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utUwh 7leans lepid Soc. Jopan 48(1): 25-30, March 1997

Notes on the biology of Dereas gobrias (Hewitson, 1864) ( : , )

Christian H. ScHuLzE and Konrad FiEDLER

Lehrstuhl Tier6kologie I, Universittit Bayreuth,

D-95440 Bayreuth, Germany

Abstract The mature larva and pupa of Dercas gobrias (Hewitson, 1864) from Borneo (Mt Kinabalu National Park, Sabah) are described and figured. Additional {nfbrmation on habitat preferences, vertical stratifieation inside the forest, sex ratio and behaviour of the adults is presented. D. gobrias seems to be restricted to the canopy layer ofprimary rain forest habitats, The taxonomic status of the genus Dercas is briefly discussed in consideration of available information concerning host-plants and early stages.

Key words Pieridae, Coliadinae, Dercas gobn'as, immature stages, adult behaviour, habitat preferences, vertical stratification, Borneo.

Introduction

Little is known about the biology of the pierid species in the genus Dercas Doubleday, [1847]. This genus contains 4 iarge species (Bridges, 1988) which are distributed from Sikkim across Myanmar eastwards to China, and southwards to Java and Neomalaya (Malay Peninsula, Sumatra and Borneo) (Eliot, 1992; Otsuka, 1988; Wynter-BIyth, 1982); Among the deseribed nominal species, D. lycorias (Doubleday, 1842), n nina Mell, 1913, D, gobuas (Hewitson, 1864) and n verhueut (Van der Hoeven, 1839), the last two remain doubtfu1 about their specific status (Yata, 1985). As a consequence Otsuka (1988) includes West- Malaysia in the disnibution range of D. gobrias, whereas only D verkueM occurs in the Malay Peninsula aecording to Eliot (1992),

"the Although Eliot (1992) stated that early stages [of Dereas] are unknown", it is errone- ous. A rough description of egg, larva, and pupa was given by Mell (1943) for the genus Dereas in general and, additionally, the egg of D, verhueth was figured. A photograph of a larva ofn verhuent from Hong Kong can be fbund in Johnston & Johnston (1980). Some inforrnation on larval host-plants has been reported (Mell, 1913, 1943 ; Johnston & Johnston, i980), A detailed description of the larva, or pupa, however, has not yet been published. More precise data on the phenology and habitat preferences of the two tropical taxa, D. gobn'as and D. uethueM, are also sti11 lacking except of some infbrmation on the biology of D, vetthueM in Southern China (Mell, 1943). In this paper we describe and figure the mature larva and pupa of n gobrias. Furthermore we report our observations on habitat prefer- ences and behaviour of the adults in a rain fbrest in Sabah (North Borneo, East-Malaysia), with special reference te the vertical stratification inside the forest.

Methods

Observations were conducted in August and September 1993 and in February, March and April 1994 in the vicinity of Poring Hot Springs (Mount Kinabalu National Park) at an eleyation between 5oo-750 m a.s,1. Data about the vertical stratification of the fiying adults inside the fbrest were recorded from a canopy walkway system, which allowed us to observe

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26 Christian H. ScHuLzE and Konrad FiEDLER

al] the vegetation layers ofthe fbrest from the ground to the upper canopy. When adults of D, gobn'as are on the wing, they are very conspicuous and can easily be identified and counted using binoculars. During the standardized observation time of 20minutes each around noon, the maximum number of individuals which could be seen was counted by sexes and by vegetation layers (O-10m, 10-20 m, 20-30 rn, 30-tto m, 40-50m, and >50 m). For these standardized counts each stratum pair-O-1O ml10-20 m, 20--30 m/30-40 m, and 40-50 m/> 50 m-was scanned fbr 20 min from fixed observation positions at IO, 30 and 45 m above ground level. During the observation period in 1994 one final instar larva of n gobrias was fbund accidentally in search oflarval stages efLepidoptera in the canopy region ofthe forest. This caterpillar and the resulting pupa are presented in colour slides.

Habitat andadult behaviour

The ofn goZvtias ooeur frequently in the canopy ofmixed dipterocarp fbrest, which "hill is fioristically designated as fbrest" by Kitayama (l992). The maximum tree height is around 50 m (Kitayama 1992). We observed no adults near the forest understory except only one record of a male individual in a more open area around the station, although extensive observations (more than 150 hours) were done there. Hljuser (pei:s comm,) noted only two further males and one female near ground level during his stays at Poring Hot Springs in 1994,1995 and 1996. Furthermore, we did not observe any D. gobrias butterflies in open

60 s

× x × o I l l l iN=i6 × HE-coLm>cuJco--di.--,mao>6E.9dir 50 , i l lt- l 'l ltt 721zilv';Z;･.iliLIZ.iZ)2.li,izg".lliz;Z2Z'

'i'f" /'/li;Z2i 40 l i l ' 1 l17i･i fZ'l.llllZZ -ZZZt;)･･iva 7Z < 30 i i' i z 3 i i i 20 iti i i o iII 1 11 10 o li 1 li! 111t t / o 11111111 O,O O,2 O,4 O,6 O,8 1,O 1,2 Butterflies/Count

Fig. 1. Verttcal stratification of Dercas gobrias butterflies inside the forest, based on standard- ized counts ef flying adults in February-Aprii 1994. N:=Number ofobservation units. On the right of the bars the absolute numbers of counted individuais are given. The structure of the forest is schematically shown on the right side ofthe figure, The arrow indicates the approximate location of the eollected caterpillar.

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Biology of Dercas gobrias 27

Figs2-5. Dercas gobrias. 2. Upperside ofthe reared male. 3. Undersideofthe reared male. 4. Lateral view ofthe last instar larva. 5. Lateral view ofthe pupa.

cultiyated areas adjaoent to the close forest,

The vertical stratification ofthe adults inside the dipterocarp forest is shown in Fig. 1. The butterflies were recorded only in the strata between 20 and 50 m above ground level, and they

were most abundant in the canopy between 30 and 50 m.

The absence of records of D. gobrias during the observation period in 1993 may indicate that this species shows some kind of seasonality. Observations of females were very rare (ac- cumulated numbers: 1 female, as against 40males) like some tropical pierid species, e. g Aapias nero (Fabricius, 1793) (Eliot, 1992). Although various tree species were flowering during the observation period in 1994, we could not soe any adults visiting flowers nor feeding, while Htiuser (pet:s comm) recorded a female on flowers of Eupatorium odbratum at Poring on 9th January 1995. Mell (1943) and Wynter-Blyth (1982) noted fbr a closely related species, D vet:hueut, that males visited flowers and came to damp patches.

"patrolling D. gobrias seems to be a typical species", because males often used flight conidors between the crowns of emergent trees several times a day, probably in search for females. Mating or egg-laying behaviour could not be recorded throughout the observation period.

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28 Chtistian H. ScHuLzE and Konrad FiEDLER

Larya

On 27th March 1994 a nearly mature larva was found in the canopy ea 40 m above ground level. The food plant was a very large woody climber of the family Fabaceae with simply pinnate leaves. Two days later (29th March) the caterpillar fastened itself in a position fbr pupation which was atypical for Pieridae because the head was orientated dewnwards (Fig. 4). Pupation fo11owed on the next day (30th March),

It seems that only two earlier notes on larval host-plants of the genus Dercas exist in the literature, Mell (1913, 1943) mentioned the genus DaLbeign of the Fabaceae-tribe, Dalber- gieae, fbr n verhuent in South China, and Johnston & Johnston (1980) noted Daibergia benthami as larval host-plant ef the same Dercas species from Hong Kong. Because the

host-plant observed at Poring/Bomeo had no fiowers or seed-pods at the time of observation, a procise determination was precluded, Judging from characters offbliage and growth fbrrn, however, this plant most likely also belongs to the genus DaLbergia (Comer, 1988 ; Whitmore, 1983).

Description

Shape and colouration of the larva (Fig, 4) agreed with the typical character combination of most Coliadinae caterpillars. Head, thorax, and abdomen of the last instar larva are pale green. A diffUse yellew 1ateral stripe extended from the front of the thorax to the tip ofthe abdomen. The ventral side and the front of the head capsule are covered with white erect

setae, the dorsal side-dorsal region abeye the lateral stripe-is covered with shert hairs tipped with yellow globular structure. The abdominal spiracles are conspicuously whitish, The colouration is very similar to that of the D. vethueth caterpillar figured by Johnston & Johnston (1980).

Pupa

The pupa was fixed on a twig with the cremaster and a silken ghdle around the first abdominal segment as in most pierids, but, unlike typical pierids, the pupa was hanging head- down (Fig. 5). Whether this is the usual pupation behaviour of D. gobrias or not requires further confirmation. The form and colouration of the pupa are very similar to those of Hebomoia glauc41pe (Linnaeus, 1758). The ground colour is a pale yellow-green. Laterally and dorsally a straight reddish-brown line is stretching from the front of the head to the tip of the abdomen. In addition the antennal sheaths are tinged with reddish-brown (Fig, 5), Contrary to Mell's statement (1943) the pupal wing cases protrude distinctly. A male butterfiy (Figs 2 and 3) emerged from the pupa on orh Apri1 1994, 10 days after pupation.

Discussion

Our observations on adult behaviour as well as the location of only one larva found in Borneo indicate that DL gobhas is basically an of the canopy layer of intact rain forests, where the species is not rare at least at oertain times. Hence, the apparent searcity of Dereas butterfiies in tropical areas of SE Asia is probably an observational artifact caused by the dithcult aocess to the canopy. faunas of tropical fbrest canopy layers are among the least understood biotas on the earth (Groombridge, 1992), and we can expect that many [`rare" more butterflies oftropical rainforests will turn out to be canopy specialists rather than

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Biology of Dercas gobrias 29

to be truly species with low abundances, provided that more studies of these tree crown habitats become available. This emphasizes the urgent need of more observational and sampling efibrts in tropical forests as well as the importance of intact rain forests for preserving species which could hardly suryive in secondary habitats. As early as 1943, Mell remarked that survival of Chinese Deretzy spp. was restr:icted to remnants of forest-like vegetatlon.

The apparent restriction of Dereas butterflies to DaZbergia hostplants should be investigated in more detail, e. g by rearing 1arva ofrelated species or from other localities. Dathergia and its relatives are characterized by particular secondary metabolites (isoflavonoids ; e, g Frohne & Jensen, 1992). If Dercas larvae should turn out to be specialist herbivores ofthese plants, this specialization might be a synapomorphic trait supporting the monophyly and taxonomic distinction of the genus which is otherwise dif}ricult to separate from related Coliadines such as Goneptet:yx.

Acknowledgements

We thank Datuk Lamri Ali and Frances Liew fbr granting permission to work at Mount Kinabalu National Park. Special thanks are due to the staff of Sabah Parks at Poring Hot Springs for their kind suppert to our studies. DrChristoph L. Hh'user (Natural History Museum, Stuttgart) kindly provided access to some references, shared his own observations on Dercas gobrias, and gave critical comments on the earlier manuscript versien. Our field work was supperted through the Deutsche Forschungsgemeinschaft (Fi 547/1-1).

References

Bridges, C.A., 1988. Catalogue of Papitionidoe and Ptericine. Published by the author, Urbana, Ilinois. Corner, E.J.H., 1988, PVIiyside Tleees of Mtiidya 1 (3rd edn). xxii, 476pp., 138pls. The Malayan Nature Society, Kuala Lumpur. Eliot, J. N., 1992. 7;he Buttecflies of the Mala.v Peninsula (4th edn). x, 597 pp., 69 pls, The Malayan Nature Society, Kuala Lumpur, Frohne, D. and U.Jensen, 1992. Spstematik des Pfanzenreichs C4th edn). x, 344 pp. Gustav Fischer Verlag, Stuttgart, Jena, New York. Groombridge, B. (ed.), 1992. Global Biodivensity. xviii, 585 pp. Chapman & Hall, London, Glasgow, New York, Tokyo, Melbourne, Madras. Johnston, G. and B.Johnston, 1982. T7iis ts Hong Kong : ButterLMes. 224pp. Heng Kong Govern- ment Publication, Hong Kong. Kitayama, K., 1992, An altitudinal transect study of the vegetation on Meunt Kinabalu, Borneo, Vegetatio 102: 149-171. Mell, R., l913, Die Gattung Dereas Dbl. int, ent Z. 29: 193-194, 1pl.

, 1943. Inventurund 6kologischesMaterialzu einer Biologieder sUdchinesischen Pieriden -Beitrta'ge zur Fauna sinica XXI. ZoolQgica, Stutig 100: 1-132. Otsuka, K., 1988, Buttei:iZies qf' Borneo 1. xix, 61 pp., 80pls. Tobishima Corporation, Tokyo. Whitmore, T. C. (ed.), 1983. 7>ee Flbra oj' Madya1(2nd edn). 473,xpp, Longman,KualaLumpur. Wynter-Blyth, M.A., 1982. Buttepties qf' the indian Region, Reprinted edn. xx, 523pp., 72pls, Today & Tomorrow's Publ., Delh{. Yata, O., 1985. Pieridae. Ih Tsukada, E. (ed,), ButterLfZies of the Sbuth East Asian 1lslancts 2 (English edn). 623 pp,, 162 pls. Plapac Co. Ltd., Tokyo.

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30 Christian H ． ScHuLzE and Konrad FIEDLER

摘 要

ボ ル ネ オ 産 トガ リ キ チ ョ ウ の 生 態 （Christiun H ． Schulze and Konrad Fiedler）

ト ガ リ キ チ ョ ウ 属 （Dercas Doubleday ） は 東南 ア ジ ア か ら ス ン ダ ラ ン ド に か け て 4 種 を産 す る が ， こ れ ら の 中 に は 種 間関係 の 明 確 で な い も の も含 まれ て い る ．幼 生 期 に つ い て も未 調 査 の 部 分 が 多 く， Mell （1943） に よる こ の 属 の 卵 ，幼虫 ，蛹 の ラ フ な記 載 と D ． verhueili （Van der Hoeven ） の 卵 の 図 や Johnston＆ Johnston（1980） に よ る 香 港 産 の D ． verhuelli の 幼 虫写 真炉見 受 け られ る程 度 で あ る，私 達 は，ボ ル ネ オ の キナ バ ル 山国立 公 園で D ．gobrias （Hewitson）の 老熟幼 虫 と蛹 を観察 した の で 報告す る．また ，熱 帯雨林 で の 成虫 の 行 動 も，特 に 林 内 の 階 層 に 関 し て 調 査 した の で ，併 せ て 報 告 す る こ と に した ． − 観 察 は 1993年 8 月 ，1994 年 2 月，3 月，4 月 に Poring温 泉 （標 高 500 750 m ）周 辺 で 行 わ れ， canopy walkway system （林冠 通 路 網） か ら飛 翔 中 の 個 体 を森 林 内 で 記 録 す る方 式 に よ っ た ．飛 翔 中 の 成 虫 は 双 眼 鏡 で 追跡 し，林 床 か ら林冠 ま で を 10m 間隔 に 区切 っ て 20 分 ご と に そ の 個 体 数 を記 録 した ．樹高 − の 最 も 高 い も の で お よ そ 50m で あ っ た が ，成 虫 の 飛 翔 は 30 50 ・m の 林 冠 部 で 最 も 多 く見 ら れ た ． ま

た ，熱帯 の い くつ か の シ ロ チ ョ ウ，例 え ば ベ ニ シ ロ チ ョ ウ 等 と 同 様 ， ♂ に 比 べ て ♀ は 極 め て 少 な く，

そ の 比 は お よ そ ♂ 4e ： ♀ 1 で あ っ た ． 1994年 の 観察期 間中 は 様 々 な木 が 花 を つ け て い た が ，成 虫 の 訪

花 や 給餌 は 見 ら れ な か っ た ．交尾 や 産卵行動 も見 ら れ な か っ た が ， ♂ は し ば し ば，恐 ら く探 雌 の た め ， 日 に 数回発 生木上 部 の 飛 翔回 廊 を利用 し て い た の で ，本種 の 行動 は 典型的 な探索型 と 思 わ れ る．

幼 虫 は 1994 年 3 月 27 円，ほ ぼ 老 熟 した 1 頭 が 蔓 性 の マ メ 科 の 巨 木 の 地 il4em ほ どの と こ ろ で 得 ら れ た ． こ の 幼 虫 は 2 日後 に 前蛹 とな り，そ の 翌 日蛹 化 ，10 日後 の 4 月 9 日 に 羽 化 （♂ ） した ． こ の 植

物 の 正 確 な 鑑 定 は で き な か っ た が ，恐 ら く 1）albergia 属 の もの と思 わ れ た．文 献 記 録 に よ る と， Mell 〔1913，1943） は 中国南部 の D ．verhuelli の 食樹 と し て マ メ 科 の Datbergia tSを 挙 げて お り， Johnston ＆ JohnsLon （L980） も香港産 の 同種 の 食樹 と し て 同 じ 属 の Dathergia benthami を記録 し て い る ．

幼 虫 と 蛹 は 図示 の 通 り．幼虫 の 形態 と色彩 は ， モ ン キ チ ョ ウ 亜 科 の 多 くの 典 型 的な 特徴 を有 し，蛹 の

形 と 色合 い は ツ マ ベ ニ チ ョ ウ に よ く似 て い る ．蛹 が 下向 き な の は シ ロ チ ョ ウ 科 に あ っ て は や や 異 端だ 1 い が ， こ れ が 正 常 な も の か は こ の 例 だ け で は 判 断 で き な ．

ボ ル ネ オ で の 私達 の 観 察 か ら ，本種 は基 本 的 に は手付 か ず の 熱帯雨 林 の 林冠 層 の 昆 虫 で あ っ て ，そ の

よ うな と こ ろ で は 少 な く と も時期 的 に は稀 で な い こ と が 分 か っ た ．東南 ア ジ ア の 熱 帯域 で こ の 属 の 蝶 が 少 な い の も， そ う い っ た 林冠部 に 近 づ き に くい こ と に よ る と 思 わ れ る．熱帯雨 林 の 稀 な蝶 の 多 くは， 本 当 に 少 な い 訳 で は な く，結局 は そ の よ うな林冠 生 活者 と判明 す る こ と も期 待 され る， “ トガ リ キ チ ョ ウ属 の 食 樹 b ・ Dalbergia に 限 定 さ れ て い る か ど う か は さ ら に 調 査 さ れ ね ば な ら な い ． Dalbergia属 の 植物 は特殊 な 二 次 代謝 物 〔イ ソ フ ラ ボ ノ イ ド） で 特徴付 け ら れ る が ， も し ト ガ リ キ チ 』

こ モ マ ウ属が も っ ぱ ら の 植 物 に 結 び付 く こ と が判 明す れ ば ， 他 の 点 で は ン キ チ ョ ウ 亜 科 の 例 え ば ヤ キ チ ョ ウ属 な ど との 区別 が 難 し い こ の 属 の 単 系統性 や 分類学 的 区分 を支持 す る 派生 形質 と な る か も 知れ な い ．

［文 責 ： 吉 本 浩］

（Accepted September 26，1996）

Published by the Lepidopterological Society of Japan， c ／00gata Building，2−17， Imabashi 3−chome ， Chuo −ku， Osaka，541 Japan

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