Odonata from the Ennedi and Ounianga regions of northern Chad, with a note of the status of Orthetrum kollmannspergeri Buchholz, and a checklist of species currently known from the Republic of Chad

2005·0.89 MB·English

by  Dumont, H J

Odonatologica34(3):291-297 SeptemberI.2005
Odonatafrom theEnnediandOuniangaregions
of northernChad, witha noteof thestatus
ofOrthetrumkollmannspergeriBuchholz,
anda checklist of species currently known
from theRepublicofChad
H.J.Dumont and D.Verschuren
LimnologyGroup,GhentUniversity,Ledeganckstraat35,B-9000Ghent,Belgium
ReceivedMay25,2004 / UpdatedandAcceptedFebruary20,2005
Ahydrobiologicalsurveyofscarcepermanentaquaticenvironmentsinthe Ennedi
and Ouniangaregions ofnorthernChad yieldedasmallcollection of7 odon. spp.
Itadds 3newspp. totheknown fauna ofChad: Ischnurasenegalensis, Pseudagrion
hamoni,and Orthetrumsabina.The presence ofO.sabinaatOuniangarepresents the
westernmost record of thisoriental sp. in N. Africa.Another oriental element, O.
taeniolatum,may notexist inAfrica W.oftheNile,possiblybeingreplacedthere by
thecloselyrelated O.kollmannspergeriBuchholz.The44spp. hithertoreportedfrom
theRepublicofChad likelyrepresentonly athirdorless ofthosetobeexpectedin
thecountry.
INTRODUCTION
To dateonlythreepublications havedealtfullyorinpartwiththeOdonataof
Chad(North-CentralAfrica); NAVAS(1936) reported 6 species fromtheTibesti
mountainrangeinthefarNorthofthecountry; BUCHHOLZ(1959) reported6
species from theEnnedimountainsinthe deserticNortheast, andanadditional
7 species fromthe sahelianBiltineregion Southand South-Eastofit; and dip-
terologist C.DEJOUX (1968) provided a listof31 taxa,ofwhich26 identified
to species, fromaroundN’Djamena andLakeChadinthe West(identifications
by E.C.G. Pinhey). Thescrubandwoodedsavannahregions insouthernChad
remain unexplored. Hence, all new informationon this huge (1.2 millionkm2)
country, whichcovers 16 degrees oflatitudeandthefullNorthAfricanecotone
fromwetsavannahintheSouthtoabsolutedesertintheNorth,ismostwelcome.
Also, although knowledge on the Odonataofthe Saharadeserthasgreatly in-
292 H.J.Dumont&D.Verschuren
creasedover thepast twodecades(summarized in DUMONT, 1988),theChad-
ian partoftheSaharahasbeencovered onlyfragmentarily atbest. Thepresent
collection, although small, thereforeaddssignificant informationto ourknowl-
edge ofdragonfly biogeography inNorthAfrica.
STUDY REGION
Hand-net collections ofadultdragonfliesweremadeinDecember 2003and October2004aspart
of ageneralhydrobiological surveyof the scarcepermanent waterbodies in the semi-desert and
desertregionsofnorthernChad.These include thegueltasofArcheiand Bechikele (alsoknown as
Beskere)inthe southwesternEnnedi mountains,andthefreshtohypersalinelakesystemsofOunian-
ga Kebirand OuniangaSerirlocated west oftheMourdi Depressionand Southeastofthe Tibesti
mountains. The gueltasofArchei (Loc. 1)and Bechikele (Loc.2)arerelictsofmuchmoreextensive
aquaticsystems drainingthe Ennedi duringthe EarlyHolocene pluvial (-10,000-4,000l4C yrBP,
or 12,000-4,500calender yearsago), andtodayprovideregionallyuniqueconditions forsurvival of
tropicalAfricangallery-foresttreessuch asFicusand Boscia. Theybothconsistofasteeplyincised
rock canyon withaseriesofrock poolsfringedwith Phragmitesand Cyperaceae,exitingviaashort
permanent watercourseontothesurroundingdesertplainasaseasonallyfloodedwadi(oued)fringed
with dumpalms andAcacia trees.
TheOuniangalakes arePleistocene deflation basinsfilled like oasesbycontinuous inputofpre-
sumablyearly-Holocenefossilgroundwater.Surrounded byabsolute desert,their shoreline istoday
fringedby dumand datepalms,and somescattered Acacia trees. Shoreline dissectionby dunemi-
grationintoLake Yoa,thelargestanddeepest(26m)lakeatOuniangaKebir,locallyformed ashort
inlet where freshwater inflowexceeds itsrate ofmixingwith the hypersalinelake water, socreating
afreshwater brookwith Phragmitesand Potamogelon(Loc. 5).Similar dune migrationacrossthe
shallower basin ofOuniangaSerir(8-12m)hasovertimedissected thebasin intothelargecentral
LakeTeli (Loc.4),whichis hypersaline,and about sevensmallerlakes to theEast andWestwhich
arefresh. MostofthesefreshlakesarepartlyorfullycoveredbyfloatingPhragmitesmats;onlyLake
Boku(Loc.3) and LakeEdemprovidesufficient openwaterfor establishment ofsubmergedaquat-
icssuchasPotamogelonand Chara.Under thehyperaridclimateconditionsprevailingatOunianga,
thesepermanent freshstanding-waterenvironmentsareuniquedragonflyhabitatforalargeregion
oftheCentral Sahara.
Dragonflies werecollectedatthe followingsites:
Loc. 1.26-XI-03: Ennedi,gueltaofArchei,interconnected rock poolsathead ofguelta
Loc. 2.23-XI-03: Ennedi,gueltaofBechikele, permanentstreaminside gueltacanyon
Loc. 3.02-XII-03and 24/12/04: OuniangaSerir,LakeBoku,freshwaterlake
Loc,4.02-XII-03:OuniangaSerir,LakeTeli,hypersalinelake
Loc. 5.07-XII-03 and 18/10/04: OuniangaKebir,LakeYoa, Girki spring, and brookflowingfrom
springintohypersalinelake
Loc. 6. 27-X-04:OuniangaSerir,Lake Edem.
RESULTSAND DISCUSSION
SPECIESLIST(firstrecords forChadare asterisked, *):
— *IschnurasenegalensisRambur:loc. 5(66,4 2),loc6, 6.
—*PseudagrionhamoniFraser: loc. 1(1 S);morespecimensseenatloc.2.
—Trithemisannulata (P. deBeauvais):loc. 3,1 6.
—T. arteriosa(Burmeister);Iocs. 1,2(3 d),3(I $)
Odonata oftherepublicofChad 293
—Crocothemiserythraea(Brulle):loc. 1(1 3),loc. 5(1<J);
—Orthetrumchrysostigma(Burmeister);loc. 1(2 3); alsoseenatloc. 2.
— *O.sabina(Drury); loc.4(1 3,onthewing)
—Brachythemisleucosticta(Burmeister):16, 3$.
—Pantalaflavescens(Fabricius):loc. 3, 1<J.
This small collectionof28 specimens strikingly addsthree species (Ischnura
senegalensis, Pseudagrion hamoni, andOrthetrumsabina)to theknown dragonfly
faunaofChad, whichnowstands at44species. Reviewofthereported collection
locationsrevealsthatnosinglezoneofthislargecountry hasbeenadequately sur-
veyed, suggesting thatthe totalspecies numberwillbesignificantly higherthan
thatcurrentlyonrecord.Eventheubiquitousafrotropical-oriental species I.sen-
egalensis hadnotpreviously beenrecordedfromChad! Itis, however, interesting
that exactly this Ischnuraspecies occurs atOunianga in the desertof northern
Chad, andnot I.saharensisorI.fountaineae, already known fromotherisolated
aquatic systems inthe Saharadesert(DUMONT, 1979).
AlsosignificantisthenewrecordofPseudagrion hamoni.Thisspecies occurs in
allmajormountainmassifs oftheSaharabetweentheAtlanticcoastandtheNile
valley, buthadnotpreviouslybeenrecordedfromtheEnnedi(gapnowclosed)or
theTibesti(stillaquestion-mark). Its closestknownpopulation isfromtheSahe-
lianJebelMarraMassifinnorthwesternSudan(DUMONT, 1988).Thepresence
oftheOrientalspecies OrthetrumsabinaatOunianga maywellrepresentitslimit
ofwestward extent intoAfrica. Itwas previously foundinthe deserticMeidob
HillsNE of JebelMarrabut not at JebelMarra itself(DUMONT, 1988),sug-
gestingthatitmaybeincapable toextenditsrangeintothemorehumidenviron-
mentsofsub-SaharanAfrica.
Among “blue”Orthetrumspecies, thepresentcollectionincludesonly O. chrys-
ostigmafoundatthegueltas ofArcheiandBechikeleinthewesternEnnedi, where
BUCHHOLZ (1959)hadalready recordedthisspecies. Thepossibilityoffinding
anotherspecies, O. kollmannspergeri Buchholz, at thoselocalities prompted re-
evaluationofotheravailableOrthetrummaterialfromtheregion. BUCHHOLZ
(1959) described O. kollmannspergeri from Adre, on the Chad-Sudanborder
southeastof theEnnedi.Earlier,LONGFIELD (1936) hadidentifiedsmallblue
Orthetrumfromseverallocalitiesaroundthe JebelMarramassif(Karanga, Ki-
rima, Kurra, Killing) as the Orientalspecies O. taeniolatum.In his 1988paper,
DUMONT thought specimens fromSjachacha springs inthe MeidobHillsNE
ofJebelMarratorepresentthesecondrecordof O. taeniolatumfromtheDarfur
region ofnorthwesternSudan. Hedidnot considerthatthey mightbe O. koll-
mannspergeri, as the latterwas tacitly assumed tobea synonymof O. taeniola-
tum,orofO. ransonneti(as statedinDUMONT, 1987). Thesynonymy with O.
ransonneti,amuchlargerandrobustanimal(abdomen lengthofspecimens from
the Saharaabout 32mm, against only 24 mmforthe Meidobspecimens), can
in fact beruled out. Here, were-examinesix male Orthetrumfromthe Meidob
294 H.J.Dumont& D.Verschuren
Hillsandcompared themwithBuchholz’(1959) published figures, andwithtrue
O. taeniolatumfrom India, IranandTurkey.
This analysis reveals that the Meidobspecimens listed in DUMONT (1988)
conformexactly to Buchholz’descriptionof O. kollmannspergeri, especially with
regard to theshape of theapical alaeof the vesica seminalis.These are deeply
bifid andasymmetric(Figs 3-4),whereasinO. taeniolatumthey formtwo broad
lobes(Figs 1-2).Themacromorphology ofthetwo species isotherwiseidentical,
suggesting thatthey share a common ancestor, withkollmannspergeri probably
arecentoffshootoftaeniolatum.Micromorphological differencesbetweenthese
taxa include theanteriorlamina, whichin O. kollmamspergeri is slightly higher
Figs 1-7.ComparisonofmalegenitaliaofOrthetrumtaeniolatum fromKeoladeo naturereserve,India
(1-2,6)andO.kollmannspergerifromSjachachawells,Meidob,Sudan(3-5,7):(1-2)vesicaspermalis
ofO.taeniolatuminlateralandventralview; —(3-4)thesameofO. kollmannspergeri(alaearrowed);
—(5)lamina anteriorand hamulus ofO. kollmannspergeri, lateralview; — (6) laminaanteriorand
hamulus ofO.taeniolatum (posteriorfoldarrowed); —(7)hamulus ofO.kollmannspergeriwithapi-
calhook adpressedtointernal outgrowthbyvesicaspermalis.
OdonataoftherepublicofChad 295
andmorerobustthan inO. taeniolatum,andwithamorestronglyswollenapical
lip; andthe hamulus, whichapically formsanoutwardly turnedhookthatover-
hangs a hollowandfacesasmall, darkoutgrowth arising directly fromthe ha-
mulus body(Fig. 5). In thehamulusof O. taeniolatum, theoutgrowththatfaces
theapical hookformstheendofafoldthatrunsalong mostofthehindpartof
the hamulus, andcauses the hamulusbody to lookmore hollowed-out(Fig. 6,
arrow). Inbothspecies, extrusion ofthe vesicapushes itagainst theinnerwall
ofthe hamuli,causing theapical hooktobendoutward andmakecontact with
theoutgrowth onthesideofthehamulus, elfectivelyformingan‘eye’(Fig. 7);we
suspect thatthis hadoccurredin thespecimen figured by PINHEY(1970).
We concludethatO. kollmannspergeri Buchholzisagoodspecies, as already in-
dicatedby PINHEY(1970). Itsknown distributionisstilllimitedtoasmallSahel
region ineastern Chad andnortheasternSudan. However, thepresent findings
warrant re-examinationof OrthetrumcollectionsfromEthiopia, Somalia, Erit-
rea(PINHEY, 1962),Sudan(LONGFIELD, 1936),andevenNigeria(PINHEY,
1970) to determinethetrue distributionof O. kollmannspergeri, O. taeniolatum,
andrelatedspecies intheeastern andcentralSahel.
CHECKLISTOF ODONATA RECORDED FROM CHAD.
CD =DEJOUX(1968),KFB=BUCHHOLZ(1959),LN=NAVAS(1936)
LESTIDAE
— Lestes pallidusRambur:N’Djamena (CD)
L— . dissimulansFraser(sub L. simulans): N’Djamena (CD)
COENAGRION1DAE
- Agriocnemis exilisSelys: N’Djamena (CD)
I—schnura senegalensis Rambur: thispaper
-Pseudagrion coelesteLongfield: N’Djamena (CD)
- P. hamoniFraser: this paper
- P.nubicum Selys: N’Djamena (CD)
~P.(?)kersteni: Adre(KFB)
- Ceriagrion glabrum(Burmeister) (presumed): N’Djamena (CD)
PLATYCNEMIDIDAE
- Platycnemis sp.(larvae): macrophyte zoneof eastern partofLakeChad(CD)
AESHN1DAE
—Anax parthenope (Selys): Oued Yokou, N. fringe of Ennedi (ssp “geyri”)
(KFB)
—A. tristisHagen: N’Djamena (CD)
—Hemianax ephippiger (Burmeister): Gueltain Oued Zebre, E. Ennedi(KFB);
spring atTorres, 1750masl, Tibesti(LN);aroundN’Djamena, lakes Fianga
andTikem(CD)
GOMPHIDAE
I—ctinogomphus sp.:Tandjile Riverbetween MoundouandPola(larvae) (CD)
296 H.J.Dumont&D.Verschuren
—Lestinogomphus sp.:LacFianga (larvae)(CD)
-Paragomphus sp.: RiverChari, includingdelta;lakesFitriandLere(larvae)(CD)
—Phyllogomphus sp.: TandjileRiverbetweenMoundouandPola; ChariRiver at
N'Djamena (larvae) (CD)
MACROMIIDAE
—Phyllomacromia sp. (pictal);N’Djamena (CD)
LIBELLULIDAE
—Acisomapanorpoides ascalaphoides (Rambur): floodplain ofChariRiver(CD)
Brachythemis leucosticta (Burmeister): all around lakeChad; also Moundou,
Deli,Bongor, LacLere,Tikem, Fianga,Lakesof Mombolo,RiversofKanem,
along ChariRiver(CD);Fort Lamy andAdre(KFB).
- Crocothemiserythraea (Brulle);around N'Djamenaandelsewhere(CD); Mis-
ki valley, S. Tibestiand between Guezentiand Bardai, N. Tibesti (LN); this
paper.
C. sanguinolenta (Burmeister): Aneche(KFB)
-
D— iplacodes lebebvrii(Rambur): temporaryswampsnear N’Djamenaandeast-
ern zoneofLakeChad(CD)
- Hemistigma albipunctum (Rambur); aroundN’Djamena andin eastern Chad
(CD)
- Olpogastra lugubris Karsch: nearN’Djamena andalong riverChari(CD)
—Orthetrumbrachiale(P. deBeauvais): N’Djamena (CD)
- O. caffrum (Burmeister): AdreonborderwithSudan(KFB)
- O. chrysostigma (Burmeister): Beskereand Archei inEnnedi(KFB); this pa-
per.
- O. icteromelasRis: N’Djamena (CD)
- O. kollmannspergeri Buchholz;AdreonborderwithSudan(KFB)
- O. sabina(Drury); thispaper
- Palpopleura lucia(Drury); shoresofLogone River at Bebo, 50km S.ofDoha
(CD)
P— . deceptor (Calvert): AbouGoulembetweenAbecheandAdre(KFB)
- Pantalaflavescens (Fabricius): shoresofLakeFianga andacross mostofChad
(CD)
—PhilonomonluminansKarsch; nearN’Djamena (CD)
—Sympetrum fonscolombii (Selys): Wadi Rei, Ennedi(KFB); Miski valley, Ti-
besti(LN)
- Tholymis tillarga(Fabricius): commonaround N’Djamena and along River
Chari(e.g. at Niellim)(CD)
- Trameabasilaris(P. deBeauvais):alongChariRiverbetweenNiellimandDjun-
tiloandaroundN’Djamena.
- Trithemisannulata(P. deBeauvais): ChariRivernearNiellimandN’Djamena
(CD);this paper
- T.arteriosa (Burmeister):Ennedi, severalstations(KFB); Bardai, Yebbi, Cen-
OdonataoftherepublicofChad 297
tralTibesti andTorosspring. EasternTibesti(LN); thispaper
- T.hecateRis: ChariRivernearNiellim(CD)
- T.kirbyi ardensGerstacker; "Ennedi" (KFB); between BardaiandYebbi, ca
1100m a.s.l., CentralTibesti (LN)
- T.furva (Karsch)(sub T. risi):Adre(KFB)
Urothemisedwardsii(Selys): allaroundlakeChad, Bol,all islandsintheEast,
-
Ndjora,LakesFitri,Tikel andFianga (CD)
ACKNOWLEDGEMENTS
DirkVerschurenthanksSTEFANKROPELINfortheopportunitytoparticipateingeologicaland
limnologicalfieldwork innorthernChad,fundedbythe DeutscheForschungsgemeinschaftthrough
theprogrammeACACIA "AridClimate,AdaptationandCultural Innovation in Africa".
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