A Flightless Grasshopper of the genus Uganda Bolivar, from the Aberdares National Park, Kenya (Orthoptera, Acrididae)

9 Pages·1992·2.9 MB·English

by  J Mark Ritchie

JOURNAL.
OF THE EAST AFRICA NATURAL HISTORY
SOCIETY AND NATIONAL MUSEUM
June 1992 Volume82 No200
A FLIGHTLESS GRASSHOPPER OF THE GENUS UGANDA
BOLIVAR, FROM THE ABERDARES NATIONAL PARK,
KENYA (ORTHOPTERA, ACRIDIDAE)
MARK RITCHIE
J.
InternationalInstituteofEntomology,
56Queen’sGate,London, SW7 5JR,UK.
ABSTRACT
AnewspeciesofthegenusUganda, U.darlingtonae,isdescribedfrommoorlandabove3000minthe
AberdaresNationalPark,Kenya. Thehabitatofthespeciesisdescribedandmorphologicalcharacters
distinguishingU.darlingtonaefromtheothermontanespeciesofthegenusaredescribedandfiguredwith
comparativemeasurements.
INTRODUCTION
ThemontanegrasshopperfaunaofAfricacontainsanumberofshort-wingedspecieswhichare
usuallyrecognisablyderivedfrom lowlandmacropterous species,as forexampleinsuch generaas
CoryphosimaandEyprepocnemis. Uvarov (1977)commentedthatParacinemawasreplacedat
higheraltitudesby thecloselyrelatedbrachypterousgenus Uganda.
ThegenusParacinemawaslastrevisedby Key (1936) whorecognised twospecies,
Paracinema luculenta KarschandP. tricolor(Thunberg). P. luculentaoccurs inWestandCentral
Africa(Togo,Ghana, SierraLeone,Zaire) whileP. tricoloroccursthroughoutthewetterpartsof
Africaandinto MadagascarandsouthernEurope. InEastAfrica,P. tricoloroccursas subspecies
montana Key in Ethiopia(Wouramboulchi,nr. Djem Djem),ataround2800metres(Key 1936).
Specimensofthenominate subspecieshavebeen foundataround2400 metresin theImpenetrable
(Bwindi)Forest,SWUganda(Ritchie,unpublished)andmaterial intermediatebetween the two
subspecies wasrecordedfrom thesamealtitudeinEthiopia(Key 1936). Both speciesof
Paracinemaaremacropterousalthough inP.t. montanathetegminaandwingsonlyjustexceed the
hindknees in length.
Thegenus Ugandawasdescribedby Bolivar(1909)withoutany includedspeciesandwas later
placedbyitsauthorin thegroupParacinemae(Bolivar 1914). Hecitedtwoincludedspeciesof
whichone, thetypespecies, U. kilimandjarica(SjOstedt),occursatbetween2300and4300m on
m
Mt.KilimanjaroinTanzaniawherethesyntypeserieswascollectedatKiboschoat3000
(Sjbstedt 1909). Theotherspecies,U. acutipennisBolivar,wasapparentlycollectedatlowaltitude
1
J. MarkRitchie• AflightlessgrasshopperfromtheAberdareRange,Kenya 34
on theSesseIslands,LakeVictoria,Uganda(Bolivar 1914). Itisnotmentionedagain in the
literatureafteritsoriginaldescriptionby Bolivar. Sincethis specieshasnotbeenrecognised
subsequentlyincollections from lowlandsouthernUganda, theremustbesomesuspicionthatitis
notamemberofthegenusUgandabutabrachypterousrepresentativeofanotheracridinegenus,
suchas GymnobothrusorGymnobothroides. Thelocationofthetypespecimens is unknown tome,
andnomaterialreferable tothisspecieshasbeenexaminedduringthis study.
ThenewspeciesofUganda describedherewasfirstbroughttomyattentionbyDrJohanna
Darlington,andisnamed in herhonour. Mostofthespecimenswerecollectedfrom thevicinityof
Muir’s Massif(0°17’S 36°37’E)atthenorthern endoftheAberdaresRange,Kenyaataltitudes
ranging from 3250to 3650metres. Subsequently asingle female wasfoundtohavebeencollected
in 1934 at3700m on Ml Kinangopatthesouthern endoftheAberdareRange.
RESULTS
KeytomontanespeciesofUganda Bolivar
1. Largerspecies(Table 1). Total length: male, 11.5 - 13.8mm (mean 12.99mm); female,
22.8 - 27.5mm (mean 24.32mm). Dorsumofpronotum withpale,raised,shiny lateral carinae,
visiblein metazonaas wellasprozona (Fig. 1). Generalcolourationdarkbrown, with variable
degreeofgreen colourin somespecimens; hind femurlowerouterand innerareasandhindtibia
distinctly orange-red. (Kilimanjaro) U.kilimandjarica (SjOstedt)
2. Smallerspecies (Table2). Total length: male, 10.1 - 11.3mm (mean 10.6mm); female,
18.1 - 20.9mm (mean 19.4mm). Dorsumofpronotumwithpale,raised, shinylateralcarinae
visibleinprozonaonly (Fig. 2). Generalcolourationgreenishorstraw; hind femur innerareaand
hindtibiasometimes faintlytingedwithorange-redbutlowerouterareaoffemurneverorange-red.
(Aberdares) U. darlingtonaesp. n.
Table 1. Measurements(mm)ofadultmaterialofUgandakilimandjarica(Sjdstedt)
from Mt. Kilimanjaro,Tanzania
Total Head Pronotum Tegmen Femur Femur
length width* length length length length
Male
Mean 12.99 2.63 2.84 3.84 9.08 2.2
Range 11.55-13.8 2.4-2.9 2.7-3. 3.4-4.2 8.6-9.9 2.15-2.25
Number
measured 7 7 7 7 5 5
Female
Mean 24.32 4.62 4.69 5.89 14.28 3.29
Range 22.8-27.45 4.3-5.35 4.15-5.6 5.0-7.8 12.35-17.5 3.05-3.7
Number
measured 9 7 9 9 8 8
* acrossgenae
J. EANHS & Nat. Mus. 82(200)June 1992
35 J. MarkRitchie• Aflightlessgrasshopperfrom theAberdareRange,Kenya
2mm
Figure 1. Uganda kilimandjarica(Sjostedt) Figure2. U. darlingtonaesp.n.
headandpronotum,male,dorsal view
J. EANHS & Nat Mus. 82 (200)June 1992
J. MarieRitchie • AflightlessgrasshopperfromtheAberdareRange,Kenya 36
Table2. Measurements(mm)ofallknown adultmaterialofUgandadarlingtonaesp. n.
Total Head Pronotum Tegmen Femur Femur
length width* length length length length
Male
Mean 10.57 2.19 2.39 3.39 8.37 1.84
Range 10.1-11.25 2.05-2.25 2.3-2.5 3.2-3.5 8.1-8.8 1.75-1.95
Number
measured 4 4 4 4 4 4
Female
Mean 19.4 3.7 3.79 5.15 12.73 2.84
Range 18.15-20.9 3.55-3.85 3.65-3.9 4.4-5.65 12.55-12.95 2.75-2.95
Number
measured 5 5 5 5 5 5
* acrossgenae
Description ofnewspecies
Uganda darlingtonae sp. n.
Male. Small species(total length 10.1 - 11.3mm)(Table2.). Antennawith 18 segments,distinctly
shorterthanlengthofheadandpronotum combined(longerinParacinemaspecies). Interocular
distancelittlemore thanonethirdaslongaslongaxisofeye. Fronsoblique,curved; frontalridge
constrictedatapex tohalfitsbasalwidth,slightlysulcateatmedian ocellus, smoothlyconvex
above,meetingvertex inacutelyroundedcurve; fastigiumofvertexlanceolate,angularin front,
roundedbehind, formingashallowdepressionwithroundedmargins; fastigial foveolaeabsent.
Pronotum weakly tectiform withobtusemediancarina,crossedbyposteriortransverse sulcus;
lateralcarinaestraightinprozona,diverging forwards,convergingandobsolescentbeforeposterior
sulcus; metazonawithobtuseexcurvedouterlateralcarinaeborderedinternallybydarkfascia
(Fig. 2); metazonaslightly shorterthanprozona,withroundedposteriormargin. Mesostemal
interspacerectangular,distinctlywiderthan long(longerthan wide inParacinema species). Elytra
and wingsreduced; elytralateral,lanceolate,touchingorslightlyoverlappingdorsally,with
reducedvenationandreticulation(Fig. 3),shiny,reachingtomiddleofthirdabdominal tergite;
tympanum welldeveloped,coveredbyelytron. Hindfemurabout4.S timesaslongasmaximum
depth; lowerlobesofhindkneerounded; hindtibiaexpanded inapical third,with9outerand 10
innerspines; tibial spurs unspecialised,aroliumofnormal size. Supra-analplatespade-like,
apicallyrounded,barelylongerthanwide; subgenitalplatesubconical withsubacuteapex. Cercus
elongate, finger-like. Epiphallusvariable(Figs.4 & 5),oftypicalacridineform, subrectangularto
rhomboidal,with widely-spacedancoraeandbilobate lophi; aedeagusslenderandunspecialised,
with ventral sub-apicallobe(absentinP. tricolorbutpresentin U. kilimandjaricaand
P. luculenta).
J. EANHS & Nat. Mus. 82(200)June 1992
37 J. MarkRitchie• Aflightlessgrasshopperfrom theAberdareRange,Kenya
2mm
Figure3. U. darlingtonaesp.n. thoraxandleftlegmen, lateral view
Figure4. Figure 5.
t. mm A
1
Figures4 and5: U. darlingtonaesp.n.epiphallus,dorsal view,showingtherangeofvariability
J.EANHS & Nat Mus.82(200)June 1992
J. MarkRitchie• AflightlessgrasshopperfromtheAberdareRange,Kenya 38
Colouration
Generalcolourationpalegreen fadingtostraw-colouredafterpreservation; antennaereddish-
brown; headbehindeyesandpronotum withlongitudinaldarkchocolatebrown lateralfasciae
(Fig. 2)continuingonelytraandabdominal tergites; lateralsurfacesofpronotum,meso- and
metanotum with indistinctdarkmarkings; hindfemurwithdarklongitudinalfasciaalongupperhalf
ofexternalmedialarea,fading togroundcolourin lowerhalf; internal ventralsurfacestraw-
coloured,sometimesfaintlytingedwithpalered; hindkneelunulesdarkbrown; tibiaeandtarsi
straw-colouredwithorwithoutfaintpaleorangeredtinge,spinesblacktipped.
Female
Similartomalebutmuchlargerandstockier(total length 18.1 -20.9mm). Hind femurinternal
ventralsurfaceandhindtibiadistinctlyflushedwithpaleorange-red. Ovipositorshortwithrobust
valvescurvingatapices.
Measurements
SeeTable2.
Materialexamined
KENYA: Holotypemale,3 male,4femaleparatypes, 1 femalenymph,AberdaresNationalPark,
0°14’S 36°35’30"E,AlchemillalEleusine/AndropogonlAgrostismoorland,SE footofChebuswa,
alt. 3250m, 19.iii.1987,(JM.Ritchie)(1 maleparatypein British Museum (Natural History)
(BMNH),London,remainderinNational MuseumsKenya(NMK),Nairobi); 1 femaleparatype,
AberdaresNat.He,northend,Muir’s Massif,0°17’S 36°37’E,alpinemoorland,alt 3650m,
7.ix.l985 (JF.E.C.Darlington) (NMK); 1 femaleparatype, AberdareRange,Mt. Kinangop, 12000
ft,30.ix.1934,(F.W.Edwards) (BMNH).
DISCUSSION
Thepronotalmorphologyofthenew speciesalliesitwithP. tricolor,especiallyin thepresenceof
anteriordorso-lateralcarinaewhichreach onlyasfaras thefirsttransversesulcus (Fig. 2). In
P. luculentatherearcnosuchcarinaeandin UgandakHimandjaricathecarinaecontinue
posteriorlybeyondthefirstsulcus (Fig. 1). Thedistinctivepairofdarklongitudinaldorsalbands
onthepronotumalsoallies U. darlingtonaetoP. tricolor. However,thegenitaliaandgeneral
appearanceofU. darlingtonaeindicateaverycloserelationshipwith U. Idlimandjarica. The
epiphallusandaedeagusofthetwotaxaarenotreadilydistinguishable,suggestingarecentcom-
monancestry,perhapsduringaperiodofclimaticameliorationduringthePleistocene(<1 million
yearsbeforepresent) whichcouldhaveenlargedtheavailableareaofmoorlandhabitatsufficiendy
topermitexchangeofpopulationsbetweenMtKilimanjaroandtheAberdareRangenearly
300kmapart
Themontanemoorland habitat
TheAberdaresRange,togetherwith Mt Kenya,50kmtotheeast, formtheeasternhighlandsof
Kenyaseparatedfrom theWesternhighlandsbytheGregoryRiftValley. TheAberdaresarethe
highestmountainrangeinKenyaafterMt Kenyaand MtElgon. Theclimateatabove3000m is
extreme,with frequentnightfrosts. Formuchofthedaythesun isconcealedbycloudandrain
fallsalmostdaily. ThetemperatureregimeduringMarchandApril inasimilarhabitatonthewest
sideofMt KenyawasexaminedbyBecketal. (1981)whofound thatinanaverageperiodof
J. EANHS & NaL Mus.82(200)June 1992
39 J. MarkRitchie•AflightlessgrasshopperfromtheAberdareRange,Kenya
24 hours,theairtemperatureatgroundlevelwasbelow0°Cformorethan6 hoursandbetween0°
and5°forafurther6hours. Overall temperaturesvariedbetween-5°Cand25°C. Atadepthof20
mmbelow thesoil surfacethelowtemperatureswerelesssevere,seldom fallingbelow0°Cbut
averaging morethan 12hoursbetween0°and5°C.
ThevegetationonMuir’sMassifisshowninPlate 1. This is typicalofthehabitatwhere
U. darlingtonaewascollected(3650m)butwithlessbaregroundandthickervegetationthanthe
slightlylowercollectinglocalityatthefootofChebuswa(3250m). Theafromontanemoorlandof
thenorthernAberdareRangeisanopen habitatwithdwarfshrubs,herbsandgrasses.
InthemoreopenareasoftruemoorlandatthefootofChebuswahill thefloraisdominatedby
grasses,ofwhich 10 -20%coverisaccountedforbytussocksofEleusinejaegeriPilg., 20- 30%
byAndropogonamethystinusSteudL and 10% byEragrostisschweinfurthiiChiov. Festuca
abyssinicaA.Rich,occursoccasionallyandthedwarfshrubAlchemillaargyrophyllaOliv. isalso
present Upto20% oftheareaisbaresoilasaresultoftheactivitiesofmolerats(Jachyoryctes
splendens(Riippell). ForbsincludeAnagalliscf.serpensD.C.,TrifoliumcryptopodiumA.Rich,
(common),AnthemistigrensisA.Rich.,GeraniumarabicumForssk. (frequent),Gnaphaliumluteo-
albumL. and TrifoliumrueppellianumFiesen. Inthis habitat U. darlingtonaewasfoundbutwas
lesscommonthananotherflightlessgrasshopper,Coryphosima sp„ which isperhapsthemost
noticeableinvertebrateatthisaltitude.
Within theopenmoorlandhabitat,somedenserpatchesofvegetationoccur,withupto75%
coverofA. argyrophyllaand20%coverofasmall tussockgrass,Agrostiscf.gracilifolia
C.E.Hubbard. Herbsandbaregroundmakeuptheremaining5%,withEuphorbiabrevicornuPax.
(common),Saturejakilimandschari(GuerkeHedb.)(frequent),andPolygonumqfromontanum
Greenway. T. ruepellianumandyoungHypericumrevolutum Vahl ssp.keniense (Schweinf.)
N.Robson asoccasional. Herealso U darlingtonaewaspresent,butonlyemergedfrom the
denseAgrostistussocksandAlchemillaandbecameactivewhen thesunhadbeenshiningforhalf
anhourandtheairtemperaturehadbeguntofeelpleasantly warm(c.l5°C). Theonsetofrain
towardsmidday causedtheinsectstodisappearonceagain.
NearChebuswaHill themoorlandgradesintoaHageniawoodlandJStoebebushlandmosaic
with scatteredtreesofHageniaabyssinica(Bruce)J.F. Gmel. HerethecommonshrubsareStoebe
kilimandscharicaO. Hoffm. vardensifloraO. Hoffm.,H. kenienseandA. argyrophylla
,
P. afromontanum ErlangeafuscaS.Moore,HebenstretiadentataL.andClutiakilimandscharica
,
Engl.* Theherbs includeatleastninespeciesandtherearefourscramblersandclimbers.
U. darlingtonaewasnotfoundwithinthisformationthoughitmay well occur. Insuchanextreme
habitatitis likelythatagraminivorousgrasshopperlikeUganda would tend tospendmostofits
periodsofactivity in moreopenareaswithgrassesofferinggreateropportunities tobaskand feed
during the infrequentperiodsofbrightsunshine.
ACKNOWLEDGEMENTS
Iam indebtedtoDrHenkBeentjeforhiscompanyonacollectingtriptothenorthernAberdares
and foridentifying theprincipalplantspeciesoccurringin themoorland habitatofP. darlingtonae.
ThanksarealsoduetoDrJohanna Darlington whoprovidedaphotographofthemoorlandbelow
Muir’sMassif. Iam grateful totheDirector,WildlifeConservationand ManagementDepartment,
MinistryofTourismandWildlife,Kenya,forpermission to work in theAberdaresNational Park.
Mr. QuentinLukekindlyprovidedtheplantauthorities.
Thetypespecimenhasbeendestroyed. This isprobably ClutiarobustaPax,butwouldbe
calledC. kilimandscharicaEngl, ifitcouldbeproved thattheyaresynonomous.
J. EANHS & Nat. Mus. 82(200)June 1992
J. MarkRitchie• Aflightlessgrasshopperfrom theAberdareRange,Kenya 40
m.
3650
altitude
moorland,
Afroalpine
Bolossat.
01
Lake
towards
west
north
looking
Kenya,
Range,
Aberdare
northern Darlington.
Massif,
JP.E.C.
Muir’s Photo
6.
Plate.
J. EANHS &NaL Mus. 82(200)June 1992
41 J. MarieRitchie• AflightlessgrasshopperfromtheAberdareRange,Kenya
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Manuscriptreceived: 2January 1992
Editor: C.F. Dewhurst
J. EANHS & Nat Mus.82 (200)June 1992