The freshwater prawns of the genus Macrobrachium Bate, 1868 (Crustacea: Decapoda: Palaemonidae) from Brunei Darussalam

21 Pages·2001·2.2 MB·English

by  Wowor, D

THE RAFFLES BULLETIN OF ZOOLOGY 2001 49(2): 269-289
© National University ofSingapore
THE FRESHWATER PRAWNS OF THE GENUS MACROBRACHIUM BATE, 1868
(CRUSTACEA: DECAPODA: PALAEMONIDAE) FROM BRUNEI DARUSSALAM
Daisy Wowor
Division ofZoology, ResearchandDevelopment Centerfor Biology, Indonesian Institute ofSciences (L/PI), Jl. Raya BogorJakarta Km 46,
Cibinong 1691I, Indonesia. Currentaddress: DepartmentofBiologicalSciences, National University ofSingapore, IO KentRidge Crescent,
Singapore 119260
Satish C. Choy
QueenslandDepartmentofNatural ResourcesandCo-operative Research Centrefor FreshwaterEcology, 80Meiers Road, Indooroopilly,
Queensland4068, Australia
ABSTRACT.- ThetaxonomyoftheBruneianfreshwaterprawnsofthegenusMacrobrachium Bate, 1868
istreated. Materialcollectedfromthroughoutthecountryshowthatthereare 11 speciesofMacrobrachium
ofwhichtwo [M. lopopodus andM. leucodactylus] are heredescribedas new andseven [M. clymene(De
Man, 1902),M. equidens(Dana, 1852),M. idae(Helier, 1862),M.javanicum(Helier, 1862),M. lanchesteri
(De Man, 1911),M. lar(Fabricius, 1798)andM. scabriculum(Helier, 1862)] are new records for Brunei
Darussalam. A key for the identification ofthe species is provided.
KEYWORDS.- Freshwaterprawn,Palaemonidae,Macrobrachium,BruneiDarussalam,newspecies,new
record, taxonomy.
INTRODUCTION Cibinong, Indonesia; Naturhistorisches Museum in Wien
(NHMW), Vienna, Austria; Instituut voor Systematiek en
AccordingtoChoy(1991), onlythree speciesoffreshwater Populatiebiologie[ZoOlogischMuseumAmsterdam(ZMA)],
prawns ofthe genusMacrobrachium Bate, 1868have been Universiteit van Amsterdam, Amsterdam and Nationaal
reported from Brunei Darussalam, viz. Macrobrachium Natuurhistorisch Museum [formerly Rijksmuseum van
rosenbergii (DeMan, 1879),M. pilimanus (DeMan, 1879) Natuurlijke Historie (RMNH)], Leiden, The Netherlands.
andM. malayanum(Roux, 1934). Thelargestandthe most Malay words used in the text are Sg. or Sungai [=River or
important commercial species is 'Udang Galah' (M. stream], Kg. or Kampung [=Village] and Bukit [=Hill].
rosenbergii). Sofar, therehas beennothoroughsystematic Although Brunei Darussalam is the proper name for the
study ofthe genus Macrobrachium in Brunei Darussalam. country, for convenience the rest of the paper will use its
This deficiency is now addressed in hope that once the more widely known and shortened name of Brunei. All
systematics is reviewed more effortcould go into studying material from Brunei was collected by the second author
the ecology of these species and subsequent sustainable unless otherwise stated, with exception ofsome specimens
management ofthe fished species. from Sabah for whom the name of the collector is
unavailable. The abbreviations used are CL for carapace
The material examined is deposited in the Sabah State length,measuredfromthepostorbitalmargintotheposterior
Museum (SSM), Kota Kinabalu, Sabah, Malaysia; Brunei median margin of the carapace; PL for postorbital teeth
Museum(BDM),BandarSeriBegawan,BruneiDarussalam; length, measuredfrom thepostorbitalmargintothebaseof
Zoological Reference Collection (ZRC) of the Raffles the last tooth on carapace; T4 for thoracic sternite 4.
MuseumofBiodiversityResearch,DepartmentofBiological Descriptionsarebasedonholotypespecimenswithparatypic
Sciences, National University of Singapore (NUS), variationincludedinparentheses. Allsynonymiesprovided
Singapore;DivisionofZoology,ResearchandDevelopment are restricted, with readers requested to consult Holthuis
Center for Biology, Indonesian Institute of Sciences (1950) and Chace & Bruce (1993) for details.
[formerly Museum Zoologicum Bogoriense (MZB)),
Received 27 Fcb 2001 Accepted 13 Sep 2001
269
Wowor & Choy: Macrobrachium from Brunei Darussalam
114°E 115°E
5°N
SouthChinaSea
SARAWAK(MALAYSIA)
4°N
Fig. I. Map ofBrunei Darussalam showing drainages.
TAXONOMY (11.9mmCL), Iovigerousfemale(12.5mmCL)(ZRC2000.2412),
Sg. KinaromatKp. Loguhang,ca. 6kmdownstreamofSerinsim
Station, Kota Marudu District, Sabah, Malaysia, coIl. R. Goh et
FAMILY PALAEMONIDAE RAFINESQUE, 1815
aI., 15 Dec.2000; I male (13.0mmCL), I ovigerous female (8.8
mmCL)(ZRC2000.2413), Sg. Belalong,TemburongDistrict,25
Genus Macrobrachium Bate, 1868 Aug.1990; 2 males (9.7-14.0 mm CL)(ZRC 2000.2414), Sg.
TemburongatBatangDuri, TemburongDistrict, 29 Aug.1990; I
Macrobrachium lopopodus, new species male (14.4 mm CL), I ovigerous female (9.3 mm CL)(RMNH),
Sg.TemburongatBatangDuri,TemburongDistrict,29Aug.1990;
(Figs. 2, 3)
1male(8.5mmCL)(ZRC2000.2416),Sg.Engkabang,Temburong
District, 8 Feb.1991; I male (19.2 mm CL)(BDM), Sg. Apan,
Materialexamined.- Holotype-male(19.9mmCL)(SSM616), Temburong District, 9 Feb.1991; 1 male (15.0 mm CL)(ZRC
DIu Sg. Sawatan, Kimanis, Papar District, Sabah, Malaysia, 3 2000.2415),Sg.BelalongatBatangDuri,TemburongDistrict,23
Jun.1998. Jun.1991; I ovigerous female (9.9 mm CL)(BDM), Sg. Belalong
at KuaJa Belalong, Temburong District, 14-17 Jun.1995; I male
Paratypes-3males(17.7-19.9mmCL), Iovigerousfemale(13.7 (11.5mmCL), Iovigerousfemale(11.3mmCL)(ZRC2000.2417),
mm CL)(SSM 616), same data as holotype; 2 males (16.1-16.7 Sg. Belalong at Kuala Belalong, Temburong District, 14-17
mm CL)(SSM 622), DIu Sg. Sawatan, Kimanis, Papar District, Jun.1995.
Sabah,Malaysia,4Jun.1998; 1male(15.9 mmCL), I ovigerous
female(10.0mmCL)(SSM639),DIuSg.Sawatan,Kimanis,Papar
Diagnosis.- Asmall-sizedspecieswithsubcylindricalbody
District, Sabah, Malaysia, 6 Jun. 1998; 26 males (5.8-20.7 mm
CL),5females (5.8-13.6mmCL),8ovigerousfemales (9.7-12.9 form. Rostrum short, not reaching end of antennular
mmCL)(ZRC2000.2409),Sg.KimanisatKp.Wolit,DIuKimanis, peduncle,dorsalmarginconvexorslightlysinuous. Rostral
PaparDistrict, Sabah,Malaysia,coli. R. GohetaI., 8Dec. 2000; formula: 5-6)10-12/1-3. Scaphocerite with outer margin
5 ovigerous females (10.2-15.2 mm CL)(ZRC 2000.2410), Sg. slightly concave, about 2.4 times as long as wide. Second
Malamum, tributary to Sg. Mengalong, Sipitang District, Sabah,
pereiopodswithcarpusreachingbeyondscaphocerite,carpus
Malaysia,coIl. R. GohetaI., 9Dec.2000; I male(17.7 mmCL),
longerthanmerus, similarinform, unequalinsize,covered
Iovigerousfemale(16.1 mmCL)(MZBCru1457),Sg.Malamum,
tributary to Sg. Mengalong, Sipitang District, Sabah, Malaysia, by appressed scales. Major second pereiopod of mature
coIl. R. Goh et aI., 9 Dec. 2000; 6 males (7.0-21.7 mm CL), I males bearing row oftubercles on fingers. Pre-anal carina
female(9.1 mmCL),9ovigerousfemales(12.3-16.7mmCL)(ZRC present. Mobile mesial spine ofexopod of uropod big and
2000.2411),Sg.MoyogatKp.Kibunut,Petagasbasin,Penampang
strong, longer than distolateral tooth. Eggs small (O.6x0.4
District,Sabah,Malaysia,coli.R.GohetaI., 10Dec.2000; 1male
mm), numerous.
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THE RAFFLES BULLETIN OFZOOLOGY 2001
Description. - Rostrum. Short, 0.39 CL (0.37-0.50 in andparallel,upperandlowermarginsrounded,outermargin
paratypes), reaching to or beyond second segment of more densely scaled than upper and lower margins, inner
antennularpedunclebutneverreachingendofthirdsegment margin with more sparsely scattered big spines, scales of
ofantennular peduncle (Figs. 2A, B); moderately slender, equal size on all surfaces; fingers 0.65 times palm length
maximum depth about equal to maximum dorsoventral (0.71-0.85 in male and 1.10in female paratypes ), slightly
diameterofcornea;lateralcarinawelldeveloped,continuing gaping, cutting edges with well-developed teeth; dactylus
almosttotip; dorsalcarinadistinctlybentdownwardsinfront with first big conical tooth at proximal 0.60, second at
oforbitwithtipdirectedanteriorly,armedwith 12teeth(10 proximal0.35, thirdatproximal0.24,firstandsecondteeth
12 in paratypes, mode 11), interspaces setose, teeth samesize,thirdtoothsmaller,2rowsoftuberclesalongdistal
distributedsubequallyandtendingtobemorecloselyspaced 0.40with8and2tuberclesonouterandinnersideofcutting
aboveorbitthandistallyorpost-orbitally,5teethcompletely edges respectively, tubercles on outer side subequally
postorbital (5-6 in paratypes, mode 5), postorbital teeth on distributed, tubercles on inner side distributed along distal
anterior 0.39 ofcarapace (0.35-0.43 in paratypes); ventral 0.15; pollex with largest tooth of chela at proximal 0.50,
carina convex, armed with 2teeth (1-3 in paratypes, mode other6smallerteethdistributedsubequallybetweenproximal
2), the first tooth at about proximal half. 0.32andarticulationoffingers, sizeofsmallteethdecreases
gradually towards articulation, 2 rows of tubercles along
Generalcephalon. Ocularcorneawelldeveloped, 0.13 CL distal 0.50 with 8and6tubercles distributedsubequallyon
(0.14-0.17inparatypes),wellpigmented,accessorypigment outerandinnersideofcuttingedgesrespectively;fingertips
spotpresent. Inferiororbital margin moderately produced, stout,stronglyuncinate;carpus 1.19palmlength (1.18-1.24
obtuse, postantennular carapace margin evenly rounded. in male and 1.72 in female paratypes), slightly subconical,
Antennal spine sharp, slender, continuing posteriorly as length 5.85 times distal width (4.28-5.31 in male and 5.58
ridge, situated below lower orbital angle; hepatic spine in female paratypes), 0.72 times chelalength (0.64-0.69 in
smaller, situated behind and below antennal spine; maleand0.82infemaleparatypes), 1.43timesmeruslength
branchiostegalsuturerunningfromhepaticspinetocarapace (1.26-1.48 in male and 1.44 in female paratypes), outer
margin. Carapaceglabrous. Epistome trilobed, two lateral margin more densely scaledthanupperandlowermargins,
lobes separated by median lobe anteriorly, lobes bluntly inner margin with more widely spaced big spines; merus
rounded (Fig. 2C). Basal segment ofantennular peduncle subcylindrical, distribution and size of scales similar to
with sharply pointed stylocerite, stylocerite reaching to carpus, ischium shorter than merus, strongly tapered, well
middle segment, anterolateral margin strongly producedas developed median groove on upper margin, entire surface
stout tooth, extending to almost end of second pedunclar coveredwithequalsizedscales. Minorcheliped. Generally
segment. Scaphoceritestout,reachingbeyondrostrum,0.45 resembling major cheliped; appressed scales abundant on
times carapace length (0.46-0.54 in paratypes), length 2.37 all segments, those on inner margin spiniform, pliable like
times maximum breadth (2.30-2.57 in paratypes), lateral hardrubber;chelalength0.62majorchela(0.68-0.82inmale
margin concave, distolateral tooth failing to reach end of and0.96infemaleparatypes);palmlength1.10fingers (1.01
lamella. Thirdmaxillipedrelativelystout,ultimatesegment 1.09 in male and 0.95 in female paratypes), margins
reaching beyond antennal peduncle; ultimate segment0.77 subparallel, width equal to maximum merus width; fingers
(0.77-0.88 in paratypes) as long as penultimate and 0.60 slightlygaping, cuttingedges withfew scattered stiftsetae;
(0.54-0.60inparatypes)as longasantepenultimate;exopod dactylus withfirst moderately large tooth atproximal0.45,
shorter than ischiomerus (Fig. 2E). second is largest tooth ofthe chela at proximal 0.30, third
at proximal 0.22; pollex with moderately large tooth at
Firstpereiopod. Slender, exceeding scaphoceriteby chela proximal 0.39, other 6 small teeth distributed subequally
and distal half of carpus; fingers as long as palm; carpus betweenproximal0.33andarticulationoffingers withsame
1.67chelalength(1.63-1.79inparatypes), 1.08meruslength structure as those on major cheliped; both fingers with
(1.04-1.18 in paratypes); scattered stiffsetae presenton all obliquecarinaonaboutdistal0.60offingers; carpusshorter
segments. thanchela,slightlysubconical,1.37timespalmlength(1.33
1.44in male and 1.59infemale paratypes) and 1.12 merus
Second pereiopod. Left and right pereiopods similar in length (1.19-1.31 in male and 1.38 in female paratypes);
shape, unequal in size; not prominantly elongated, merus subcylindrical; ischium shorterthan merus, tapered,
moderately slendercarpus, one-thirddistal merus ofminor well developed groove on upper margin.
chelipedreachingbeyondtipofscaphocerite;largerandmore
developed in males than females. Major cheliped. Third pereiopod. Entire dactylus reaching beyond
Appressed scales abundant in all segments; those on inner scaphocerite; appressed scales present on all segments;
margin spiniform, pliable, like hard rubber; chela 1.87 CL dactylus stout, curved, fringed with dorsolateral setae, tip
(1.05-1.95inmaleand0.82infemaleparatypes),length6.83 claw type; propodus length 3.10 times dactylus (2.48-2.90
times width (5.94-6.90 in paratypes); palm subcylindrical, in paratypes), 5.91 times longer than wide (5.83-6.89 in
somewhatbroadened, widthslightlygreaterthanmaximum paratypes); 9 ventral spines distributed along length of
meruswidth,length4.10times width(3.24-3.60inmaleand propodus, 2 distal most spines paired; carpus 0.62 times
3.00 in female paratypes), slightly compressed, width 1.24 propoduslength(0.56-0.63 inparatypes); merus 1.23times
timesdepth(1.30-1.42inmaleand 1.44infemaleparatypes), propoduslength(1.18-1.29inparatypes), 1.78timesischium
outer and inner margins slightly convex to almost straight length (1.93-2.25 in paratypes).
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Wowor & Choy: Macrobrachium from Brunei Darussalam
Fourthpereiopod. Reaching by one-thirddactylus beyond the northwest lowland ofBorneo. Apparently, this species
scaphoceritetojustreachingby tip ofdactylusatdistalend is common in lowland western Sabah, from 50 to 225 m
ofscaphocerite;appressedscalespresentonallsegments;9 above sealevel, with the waterneutralto slightlybasic (pH
ventral spinesdistributedalong lengthofpropodus, 2distal 7.0-8.4). Thesmallandyoung arefound among vegetation
mostspines paired; merus 2.00times ischiumlength (2.06 along moderate flowing streams and the adults are hiding
2.14 in paratypes). under big rocks in fast flowing rivers (H. H. Tan, pers.
comm.). InBrunei,thisspecieshasbeencollectedfromonly
Fifth pereiopod. Tip of dactylus reaching three fourth one river system and its lower tributaries. The altitudinal
proximal scaphocerite; appressed scales present on all rangeisfromabout20matBatangDuri(whichisjustabove
segments; 6 ventral spines distributed along length of thetidallimit)toabout80matSg.ApanandSg.Engkabang.
propodus; merus 1.05 as long as propodus (0.93-1.01 in Stream orders range from 2-5 based on a 1:50, 000
paratypes),2.05longerthanischium(2.10-2.56inparatypes). topographic map with stream gradient of<l0% and sandy
to cobble and boulder substrate. Habitat and waterquality
Abdomen. Smooth,glabrous;pleurites 1-3broadlyrounded, were as follows: stream width 5-30 m, depth 0.2-1.5 m,
pleurites 4 and 5 bluntly angular; sixth abdominal somite velocity0.1-0.5 rn/s,watertemperature21-25°CandpH5.4
1.36times longer than fifth (1.09-1.69 in paratypes). First 6.5. The small egg size is typical of lowland species and
pleopod. Endopod kidney-shaped, inner margin concave, suggests a planktonic larval stage. Most specimens were
outer margin convex, apex rounded. Second pleopod. collectedfrom the rocky areas, oftenamong plantlitterand
Appendices at about 0.3 ofmesial margin length, endopod were neverfound in high abundance, which may be due to
broadlyrounded;appendixmasculinaabout 1.5timeslonger eitherhighcompetitionand/orhighpredationpressures. At
than appendix interna, more rigid than appendix interna, least25 species offish, many ofwhich are predatory, have
bearing numerous setae on anteriorface. Male abdominal beenrecordedfromthesestreamreaches(Choy, 1996;Choy
sternites. First three abdominal sternites with triangular et aI., 1996).
median process; lateral margin of process on first sternite
sloping ca. 50° from horizontal; process on second sternite Remarks. - Macrobrachium lopopodus, new species,
similar in form but slightly larger than first, lateral margin belongs to the M. horstii group - a group whose members
slopingca. 50°from horizontal;thirdsamesizeandformto have pereiopods 2-5 covered by scale-like spinules, the
first (Fig. 21). Inter-uropodal sclerite. Well developed, second pereiopods similar in form but unequal in size, the
elevated as longitudinal pre-anal carina, carina medium cutting edges ofthe major second pereiopod chelabearing
sized, slightly bigger than posterolateral teeth of sixth rowsoftuberclesandthefingersbeingnakedorbearingonly
abdominalsomite. Telson. Stout, 1.47timessixthabdominal fewshortstiffsetaebutnotconcealingthesurface. However,
somite length (1.28-1.53 in paratypes), length 3.50 times M. lopopodus can be easily distinguished from M. horstii
median width (3.27-3.85 in paratypes), lateral margin (De Man, 1892) by several characters. Examination ofthe
straight, convergent, 2pairs ofdorsal spines at 0.52 (0.49 syntypesofM. horstiishowsthatM. lopopodushasashorter
0.55 in paratypes) and 0.73 (0.71-0.77 in paratypes) rostrumwithitstipnotreachingtheendofthethirdsegment
respectively,posteriorsubventralmarginsinuouswithlarge ofthe antennularpeduncle (vs. overreachingthe endofthe
rounded median point, median projection overreached by thirdsegmentoftheantennularpeduncle),longerpostorbital
innerpairofposterior spines, innerpairofposteriorspines teeth length (ratio of PL to CL 0.35-0.45 vs. 0.32-0.33),
about 2.5 times longer than outer pair, 10 pairs of long shorter and broader scaphocerite (ratio of scaphocerite to
plumose setae between inner pair of spines. Uropods. carapace length 0.45-0.54 vs. 0.54-0.58 and ratio of
Exceeding tip of telson, lateral margin ofexopod straight, scaphoceritelengthtoscaphoceritewidth2.30-2.57vs. 2.56
with acute distolateral tooth, mobile mesial spine slightly 2.65 respectively), more robust third pereiopod (ratio of
longer than distolateral tooth (Fig. 2K), exopod 1.87 times propoduslengthtopropodus width5.83-6.89vs.7.78)with
longerthanbroad(1.98-2.30inparatypes),endopodsmaller arelatively shortermerus (ratioofmerus to ischium length
than exopod. 1.78-2.25vs. 2.42),afourthpereiopodwitharelativelyshort
merus (ratioofmerus to ischium length 2.00-2.14 vs. 2.53
Etymology. - Thespecificname lopopodus isderivedfrom 2.56), and a fifth pereiopod with a shorter merus (ratio of
Greek words lopos for scale andpodosfor foot, alluding to merus to ischium length 2.05-2.56 vs. 2.66).
the scales present on pereiopods. It is used as a noun in
apposition. Comparisonofadultspecimensofequivalentsize(holotype
ofM. lopopodus, 19.90 mm CL and syntype ofM. horstii,
Size.- Malesreachlargersizesthanfemales;thelargestmale 20.00 mm CL) shows that the second pereiopods of M.
recorded being 21.7 mm CL; the largest female 16.7 mm lopopodus(measuredfromtipoffingerstoproximalmargin
CL and ovigerous females are between 8.8 to 16.7 mmCL of ischium) are distinctly longer than those of M. horstii;
(n=30). The eggs are small, 0.6 by 0.4 mm, ovoid and withtheratioofthemajorpereiopodtocarapacelengthbeing
numerous. 4.63vs.2.86;andtheratiooftheminorpereiopodtocarapace
lengthbeing2.87vs. 1.98. Themajorsecondpereiopodchela
Distributionandecology.- Sofarthespeciesrangeisonly ofM. lopopodus is also longer (ratio of chela to carapace
known from Kota Marudu District, Sabah down to length 1.87vs.l.18) andmore slender(ratioofchelalength
TemburongDistrict,BruneiDarussalam. Thesesitesareon to chela width 6.83 vs. 4.81). The carpus ofthe holotype
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THE RAFFLES BULLETIN OF ZOOLOGY 2001
o
A
L
K
o
c:: <
I
J
Fig. 2. Macrobrachium lopopodus, new species. Holotype, male 19.9 mm CL, SSM 616. A, lateral view ofcarapace; B, dorsal view
ofcarapace; C, epistome; D, scaphocerite; E, third maxilliped; F, third pereiopod; G, dactylus ofthird pereiopod; H, fifth pereiopod; I,
abdominal sternite; J, telson; K, mobile mesial spine ofexopod ofuropod; L, T4. Setae omitted. Scales: A, B, D, F, H, 1=5.0 mm; E,
J=2.0 mm; C, G, K, L=l.O mm.
273
Wowor & Choy: Macrobrachium from Brunei Darussalam
ofM. lopopodusisalsolonger(ratioofcarpustochelalength and Yeo et al. (1999). However, M. lopopodus can be
0.72 vs. 0.57), slightly longer than the palm (vs. slightly differentiated from M. meridionalis by several characters,
shorter than the palm), less conical (ratio ofcarpus length viz. i) shorterrostrum (tip does not reach vs. reaching end
todistalcarpuswidth5.85vs.3.10)andlongerthanthemerus ofthirdsegmentofantennularpeduncle), ii)lessdorsaland
(ratio of carpus to merus length 1.43 vs. 1.01). All M. ventral teeth [10-12 (mode 11) vs. 11-14 (mode 13) and 1
lopopodus specimensexaminedshow thatthe carpusofthe 3(mode2)vs. 2-4(mode3)respectively],iii)T4(armedvs.
majorsecondpereiopodisdistinctlylongerthanthe merus; unarmed),iv)majorsecondpereiopodwithrelativelylonger
andthattheminorsecondpereiopodchelahasashorterpalm fingers (ratio of finger to palm length 0.65-0.85 vs. 0.53
(ratioofpalmtofingerlength l.l0vs. 1.29)withthecarpus 0.56), longer carpus with regard to the palm and merus
longerthanthepalm(ratioofcarpustopalmlength 1.37vs. lengths (ratio ofcarpus to palm length 1.18-1.24 vs. 0.68
1.10). 0.75 andratioofcarpusto merus length 1.26-1.48vs. 1.08
1.22 respectively), relatively more slender carpus (ratio of
Themedianprocessofthefirstthreeabdominalsternitesof carpuslengthtocarpusdistalwidth4.28-5.85 vs.2.79-3.05),
M. lopopodus maleis much smallerthan that ofM. horstii; v) absence ofalongitudinal sulcus on the proximal part of
the lateral margin of the first process being relatively less the palm and carpus (vs. present), vi) fewer number of
steep (slope ca. 50° vs. 60° from horizontal); the second tuberclesonthemajorsecondpereiopodchela«9tubercles
process with same angled lateral margin slope; the third vs. >9tubercles),andvii)absenceofappressedscalesonall
processlateralmarginisalsorelativelylesssteep(slopeca. segments ofthe first pereiopods (vs. present on merus and
50° vs 65°). The pre-anal carina ofM. lopopodus is also ischium).
smaller and less steep then that ofM. horstii.
Besides M. meridionalis, there is also another species
Macrobrachium lopopodus alsoresembles M. meridionalis belonging to the M. horstii group in the region, i.e. M.
Liang&Yan, 1983,amemberoftheM. horstiigroup. The spinosum Cai & Ng, 2001. This species is found in
differences between M. meridionalis and M. horstii were Halmahera, BaliandSumatra,Indonesia(Cai&Ng, 2001).
discussed in detail by Yeoetal. (1999). The specimens of Macrobrachium lopopodus differs from M. spinosum by
M. meridionalis from Hainan (type locality) and Tioman several characters, i.e. i) stouter scaphocerite (ratio of
Island on hand for comparison agree quite well with the scaphocerite length to scaphocerite width 2.4 vs. 2.7), ii)
descriptionandfiguresofthatspeciesbyLiang& Yan(1983) majorsecondpereiopodwiththecarpuslongerthanthepalm
(vs. shorter than the palm), relatively more slender carpus
(ratio ofcarpus length to carpus distal width 5.9 vs. 4.3),
andthecarpusisdistinctlylongerthanthemerus(vs.slightly
longer than the merus).
Comparativematerialexamined.- Macrobrachium horstii
-3males(16.7-20.0mmCL)(ZMADe 102.555),syntypes,
RivernearPalopo, Celebes (=Sulawesi). M. meridionalis
11 males (11.3-21.0 mm CL)(ZRC), purchased, Qionghai
CentralMarket, HainanProvince, China; 1male (24.0 mm
CL)(ZRC 1996.1719),Sg.Nipah,TiomanIsland,Peninsular
Malaysia.
Macrobrachium leucodactylus, new species
(Figs. 4-6)
Material examined. - Holotype - male (10.6 mm CL)(ZRC
2000.2418), tributary of Sg. Temburong-Machang, Temburong
District, altitude 580 m, 27 Jun.1991.
Paratypes - 7 males (7.1-10.0 mm CL), 6 females (5.2-8.9 mm
CL),2juveniles(4.5-5.0mmCL)(ZRC2000.2419),samedataas
holotype; I male (8.6 mm CL), I female (8.5 mm CL)(BDM),
tributaryofSg.Temburong-Machang,TemburongDistrict,altitude
580 m, 24 Jun. 1991; 2 females (6.3-10.1 mm CL)(ZRC
2000.2420), upperSg. Babi,TemburongDistrict, altitude 335 m,
coIl. S. Choy & S. Nyawa, 6Jun.1991.
Diagnosis. - A relatively small-sized species with
Fig.3. Macrobrachium lopopodus, newspecies. Holotype,male
subcylindrical body form. Rostrum short, reaching to or
19.9 mm CL, SSM 616. A, first pereiopod; B, major chela of
slightly beyond second segment of antennular peduncle,
secondpereiopod;C,carpus,merusandischiumofmajorcheliped
dorsal margin faintly sinuous. Rostral formula: 2)7-9/2.
of second pereiopod; D, minor cheliped of second pereiopod.
Scaphocerite with outer margin straight, distolateral tooth
Scales: 5.0 mm.
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THE RAFFLES BULLETIN OF ZOOLOGY2001
bent inwards, about 2.5 times as long as wide. Second
pereiopodswithchelareachingbeyondscaphocerite,carpus
shorter than merus, similar form, unequal in size. covered
by largespines. Firstabdominalsterniteprojectionbilobed.
Pre-anal carina absent. Mobile mesial spine ofexopod of
uropodsmallerthandistolateral tooth. Thelivingspecimens
have whitecoloured fingers ofthe second pereiopods (Fig.
4).
Description. - Rostrum. Short, 0.43 CL (0.38-0.51 in
Fig. 4. Living colour of Macrobrachium leucodactylus. new
paratypes). reaching to or slightly beyond second segment
species.
of antennular peduncle but never reaching end of third
segment ofantennular peduncle (Figs. 5A, B); moderately
CL (paratypes same as holotype), length 5.07 times width
slender, maximum depth slightly less than maximum
(4.67-4.98 in paratypes); palm subcylindrical, somewhat
dorsoventral diameter of cornea; lateral carina well
broadened,widthgreaterthan maximum meruswidth,length
developed, continuing almost to tip; dorsal carina bent
2.77 times width (2.56-2.57 in paratypes), slightly
downwards with tip slightly curved upwards, armed with 7
compressed,width 1.20timesdepth(1.15-1.20in paratypes),
teeth (7-9 in paratypes, mode 7), interspaces setose, teeth
outer and inner margins almost straight to slightly convex
distributed subequally (in holotype)and tending to bemore
andparallel,upperand lowermarginsrounded,outermargin
closely spaced beyond orbit than above and post-orbitaJly
moredenselyspinulosethanupperand lowermargins, inner
(in paratypes), 2 teeth completely postorbital, postorbital
margin least spinulose with more sparsely scattered large
teeth on anterior0.27 ofcarapace (0.17-0.26 in paratypes);
spines, spines on inner margin larger than those on other
ventral carina convex, armed with 2 teeth, unarmed on
surfaces; fingers 0.75 times palm length (0.66-0.78 in
proximal two-thirds.
paratypes ), weakly gaping, cutting edges with developed
teeth; dactylus with first tooth at proximal 0.57, remaining
Generalcephalon. Ocularcornea well developed,0.19CL
3 small teethdistributed subequally between proximal 0.40
(0.18-0.19in paratypes).well pigmented,accessorypigment
and0.25;pollex withfirst toothatproximal0.48, remaining
spot present. Inferiororbital margin moderately produced,
5smallerteethdistributedsubequallybetweenproximal0.33
obtuse, postantennular carapace margin evenly rounded.
andarticulationoffingers; both fingers withslightlyoblique
Antennal spine sharp, slender, situated below lower orbital
carinadistally,fingertipsstout.stronglyuncinate;carpus0.53
angle;hepaticspineofsimilarsize,situatedbehindandbelow
palm length (0.57-0.58 in paratypes), conical. length 1.84
antennal spine; branchiostegal suture running from hepatic
timesdistal width(1.75-2.00in paratypes),0.30timeschela
spine to carapace margin. Carapace glabrous. Epistome
length (0.32-0.35 in paratypes), 0.73 times merus length
completely divided into two lobes by median depression,
(0.74-0.85 in paratypes), few widely spaced large spines
depression broad anteriorly and gradually narrowing
present on all surfaces; merus subcylindrical. inner margin
posteriorly, lobes bluntly rounded strongly divergent (Fig.
with few scattered smaller spines, other surfaces glabrous;
5C). Basal segment of antennular peduncle with sharply
ischiumshorterthan merus,stronglytapered,withoutmedian
pointed stylocerite, stylocerite reaching to middle segment,
grooveon uppermargin,allsurfacesglabrousexceptforfew
anterolateral margin strongly produced as stout tooth,
small spines on inner surface. Minor cheliped. Generally
extending to almost end of second peduncular segment.
resemblingmajorcheliped;spinesabundantonall segments
Scaphoceritestout,reachingbeyond rostrum,0.52CL(0.54
except ischium;chelalength0.89 majorchela(0.91-0.94 in
in paratypes), length 2.50 times maximum breadth (2.53
paratypes);palmlength 1.10fingers (1.10-1.16inparatypes),
2.57 in paratypes), lateral margin straight,distolateral tooth
margins subparallel, slightly convex, width greater than
bentinwards, notreachingendoflamella. Third maxilliped
maximum merus width;fingers closingtightly withoutgap;
relativelystout,ultimatesegmentreaching beyondantennal
dactylus with 5 small teeth distributed subequally along
peduncle;ultimatesegment0.9I (0.95 in paratypes)as long
proximal 0.30 and articulation of fingers; pollex without
as penultimateand 0.54 (0.54-0.56 in paratypes) as long as
tooth;bothfingerswithobliquecarinadistally;carpusshorter
antepenultimate;exopod longerthan ischiomerus(Fig. 5E).
than chela, conical, 0.72 times palm length (0.65 in
paratypes) and 0.79 merus length (0.70-0.76 in paratypes);
Firstpereiopod. Slender,exceedingscaphoceritebychela;
merus subcylindrical; ischium slightly shorter than merus,
fingers as longas palm;carpus 1.50chela length (1.35-1.39
tapered, without median groove on upper margin.
in paratypes). 1.J7 merus length (1.09-1.11 in paratypes);
scatteredstiffsetaepresenton halfproximal merus, ischium
Third pereiopod. Tip ofdactylus reaching distal end of
and basal segments.
scaphocerite; short stiff setae present on all segments;
dactylusstout,feeblycurved,fringed withdorsolateralsetae;
Second pereiopod. Left and right pereiopods similar in
propoduslength3.73timesdactylus(3.33-4.50inparatypes).
shape, unequal in size; short, robust. about proximal half
8.20 times longer than wide (8.00 in paratypes); 12 ventral
chelaofminorcheliped reaching tip ofscaphocerite; larger
spines distributed along length of propodus, 2 distal most
and moredeveloped in malesthan females. Majorcheliped.
spines paired;carpus0.54timespropoduslength(0.44-0.45
Spines abundant inall segmentsexcept ischium;chela 1.10
in paratypes); merus 1.10times propodus length (1.08-1.10
275
Wowor & Choy: Macrobrachium from Brunei Darussalam
I
L
K
/
B \
o
Fig. 5. Macrobrachium leucodactylus, new species. A, B, E-I, L, holotype, male 10.6 mm CL, ZRC 2000.2418; C-D, paratype, male
10.0mmCL,ZRC2000.2419;J,paratype,female 8.5mmCL, BDM; K,paratype,female 10.1 mmCL,ZRC2000.2420. A, lateral view
ofcarapace;B,dorsalviewofcarapace;C,epistome;D,scaphocerite;E,thirdmaxilliped;F,thirdpereiopod;G,dactyIusofthirdpereiopod;
H,fifthpereiopod; I,J, abdominalsternite;K,telson;L, mobilemesial spineofexopodofuropod. Setaeomitted. Scales: A, B=2.0mm;
C-L=1.0 mm.
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THE RAFFLES BULLETIN OF ZOOLOGY 2001
in paratypes), 2.05 times ischium length (2.10-2.29 in broadly rounded; appendix masculinaabout 2 times longer
paratypes). than appendix interna, more rigid than appendix interna,
bearing numerous setae on anterior face. Male abdominal
Fourth pereiopod. Tip of dactylus reaching three fourths sternites. First three abdominal sternites with triangular
proximal scaphocerite; not covered with spines or scales, median process; tip offirst process bilobed, lateral margin
shortstiffsetaeonallsegments; 11ventralspinesdistributed sloping ca. 50° from horizontal; second process similar in
alonglengthofpropodus,2distalmostspinespaired;merus sizetofirst,tipunilobed,lateralmarginslopingca.40°from
2.09 times ischium length (1.95-2.22 in paratypes). horizontal;third muchsmallerbutsimilarinformto second
Fifth pereiopod. Tip of dactylus reaching middle of (Fig. 51). In immature gonad female, first sternite with 2
scaphocerite; not covered with spines or scales, short stiff low processes; second process triangular, lateral margin
setae on all segments; I1 ventral spines distributed along slopingca.30°fromhorizontal;thirdflat, withouttriangular
length of propodus; merus 0.96 as long as propodus (0.93 median process (Fig. 5J). In young male, only first two
in paratypes), 1.95 longer than ischium (2.21-2.24 in abdominal sternites with triangular median process which
paratypes). resembles those of adult male but smaller in size. Inter
uropodal sclerite. Undeveloped, pre-anal carina absent.
Abdomen. Smooth,glabrous;pleurites 1-3broadlyrounded, Telson. Stout, 1.35 times sixth abdominal somite length
pleurites 4 and 5 bluntly angular; sixth abdominal somite (1.29-1.50 in paratypes), length 3.33 times median width
1.42times longerthan fifth (1.30-1.40 in paratypes). First (3.23-3.46inparatypes),lateralmarginstraight,convergent,
pleopod. Endopod kidney-shaped, inner margin concave, 2pairsofdorsal spines at0.52 (0.52-0.53 inparatypes) and
outer margin convex, apex rounded. Second pleopod. 0.74 in paratypes respectively, posterior subventral margin
Appendices at about 0.4 ofmesial margin length, endopod slightly convex to almost straightwith acute median point,
... .,. ~ ,.."
'- 7' 7 ...
.,. • .. '"' -7
~
-
Fig.6. Macrobrachium leucodactylus, new species. A, holotype, male 10.6mmCL,ZRC2000.241g; B-E,paratype, male 10.0mmCL,
ZRC2000.2419. A, first pereiopod; B,uppermargin view ofmajorchelaofsecondpereiopod; C, outermargin view ofmajorcheliped
of second pereiopod; D, upper margin view of minor chela of second pereiopod; E, outer margin view of minor cheliped ofsecond
pereiopod. Scales: 1.0 mm.
277
Wowor & Choy: Macrobrachium from Brunei Darussalam
median projection overreaching by inner pair of posterior M. clymene specimens examined for comparison study are
spines, inner pair ofposterior spines about 3 times longer from around Marudi, an area at the Baram River (type
thanouterpair, 10pairsoflongplumosesetaebetweeninner locality). Theyagreeverywell withtheoriginaldescription
pair of spines. Uropods. Exceeding tip of telson, lateral andfiguresofDeMan(1902)andthereisnoreasontodoubt
margin of exopod straight, with acute distolateral tooth, their conspecificity.
mobilemesialspinesmallerthandistolateraltooth (Fig.5L),
exopod2.30timeslongerthanbroad(2.05-2.14inparatypes), Overall, M. leucodactylus looks like the long lancet rostral
endopod smaller than exopod. form ofM. clymene (see discussion for M. clymene) with a
subadultform (malejuvenileform) ofthesecondpereiopod
Etymology. - The specific name leucodactylus is derived andtheteethonthecuttingedgesrelativelysmall. However,
from the Greek words leukos for white and dactylos for M. leucodactylus can be easily separated from this form of
finger, alludingtothewhitefingers ofthespecies. Itisused M. clymene by several characters, viz. shorter rostrum (tip
as a noun in apposition. reachingtoorslightlybeyondsecondsegmentofantennular
pedunclevs.overreachingendofthirdsegmentofantennular
Size. - Males appearto reach largersizes than females; the peduncle to almost reaching distal borderofscaphocerite),
largest male recorded being 10.6 mm CL while the largest fewerdorsal teeth [7-9 (mode7)vs. 8-10(mode9)], shorter
female recorded is 8.9 mm CL. Ovigerous females are not postorbitalteethlength(ratioofPLtoCL0.17-0.27 vs.0.29
available. 0.35),thirdmaxillipedwithalongerultimatesegment(ratio
ofultimatetopenultimatelength0.91-0.95 vs. 0.78-0.89and
Colour. - Juveniles are transluscent brown with reddish ratioofultimatetoantepenultimatelength0.54-0.56vs.0.45
colouration between abdominal and appendage segments. 0.50),firstpereiopods witharelatively shortercarpus (ratio
Adults areeitherdarkerbrowntoblackishorbrownish-red. of carpus to chela length 1.35-1.50 vs. 1.50-1.63), third
The fingers of the chelae are white and the third to fifth pereiopods with a relatively longer and broader propodus
pereiopods are brownish white (Fig. 4). (ratioofpropodustodactyluslength3.33-4.50vs. 2.85-3.15;
ratio of propodus length to propodus width 8.00-8.20 vs.
Distributionandecology.- Sofar, thisspeciesisonlyfound 8.33-11.75 respectively), and more slender telson (ratio of
from small headwater streams (stream orders 1-3) of the telsonlengthtotelsonmedianwidth3.23-3.46vs.2.67-3.18).
upperreachesoftheSg.Temburong-MachanginTemburong Comparisonofthe holotypeofM. leucodactylusand amale
District, Brunei. These streams arisefrom nearBukit(Mt.) ofthe long lancet rostral form ofM. clymene of 10.30 mm
Belalongandflow northwards into Sg. Temburongatabout CL shows several character differences of the second
70 m above mean sea level. They occur in undisturbed pereiopods, i.e. themajorchelais relativelyshorter(ratioof
dipterocarprainforestswithrockysubstrates. Streamwidths chelato carapace length 1.10 vs. 1.27), more slender (ratio
rangefromabout 1-10m,withadepthof0.1-1.5 m,velocity ofchela length to chela width 5.07 vs. 4.09; ratio ofpalm
of0.1-0.3m/s, and a water temperature of23-26°C and pH length to palm width 2.77 vs. 2.53) with relatively longer
of5.8-6.2. fingers (ratiooffingertopalmlength0.75 vs. 0.52),andthe
minor chela has relatively longer fingers (ratio offinger to
At Sg. Temburong-Machang, a spring-fed stream was palm length 0.91 vs. 0.57).
surveyed from its source at about 610 m above sea level.
No shrimps were collectedfrom the source until about580 The first three abdominal sternal projections of the M.
mabovesealevel wherethey werefoundwiththreespecies leucodactylusmalearedifferentfromthatofallthree forms
ofbalitoridfish (Gastromyzonlepidogaster,Neogastromyzon of M. clymene (see M. clymene), viz. the first median
nieuwenhuisi and Glaniopsis hanitschi), a species of abdominal process is bilobed and the lateral margin has a
freshwatersnail(Brotia sp.),tadpolesandinsectlarvae. The less steep slope (vs. unilobed and ca. 50° vs. 60°
shrimps are found in the pools and tributaries with slow respectively), the first two processes are of the same size
flowing currentsoftheupperstreamsabovewaterfalls. This (vs. thesecondprocessis largerthanthefirstone),thethird
small-sized shrimp is not common in the streams below process is the smallest with smaller lateral margin sloping
waterfalls where the water current is stronger and more (vs. the first and the third processes are same sizeand form
species (up to 19 species) offish occur. It may be that the and ca. 40° vs. 60° respectively).
shrimp prefers weaker currents and lower predation
pressures. The three balitorids found above the waterfalls Macrobrachium leucodactylus is also similar to the short
are mainly herbivores and/or insectivorous, while many of high rostral form ofM. clymene. However, in addition to
thespeciesbelowthewaterfallsarehighlypredacious(Choy differences inthe form oftheirfirst three abdominal sternal
et aI., 1996). projections, they can also be distinguished by their living
colour (see below).
Remarks. - This new species is close to Macrobrachium
clymene(DeMan, 1902),aspeciespreviouslyrecordedfrom Macrobrachium rhodochirNg, 1995, a sisterspecies ofM.
northern Sarawak,viz. the Baram RiverandMulu National clymene, is also similar to M. leucodactylus. However,
Park which borders Brunei Darussalam (De Man, 1902; comparisonofasimilarlysizedparatypeofM. leucodactylus
Holthuis, 1950, 1979; Chace & Bruce, 1993; Ng, 1995). It (l0.00 mm CL) (ZRC 2000.2419) and the holotype ofM.
isrecordedfrom Bruneiforthefirst timein thispaper. The rhodochir shows that there are several characters that can
278