Studies on the intraspecific variations in Rhyothemis variegata variegata (Linnaeus) (Odonata: Libellulidae)

Variations in the wing markings of male and female representatives of Rhyothemis variegata variegata (Linnaeus) collected from different parts of North-West India have been studied and illustrated in detail.


Introduction
erected genus Rhyothemis by giving a brief account of type species Libellula phyllis Sulzer. A total number of 4 species i.e., obsolescens Kirby, plutonia Selys, triangularis Kirby and variegata variegata (Linnaeus) are known from India under this genus. During different collection-cum-survey tours from various localities of North-West India, only two species Rhyothemis triangularis Kirby and Rhyothemis variegata variegata (Linnaeus) could be collected. The species of this genus are gregarious and occur in large colonies over marshy lands and are weak fliers.
Variations within the species of Odonata have been briefly studied and reported by Asahina (1952-53), Singh and Baijal (1954); Baijal and Agarwal (1955), Prasad (1976, 1977), Prasad (1976Prasad ( , 1976aPrasad ( , 1994, Ghosh 1983, Prasad andKumar (1981). The present research paper deals with the variations in the wing markings of male and female representatives of Rhyothemis variegata variegata also called as "Common Picture Wing". The wing markings are distinctly different in both the sexes of this species (Figures 1 and 2). A total number of five variations in wings have been reported (three in male and two in female).

Material and Methods
The adult dragonflies were collected with the help of insect collecting net from different localities of North-Western states of India i.e., Himachal Pradesh, Punjab, Haryana and Uttarakhand in different seasons from August 1997 to October 2000. The adult representatives of dragonflies were killed with ethyl acetate vapours in the killing bottle, and in case of teneral specimens or put alive into triangular paper packets and starved to death. The dead specimens were then bristled, pinned, stretched, dried and preserved. Fraser (1934Fraser ( , 1936 and Lahiri 1987 were followed for identification of the adult representatives.

Results and Discussion
The present observations have been made on 50 specimens collected from various localities of North West India. Rhyothemis variegata variegata (Linnaeus) was found to be predominant in Kanjli and Harike wetland of Punjab, where it is usually seen in swarms. In this subspecies wing markings are distinctly different in both the sexes.
During the present course of study, three forms of wings have been observed in the male of Rhyothemis variegata variegata (Linnaeus) as follows: that wing markings are subject to considerable variation. Besides variations in wing markings, 2 males were having 2 cubitoanal nervures in forewing in place of one.
Coloration and variations in body length size play an important role in determining the age and sex of the species. Morphological variations are common in many genera like Orthetrum and have been reported by many workers like Samsudin, 2013. Identification of female dragonflies is much more difficult as compared to male dragonflies. They can be differentiated according to the color patterns of wings and abdomen. (Johnson and Triplehorn, 2005;Bedjanic et al., 2007). However, the variability of color sometimes leads to the confusion to determine the species. Therefore, reports of these morphological variations would prove helpful in such cases.
1. Markings more extensive, forewing with nodal spot extending posteriorly up to median planate; well defined subapical spot present, apical spot extending inwards to as far as middle of pterostigma; spot at discoidal cell much larger; slight vestiges of marking in subcoastal space, hindwing with basal spot confluent with nodal spot and nodal spot joined by a narrow isthmus to spots in discoidal field. (Figure 3a). 2. Markings more or less restricted forewing with a very small spot at base of discoidal cell, hindwing with vestiges of subapical spot and spots present in discoidal field (Figure 3b). 3. Forewing with nodal spot extending posteriorly up to Riv+v, hindwing with nodal spot and those present in discoidal field well separated from one another ( Figure 3c).
Variations in the wing markings of female: 1. Forewing with a distinct small spot at discoidal cell and a broad nodal spot extending proximally up to eighth antenodal nervure and posteriorly up to vein Cuii, hindwing with subapical broad fascia confined to posterior half of wing ( Figure 4a). 2. Hindwing with subapical and basal markings well separated, not joined by an isthmus (Figure 4b).