A new species of freshwater crab (Brachyura, Potamoidea, Potamonautidae) from Principe, Gulf of Guinea, Central Africa

6 Pages·2002·2.5 MB·

by  Neil Cumberlidge

yy (-3>szt^- \j
Bull. nur. Hist. Mus. Land. (Zool.)68(1): 13-18 Issued27June2002
A new species of freshwater crab (Brachyura,
Potamoidea, Potamonautidae) from Principe,
Gulf of Guinea, Central Africa
NEIL CUMBERLIDGE
DepartmentofBiology, Northern Michigan University. Marquette. Michigan 49855, U.S.A.
PAUL CLARK
F.
DepartmentofZoology, TheNaturalHistoryMuseum. CromwellRoad, London, SW75BD, U.K.
JONATHANBAILLIE
InstituteofZoology, ZoologicalSocietyofLondon, RegentsPark, London NW1 4RY, UK.
CONTENTS
Introduction 13
SystematicAccount 13
P.principesp.nov 13
EcologicalNotes 17
Acknowledgements 17
References 17
Synopsis. AnewspeciesoffreshwatercrabofthegenusPotamonautesMacleay. 1838isdescribedfromPrincipe(Democratic
RepublicofSaoTomeandPrincipe),anislandintheGulfofGuineaoftthecoastofCentralAfrica.Thespecimenswerecollected
duringarecentzoologicalexpeditionbytheZoological SocietyofLondon.This isalsothe first recordofafreshwatercrabon
theislandofPrincipe.
INTRODUCTION nevertheless provided here, based on several unique somatic
charactersofthespecimen.Charactersofthegonopods,maleabdo-
men, and male chelipeds will be described when more material
The freshwater crabs reported on here were collected during a (including an adult male) becomes available.
zoologicalexpeditiontotheislandofPrincipe,maderecentlybythe Figureswereprepared usingacameralucida, andthespecimens
ZoologicalSocietyofLondon.TheislandofPrincipe,togetherwith were deposited in The Natural History Museum, London, U.K.
the island of Sao Tome, constitutes a small independent country (BMNH). Abbreviations: cw, distance across the carapace at the
(TheDemocraticRepublicofSaoTomeandPrincipe)intheGulfof widest point; cl, carapace length measured along the median line,
Guinea. Principe is the second in a chain of volcanic islands that from the anterior to the posterior margin; ch, carapace height, the
makeuptheAtlanticOceanIslandsgroup,thatliesoffthecoastsof maximum height ofthe cephalothorax); fw, front width measured
Cgraomueproaorne,BiEoqukaot,orSiaaolTGouimneeaanadndAnGnaobboonn..ThBeiooktoheirsicslloasnedsstitnotthhies as4l/osn5g,thse4/asn5t,ersi5o/rs6m.args6i/ns;7,s,tsh7/osr8a,cicstsetrenmailtes;ulec,ithboeratcwieceenpisatdejrancietnet;
mainland and has two species of potamonautid freshwater crabs, thoracicsternites;s4/e4,s5/e5,s6/e6,s7/e7,episternalsulcibetween
Sudanonautesfloweri (De Man, 1901) and S. granulatus (Balss, adjacentthoracicsternitesandepistemites;P1-P5,pereiopods 1-5,
1929), both of which are also found in nearby Cameroon al-a6, abdominal segments 1-6, a7, telson oftheabdomen.
(Cumberlidge, 1993, 1995, 1999).SaoTomeisthethirdislandinthe
group,andhasoneendemicspeciesoffreshwatercrab,Potamonautes
margaritarius (A. Milne-Edwards, 1886). There are no records of
freshwater crabs occurring on Annobon, the fourth island in the SYSTEMATIC ACCOUNT
chain, and the furthestfrom the mainland.
Until the present report, freshwatercrabs were not known to be
present on Principe. The new species from Principe was collected Family POTAMONAUTIDAE Bott, 1970
fromstreamsandnearby landincloudforestintheremoteroadless GenusPOTAMONAUTESMzcLeay, 1838
highlandregioninthesouthwestpartoftheisland.Thenewspecies
is compared to Potamonautes anchietae (De Brito-Capello, 1871) Potamonautesprincipe sp. nov.
and to P. margaritarius, but differs from each in a number of
(Fig. 1)
importantcharacters (Bott, 1953, 1955, 1964). Althoughthe speci-
mensfromPrincipe arebothsubadultfemales, and ideally an adult Materialexamined
male is needed to make a definitive identification, a description is Holotype. BMNH 2001.6907. 1 subadultfemale,cw40.5,cl27.5,
)TheNaturalHistoryMuseum.2002
14 N.CUMBERLIDGE,P.F.CLARK ANDJ. BAILLIE
^rv
Fig. 1 Potamonautesprincipesp.nov.Holotypesubadultfemale,cw40.5mm,BMNH2001.6907.A,carapace,dorsalview;B.cephalothorax,frontal
view;C,leftthirdmaxilliped;D.abdomen;E.anteriorsternum;F,rightcheliped,frontalview;G,leftcheliped,frontal view;H,carpusandmerusof
rightcheliped,dorsalview;I,carpusandmerusofrightcheliped,inferiorview.Scale=A,H,I, 13.1 mm;B,D,C,E, 10.5mm;F,G,8.3mm.
A NEW FRESHWATERCRAB FROM PRINCIPE 15
ch 14.8,fw 10.5mm,summitofPicodoPrincipe(01°34',5l''N,07° alcohol preservation) was creamy white with a very light purplish
22', 57"E), 945 m, coll. J. E. M. Baillie, 26 Sept. 1999. tone, however one specimen was more white than the other. This
Paratype. BMNH 2001.6908.1 subadult female, cw 33.2, cl 22.8, colorationwasrelativelyuniformthroughoutthebodyincludingthe
ch 11.6,fw 10.0mm,summitofPicodoPrincipe(01°34'. 51"N,07° dorsal carapace, underside, and legs. The purplishtone was darker
22', 57"E), 945 m, coll. J. E. M. Baillie, 1 Sept. 1999. on the carapace just behind the eyes, which turned to an orange
reddishcoloroncethe specimens were placed in alcohol.
DIAGNOSIS. Postfrontal crest straight, smooth, spanning entire
carapace,ends meeting anterolateral margins atepibranchial teeth. Distribution. Thisspeciesisknownonlyfromthesummitofthe
Exorbital tooth small, pointed; epibranchial tooth representedonly PicodoPrincipe: (01° 34', 51'N,07° 22', 57"E)at945 meters,The
by small granule; anterolateral margin posterior to epibranchial Democratic Republic of Sao Tome and Principe, GulfofGuinea,
tooth raised, completely smooth, continuous with posterolateral Central Africa.
margin.Carapacesurfacecompletelysmooth;highlyarched,height ETYMOLOGY. The species is named for the island of Principe
greater than front width (ch/fw 1.5). Pleural (vertical) suture on where it was collected. The species name principe is a noun in
carapacesidewallY-shaped,endsmeetingexorbitalandepibranchial
apposition.
teeth.Suborbitalmarginraised,completelysmooth.Ischiumofthird
maxilliped with deep vertical sulcus. Third sternal sulcus s3/s4 Taxonomic remarks. The new species is assigned to Pota-
deep,v-shaped,meetingsterno-abdominalcavity.Thoracicepister- monautes because it possesses the following combination of
nal sulci s4/e4, s5/e5, s6/e6 and s7/e7 distinct. Anterior inferior characters: the anterolateral margin lacks an intermediate tooth
marginofmerusofchelipedlinedbyrowofsmall sharpteeth,with betweentheexorbitalandepibranchialteeth;themandibularpalpis
large pointedtooth nearjunction with carpus. two-segmented:andthethirdmaxillipedexopodhasalongflagellum.
Potamonautes is a widespread genus of African freshwater crabs
Description. Carapaceovoid, wide (cw/fw 3.88), highly arched found throughout Africa from Senegal to the Horn ofAfrica, and
(ch/fw 1.45); surface completely smooth semi-circular, urogastric, fromEgypttoSouthAfrica. Bott's(1955)revisionofthefreshwater
transversebranchialgroovesfaint. Frontstraight,relativelynarrow, crabsofAfricarecognisedsome34speciesinthisgenus.Sincethen,
about one-quarter carapace width (fw/cw 0.26), anterior margin the number ofspecies ofPotamonautes has risen to more than 60
sharply deflexed. Postfrontal crest distinct, smooth, straight, span- (Bott, 1959, 1960, 1964, 1968, 1970; Stewartetal., 1995; Stewart,
ning entire carapace, consisting of fused epigastric, postorbital 1997a,b; Daniels et al., 1998; Cumberlidge, 1999; Corace et al,
crests; ends of postfrontal crest meeting anterolateral margins at 2001). Although Bott (1955) recognised 15 subgenera of
epibranchial teeth. Anterolateral margin between exorbital. Potamonautes, the authors of the present study prefer to follow
epibranchialteethsmooth, lacking intermediatetooth; anterolateral Cumberlidge (1999) and use Potamonautes [sensu lato \ for all
margin posterior to epibranchial tooth raised, completely smooth, species, pending a revision of the entire genus (Cumberlidge, un-
continuouswithposterolateralmargin.Exorbitaltoothsmall,pointed; published).
epibranchial tooth represented only by small granule. Suborbital It is not normally good practicetodescribeanew species froma
margin raised, completely smooth. Suborbital, subhepatic, subadult female. However, we have decidedtoestablish this taxon
pterygostomialregionsallcompletelysmooth;sidewalldividedinto in the light of the distinct nature of the available morphological
three parts by longitudinal (epimeral) suture (dividing suborbital, characters,andbecauseoftheisolatednatureofthestudyareawhich
subhepatic regions from pterygostomial region), and by Y-shaped may mean that further specimens of P. principe are unlikely to
vertical (pleural) groove (dividing suborbital from subhepatic become available forsometime. Charactersofthe gonopods, adult
regions). Superior ends of Y-shaped vertical groove meeting male chelipeds. abdomen and sternum are not at present known
exorbital,epibranchialteeth.Firstthoracicsternalsulcussi/s2deep; because the only specimens of P. principe are subadult females.
secondsulcuss2/s3deep,runninghorizontallyacrosssternum;third Nevertheless,thereareanumberofuniquecharactersthatdistinguish
sulcuss3/s4deep,v-shaped,meetingsterno-abdominalcavity.Tho- P. principe from otherspecies in the genus.
racic episternal sulci s4/e4, s5/e5, s6/e6 and s7/e7 distinct. Third
maxillipeds filling entire oral field, except for transversely ovate COMPARISONS WITH OTHER SPECIES. Potamonautes principe is
respiratory openings at superior lateral corners; long flagellum on closest to P. anchietae, a medium-sized species offreshwatercrab
exopod of third maxilliped; ischium with deep vertical sulcus. fromAngola(DeBrito-Capello, 1871,Bott, 1953, 1955, 1964).This
Epistome prominent, smooth, triangular. Mandibular palp 2-seg- specieswasmostrecentlydescribedandillustratedbyBott(1955,p.
mented; terminal segmentsingle, undivided, with hair(butnohard 247-249,figs. 24, 76,77,pi. IX,fig. la-d)asP. (Isopotamonautes)
flap) at junction between segments. Subadult female abdomen anchietae. Potamonautes principe and P. anchietae are similar in
subcircular, segments al-a6 of female abdomen quadrate, telson that both species have a highly arched carapace, a prominent and
(a7) abroadtriangle with rounded apex; segments a5-a6broadest. completepostfrontalcrest,apointedexorbitaltooth,asmall granu-
Majorchelipedofsubadult female relatively slender, with elon- larepibranchialtooth,av-shapedthoracicsternalgrooves3/s4,and
gateddactylusandpropodus, palm ofpropodus swollen; fingersof a similar-sized first carpal tooth on the carpus of the cheliped.
digits of cheliped with small even teeth, forming long narrow However, there are a number of characters that distinguish the
interspacewhenclosed. Firstcarpaltoothofinnermarginofcarpus specimens from Vissabenguilla, Angola (SMF 1890) describedby
ofchelipedlarge, pointed; secondcarpal toothpointed, halfsizeof Bott (1955) as P. (I.) anchietae from the specimens from Principe
first tooth. Posterior inferior margin ofmerus ofcheliped smooth, underconsideration here.
with few small teeth distally; medial inferior margin with row of The carapace height of P. principe is greater than that of P.
small sharp teeth along entire length, large pointed tooth at distal anchietae(ch/fwP.principe 1.45,P.anchietae 1.19),andthefrontal
end; superiorsurface ofmerus smooth. Pereiopods P2-P5 slender, marginofP.principeisnarrowerthanthatofP. anchietae(fw/cwP.
P3 longest, P5 shortest. Dactyli of P2-P5 tapering to point, each principe0.26,P. anchietae0.39).Further,theanterolateral margins
bearing fourrows ofdownward-pointing short, sharp spines. ofthecarapaceofP.principearecompletelysmoothandlackteeth
of any kind, whereas these margins in P. anchietae are distinctly
COLOUR. Thecolourofthespecimenswhenfreshlycaught(before granular.Themedialinferiormarginofthemerusofthechelipedof
16 N. CUMBERLIDGE,P.F.CLARK ANDJ. BAILLIE
U
Q
tt.
U
i-
g
PQ
i
E
1 .
ANEW FRESHWATERCRAB FROM PRINCIPE 17
P. principe has a row of distinct pointed teeth along its length, Acknowledgments. GillesJoffroy andTariq Stevart(Universite libre
whereas this margin in P. anchietae, lacks teeth, and is either de Bruxelles) assisted in the collection of specimens. Phil Crabb (NHM
granularorsmooth.Finally,thesuborbitalandpterygostomialregions Photo. Unit)tookthephotographsreproducedinthispaper.
of P. principe are smooth, whereas these regions are distinctly
granularin P. anchietae.
Bott(1953, 1955, 1964)describedtwosubspeciesofP.anchietae: REFERENCES
P. (I.) a. biballensis Rathbun, 1905, and P. (I.) a. machedoi Bott,
1964, bothofwhichare found in Angola. However, comparisonof Balss, H. 1929. Crustacea V. Potamonidae au Cameroun. In: Th. Monod, ed..
the types of these taxa with P. principe indicates that both differ ContributionsaIeludedelafaunedttCameroun.FaunedesColoniesfrancaises3:
substantiallyfromthenewspeciesdescribedhere.Forexample,the 115-129
epibranchial tooth of P. (I.) a. biballensis is large and pointed DeBrito-Capello.F.1871.Algumasespeciesnovasoupoucoconhecidaspertencentes
whereasthatof/5,principeissmallandgranular,andthecarapaceof nduolsurgaeenser(oLsisCbaolna)p3p:u1e28T-h1e3l4p.husa.JornaldeScienciasmathematicas, physicas e
P. (I.)a. biballensisisflattened,whereasthatP.principeishigh(ch/ Bott, R. 1953. Potamoniden (Crust. Decap.) von Angola. Publicacoescuhuruisda
fw P. principe 1.45, P. (I.) a. biballensis 1.25). Similarly, the CompanhiadeDiamantesdeAngola. Lisbon 16: 133-148.
epibranchialtoothofP.(I.)a.machedoiislargeandpointedwhereas 1955. Die SuBwasserkrabben von Afrika (Crust.. Decap.) und ihre
thatofP.principeissmallandgranular,andthefrontal marginofP. Stammesgeschichte. Annates du Musc'e dit Congo Beige (Tervuren, Belgique) C-
principe is narrower than that of P. (I.) a. machedoi (fw/cw P. Zooh19g5i9e..PSoetraimeson1i11d.enIIIa.u3s:W2e0s9t--3A5f2r.ika(Crust..Dec).BulletindeI'lnstiiutfrancais
principe0.26, P. (I.)a. machedoi0.33). d'Afriquenoire21.serieA(3):994-1008.
Potamonautesprincipewasalsocomparedherewithaspecimen I960. Crustacea(Decapoda): Potamonidae. hi: Hansstrom. B. & others. South
ofP. margaritarius from Sao Tome (SMF 2668), and the twotaxa AfricanAnimalLife. ResultsofLundUniversityExpeditionin 1950-1952: 13-18.
cthaenlbatetedrisspteicnigeusisihseddisbtyinctthleyffollatltoewniendg(cchha/rfawctPermsa.rTgahreitcaarriaupsac0.e95o,f (PCurbu1ls9it6c.4a.DceoDceeascpac.pu)loiudunerdnaieasiunsdaeAmnCgAoonmlhpaaaunnnghtie:raDbideeesoTDnyidpaeemrnearnvtBoeenrsiTdihceeklAspnihcguhostliaag.puenLlgiiidsebHroearPko6lt9oa:tms2.o3n1-i83d64e1.n.
P. principe 1.45), the anterolateral margin of P margaritarius 1968. Decapoden aus dem Museu do Dundo (Crust. Decap.). Publicacoes
behindtheepibranchialtoothisclearlytoothed(whereasthismargin culiuraisdaCompanhiadeDiamantesdeAngola. Lisboa77: 165-172.
misaxciolmlpilpeetdeloyfPsmmoaortghariintaPripursinicsispme)o,otahndantdhelaicskcshaiuvmertoifcatlhesutthuirred SScUhBww1ea9is7zs0..erR-BeKevrturaeabcbSheulinusnsnegaecdnheduZeboreorlSoagdmiieeml7Eu7n:ntgw3i2dc7ek-sl3u4Nn4ag.tsugrehsicshtiocrihstceheunndMuVseerubmresitiunngGendte/r
(whereas this suture is deep in P principe). Bredero. J. T., Heemskerk, VV. & Toxopeus, H. 1977. Agriculture and livestock
productioninSaoTomeandPrincipeIWestAfrica).Unpublishedreport.Foundation
forAgricultural Plant Breeding.Wageningen.
Corace,R.G.,Cumberlidge.N.&Garms.R. 2001.Anewspeciesoffreshwatercrab
ECOLOGICAL NOTES fromRukwan/i.East Africa. ProceedingsojtheBiologicalSocietyofWashington.
114(1): 178-187.
Cumberlidge, N. 1993. Redescription of Sudanonautes granulaius (Balss. 1929)
The islandofPrincipe is ovoid in outline, with atotal land areaof iPiiiamoidea,Potamonautidae)fromWestAfrica.JournalofCrustaceanBiology13:
about 139 sq km (Fig. 3). The highest point is Pico de Principe 805-816.
1995. Redescription of Sudanonautes floweri (De Man. 1901) (Brachyura:
(945 m), which is a volcanic mountain whose lower slopes are Potamoidca: Potamonautidae) from Nigeria and Central Africa. Bulletin oj the
vegetated by lowland rain forest that grades into cloud forest at BritishMuseumofNaturalHistory(Zoology), London61 (2): 111-119.
higher elevations. The climate of Principe is tropical, hot, and 1999. Thefreshwatercrabs ofWestAfrica. Family Potamonautidae. Faune et
humid, and there is a single rainy season from October to May. FloreTropicales35, nstitutderecherchepourledeveloppementdRD,ex-ORSTOM),
mm Paris. 1-382.
Rainfall levels are himghm, averaging around 1,000 per year in Daniels,S.R.,Stewart,B.A.&Gibbons,M.J. 1998.Potamonautesgranulanssp.
the north and 5,000 per year in the south, and monthly tem- ttOV, (Brachyura: Potamonautidae). a new cryptic species ofrivercrab from the
peraturesrangebetween 25° and 31°C (Brederoetal., 1977). The Olilantsri\crsystem, SouthAfrica.Crustaceana71: 885-903.
two specimens were collected from the summit of the Pico do MacLeay,W.S.1838.BrachyurousDecapodCrustacea.IllustrationsoftheZoologyof
Principe at 945 meters above sea level on two separate occasions. SouthAfrica5;beingaPortionoftheObjectsofNaturalHistoryChieflyCollected
during an Expedition intothe InteriorofSouth Africa, underthe DirectionofDr.
The terrain at the summit ofthe Pico do Principe is volcanic and AndrewSmith,intheYears 1834. 1835.and1836;FittedOutbyTheCapeofGood
mountainous, and the vegetation cover is cloud forest with small Hope Association forExploringCentral Africa.' In:A. Smith. Illustrations oj the
stunted trees, and a high abundance ofepiphytes and bryophytes. Zoology ofSouth Africa; Consisting Chiefly ofFigures and Descriptions ofthe
The thick cloud cover and regular rainfall keep the soil and leaf ObjectsofNaturalHistoryCollectedDuringanExpeditionintotheInteriorofSouth
littervery damp. Onbothoccasions when crabs werecollected the AAfsrsioccai,atiinotnhfeorYeEaxrspl1o8r3i4n.g1C8e3n5t.raalnAdfr1i8c3a6.':(FIintvteerdteOburtatbeys):Th1e-7C5a.peofGoodHope
weather was extremely damp and the mountain top engulfed in DeMan,J.G. 1901. Description ofanew fresh-waterCrustacea fromthe Soudan:
cloud cover. Both specimens were collected on land from under followed by some remarks on an allied species. Proceedings ofthe Zoological
dampanddecaying leaflitter. There was noriverorbody ofwater SocietyofLondon, 1901:94-104.
near the location where the specimens were found. The nearest Milrenceue-iEldliwsarpdasr,MA..d1e886B.raLzazadedsacrnisptlieosnrdeegiqouneslqduuesCCornugsot.aceBuslldeutignendreeTlaheSlopchiuestae
stream was observed at lower altitudes (830 m), but there were PhilosophiqtteParisseries7(10): 148-151
numerous temporary small pools at the summit which form after Rathbun,M.J. 1905.Lescrabesd'eaudouce(Potamonidae).NouvellesArchivesdu
heavy precipitation. It is likely that P principe can breathe air, Museumd'Histoirenaturelle(Paris)7(4): 159-322.
given itsextremelyterrestrial lifestyle. Whencrabs weredisturbed Steowfarritv,erB.crAa.bs19(9D7eac.apMoodrap:hoPlootgaimcoanlaauntiddgaeen)etfircodmiftfheereWnetisatteironnbCeatpwee,eSnopuotphulAaftriiocnas,
by removing the leaflittercover, theyranrapidly across theforest withataxonomicre-examinationofGecarcinautesbrincki.ZoologicalJournalof
floor and took cover under leaf litter or any available crevasse. theLinneanSociety199: 1—21.
Specimenswerecollectedclosetoholes nearthe PicodoPrincipe, 1997b.Biochemicalandmorphologicalevidenceforanewspeciesofrivercrab
hboultesc,raabnsdwiterraemaniontsapcotsusailbllyeotbhastertvheedhomloesvimnagyinnotorhaovuetboefenthdeusge cProat,bCaom(koBerna,acuMhty.eus&rap:CaorPovokits,apmPio.niAad.e(aD1:9e9cP5ao.ptoPadomato:anmaPouonttiaadumatoene)asufdterinodtmaaetK)uw.sa.ZCnureluuws-tsNapacetecaaielns.a,S7a0of:urte7hs3h7A-f-wr7ai5tc3ae..r
by the crabs. JournalofCrustaceanBiology15:558.
N.CUMBERLIDGE,P.F.CLARK ANDJ. BAILLIE
Principe
GulfofGuinea
Bombom
N
1°40'
PortoReal
Terriro Velho
MariaCorreia
1°35'N
PicodoPrincipe
AntonioEnes •
^Zj Bone doJoquei
7°20'E 7°25' E
Fig.3 MapofPrincipeshowingthetypelocalityofPotamonautesprincipesp.nov.