Fine Nanostructural Variation in the Wing Pattern of a Moth Chiasmia Eleonora Cramer (1780)

J Biosci Vol. 43, No. 4, September 2018, pp. 673–684 Ó Indian Academy of Sciences DOI: 10.1007/s12038-018-9793-y

Fine nanostructural variation in the wing pattern of a moth Chiasmia eleonora Cramer (1780)

1 2 SHAUNAK GHOSH and MONALISA MISHRA * 1Department of Biotechnology, Heritage Institute of Technology, Chowbaga Road, Anandapur, P.O. East Kolkata Township, Kolkata, West Bengal 700107, India 2Neural Developmental Biology Lab, Department of Life Science, NIT Rourkela, Rourkela, Odisha 769008, India

*Corresponding author (Email, [email protected]) MS received 23 February 2018; accepted 11 June 2018; published online 16 August 2018

Butterflies and moths possess diverse patterns on their wings. Butterflies employ miscellaneous colour in the wings whereas moths use a combination of dull colours like white, grey, brown and black for the patterning of their wings. The exception is some of the toxic diurnal moths which possess bright wing colouration. Moths possess an obscure pattern in the dorsal part of the wings which may be a line, zigzag or swirl. Such patterns help in camouflage during resting period. Thus, the dorsal wing pattern of the moth is used for both intra- as well as inter-specific signal communication. Chiasmia eleonora is a nocturnal moth of greyish black colouration. The dorsal hindwing possesses yellow and black colour patches. A white- coloured oblique line crosses both left and right fore- and hindwings to form a V-shaped pattern across the dorsal wing. This V-shaped pattern possesses a UV signal. Closer to the body, the colour appears darker, which fades towards the margin. The fine nanostructural variation is observed throughout the wings. This study elucidates the wing pattern of the geometrid moth C. eleonora using high-resolution microscopy techniques that has not been described in previous studies.

Keywords. Chiasmia eleonora; moth wing pattern; scanning electron microscope; structural and pigmentary colouration

1. Introduction background matching is poor (Merilaita and Tullberg 2005). In this context, prey with disruptive countershading with The family Lepidoptera includes members of butterflies and close likeness to the surroundings survived better compared moths. The members of this family possess unique charac- to a few cryptic prey that accurately matched the environ- teristic pattern in its wings (Nijhout 2001; Monteiro et al. ment (Merilaita and Lind 2005). Disruptive colouration 2006). The wing colouration is produced due to diverse function is independent of background thus gives better types of scales present throughout the body. The wing pat- survivability to the insect than cryptic ones (Sherratt et al. tern arises to provide maximum advantage to the insect in 2005). Crypsis and disruptive colouration increases the that environment (Hazel 2002; Monteiro et al. 2006). The efficacy of the insect to survive in different environments scales present on the body help in insulation, thermoregu- (Schaefer and Stobbe 2006). Most of the geometrid moths lation, hormone production (in case of a male) (Hill et al. possess such types of patterns on their wings. 2002) and supporting smooth flight. Besides this, the most In moths, the wing pattern shares similarity with the important function of the scale is to send signals for survival resting substratum. The moths’ behaviour is comprehen- as well as propagation. Thus, the scales help in camouflage, sively studied for its preferences to choose the background which is essential to safeguard the insect and find a potential substrate. Most moths consider two different parameters mate (Papke et al. 2007; Kolle et al. 2010). Moths are well while selecting its resting site. (1) Selection of a matching known for their camouflage mechanism. background colour (Stuart-Fox et al. 2004) and (2) appro- Camouflage mechanisms are of two types: (1) cryptic and priate resting orientation. Landing behaviour of a geometrid (2) disruptive colouration (Cuthill et al. 2005). In the cryptic moth was studied by various authors (Webster et al. 2009; mechanism, the contrast between prey and background is Kang et al. 2012; Wang and Schaefer 2012). According to reduced (Endler 1978). However, crypsis is specific to a this study, the moth cannot recognize the fine pattern of the particular background and it is not an effective camouflage trunk or wing or boundaries formed by shadow. Most of the (Lev-Yadun et al. 2004; Ruxton et al. 2004) when the geometrid moths possess a typical pattern on the dorsal side http://www.ias.ac.in/jbiosci 673 674 Shaunak Ghosh and Monalisa Mishra of the wing (Sihvonen et al. 2011; Kang et al. 2012). colourations of various regions were imaged and transferred However, a structural study from the wing pattern of a to ImageJ. geometrid moth is missing from the literature. Chiasmia eleonora Cramer (1780), a moth belonging to the Geometridae family and found in parts of south-west 2.4 Field-emission scanning electron microscopy Asia countries like India. We analysed the wing pattern for (FESEM) the following reasons. (1) The wing pattern of the geometrid moth is not described at high resolution in earlier studies. (2) Various coloured regions as described for optical micro- What contributes for the colour of the wing? Is it the scopy were mounted on a stub. Each stub has double structure or pigment is also not known. (3) Moreover, moth adhesive carbon tape on it. Various wing regions were patterning is less studied in comparison to butterfly. Thus, a coated with platinum with a sputter coater (JEOL- study on wing patterning of C. eleonora will be beneficial JFC1600 auto find coater) for 15 mins. Samples were for physicists, biologists as well as for material scientists. analysed under a FESEM (FEI, NOVA NANOSEM 450) at an operating voltage of 12 kV. Images were captured at various magnifications and processed and analysed using 2. Materials and methods ImageJ. Measurements of various morphological parameters like the distance between both the ribs, length of the 2.1 Collection of moths lamellae, microrib, crossrib, trabeculae and area of windows were conducted using the SEM images. Species of C. eleonora were collected from the National For morphological measurements, 10 moth wings were Institute of Technology, Rourkela campus, Odisha, India imaged using SEM. From each moth 20 measurements were (N22°1405700, E84°5205800) during June–July 2017 in live taken for each parameter. All the values were presented as condition. Moths were collected in the morning perched on mean ± standard deviation. green leaves of Jasminum grandiflorum and Ixora coccinea in a sitting posture. During early afternoon, moths were collected from damped walls of the corridor. Thirty moths 3. Results were collected and kept in a zipper bag at 4 °C. Later, fore- and hindwings were dissected out using a sharp blade. The C. eleonora possess body length of 1.8–2 cm and a dissected wings were kept in a glass petri dish in desiccators wingspan of 4–4.5 cm. The length of the forewing is at room temperature. Twenty wings were imaged with a ruler 1.21 ± 0.06 cm and the hindwing is 1.19 ± 0.02 cm. The and various measurements of the wings were taken using wings are brown in colour with white shades. The brown ImageJ. colour appears like a gradient in both dorsal and ventral regions (figure 1A and B). Closer to the body, the wing colour appears darker which fades towards the margin. 2.2 Analysis of UV signals The dark and light regions are separated by means of a white oblique line in both fore- and hindwings. A very The intact moth was placed inside a Gel Doc (Bio-Rad, thin black border is present on the side of the white band USA), and the images were captured under UV light. The of the hindwing, which gradually vanishes from the images were taken from both dorsal as well as ventral sides. forewing. The white band passes to the maximum extent Images were transferred to ImageJ for further analysis. of wings and covers both left and right half of the body to make a V-shaped structure over the wing (figure 1Aand B). In the hindwing, a rectangular-shaped black patch is 2.3 Optical microscopy analysis found. Next to the black patch another mixed yellow and black colour patch was found. The marginal region of the Various regions of the wings having distinct coloured pat- wing has white shedding and thorax is golden brown in terns were chosen for analysis. From the forewing region, (1) colour. brown (closer to the body), (2) white part and (3) greyish- Analysis of the wing under UV light: Under UV light, white part were chosen. Similarly, from the hindwing, (1) the V-shaped white pattern and the marginal region of the dark brown (closer to the body), (2) white, (3) yellow and (4) fore- and hindwings possess UV signals (figure 1C and D). black regions were selected for analysis. Appropriate regions The same pattern of the UV signal is observed for both were cut and placed on a glass slide. Slides were observed dorsal and ventral wings. under the optical-light microscope in reflection mode (Carl Light and optical microscopy (scale stacking): Various Zeiss, Inverted Optical light microscope, reflection mode) at regions of the dorsal and ventral fore- and hindwings were 409 in a 90° inverted position. In the reflection mode, the analysed under an optical microscope. Nanostructural variation in wing of C.elenora 675

Figure 1. An individual of C. eleonora:(A) dorsal and (B) ventral view. Note the colour variation between the dorsal and ventral side. The dorsal hindwing has black patch surrounded by yellow colour which is absent from the ventral hindwing. Moth under UV illumination: (C) dorsal and (D) ventral view.

3.1 Dorsal forewing scales are found in the marginal region which appears dull blue under the optical microscope (figure 2F). Dorsal forewing is divided into three different regions: A, B and C depending on the distance from the body. The region closer to the body is labelled as (A) major brownish-black 3.3 Dorsal hindwing and few white scales are found under the polarized optical microscope. The scales do not possess notch at its apical part The hindwing is divided into four different regions: A, B, C (figure 2A). (B) The white region of the wing. The scales and D based on the colour. (A) The grey region closer to the appear blue and the veins appear golden yellow under the body and scales are not easy to distinguish from each other polarized optical microscope (figure 2B). The apical parts of under the polarized optical microscope (figure 3A). (B)The the scales appear wavy. (C) The scales are dark brown white part of the wing and the scales look blue under the (figure 2C) and white in colour. The structure of the white optical microscope (figure 3B). Subsequently, (C) is the grey scale remains the same throughout the wing. region which is formed of black- and white-coloured scales. A rectangular black structure is found in the grey area. A patch of yellow- and black-coloured scales are found in this 3.2 Ventral forewing area. Yellow-coloured scales with golden-orange tinge are observed under the optical microscope (figure 3C). (D) The The ventral forewing is marked as D, E and F. The regions region after yellow which appears white, black or grey under closer to the body are marked as ‘D’ and possess golden- the polarized optical microscope (figure 3D). The apical part brown- and black-coloured scales. The white-coloured scales of the scale is wavy in its shape. as observed on the dorsal side are absent (figure 2D). The ventral white-coloured region marked as ‘E’ and the scales share similarity with scales of the white dorsal region. 3.4 Ventral hindwing However, the golden-coloured vein is absent from the ventral part (figure 2E). In the brownish region, both dark- and The ventral hindwing is marked as four different white-coloured scales are found. Elongated highly notched regions: E, F, G and H. E is the golden-brown region 676 Shaunak Ghosh and Monalisa Mishra

Figure 2. Colour variations observed in the forewing of C. eleonora under a polarized microscope. Normal photograph of the isolated dorsal and ventral sides of the forewing is shown in the central part of the image. The selected region of the dorsal and ventral forewing is marked based on the variation of colour. (A) Forewing dorsal region closer to the body possesses brown and white scales. (B) Forewing dorsal scales appear blue and the veins of this region appear orange under a microscope. (C) Light brown scales of the region away from the body possess both blue- and brown-coloured scales. (D) Ventral forewing closer to the body possesses golden-yellow-coloured scales and brown-coloured scales. (E) White scales of the ventral forewing appear similar to the dorsal one. The orange-coloured veins are absent from this region. (F) The ventral forewing marginal region appears bluish-white in colour.

and the scales are easily distinguished from each other. the marginal region of the forewing which appears blue The apical part of the scales is darker than the basal under the polarized optical microscope (figure 3H). part (figure 3E). (F) is the white region and the scales appear brownish-blue under the optical microscope (figure 3F). The scales are devoid of any wavy structure 4. Scanning electron microscopy in it. (G) This is the brown region and the scales are difficult to distinguish from each other. Brown scales Fine structural arrangement under FESEM: Moth wings have equal distance grey and white lining in it (fig- areformedofmanyscales(figure4). Different coloured ure 3G). Elongated, highly notched scales are found in scales were observed under an FESEM to reveal the fine Nanostructural variation in wing of C.elenora 677

Figure 3. Optical microscopy image of scales of the hindwing. Normal photograph of the dorsal and ventral regions of the hindwing is represented at the centre of the plate. Various regions are labelled based on the colour variation. (A) An image of the hindwing brown region and (B) white line of the hindwing. (C) The golden patch appears at the hindwing and marks the difference in the colour intensity of the golden region. (D) The region next to the white region possesses brown- and white-coloured scales. (E) Hindwing golden-coloured scales. (F) Scales from the white line appear brownish blue colour. (G) The brown-coloured scales appear white and difficult to distinguish among themselves. (H) The marginal scales appear blue in colour. structural arrangement. The general arrangement of a measured from different coloured scales present in the scale possesses many ridges/ribs which run throughout the currently studied moth wing. length (figure 4). Each rib is formed by overlapping of many lamellae. Ribs are joined with each other by crossribs. Attached to the rib often many microribs found 4.1 Dorsal forewing (figure 4). Crossribs form windows within the wing. Many projections are there from the crossrib which are called as The brown-coloured scales closer to the body (figure 5A) trabeculae. The shape and size of various structures vary have a length of 121.28 ± 10.37 lm and a breadth of for different coloured scales. All these parameters were 46.08 ± 0.91 lm. The distance between two midribs 678 Shaunak Ghosh and Monalisa Mishra

Figure 4. Graphical representation of various parts of scales: moth wing has overlapping of many scales. Each scale shows many ridges/ ribs. Each rib is formed of many lamellae. Attaching to the rib many microribs are found. Two ribs are joined with each other by crossribs. Between microrib and crossrib many empty spaces are found which are known as windows. From the crossrib many projections are found, which are known as trabeculae. measures 1.59 ± 0.05 lm and the crossrib measures between two ribs. The crossrib forms a reverse C-shaped 0.74 ± 0.11 lm. The windows have a wavy margin with an structure between two ribs (figure 5I). Each crossrib along with area of 0.362 ± 0.1 lm2. The crossrib makes a reverse microrib forms irregular wavy windows of 0.53 ± 0.12 lm C-shaped structure with both the ribs (figure 5B and C). diameter. The windows are either circular or oval in its shape. The white dorsal region of the wings has a linear The area of the window is 0.53 ± 0.12 lm2. Trabeculae-like arrangement of the scales (figure 5D). Each scale has a structures are not found (figure 5I). length of 97.44 ± 12.02 lm and a breadth of 45.80 ± 2.29 lm. The distance between two ribs measures 2.37 ± 0.37 lm and the length of each lamella is 4.2 Ventral forewing 0.505 ± 0.12 lm. The distance between two crossribs is 1.14 ± 0.13 lm. The microrib along with crossrib forms an The scales closer to the body are golden and deep brown in oval-shaped window (figure 5E and F). Trabeculae-like colour. Scales of this region are of various shapes (fig- structures are found within the window which measures ure 6A). The distance between two ridges is 1.2 ± 0.23 lm. 0.99 ± 0.31 lm. Windows are prominent but all are not The length of the trabeculae is 0.29 ± 0.15 lm, that of the open (figure 5E and F). The window area measures crossribs is 1.6 ± 0.06 lm and the diameter of the windows 1.05 ± 0.16 lm2. is 0.55 ± 0.11 lm. Trabeculae are absent in this type of The marginal scales are sharply notched (figure 5H) and scale. Crossribs are wavy and there is a window in every have a length of 171.88 ± 25.77 lm. The depth of the notch membranous structure (figure 6B and C). The area of the varies from 22.94 ± 5.38 to 25.07 ± 3.92 lm. The ribs are window is 0.413 ± 0.050 lm2. separated from each other by 1.39 ± 0.13 lm. Each rib is The scales of the white region do not have wavy tip. The formed by the crossover of lamellae which measures scale measures a length of 88.04 ± 23.17 lm and a breadth 0.45 ± 0.14 lm. The microrib forms a membranous structure of 46.17 ± 7.44 lm. All windows are unequal in size Nanostructural variation in wing of C.elenora 679

Figure 5. Scanning electron micrograph of the dorsal forewing. (A) Scales of this region have a smiley shape in the apical region. (B) The ridges are like parallel lines formed by overlapping of many lamellae. Crossribs are interconnected by a membranous structure having wavy holes at the centre. (C) At higher magniﬁcation, the crossrib appears like a reverse C-shaped structure. (D) The scales arranged in the white line of the forewing. (E) Parallel lines interconnected by means of the crossrib. Only two rows have windows and the adjacent rows are ﬁlled with membranous structures. (F) The window sends projection to the lamellae. (G) The marginal scales depict the elongated deeply notched area at the apical part. (H) Scales showing the distance between the ridge and the size of the windows. (I) The connection between two crossribs and the circular window can be seen in this image.

(figure 6D). The size of the window measures colour and the apical part of the scale appears wavy (fig- 0.51 ± 0.11 lm in diameter. The trabeculae are prominent ure 7A). The length of the ribs is 0.68 ± 0.08 lm and the for each of the open windows (figure 6E and F). The lengths length of microribs measures 0.4 ± 0.07 lm. The area of of the ridges and crossribs are 1.03 ± 0.06 lm and the windows is 0.67 ± 0.06 lm2. The trabeculae and 1.66 ± 0.08 lm, respectively. The distance between two crossribs measure 0.45 ± 0.15 and 1.48 ± 0.15 lm, parallel ridges and distance between two microribs are respectively. The crossrib has a membranous structure which 1.47 ± 0.08 and 0.154 ± 0.06 lm, respectively. The length gives irregular shape to the windows (figure 7B and C). of the trabeculae is 0.3 ± 0.09 lm. White-coloured scales present on the dorsal wings are The marginal scales appear like hairs (figure 6G). It has a shorter in size compared to other scales. The scale possesses length of 397.04 ± 30.37 lm and a breadth of notch in its apical region (figure 7D). The distances between 10.56 ± 0.38 lm. The distance between two ridges is two ridges and microribs are 1.79 ± 0.25 and 0.93 ± 0.11 lm and crossribs is 0.39 ± 0.05 lm. The 0.22 ± 0.13 lm, respectively. The length of the crossribs is windows are circular and have an area of 0.26 ± 0.07 lm2. 2.37 ± 0.37 lm. The lengths of the ridges and trabeculae Trabeculae-like structures are not seen in this type of scale are 1.06 ± 0.24 and 0.99 ± 0.31 lm, respectively. Win- (figure 6H and I). dows are prominent but all windows are not open (figure 7E). The window area is 1.05 ± 0.16 lm2. Window size and distance between the crossrib vary within the scale 4.3 Dorsal hindwing (figure 7F). The black scales are folded at the apical region (fig- The scales closer to the body share similarity with the scales ure 7G). The distance between the two ribs is of other forewing regions. The dorsal hindwing is yellow in 1.57 ± 0.13 lm and that of the crossrib is 0.89 ± 0.09 lm. 680 Shaunak Ghosh and Monalisa Mishra

Figure 6. Scanning electron micrograph of scales of ventral forewing region. (A) The scales of the ventral yellow region appear irregularly wavy at its apical part. (B) Higher magnification reveals parallel scales with circular windows. (C) The crossrib appears to be a smooth V-shaped structure at higher magnification and has a hole at the centre. (D) Scales from the white region do not have many notches at the apical part. (E) Windows present within the scales are irregular in its size. (F) Very few micro-ribs are found within the scale. (G) Scales present in the marginal region of the scales have the flat apical part and hairy scales are present in the margin. (H) Scales have many ridges and windows. (I) Windows are irregular in size.

The windows form an irregular oval-shaped structure (fig- scale and the depth of the crossrib is more (figure 8E and F). ure 7H) with an area of 0.55 ± 0.08 lm2. The windows The size of the projection is 0.24 ± 0.01 lm. send projection to the lamellae (figure 7I). The scales in the marginal regions have deeply notched apical region (figure 8G and H). The distance between two ribs is 1.39 ± 0.11 lm and that between two crossribs is 4.4 Ventral hindwing 0.7 ± 0.15 lm. The microribs are prominently visible. The microrib of two adjacent ribs forms a V-shaped membranous The ventral hindwing closer to the body is golden yellow in structure (figure 8I). A window of 0.22 ± 0.02 lm diameter colour and share structural similarity with the yellow scale of is found at the centre of the membranous structure. The area the dorsal region. The scales of the white regions are equally of the window is 0.11 ± 0.02 lm2. notched. Next, to the white region brown and the white mixed regions are found. White scales have the apical tooth- like structure (figure 8A and B). The distance between two 5. Discussion ribs is 1.47 ± 0.08 lm and trabeculae length is 0.27 ± 0.06 lm. The area of window is 0.32 ± 0.06 lm2. In this paper, we have investigated the wing pattern of a The scales possess numerous trabeculae on it (figure 8C). moth C. eleonora using various microscopy techniques. The brown scales are wavy at its apical part (figure 8D). The The most striking pattern of this moth is the white V-shaped scale has a length of 93.16 ± 7.94 lm and a breadth of pattern present on the wing. Further, in C. eleonora, the 38.26 ± 3.7 lm. The distance between two ridges is scales of the white region are separated by the dark area in 1.53 ± 0.12 lm and that between crossrib is the dorsal hindwing. What is the biological significance of 0.78 ± 0.08 lm. The crossrib forms a wavy structure in the this pattern? Is it advantageous for the insect? If we apply Nanostructural variation in wing of C.elenora 681

Figure 7. Scanning electron micrograph of dorsal hindwing region. (A) Dorsal scales of the yellow region is wavy at its apical part. (B) Parallel ridges are found within the scales at higher magnification. (C) Windows are rectangular in shape and membranous structures are flanking from the side of the crossrib. (D) Most of the scales from the dorsal region appear rectangular in shape with few notches in the apical region. (E) Two ridges have windows which are flanked by the blind membranous structure. (F) Windows are irregular in its shape. (G) Scales present in the black region have twisted apical region. (H) Parallel ridges are present within the scale. (I) Windows are oval in its shape. the theory of physics to the wing of C. eleonora the In this study, the dorsal yellow patches with UV signal prob- combination of such white and dark parts physically con- ably essential for inter-specific communication. stitutes the diffraction grating pattern for the wing. Thus it The wing of various parts of C. eleonora appears different is easy to detect the pattern of the wing even if the insect under a polarized optical microscope. The colour variation does not possess high resolution in its eye. Geometrid moth suggests that the wing reflects polarized light and thus gives does not have good vision to recognize minute variation in a different colour to the wing. The wing colours originated pattern (Stuart-Fox et al. 2004). Thus, a three-dimensional from various physical phenomena of light such as reflection, clue is required for the pattern recognition. The V-shaped polarization and special distribution (Konnen 1985; Genet pattern of the wing probably helps the moth to detect the and Ebbesen 2007). Insects use polarized signals as a secret partner. Further, the V-shaped pattern possesses UV signal for inter-specific communication (Kelber 1999; Douglas in it. UV is a honest signal for the partner recognition in et al. 2007; Stavenga et al. 2012). Besides that butterflies use moths (Mishra et al. 2017b). The current study also antic- polarized signals for navigation and finding the oviposition ipates the V-shaped pattern has a similar mechanism for C. site (Sweeney et al. 2003; Reppert et al. 2004; Cuthill et al. eleonora. 2005). Polarized signals of the wing arise due to various The wing colouration appears darker closer to the body microstructures present within the scales (Vukusic et al. which fades towards the margin. The gradient colouration is 2000; Saba et al. 2011; Wilts et al. 2011). The microstruc- not seen on the ventral side of the wing. The dorsal hindwing tures were categorized as ridge lamellae, body lamellae and possesses patches which are missing from the ventral side. In photonic crystal (Gorb 2009). Various studies already the case of moth, the dorsal part of the wing is visible during reported that the ridges of butterfly wing scales contribute to the resting condition. Further, the patches present in the wing metallic-white colour (Watanabe et al. 2004; Vukusic et al. provide various intra- as well as inter-specific communication. 2009; Chen et al. 2012). 682 Shaunak Ghosh and Monalisa Mishra

Figure 8. Scanning electron micrograph of ventral hindwing region. (A) Lower magnification of scales of the white region present in the marginal part of the wing. (B) Higher magnification shows the arrangement of the ridges. (C) Arrow represents the trabeculae. (D) Black scales in the marginal region. (E) Parallel lines are present within the scale. (F) Crossribs are thick as the ridges. (G) Lower magnification of marginal scales. (H) Higher magnification depict the arrangement of ribs. (I) Microribs of two adjacent ribs formed a V-shaped structure having a window at the centre.

SEM analysis further reveals different dimensions of (Shiel et al. 2015). The window size present in the black ridges, windows and crossribs for different coloured scales. patch is very narrow. A similar structural arrangement is The physical parameter of each scale, diffracts the light in also reported for black scales of pierid butterflies (Stavenga various directions and thus helps in the production of dif- et al. 2004;Mishraet al. 2017a). The golden- or orange- ferent colours (Vukusic et al. 2000). The scales closer to coloured scales share structural similarity with other the body possess a membranous structure attached to the reported golden-coloured scales (Ve´rtesy et al. 2006; window. The membranous arrangement gives wavy Mishra et al. 2017b). The golden patch of the currently appearance to the window. Such structural arrangement is studied species possesses UV signals in it. The golden not reported from other moths. The scales of the white patch along with UV signals helps in mate selection in V-shaped pattern are blind for some of the ridges. Usually, Heliconius erato (Finkbeiner et al. 2017). The apical part of white-coloured scales possess open windows (Stavenga the scales found in the black-coloured patch is twisted. et al. 2004). In this context, the role of many blind win- Such structural arrangement helps in colour mixing as dows present in the V-shaped white pattern is an open reported from other species (Yoshioka and Kinoshita 2007; question at this moment. We are reporting such a kind of Yoshioka et al. 2008). The marginal scales are larger and its arrangement for the first time in the scales which possess shape varies from the scales present in any other part of the UV signals. Black and yellow patches are present in the wing. However, the nanostructural arrangement of the scale hindwing. The patches possess numerous signals for shares similarity with the scales present in other parts of the intraspecific communication in Lepidoptera (Dey et al. body. The white scales present away from the body possess 1998). Recently in moth A. caricae, the role of the dorsal more trabeculae as reported from Hypolimnas salmacis patch for intraspecific communication has been established (Siddique et al. 2016). Although we did not observe any (Mishra et al. 2017b). The role of orange patch of hindwing pigment in the dorsal side, pigments are found in the is established as a warning signal in moth Teia anartoides ventral part of the wing attached to the crossribs. Nanostructural variation in wing of C.elenora 683 The wing colouration of the moth C. eleonora is due to Kelber A 1999 Why ‘false’ colours are seen by butterflies. Nature the pigment as well as the fine nanostructural changes pre- 402 251 sent in the wing. 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