Callerebia dibangensis (Lepidoptera: Nymphalidae: Satyrinae), a new butterfly species from the eastern Himalaya, India

 

Purnendu Roy

 

1 Gabriel’s Wharf, 56 Upper Ground, London SE1 9PP, UK

1 purnendu@ganesha.co.uk

 

 

Abstract: A new species of butterfly in the genus Callerebia (Butler, 1867) is described from the Upper Dibang Valley district, Arunachal Pradesh, India.  A combination of very distinctive characters: large size; highly rounded wings; striking under hindwing white scales; distinctive under hindwing tornal ocelli; large round forewing orange apical spot and a dark brown under ground colour distinguishes this butterfly from any other Callerebia species. 

 

Keywords: Arunachal Pradesh, Callerebia opima, C. scanda, C. orixa, C. annada, C. suroia, Dibang Valley, Mithun River.

 

 

doi: http://dx.doi.org/10.11609/JoTT.o3293.4725-33   |  ZooBank:urn:lsid:zoobank.org:pub:CA33D1C9-AD1B-4CE6-8C33-CBCEDEB81D29

 

Editor: Peter Smetacek, Butterfly Research Centre, Bhimtal, India.             Date of publication: 26 September 2013 (online & print)

 

Manuscript details: Ms # o3293 | Received 06 August 2012 | Final received 12 September 2013 | Finally accepted 13 September 2013

 

Citation: Roy, P. (2013). Callerebia dibangensis (Lepidoptera: Nymphalidae: Satyrinae), a new butterfly species from the eastern Himalaya, India. Journal of Threatened Taxa 5(13): 4725-4733; http://dx.doi.org/10.11609/JoTT.o3293.4725-33

 

Copyright: © Roy 2013. Creative Commons Attribution 3.0 Unported License. JoTT allows unrestricted use of this article in any medium, reproduction and distribution by providing adequate credit to the authors and the source of publication.

 

Funding: Self funded.

 

Competing Interest: Author declare no competing interest.

 

Author Details: Purnendu Roy is a naturalist with a particular interest in the eastern Himalaya where he has recorded several new Indian butterfly records.  He is currently working as a volunteer with Ifoundbutterflies.org developing the database and source code and is committed to open access resources for naturalists.

 

Acknowledgements: Dr. David Lees, Curator - Lepidoptera, Natural History Museum for his valuable views and assistance. Tipa Umbrey who guided me on many occasions in the Dibang Valley. Dibang Valley Political officer who also guided me several times. The many people of the Dibang Valley who provided me hospitality throughout my stay. Sanjay Sondhi,Titli Trust for giving me the opportunity to renew my passion for butterflies. Jo Lawbuary my partner for her love and support.

 

 

For figures, images, tables -- click here

 

 

Introduction

 

Callerebia (Butler, 1867) is a genus of approximately 11 species and 20 subspecies (Appendix 1), almost entirely confined to the Sino-Himalayan region.  The genus is composed of medium to large butterflies with small bodies in relation to their broad, rounded wings. The hindwing in many species is produced at the tornus to form a slight lobe.  The antennae are thin, only slightly thickening towards the tip.  The markings, though very variable follow a fairly constant arrangement: the upper ground colour is dark brown to blackish; the forewing with a bi-pupilled apical ocellus; the upper hindwing with or without one tornal spot; the under hindwingsare often covered by whitish scales of different densities, tones and patterns, with or without one or two tornal ocelli; in addition, some species have a set of up to four post-discalwhite dots on the under hindwing.  All species may also have additional ocelli as part of their variation.  Older literature on Indian butterflies (Talbot 1947; Wynter-Blyth 1957) places Callerebia under Erebia. Bruna et al. (2000) treat these species as being under Callerebia, Hemadaraand Paralasa.  Huang (2003) described a new species of Callerebia - C. ulfi fromnorthwestern Yunnan and did a revision of C. polyphemus and its subspecies and had a note on the status of C. suroia.  Bruna et al. (2000) comments on the taxonomic uncertainty of this genus, the remarkable variation in wing pattern and genitalia morphology.  It is certainly the case that the variation in pattern that exists between different populations has made the use of key-based identification very difficult and has led to confusion over the status and identity of certain species and forms. Several of the eastern Himalayan species are characterised by their large orange-ringed forewing apical ocellus contrasting prominently against a dark brown, blackish upper ground colour. The under hindwings are covered with prominent white striations.  Though many of the species appear confusingly similar, this new species is visually very distinct and is a beautiful and striking addition to the eastern Himalayan fauna.

The Upper Dibang Valley District (Fig. 1) lies between 95015’–96035’E & 28022’–29027’N.  It is further north than Bhutan, Sikkim and eastern Nepal.  It is situated in a very complex and active geological zone where the main Himalayan axis turns abruptly north-west to south-east forming a ridge of moderately high mountains to the north and east, between 4000–5400 m, which separate the Dibang Valley from the Pemakoregion of Tibet to the north and Chayu county of Tibet to the east.  A western ridge largely above 3600m separates the Dihang and Dibang valleys. The district capital Anini (1,968m) is situated on a plateau between the confluence of the Driand Mithun rivers and its annual rainfall (2003) was 3,281.33mm (Upper Dibang Valley official website 2012).  The predominant natural vegetation around 1800m is sub-tropical hill forest and temperate forest.  However, there are quite large areas of grasslands in the Dri and Mithunvalleys probably formed principally by human activity.  The district is sometimes regarded as India’s remotest, on account that the road connection is frequently closed by landslides from April to October.  72.32% of the district is recorded as forested (Department of Environment and Forests, Government of Arunachal 2012) and has the lowest population density of any district in India (<1km-2) (Upper Dibang Valley official website 2012) (Fig. 1 – Satellite Image of Upper Dibang Valley District).

 

 

Method and Materials

 

The majority of the sites visited were in the Driand Mithun valleys within a day’s return walk from Anini (c. 2,000m) from the period of 17 July to 13 August 1987.  14 to 16 August 1987 were spent travelling to the Ithun Valley on the southern edge of the Upper Dibang Valley District.  The DibangValley government provided a guide and assistance, which was invaluable.  Only species considered of interest and which could not be determined in the field were collected. These are deposited in the Natural History Museum, London, U.K.

Previous to the visit to the Upper DibangValley, the author had undertaken numerous visits to Nagaland, Manipur and Arunachal Pradesh and so was familiar with many of the butterfly species that commonly occur in northeastern India.

 

Callerebia dibangensis sp. nov.

(Image 1)

urn:lsid:zoobank.org:act:E75C7E6D-3C75-4AF5-853F-C9981CD51C53

 

Material examined

Holotype: # 982926, 24.vii.1987, male, 28.880N & 95.850E, ±10km, c.1,830m, MithunValley, Upper Dibang Valley District, Arunachal Pradesh, India, coll. Purnendu Roy, The Natural History Museum, London.

 

Diagnosis

There does not appear to be any other species of Callerebia like this species in the Natural History Museum collection.

The following is a list of characteristics that are unique to this specimen and/or rarely expressed by other Callerebia species. Reference can also be made to images 2–4 which feature the other Indian Eastern Himalayan species C. scanda opima,C. suroia, C. scanda scanda, C. orixa and C. annada annada.  A Chinese species, C. polyphemus, is similar toC. suroia, but is usually not so well marked on the under hindwing.  Comparison has only been made against male specimens.  Females are usually larger, upper ground colour paler, underside markings more pronounced and the apical ocellus rounder.

(i) Size: One of the largest male Callerebia specimens (Table 3); only large forms of C. polyphemusand C. scanda opimaare of comparable size.  Within the NHM collection, C. dibangensis sp. nov. isnoticeably larger than other male specimens.

(ii) Wing shape: The forewings are very large and broad, the costa convex and forming a smooth curve all around the apex to the termen.  The hindwing tornus is barely produced and rather round.  Only specimens of C. scanda opima from eastern Bhutan express a similar forewing shape, but their hindwing tornus tends to be noticeably produced.

(iii) Underside hindwingpattern: The under hindwingpatterns of Callerebia (Image 4) are complex and difficult to describe. In several species the scales on the hindwing are arranged as short little white lines called striae.  In the new species the white striae on the basal half of the wing are very well separated, regular and straight.  They contrast prominently with the dark brown ground colour.  Apart from the costal margin and apex the striae are always white with no evidence of variegation or bands in the hindwingpattern. The tone of the white scales is slightly violaceous.

(iv) Underside hindwing tornal ocelli: The ocellus in space 2 is larger than is typical for Callerebia and the ocellus in 1c tiny and blind.  It is the only species where the ring colour is orange rather then yellow-fulvous.  When ocelliare expressed in other species this combination of a large ocellusin space 2, with a tiny blind ocellus in 1c, does not appear typical.

(v) Forewing apical ocellus: The ocellusis very large, rather round and has a wide and fairly regular orange ring of a uniform colour. C. suroia and C. polyphemus also have a large ocellus, but it is very different from the new species: when large the ring is constrained distally; far more irregular; elongated posteriorly and with a greater amount of red suffusion.  The ocellus ofC. orixa is the most similar in terms of appearance and roundness, but the orange ring is never as wide as the new species in relation to ocellus size.

(vi) Under ground colour: Dark chocolate brown, much darker and plainer then C. scanda, C. orixa, C. suroia and C.annada.

The closest species appears to be C. scanda opima (Images 2–4, Fig. 2).  Fourteen males of C. scanda opima in the NHM collection were compared with C. dibangensissp. nov. andthe key external features are summarised in Table 1.

Table 2 is a list of all Callerebia species with their key characteristics. It has been highlighted where they differ from C. dibangensissp. nov. eitheras a group or individually.

Species names and genera were referenced in LepIndex (Beccaloni et al. 2003) and Savela (2012) to ensure that I have compared the new species with all possible species of Callerebia. There was no comparable species in the allied genera of Hemadara,Loxerebia, Argestinaand Paralasa which are comprehensively covered by Brunaet al. (2000).  The plates of d’Abrera (1985, 1990, 1992) covering Satyrinaein the Holarctic and Oriental regions were also referred to and there appears to be no other genera this species may belong to.

On the basis of the unique combination of these characteristics mentioned above I propose this as a new species.

 

Description

Holotype: # 982926, 24.vii.1987, male (Image 1). Forewing length 34mm. 28.880N & 95.850E ±10km, c.1,830m,Mithun Valley, Upper DibangValley District, Arunachal Pradesh, India, coll. PurnenduRoy, the Natural History Museum, London.

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 termenmargin covered with a thin scattering of white scales tapering towards tornus.  Hindwing white scales forming prominent small lines (striae) with slight violet tones covering the whole wing apart from a narrow area around the tornal ocelli.  Striae become darker towards the costa and apex giving a fading effect.  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 two tornal ocelli, ocellus in space 2 much larger then 1c which is blind.  Bothocelli orange-ringed with a black centre.  Ocellus in space 2 with a white pupil.

 

Etymology

Named after the Dibang Valley District in Arunachal Pradesh, India.

 

Location

Only one specimen was observed and collected on the 27 July 1987 and is the holotype. The species was collected along the track that leads from Anini to Mipi between the altitude of 1600–1800 m approximately 5–10 km from Anini. The surrounding vegetation was mixed sub-tropical broad-leaf forest.  There was no GPS available and there was no nearby habitation or named place.

 

 

Discussion

 

This very distinctive butterfly was collected in 1987.  It is possible this butterfly was overlooked for the following reasons:

(i) There appear to have been very few butterfly surveys of the Dibang Valley.  Evans (1914) lists the butterflies collected by F.M. Bailey during his tour of southeasternTibet. He started his trip from the Mithun Valley in mid May 1913, but does not appear to have recorded any butterflies from the region.  Borang et al. (2008) conducted a survey of the Dihang-Dibang Biosphere Reserve during November 2006 and October 2007 and recorded 134 species/subspecies, but this covered many places outside of the Dibang Valley and the survey dates were probably rather late for higher elevations and they did not record any Callerebia species.   Endemicityis not a feature of Himalayan butterflies, but as outlined in the introduction the Dibang Valley is in a very unique geographical zone.  Two Callerebiaspecies from neighbouring regions of Tibet - C. tsiravaand C. baileyi appear to have very restricted distributions.

(ii) The specimen was collected at the end of July in Upper Dibang Valley. Many places such as Eaglenest (West Kameng District) have access problems in the monsoon and are consequently poorly surveyed in the months of July and August which also appears to be the main flight period for C. scanda opima according to the NHM collection labels.

(iii) The most surveyed areas in Arunachal Pradesh appear to be Eaglenest (West Kameng District) and Namdapha (ChanglangDistrict).  Both these areas are on the outer ranges and are not an interior location where this species was collected.

 

C. orixa, C. annada, C. suroia, C. scanda scanda and C. scanda opima are the present known Callerebiaspecies from northeastern India (Images 2–4).  In addition an allied species Hemadara narasingha has been recorded from Sikkim, Arunachal Pradesh (AborHills) and the Lower Tsang Po.  This species is smaller, with narrow forewings and the hindwingangled on the termen and produced at the tornus.  A description may be found in Talbot (1947). I cannot find much literature regarding recent records of Callerebia in Arunachal Pradesh. Betts (1950) records C.orixa from West Kameng‘Rupa, 5000ft. Sept. Common in grassland in sheltered valleys in the temperate Momba country.’  Older literature records two more possible Indian species.  South (1914) records a specimen of C. polyphemus collected by F.M. Bailey at Tawang, Arunachal Pradesh.  It should be noted that C.polyphemus has not been recorded so far west and C. suroia was only described in 1914 so the identification of this record needs to be confirmed.  South (1913) also records that F.M. Bailey collected a specimen of C. baileyi fromDichu (6000ft, 1829m). The DichuRiver, Anjaw District, Arunachal Pradesh is just before the border with Tibet.  The majority of the specimens were from Drowa Gompa, Tibet (3,048m) to the north of the Mishmi Hills.  I have not seen any contemporary records for this species in India.

Rather speculatively I think the new species is closely allied to C. scanda opima on the basis of wing shape and the under hindwing pattern.  There also appear to be minute white dots in space 6 of the under hindwing.  These white dots do not appear to occur in C. polyphemus, C. suroia, C. annada and C. orixa. Bruna et al. (2000) comment that most Callerebia species are allopatric.  However, the distributions of C. suroia and C. orixa overlap in Manipur and Nagaland, though it is not known if they fly together in the same habitat.  It will be interesting to have contemporary field data and phylogenetic studies to clarify the relationships of the different forms and species.

 

Conclusions

Callerebia dibangensis sp. nov is a new species of Satyrinebutterfly from the Dibang Valley in the eastern Himalayan region of India possibly allied to Callerebia scanda opima.  I propose that this common name is determined by the people of the DibangValley, since this butterfly appears to be endemic to that valley.

 

 

REFERENCES

 

d’Abrera, B.L. (1985). Butterflies of the Oriental region. part 2 Nymphalidae,Satyridaeand Amathusidae. Melbourne: Hill House,  248–534pp: col. ill; 35cm.

d’Abrera, B.L. (1990). Butterflies of the Holarctic Region. Part 1 Papilionidae, Pieridae, Danaidae and Satyridae (partim). Vic.: Hill House, 185p: col ill, maps, ports; 36cm.

d’Abrera, B.L. (1992). Butterflies of the Holarctic Region. Part 2 Satyridae(concl.) & Nymphalidae(partim). Black Rock, Vic.: Hill House, 1992. xv,[3], 186–334pp: chiefly col ill, maps, port; 35cm.

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Department of Environment and Forests, Government of Arunachal (2012). Forest Statistics <http://arunachalforests.nic.in> Onlineversion dated 12 July 2012

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Huang (2003). A list of butterflies collected from Nujiang(Lou Tse Kiang) and Dulongiang, China with descriptions of new species, and revisionalnotes Neue Entomologische Nachrichten 55: 3–114.

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South, R. (1913). A list of butterflies collected by Captain F.M. Bailey in western China, south-easternTibet, and the Mishmi Hills, 1911 Journal of the Bombay Natural History Society 22(2): 345–365, (3): 598–615.

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