News of the Lepidopterists' Society Volume 51, Number 3 111e Polyommatine wing pattern elements and seasonal polYDhenism Of the Indian Chilades pandava butterfly (Lepidoptera: Lycaenidae) Krushnamegh Kunte1 and Ashish Tiple2 FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA 1 [email protected] Department of Zoology (Entomology Division) and Centre for Sericulture and Biological Pest Management Research (CSBR), RTM Nagpur University Campus, Nagpur 440033, India.2 [email protected]
Many butterfly species show The Polyommatine wing pattern wing pattern elements in the wet season environmentally induced but elements are clearly homologous to form are nearly invariable, as evidenced genetically determined discrete the nymphalid ground-plan (Nijhout by only slight individual variation seasonal forms. This is known as 1991). These are illustrated in Fig. 1 among the several hundred specimens seasonal polyphenism. The seasonal and Fig. 2.3 by the wet season form that we have inspected in the field and forms may have contrasting life history of C. pandava, and are as follows: (1) in research collections. strategies in response to varying Both wings have a dark brown bar at The dry season form, on the other hand, seasonal and social conditions such as the terminal end of the cell. (2) Both is remarkably variable. Individuals only ambient temperature and day-length, wings have a dark brown discal band differential availability of secure resting between veins 1b and 7 (the distal places, nectar plants for adults and band of the central symmetry system, larval host plants, and a different set Nijhout 1991). This band is composed of predators and predation risk of spots that are bounded by wing (reviews in Brakefield and Larsen 1984; veins. The positions of these spots Brakefield et al. 2007; Nijhout 2003, differ in each wing area, as also seen 1991; Shapiro 1976). Although in nymphalids (Nijhout 2001). (3) extensively investigated only in some Both wings have a sub-marginal dark Holarctic and African pierid and brown band. (4) The hind wing has a nymphalid butterflies such as Colias, large, black costal spot in wing space Araschnia and Bicyclus, seasonal 7 (between veins 7 and 8). (5) The hind polyphenism occurs extensively outside wing also has a series of sub-basal these groups within Pieridae, black or dark brown spots: one in wing Nymphalidae and in some Hesperiidae space 7, one in the cell, one in wing (Brakefield and Larsen 1984). The space 1c closely juxtaposed with the nature and diversity of seasonal spot in the cell, and one in space 1a polyphenism in these groups, however, along the dorsal wing margin. The are poorly known. first three wing pattern elements are H ere we describe in detail seasonal bounded on both sides by narrow polyphenism of Chilades pandava white bands, and the last two pandava Horsfield, 1829 (Lycaenidae: elements are ringed white. The inner Lycaeninae: Polyommatini). First we white margins of.the sub-marginal will describe in detail the wing pattern band on the hind wing are crescent elements of C. pandava, which follow shaped and much broader than the the general Polyommatine pattern. rest. (6) Among the series of marginal Then we will show how individually spots, the tornal spot in wing space 2 variable change in coloration of spaces (just above the tail) is large, black and Fig. 1: Wi ng pattern elements of C. pandava. broadly crowned orange. The tornal The veins are numbered. The wing pattern between specific wing pattern elements elements, demarcated by veins, are organized produces the remarkable diversity of dry spots in 1c are much smaller and into several series of spots, some of which form season forms in this species. narrowly crowned orange. The ground bands: 1: cell-end bar; 2: discal band; 3: sub color of the wings is usually very light marginal band; 4: costal spot in the wing space Wing pattern elements of brown but may be light grey or grey 7; 5: sub-basal spot in space 7, followed by three sub-basal spots in the cell and spaces 1c Chi/ades panda va, and changes brown in some specimens. However, and 1a; 6: tomal orange-crowned black spots. between the seasonal forms: the arrangement and presence of these Illustration: Krushnamegh Kunte.
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Fig. 2: Diversity and individual variation in the seasonal forms of C. pandava. Note how individual variation in the extent and coloration of the wing pattern elements produces the remarkable diversity of the dry season forms in this species. 1 & 2: upper sides of male, 4: upper side of female. 1, 3 & 4: wet season form of C. pandava. 2 & 5-12: dry season forms of C. pandava. 13 & 14: wet and dry season forms of C. Zajus . 15 & 16: normal and aberrant forms of Azanus jesous. The specimen details are as follows: 1: Indira Gandhi National Park (IGNP), theAnamalais, Tamil Nadu, 2S.v.2004. 2 & 8: Indian Botanic Garden, Shibpur, West Bengal, 4.xi.07. 3: Palamau Wildlife Sanctuary (WLS), Jharkhand, 17.vii.2004. 4: Dandeli WLS, Karnataka, 2.xi.OS. 5-7, 9-11: Ambazari Garden, Nagpur, Maharashtra, 5: 16.iii.200S, 6: 23.ii.200S, 7: 25.x.2007, 9: 4.xi.2007, 10: 30.x.2007, 11: 30.x.07. 12: Simlipal Tiger Reserve, Orissa, 7.i.200S. 13: IGNp, Tamil Nadu, 3.vi.2004. 14: Pune, Maharashtra, 26.xi.2006. 15: Kumbalgadh WLS, Rajastan, 4.vii.2004. 16: Chinnar WLS, Kerala, 6.ii.OS . (Photo credits: Rudraprasad Das [2, S] , Aniruddha Dhamorikar [4], Shreepad Hardas [14], Rafeek Khalid [16], Krushnamegh Kunte [1, 3, 13, 15], Manoj Nair [12], Ashish Tiple [5-7, 9-11]).
Volume 51, Number 3 S7 News of the Lepidopterists' Society Volume 51, Number 3 slightly affected by the climatic there are small seasonal differences in wing coloration and shape change conditions that produce the dry season the coloration and wing patterns on the between the seasons (Brakefield and form show all the characteristic wing upper side in both the sexes. In some Larsen 1984; Kunte 2000). The wet pattern elements of the wet season form males the blue coloration may be duller season form in E. laeta is bright yellow except that (1) the costal spot and the and the black border may be broader with rounded wings, and the dry season sub-basal spot in 7 on their hind wing towards the apex (Fig. 2.2), but we do form is very dull yellow with pointed turn brownish, and (2) the discal bands not know how commonly this occurs. wings, which helps the butterflies blend become lighter, sometimes almost as The seasonal polyphenism in C. with leaf litter during the dry season light as the ground color (Fig. 2.5-6). pandaua is not an isolated occurrence and escape predation. This note The typical dry season form, however, among Indian Polyommatini or highlights a little-known but promising differs from the wet season form as Lycaeninae is general. In Chilades lajus and phylogenetically distant example for follows: (1) The dark brown spots of the Stoll, 1780, the dry season form has an further studies on seasonal discal band in spaces 4 and 5 on the extensive smear of dark brown on the polyphenism. Population dynamics and hind wing extend inwards and coalesce hind wing from the cell-end bar to the seasonal polyphenism in C. pandaua with the cell-end bar, forming a large wing margin, which is lacking in the have already been reported (Tiple et al. brown area (Fig. 2.7-10). (2) The outer wet season form (Fig. 2.13-14). In the 2009). However, other aspects of white margin of the discal band and dry season form of Jamides celeno seasonal polyphenism may also shed inner white margin of the sub-marginal Cramer, 1775, the spaces between the light on its ecology and evolution in C. band coalesce either on both the wings discal bands on both the wings are filled pandaua. For example, there is (Fig. 2.10) or only on the hind-wing with dark brown whereas the tornal geographic variation in the occurrence (Fig. 2.7-9 and 2.11), forming a broad orange-crowned black spot is highly of seasonal forms in C. pandaua. The white discal or post-discal band (Evans reduced in size and orange coloration dry season forms have not been reported 1932; Pinratana 1981). (Kunte 2000). In Azanus jesous Guerin in the Sri Lankan subspecies, C. p. Individual variation and stability Meneville, 1849, we have not observed lanka Evans, 1925, and in populations of C. p. pandaua in the humid tropical of the seasonal forms: a dry season form in southern India but an aberrant specimen photographed areas in south-east Asia (Evans 1932). The following changes in coloration during the dry season showed several These population and subspecific show considerable individual variation, discal and sub-marginal wing pattern differences may merely indicate the lack which produce additional notable elements coalesced to form brown of climatic factors (high temperatures patterns among the dry season forms blotches (Fig. 2.15-16). Torben Larsen and lower rainfall and relative of C. pandaua: (1) discal spots and cell (personal communication) has seen humidity) that induce the dry season end bar may either coalesce on the fore neither seasonal forms nor aberrantly forms in C. pandaua (Tiple et al. 2009). wing (Fig. 2.10) or the discal spots marked individuals among thousands However, the possibility of increase in width (Fig. 2.7 and 2.12). of A. jesous in Africa. However, the polyphenism-related genetic differences (2) The white inner margin of the fore aberrantly patterned specimen depicted and genetic assimilation cannot be wing sub-marginal band becomes in Fig. 2.16 shows that there is overruled. Detailed comparative studies diffused to a variable extent (Fig. 2.5- developmental and/or genetic potential of the central Indian populations of C. 11). (3) The area between the discal for seasonally polyphenic coloration in pandaua with other subspecies and spots 4 and 5 and the cell-end bar on A. jesous. It also shows that similar closely related, seasonally non the hind wing becomes sooty-brown or type of color smearing between the wing polyphenic species may inform on the black (Fig. 2.9-10). (4) The tornal pattern elements occurs in A. jesous evolution of seasonal polyphenism in orange-crowned black spots on the hind and in C. pandaua, which appears to be the tribe Polyommatini. wing are either absent, greatly reduced a common response to high summer Literature Cited in size, or without the orange (Fig. 2.5- temperatures in Chi lades and other 12). (5) In highly unusual dry season Brakefield, P M. and T. B. Larsen. 1984. The Polyommatine and Lycaeninine evolutionary significance of dry and wet forms, the discal and sub-marginal butterflies. season forms in some tropical butterflies. elements appear smeared (Fig. 2.12). (6) Biological Journal of the Linnean Society, The Indian butterfly fauna offers several If the discal and sub-basal spots are 22: 1-12. elongated, their outer margins may nymphalid examples of seasonal Brakefield, PM., J. Pijpe and B. J. Zwaan. 2007. Developmental plasticity and acclimation turn black (Fig. 2.9-10). polyphenism: Melanitis leda, Mycalesis spp., Junonia almana, as well as their both contribute to adaptive responses to The sexes are similar on the underside, alternating seasons of plenty and of stress close relatives (Brakefield and Larsen in Bicyclus butterflies. Journal of although on the upper side males are 1984; Nijhout 1991). Many pierids are Biosciences, 32: 465-475. brighter blue with narrow black borders also known to be seasonally polyphenic, Eva n s, W. H . 1932. The Identification of whereas females have much broader Eurema laeta Boisduval, 1836, being a Indian butterflies. 2nd ed. Bombay Natural borders (Fig. 2.1 and 2.4). However, History Society, Mumbai. remarkable example in which both Continued on pp. 109
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