as a result of condensation whereas sex chromosomes still remain fused (Fig. 1c, d). While moving towards Diakinesis, the heteropyc- notic mass gradually resolves itself into 3 well defined sex chromosomes, X1, X2 and Y, which usu- 150 H. Kaur, R. Kaur and V. Suman Cytologia 74(2)

Table 1. Chromosome complements of species belonging to subfamily Stenopodainae studied so far

Sr. No. of Sex Species 2n References No Autosomes Mechanism

1 Oncocephalus impudicus Reuter 23 20 X1X2Y Jande (1959a) 2 Oncocephalus sp. 1 Klug 23 20 X1X2Y Jande (1959a) 3 Oncocephalus sp. 2 Klug 24 20 X1X2X3Y Jande (1959a) 4 Oncocephalus sp. 3 Klug 23 20 X1X2Y Manna and Deb-Mallick (1981) 5 Oncocephalus sp. 4 Klug 23 20 X1X2Y Satapathy and Patnaik (1989) 6 Oncocephalus naboides Walker 26 22 X1X2X3Y Manna and Deb-Mallick (1981) 7 Oncocephalus nubilus Van Duzee 26 22 X1X2X3Y Ueshima (1979) 8 Oncocephalus notatus Klug 23 20 X1X2Y (Present study) 9 foeda Stal 24 22 XY Banerjee (1958)

25 22 X1X2Y Jande (1959a) 10 Pygolampis sp. Stal 28 22 X1X2X3Y Kaur, R. (2009) 11 modesta Banks 25 20 X1X2X3X4Y Payne (1912) 12 Stenopoda cinerea Laporte 25 20 X1X2X3X4Y Poggio et al. (2007) 13 Sastrapada baerensprungi Stal 23 20 X1X2Y (Present study)

ally lie wide apart but sometimes appear closely associated till Diakinesis. Afterwards they com- pletely separate and became isopycnotic. Metaphase-I plate shows a definite arrangement of chro- mosomes with 9 autosomal bivalents forming a ring and 1 bivalent and 3 sex univalents lying in the centre (Fig. 1e). The first meiotic division is equational for the sex chromosomes which is clearly revealed at early and late Anaphase plates showing 3 sex chromosomes moving to both the poles, although lagging behind the autosomes (Fig. 1f, g). At Metaphase-II, autosomes are peripheral forming either a circle or a semicircle whereas sex chromosomes lie in the center. In some plates, one autosomal bivalent is seen to lie near the sex chromosomes. (Figs. 1h, 2a). Two types of Telophase nuclei are seen, one with 12 elements (10A X1X2), the other with 11 elements (10A Y) (Fig. 2b).

Sastrapada baerensprungi The diploid complement of Sastrapada baerensprungi consists of 23 elements that include 10 pairs of rod shaped autosomes and 3 dot shaped sex chromosomes, X1, X2 and Y. Y is distinctly bigger in size than X1 and X2 which are very small and dissimilar in size (Fig. 2c). At Diffuse stage, a fairly large spherical heteropycnotic mass representing fused sex chromo- somes is seen (Fig. 2d). By Diplotene, the autosomal bivalents and sex chromosomes become dis- tinct as a result of condensation (Fig. 2e). Metaphase-I plate shows 10 autosomal bivalents and 3 univalent sex chromosomes placed irregularly on the plate (Fig. 2f). At Metaphase-II, however, a characteristic arrangement is observed with autosomal bivalents forming a complete ring and X1, X2 and Y that form a pseudotrivalent, lying in the center (Fig. 2g). Two types of Telophase nuclei are formed, one with 12 elements (10A X1X2) and the other with 11 elements (10A Y) (Fig. 2h).

Discussion Oncocephalus notatus and Sastrapada baerensprungi belong to the subfamily Stenopodainae that is characterized by an autosomal diploid number of 20/22(n10A/11A) and multiple sex chromosome system of XnY/XnXn (Poggio et al. 2007). Both Oncocephalus notatus and Sastrapada baerensprungi have a diploid complement of 2n 23 20A X1X2Y. Sex chromosomes X1 and X2 are dot shaped and same sized in Oncocephalus notatus but are dissimilar in size in Sastrapada baerensprungi while Y is bigger in size in both and is indistinguishable from autosomes 2009 Meiotic studies in two species of Stenopodainae. 151 in Oncocephalus notatus but is distinctly recognizable in Sastrapada baerensprungi. A complement of 20 autosomes is present in most of the species of Stenopodainae. It is reported in Oncocephalus impudicus, Oncocephalus sp. 1 and Oncocephalus sp. 2 (Jande 1959a), Onco- cephalus sp. 3 (Manna and Deb Mallick 1981), Oncocephalus sp. 4 (Satapathy and Patnaik 1989), Pnirontis modesta (Payne 1912) and Stenopoda cinerea (Poggio et al. 2007). Only three species viz. Oncocephalus naboides (Manna and Deb Mallick 1981), Oncocephalus nubilus (Ueshima 1979) and Pygolampis foeda (Banerjee 1958, and Jande 1959a) have 22 autosomes (Table 1). It is, there- fore, clear that a diploid autosomal number of 20 dominates in the subfamily Stenopodainae and 22 seems to have been derived from 20 as a result of autosomal fragmentation. Reduviids have both simple and multiple sex chromosome systems with XY/XX (46.34%) and XnY/XnXn (51.22%) and only 3 species with an XO/XX system (Ueshima 1979). It is generally agreed that multiple systems have originated from simple systems through chromosome fragmenta- tions (Papeschi 1996) and so is widely accepted because chromosomes of this group have diffuse centromeric activity (Hughes-Schrader 1931, 1940, 1942, Schrader 1935, 1947, Troedsson 1944). Multiplicity of X is more frequent in Harpactorinae and Stenopodainae than in other subfamilies of

Reduviidae. Different systems showing X chromosome multiplicity (from X1X2Y to X1X2X3X4X5Y) are not homogeneously distributed among its subfamilies. X1X2Y is prevalent in 32.82%, X1X2X3Y in 14.06%, X1X2X3X4Y in 3.13% and X1X2X3X4X5Y in 1.56% (Poggio et al. 2007). Within Stenopodainae out of 13 species studied so far (including 2 of the present study),

X1X2Y is prevalent in 7 species, X1X2X3Y in 5 species and X1X2X3X4Y in 1 specie. Increase in number of X is not accompanied by a change in autosomal number, which indicates that X multi- plicity increases because of fragmentation of X chromosome. Further characterization is needed to establish this contention. Oncocephalus notatus is unique in having a definite arrangement of chromosomes at Metaphase-I as well as Metaphase-II. This has not been reported earlier in any of the Reduviids, which are characterized by an irregular arrangement of chromosomes at Metaphase-I. In Sastrapa- da baerensprungi, however, the general pattern of division is the same as is observed for other Re- duviids by Montgomery (1901), Payne (1909, 1912), Troedsson (1944), Manna (1950, 1951), Banerjee (1958), Jande (1959a), Ueshima (1979), Dey and Wangdi (1988), Satapathy and Patnaik (1989) and Poggio et al. (2007).

Acknowledgements The authors wish to thank the Department of Science and Technology, Ministry of Science and Technology, New Delhi for providing financial support for the present study.

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