On the female morphs, ecology and male genitalia of Callerebia dibangensis Roy (Lepidoptera: Nymphalidae: Satyrinae) recorded near Mayodia Pass in lower Dibang Valley, Arunachal Pradesh, India

Acknowledgements: I would like to thank the Indian Council of Forestry Research and Education (ICFRE), Dehradun for funding this study. I would give my our earnest gratefulness to Dr. N.S. Bisht, Director, Rain Forest Research Institute, Jorhat for providing unremitting support and necessary facilities. I appreciate the encouragement received from Mr. B.S. Sajwan, former PCCF, Arunachal Pradesh, for formulation of this project. I wish to thank Mr. J.L. Singh and Dr. N.N. Jhasa, former Chief Wildlife Wardens, Arunachal Pradesh, for their support during the project period. The assistance received from Lina Gogoi, Riyaz A. Ahmed and Abhijit Medhi, Ecology and Biodiversity Division, RFRI, in laboratory and during the field surveys to Dibang Valley, is worth mentioning. I would also express my thanks to the officials of the Arunachal Pradesh district administration and forest department for providing necessary facilities for stay during the tours, namely, Mr. T. Miso, DC, Upper Dibang Valley; Mr. Ranpok Pune, SDO, Hunli; Mr. Chetan, Range Officer, Anini. Finally, I would like to express my earnest gratitude to the local people of Dibang Valley, Arunachal Pradesh for their help rendered in the field. Abstract: Callerebia dibangensis was recently described from a single specimen collected in 1987 from Upper Dibang Valley, Arunachal Pradesh along with comparison of wing morphology of this single male individual with the congeners. However, there is no other information on the species. The current study recorded a large number of live individuals of such a species around Mayodia pass and was thus able to note the variations in wing morphology, the wing morphology of the female, distinguishing features between the sexes, observations on biology and ecology of C. dibangensis from Mayodia pass (1,900– 2,265 m) in lower Dibang Valley, Arunachal Pradesh, India along with comparison of male genitalia of C. dibangensis with its closest ally C. scanda opima from the same locality.

The author during the course of his surveys in Arunachal Pradesh covering 17 districts ( Fig. 1) from east to west (Tirap, Namsai, Changlang, Lohit, Anjaw, Upper and Lower Dibang Valleys, Upper, West and East Siang, Upper and Lower Subansari, Kurung Kumey, Popumpare, East and West Kameng and Tawang) from November 2011 to Dececember 2014 found six individuals of this Callerebia on 9 August 2012 from Mayodia pass and then again found the same species at the same place in very large numbers on 29-31 August 2013. While the author was himself thinking of describing this Callerebia, as a new species, he came across the publication in September 2013 (Roy 2013), in which a specimen of a male having similar wing morphology as that of the ones found in Mayodia pass was described as C. dibangensis. No genitalic information was given by Roy. The present findings thus give conclusive evidence to the existence of such a species from the Lower Dibang Valley.

Morphology Description
Female 1 (RFRI-39) (Image 1) : (Female not described earlier Upperside: Ground colour dark chocolate brown, slightly blackish, paler towards margins. Very large round orange-ringed apical ocellus (11mm), black inner with two white pupils. Edges of ring distinct and regular. Hindwing single tornal ocellus in space 2. Narrow reddish ring, black inner and white pupil.
Underside: Ground colour dark chocolate. Forewing apical ocellus large as on upperside, but with an additional thin reddish outer ring. Forewing termen margin covered with a thin scattering of white scales tapering towards tornus. Hindwing white scales forming prominent small striae with slight violet tones covering the whole wing apart from a narrow area around the tornal ocelli. Striae darker towards the costa and apex. In the basal half they are more separate and alternate with the dark brown ground colour producing a distinctive snow-drift like appearance. They are densest towards the discal region in spaces 1, 2 and 3 where they merge with one another. Hindwing has one tornal ocelli with white pupil, in space 2, much larger then 1c and also has a red in the dark space surrounding it. Both the ocelli are orange ringed. Ocellus in space 1 absent in this specimen but may be present as a minute dot in females.
Male 1  Upperside: Ground colour dark chocolate brown, slightly blackish, paler towards margins. The round orange-ringed apical ocellus (09mm) is not as wide as in the female and is more sharply defined, black inner with two white pupils. Edges of ring distinct and regular without orangish tinge bordering it. Hindwing single tornal ocellus in space 2. Narrow reddish ring, black inner and white pupil,but not so prominent and merging with the base wing colour.
Underside: Ground colour dark chocolate. Forewing apical ocellus large as on upperside, with an additional thin reddish outer ring. Forewing termen margin covered with a thin scattering of white scales tapering towards tornus. Hindwing white scales forming prominent small striae with slight violet tings covering the whole wing, except the narrow area around the tornal ocelli. Striae become darker towards the costa and apex. In the basal half the striae appears more separate and alternate with the dark brown ground colour. The striae are very close with each other towards the discal region in spaces 1, 2 and 3 where they merge with one another. One prominent orange ringed tornal ocelli with black centre, ocellus in space 2 very much larger and orange ringed than 1c which is blind almost insignificant, a tiny dot. A distinct dark space without white scales surrounds the ocellus in space 2.
Forewing length of 10 live individuals was measured besides these individuals in the field and it varied between 32-36mm (wingspan: 65-70 mm) while forewing length of two individuals of C. scanda opima from the same locality was 30-31 mm. The size of this species was larger than that of C. scanda opima (Images 5, 6). The specimens are at present at the Rain Forest Research Institute, Jorhat. After publication of the findings of the project, the Callerebia dibangensis specimens will be incorporated in the' National Forest Insect Reference Collection' at Forest Research Institute (ICFRE), Dehradun, which is the main and largest repository of forest insects in the country.

Male genitalia
Male genitalia (Image 4) of this Callerebia compared with C. s. opima from the same locality. The basic difference amongst them lies in the shape of the valva. In the former species the valva is much broader while it is a finger-like narrow projection in the latter. Male genitalia of this Callerebia also differs for male genitalia of Callerebia suroia Tytler and Callerebia orixa Moore as the 'uncus' is absent in these two species (Okano & Okano 1985) (http://ir.iwate-u.ac.jp/dspace/ bitstream/10140/2344/1/al-no36p157-160.pdf)

Variations in wing morphology
Female 1 (Image 2) the forewings in this individual are very large and broad, but the smooth curve of the costa convex and forming all around the apex to the termen is broken by an angle. The edges of the ring are not distinct but diffused with orange, encircling the large round apical ocellus. Hindwing has one tornal ocelli which is orange ringed but has red in the dark space surrounding it in the female while the male lacks the red in the dark space.
Individual no. 4 (Image 7) which is large in size. Hind wing has an additional third tornal ocelli which is represented in space 3, but being the smallest of the three tornal ocelli in line the others being in space 1 and 2. Ocellus in space 2 is much larger than 1c.
Individual no. 5 female (Image 8) has an additional smaller orange-ringed ocelli with a minute pupil in space 2 linked to the bigger round orange-ringed apical ocellus with white pupils in space 4 and 5.
The presence of an ocellus in space 2 on the under hindwing having a narrow reddish ring, black inner and white pupil and surrounded by dark space is the The presence of ocelli in spaces 1c and 3 has been found variable, absent especially in the females if even they are present, the ocellus in space 2 is always largest followed by ocelli in space 1c and space 3, respectively.
A total of six individuals were recorded in August 2012. Four individuals (1+1+2) were observed on 9 August 2012 from 13:30-16:10 hr on a hillside southwest facing, 70 0 slope, a few kilometers west of Mayodia. Two individuals (1+1), one male was recorded at 11:58hr near '55 Mile' and another individual at 13:15hr 13km before 'Tiwari Gaon' on 15 August 2012, while returning to Roing along the road side; both these sightings were close to human habitation.
This was the only species of Callerebia that I encountered in seven days (9-15 August 2012), the Dibang Valley up from Tiwari Gaon through Mayodia Pass-Hunli-Anini up to Mippi & from Anini to Dambuine towards Brunei. The altitude along the road varied from 1,900-2,300 m. No collections were made however.
However, during a second survey carried out from 28-31 August 2013, 93 individuals were counted at seven locations on a stretch of ca. 20km, 15km on both the sides of Mayodia pass, towards Roing on the south and Hunli towards the north at altitudes between 2,203-2,265 m. The habitat was shared with C. scanda opima which was also encountered in good numbers, both species flying together near Mayodia pass. This species was recorded from 28 0 17'20.7N-95 0 55'16.0E to 28 0 18'15N-95 0 55'21.3E in exceptionally high numbers.
During the last two surveys in the same area (Roing-Mayodia-Hunli-Etalin-Anini-Mippi route) from 11-16 March 2014 and from 6-10 June 2014 by the author this species was absent. The reason was cold weather in March (day time temperature, 17-20 0 C & low relative humidity, 44.8-72 %), but in June (day time temperature 20-25 0 C) and relative humidity (90-94.8 %) was higher than March but this species was still not to be found.

Habits and habitat
Prefers forest openings and edges along the shrubberies, moist shady rocks with over hanging grasses on hillsides (Image 12). Has a slow hopping flight, preferring to remain close to the ground flying around the same patch in circles and coming back again to the same spot after some time. When disturbed, moves up the mountain slope, but slowly comes down again after some time. Settles on stones, moist rocks, leaves and flowers of herbaceous vegetation. Individuals were observed settling on leaves of Rubus ellipticus shrub (Images 8,9 and 10), feeding on nectar of small shrubs and herbs, settling on grasses and dwarf bamboos along the roadside. Flies in all types of weather-sunny, cloudy and drizzling of rain. Individuals recorded in flight between 09:33-14:00 hr. Hides in over hanging grass to escape from heavy rain. Courtship and mating was observed in cloudy weather for two pairs (image Image 5. Callerebia scanda opima, dorsal and ventral views of a mating pair.

Conclusion
The findings of the this study suggest that this Callerebia is a cryptic species, restricted and locally common in and around 'Mayodia Pass' in lower Dibang Valley in Arunachal Pradesh in the east Himalayan region of India where it prefers rocky-grass habitat between ~1900-2300 m. July-September appears to be the main flight period of this species, this period is characterized by intermittent rains, cloudy weather and high humidity.
The wing pattern and shape shows slight variations in the female. A distinguishing feature between the sexes is that in the female the hindwing tornal ocelli, which is orange ringed, has 'red' in the dark space surrounding it while in the male this 'red' is lacking.