vol. 4, No. 1-4, March-December 1990 87

Tetngldae () With Partly Exposed Wings

RE Blackith Zoology Department TI iIlity College Dllblin-2 Ireland

Abstract

Long series of some species of project beyond the pronotal shield by some 15- 35 percent. of theIr...Ieagth, depending. on the and alary polymorphism is not normally detect- I' i ce, iw ne e ecime able. '1'00 role of such exposed wings is dis cingalensis (Walker) from the Lyman Entomological Museum of McGill University, cussed and one new species is described. Most MontIeal, show extraordinaly unifoIInity in the such species pwbabliowe their evident rela­ tionship to evolution prior to the disintegration length of exposed wings. For some reason, of the Gondwanaland super-continent. conceivably common descent or common deploy­ ment in normally wind-flee habitats, 01 both, there is a regional trend toward long wings pro­ Introduction jecting beyond the pronotal shield. Opinion as to the taxonomic value of relative wing-length in The ot"elwhelming majoIity of species of carefully circumscribed groups has sometimes Tetrigidae have the wings sborter than, or been more favorable. Kirby (1914) notes that ending close to, the caudal projection of the Euparatettix interruptus (Brunner von Watten- pronotum. There are, howevel, se'\lelal appaI­ wyl) has the wings 2 mm (about 20 percent of ently closely related species, mainly in soutb- the length) clear of the pronotum and he uses east ASIa, whose wmgs exceed the pronotaI this character in his key to the Indian species of shield by some 15 35 percent of their the genus. Hancock (1912) uses essentially the length.There has been an understandable same character in his key to the genus Saussur- reluctance to recogmze thIS peculIarIty, proba­ ella BolIvar, 1887. The extenSIOn beyond the bly because isolated individuals in collections plonotal shield has recently been used by Liang could be examples of alary polymorphism. This and Zhen (1984) as one of several characters view is taken by Tinkham (1937) who corn- diflereritiating t<110 tetrigid genera. Neverthe mented that "long and shortwinged forms ofthe less, unless sufficiently long series are available same species are commonly encountered in the to establish stability of relative wing-length, Acrydiinae and since they live side by side and reliance on this character coUld mislead. are identical in all other respects they are not Of the 250 drawings by Giinther (1939) of 'Northy of specific or subspecific recognition." tetIigids falling into his "sectio AmOIphopi" ( Nevertheless, long series from south-east Metrodorae lanett) only three show exposed Asia made avaIlable to me through the kindness wings. In defining his concept of this group of their Museum curators show little variation Gtinthel (1939) says that in one instance the 88 Insecta Mundi flIght organs consIderably exceed the hind that of P. cortlcolus IS ViSIble only m dorsal femora, y.Thlst the wings extend almost or quite view as a swelling on either side of the dorsal up to the end of the pronotum, not however carina (Fig. 2). Moreover, the eyes of P. corti­ projecting beyond it by more than I mm The colliS have a fringe ofshOrt sensilla between the conviction that tetrigid wings do not substan- facets, but only on the hind margin of the eyes; tially pIOject beyond the pronotum may have there is none in P. exilis. A key to the described led GUntber into misconstruing Hancock's species of Probolotettix is provided drawing of Orthotettix obliquifrons Hancock (1908) from 8araY.·ak, Borneo, which shows the Holotype male. Papua New Guinea: N.B. of wings exceeding the pronotum by some 28 Goroka, 22 iv 1973 at light (StrOder). Lyman percent. Gunther (1939) states of another male EntomologIcal Museum. Antennae 3.4 mID long. from Sumatra, which he refers to this species Vertex 0.2 mm narrower than eye (0.45 mm). "die Fhigel uberragennicht das Pronotumende", Mottled light and dark brown. Lateral carina of (the wings do not exceed the end of the prono­ vertex terminating against eye as slightly tum) but this specimen has the vertex substan blackened protuberance. Median ocellus ",ride, tially broader than the eye, whereas Hancock's 0.13 mm, filling intercarinal space. Eye promi­ type has the ver tex "subnarrower than the eye" nent, median carina eompressed Clypeus GUnther, however, correctly notes that Hancock medially ivory white, laterally dark brown. erred in stating that the antennae were insert­ Upper labium ivory white, lower part dark ed distinctly between tlre eyes, as the drawing brown. PlOzona upturned against occiput. shows the point of insertion to lie below the Metazonal crest visible in profile as raised eyes. crescent. Internal apodeme for protergal mus The genus Probolotettix Giinther 1939 was clefs) visible externally as open pit in meso- described as including very characteristic elon- notum. This pit, though present as an indenta­ gate, elegant, smooth, and often rather large tion in all species of the genus seen, is broader species with large eyes. I have, however, res- and deeper in P. exilis. (N.B. This pit may er vations about the status of Probolotettix as become filled witlr extraneous matteI and tlrus well as of Pseudoparatettix Gijnther 1937, and obscnred.) Pronotal disc slightly rugose, tegmi- Mazarredw Bohvar 1887 as being generically na broad elliptical (1.3 x 0.5 mm). Wing exceed­ distinct from Pamtettix Bolivar, 1887. I also ing pIonotum by about 2.6 mm (24 percent). observe that the species originally described as Transverse suture on mesepisteTDUill weakly Paratettlx angulobus Hancock, 1907 m his developed. Foretibiae with 3 hght and 3 dark Tettiginae "NaS transferred by him (Hancock, rings. FOIefemora not lobed on ventral cmina. 1913) to Criotettix Bolivar, 1887 (in a different Ventral carinae ofmiddle and hindfemora with informal diVision of roughly sUbfamily rank, the sparse (ca. 7 ) setal fringe. Hind temora JNith "scelimenae spuriae") back to Paratettix by Bei- cluster of about 5 whitish sensilla proximal to Bienko (1935), by GUntlreI (1937) to Pseudopar- internal genicular area. Hind fcmora each ex- atettix Gimther, 1937, and eventually to PrObol- ternally With ca. 12 fragae on upper surface, ca otettix by Gunther (1939). This is a poignant 4 fragae on lower surface which is without reflection of the pIoblem of geneIic assignment callosities. Hind tibiae witlr ca. 8 teetlr on outeI in this group of Tetrigidae lower carinae, ca. 6 on inner Metatarsus sub- equal in length to hind tarsomere. Length of Probofotettix exHis pronotum 9.3 mm, widtlr at shoulder 1.6 mm. new species Fig. 1 Allotype female. Papua-New Gumea: SipegUl School, 12 mi. Kundiawa. 16.vi.1972 (StrOder). Diagnosis. Very close to P. corticolus Blackith, Lyman Entomological Museum. Color as for 1987 from 'Nhich it differs in having the meta holotype, but cIypeus and labium mottled zonal crest clearly visible in profile, whereas Vertex width 0.4 mm; eye width 0.5 mm. Me- dian ocellus 0.1 mm wide, not fully filling Vol. 4, No. 1-4, March-December 1990 89 mtercannal space, Exposed wmg length 3 mm ~ Ion ., TT. .,. . L'. n , .. - ,~" • v ..,tJ'-'~ 'cu '<0" ,~"u V ...... , teeth, lower with 7 teeth. Length of pronotum r---i";.

I I ~ ~ LU "'''.1 ...... "'. .L a!Jua-.l.~t::w.. • .L ll.l.GUt::, ..:I.I.!Ja- I \. t ~ - \\ ---~---- er); 1 male, 1 female, Lae, 9.x.1973, (Stroder); 1 ,I / .... '1 ~ ... .. \ ' .... - • .....a

TT , l' nAt' "., in po, ~ \ -t -- --- I'--- ';~.~ 1 ~ ,r , . ~ ~ "'-, " . ,,,' 2'. Median ocellus not touching frontal carina ,, - ~ \.:SUlawesl) ...... cortlcolus .tllacklth ,/ --' ~ ~ ~ 3(1'). Wings not exceeding pronotum (Sarawak) - t 1--\ t { I ./ I ~ , . , 3'. Wings exceeding pronotum ...... 4 \ I ' .. ~ " ,'" ... ' • ~ , ... \ ".' ( 4' I P.l'Il .. -" 4'. Head not, or weakly, exserted ...... 6 \ ... , fi(4), eve>; (Philin- ...... " \ pmes) ...... , langwdus \..tlollvar) ---...J 5'. Antennae inserted below eyes (Philip- --

j<'lgure 1-2. Probolotettlx specIes, lateral VIew of 6'. Wings exceeding pronotum by less than 1 pronotum. 1) P. exilis, n.sp., male holotype; 2) P. mm (Borneo and Sumatra) . corticolus Blackith, male paratype...... angulobus (Hancock)

7(2). Metazonal crest comrex in profile (Sula Discussion wesi) , ... , ..... , .. kevani Blackith 7'. Metazonal crest concave m profile (Papua­ Table 1 lists seve! al :spelae::; cent!ed 011 New Guinea) ...... '... exilis n.sp. south-east Asia whose wings exceed the 90 Insecta Mundi

Tallie 1. Percentage of wmg exposure of 'I'etngIdae wIth partIy exposed Wings.

W'n!! exnosure Species Lu~a",J' 0

I'robolotettlX Kevam J:Slaclalh. l\llSl ~UlaweSl 10

Euparatettix interruptus (Brunner, 1893) Bunna 20

.w ~.uv~ .... U V~U'Tv" "'.

am euix cimza ensis ,WaJKer lIS alwan

. n1.• ~J,;." 1(\27 <::"lo",u.; ')(\

- . r . ~ ,nn~ ~ ~~ -~- " .. Probolotettix exilis sp.n. Papua-New Guinea 24

Pseudoparatettix macrophthalmus Giinther. 1937 South Melanesia 26

Orthotettix obliquifrons Hancock. 1907 Sarawak 30

Paratettix pullus Bolivar. 1887 Fiji 31

linilriana er ia uunmer, 1 ~ /4 lVlaaagascar :>:> pronotal shield by amounts substantially great­ night; we know little of what tetrigids do then. er than the 1 mm indicated by Giiiither (1939). Bright lights are a wholly unnatural and intrll- Questions that arise include that of the sive stimulus which may trigger reactions possible common origin or relationship of some only sparingly relevant to studies of tetrigid or all of tbese species, and for file possible behaViour In these circumstances it may be common environmental factor(s) leading to the more relevant that eumastacids, and possibly development of this trait. Among the facts tetIigids, living in rain-forests use the wings to which need to be borne in mind when consider- sail-plane down towards the ground rather than mg these problems IS that wmgs exposed to thIS to fly m any very pOSItive sense (Blacklth, extent are so rare in Old World tetrigids away 1973). Several tetrigid species, ineluding P. from the region in question, that we may sus- corticolus, live mainly on the bark offorest tree pect strong selection against such a traIt under trunkS (Blacklth and Blacklth, 1987). The normal circumstances. The protective function Queensland rain furest species Vingselina ofthe caudal extension ofthe tetrigid pronotum brunneri (Bolivar) ascend the trunks of trees is an inference, hut appears plausible (Rod- after dark (Key, 1974) endorf, 1949). Damage to the exposed "'lings is likely to be Some tropical grasshoppers of the family minimal during such activity because the wind­ Eumastacidae, among others, share the deep speed in rain forests can be as little as 1 per- rain forest environment with tetrigids although cent of that above the canopy (Blackith and they tend to be tree canopy inhabitants. Some Disney, 1988). All the species listed in Table 1 ofthe rain-forest tetrigid fauna appears, howev- now live in areas covered, at least until recent- er, to be associated with micro-habitats on the ly, by rain-forest, and presumably evolved in trunks of trees, and to trike to the wing fairly such a habitat. Moreover, all the regions where readily as shown by widespread records oftheir exposed wings are found once formed partofthe beingtaken "atlight". Nevertheless, the mtenor Gondwanaland super-contment WhICh splIt up of mature rain forest is dark during the day, ca. 100 million years ago, by which time tetri with about 1 percent of the incident light pene- gids had evolved to something approaching tmting to the forest floor, and pitch-black at present forms (Sharov, 1968). Vol. 4, No. 1-4, March-December 1990 91

It seems at least plausIble that many of the We do not understand the full range of species with exposed wings are linked by com selective forces actingto mediate ....·ing lengthin mon ancestry as well as by common habitat. In tetrigids. Some Palaearctic species have long some instances differences between species are wings, some have short, but although we know slight and there seem to be no clear means by what habitats they occupy now, we do not which we can be sme that we ale indeed deal­ usually know what habitats they evohed in. ing with distinct species rather than with infra- Within tbe last decade, some rain-forest tetri- specific distinctions at least until there is a gids in South - East Asia have adapted to life in successful outcome to further research on the newly established padi rice fields, and are so concealed genitalic structures involved The apparently successful there that one might large SrI Lankan speCIes Scelzmena gavzalzs never guess that the tranSItIon was so recent (Saussure) and a number of allied species ha'V'e (Blackith and Blackith, 1987). Future biologists intensely purple, curved, median glands issuing may puzzle over the many adaptations to life in from the spermatheca. Several species more rain-forests that they discover in such distantly related to S. gavialis, differing from particularly ifforests are no longer to be found those with purple glands at roughly subfamily in the vicinity. level, have simple, straight, white, glands in The evolution of exposed wings in rain- this position (Ruth M. Blackith, unpublished forests would form the opposite polarity of a observations). continuum of wing-lengths culminating in Geogmphical separation is not, of itself, apterism in highlv exposed mountain areas, adequate grounds for creating supra-specific such as the high plateau ofQinghai-Xinzang in categories, since there are '.veIl authenticated Tibet (Yin }Gang chu, 1981). We Iriight specu instances of closely similar species e. g. of late that such selective forces could counter the Xistra Bolivar, occurring in Sri Lanka and in reproductive penalty associated with flight in Taiwan, some thousands of kilometers apart, some insects with wary polymorphism, a topic with no known representative of the genus in recently reviewed by Denno et aI. (1989) al- the inteIVening legions (GUnthet, 193B}. It though the application of this idea to tetligids seems far more plausible that Xistra is a genus is conjectural that evolved before the dIsllltegratlOn of GOnd­ wanaland than that stlong comer genee is Acknowledgen lents primarily responsible For example, tbe genera Archaeotetrzx Sharov and Prototettzx Sharov are I am most grateful to Professor D.K.McE. found in the Lower Cretaceous ofTransbaikalia Kevan for helpful and extensive comments on (Sharov, 1968). Tetrigids appear to have evolved from the Triassic/Jurassic Locustop- ~:r:~;~:Z~:~~ni~~~;::I:;if~::~.:~~~ sidae well before the disintegrationofGondwan- donald College of McGill University, Ste. Anne aland. Apparently closely related species of highly characteristic genera, most notably Xistra Dr. H. Enghoff, curator ofthe Danish Zoologisk Bolivar, although not involved in the exposed Museum, Copenhagen, for an opportunity to work on tetrigids housed there I am also grate- ful to Dr. S. Simpson for kindly verifYing that cock's (1907) record of a single female Kist} a the type ofO. obIiquifrons in the Oxford Univer- ~ancoc~ f~~ sty/ata :ri I anka as the:: i:. a sity Museum does in filet nave wings as long as those portrayed by Hancock. Danish National collection v,rhich I have exam ined. This specimen is labelled "Ceylon"I"Mus. westerm" in writing consistent with other labels dated around 1810. 92 Insecta Mundi

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Hancock, PLI.. 1913 Studies of Blackith, R.E. 1973. A new eumastacid grass­ (Acrydiinae) from the Sarawak Museum, hopper. Acrida 2:109 118. Borneo. Sarawak Museum Journal 1(3):35 54 Blackitb, R.E. & RoM. Blacldtb 1987 Tridac- tylids and tetrigids (Orthoptera) from Sula- wesi (Indonesia). Tijdschrift voor Entomol

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