Bukit Sarang (Sarawak, Malaysia), an isolated limestone hill with an extraordinary snail fauna

2007·1.2 MB·Malay

by  Vermeulen, J J

BASTERIA, 71: 209-220,2007
Bukit Sarang (Sarawak,Malaysia), an isolatedlimestonehill
withanextraordinary snailfauna
J.J.Vermeulen
Nationaal Herbarium,Leiden Branch,P.O.Box 9514, NL2300 RALeiden,The Netherlands
& D.J. Junau
Grand PerfectSdn Bhd,Lot 3469&3470,Parkcity CommerceSquare, JinTunAhmad Zaidin,97008
Bintulu,Sarawak,Malaysia
BukitSarangis anisolated limestone hillinthe Tatau River basin,Sarawak,Malaysia(onthe
island ofBorneo).Outofthe 83landsnail speciesfound,26areassumed tobeendemictothe
hill. Nine ofthesearedescribed asnewin thispaper;theybelongtotheAssimineidae (Acmella:
3species),Cyclophoridae(Japonia:2species;Opisthoporus:1species),Hydrocenidae(Georissa: 1
species), Camaenidae (Amphidromus:1species),Charopidae(Teracharopa:1species).
Key words; Gastropoda, Caenogastropoda, Pulmonata, Assimineidae, Cyclophoridae,
Hydrocenidae,Camaenidae,Charopidae,taxonomy,Malaysia,Borneo.
INTRODUCTION
Limestonehills (karst) are widespread in Sarawak (Malaysia, part of the islandof
Borneo),butnot equally distributedover thestate. Extensivekarst is found in theWest,
betweenBauandSerian.IntheEast, scatteredareasoccur,such asthoseinGunungMulu
NationalPark, NiahCavesNationalPark, andintheBaramRiverheadwaters.Inbetween
EastandWestSarawakkarst areas arefew andfarapart. TheyarerestrictedtotheTatau
Riverbasin: BukitSarang downstream,theUlu Kakus range upstream. Both limestone
outcropsare extremelyisolated:thedistancebetweenthetwooutcrops isabout60km,the
nearest limestonerangestotheSW., NE. and SSE. (in adjacentKalimantan,Indonesia) of
BukitSarang areabout325km, 150 km and210km away,respectively. Afew thin,name-
lessbedsofmarland limestonealongAripRiverandnearTatau,bothabout25km tothe
W.of BukitSarang have beenmapped (see Wilford, 1956:48), these have not yetbeen
investigated.
BukitSarang consistsinfactoftwo minutelimestonehillsofTertiaryage:BukitAnyi
(800 x 300 m), and BukitLebik (300* 150m, totaloutcropsurface of thetwo about0.3
sqkm). Amapis provided byHarrison& Reavis (1966).Thehills aresituatedinan exten-
sive, partly loggedswamp area whichis notableforitsFalseGavials, Tomistomaschlegeli
S. Mueller, 1838(Crocodilia, Gavialidae). Theinaccessibility of the area, as well as pro-
tractedtribalconflicts overrights toharvestbird'snests fromthecaves,kept people from
settling nearthehills. Thisexplains theirrelativelypristine state.
ThefirstsnailcollectingonBukitSarangwas donein1962,by M.Bong, asanasideto
geological exploration. The soil sample contained no fewer than 12 endemic mollusc
species (Dance, 1970;Vermeulen,1993, 1994),whichmarkedthelocalfaunaas ofexteme
interest. Nevertheless, itwas only in 2005that the present authors could undertakea
more thorough survey. All collecting was doneby taking soil samples on alarge scale,
augmented withhand-picked specimens ofthemedium-sizedandlarger species.
Altogether, thesamples included83species of landmolluscs.Earliercollecting else-
where in Sarawakenabledusto identify species that are likely to beendemic to Bukit
210 BASTERIA,Vol. 71, No.4-6,2007
Sarang. We found26likely endemics or 31% of thelocal snail fauna.This is very high.
Usually, smalllimestoneoutcrops thesizeofBukitSarang (0.3sqkm) are hometo only a
few endemics. For example, isolatedlimestoneoutcrops in theSangkulirang Peninsula,
have6-11%endemicsamong faunasof 30to 100species (Vermeulen, 2005).BukitSarang
scores closetopercentagesusuallyfound,onBorneo,formuchlarger limestoneareas.For
instance, surveys in the Sangkulirang Peninsula(Kalimantan Timur,roughly estimated
2900sqkmof limestoneoutcrop), theBau-Serianlimestoneranges (Sarawak, 150sqkm),
Gunung MuluN.P. limestones(Sarawak, 80 sqkm), and BatuNiahN.P. (Sarawak, 9 sq.
km) yielded 26 %(of 147species), 43% (of 148species), 34%(of 97species), and 35%(of
108species) assumedly endemic species respectively (above datafromVermeulen2003,
2005). On Borneo, Bukit Sarang probably packs the highest number of endemic snail
species onthesmallestsurfaceoflimestonebedrock.
The genus Bruggennea Dance, 1972 (Streptaxidae), with three species, is entirely
endemic to Bukit Sarang (see Vermeulen, 2007). This is exceptional. On Borneo,
Platycochlium Laidlaw, 1950 (Steptaxidae), with 3 species, is endemic to the Bau-Serian
limestones,andNiahiaVermeulen,1996(Diplommatinidae), monotypic, toBatuNiahN.P.
Both areas, again, aremuchlarger than BukitSarang.
Aninteresting, littlestudiedphenomenon onBorneolimestonesis theoccurrence of
sympatric species couples thatlookvery similar. Bruggennea laidlawi(Dance, 1970)and B.
luminifera spec. nov. (Streptaxidae) are so similarthatthey maywellbesisterspecies. The
sameapplies to Japoniahyalina spec, nov., and Japonia ditropisspec, nov., describedbelow.
Elsewhere,similar couples occur: in Batu NiahN.P., Opisthostoma holzmarkiThompson,
1978,and O. grandispinosum GodwinAusten, 1889, live sympatrically withvery similar
(yetundescribed) species (Vermeulen, 2003).
Because the area hasknown littleinhabitatation, invasivemolluscspecies thatfollow
mankindinitswake,such asAchatinafulica Bowdich,1822,Bradybaena similaris(Ferussac,
1821), Subulinaoctona (Bruguiere, 1792),havenotbeenableto gain afootholdonthehills
(with possible exception of Lamellaxis clavulinus (Potier & Michaud, 1838). The smaller
streams intheswamp, particularly thosenearthe limestonehills, are stillhometolarge
colonies of the freshwater mussel Rectidens lingulatus (Drouet & Chaper, 1892)
(Unionidae). Borneo Unionidaeare severely threatenedby thecombinedeffects of log-
ging(silting upof rivers), pollution and collecting for food.Luckily, settlementnear the
hillsis stillnotallowed, andthehills are well-guarded to enforceasustainableexploita-
tionof the bird'snests.Theregular patrols of theguards and thegeneral inaccessibility
make Bukit Sarang and its unique biodiversity comparatively well-protected, though
always vulnerablebecauseofitssmallsize.
Below,ninenew, endemic species are describedforBt. Sarang. More newendemics
havebeenidentified,buta closerinvestigation is neededbeforethese,too,canbeformal-
ly described.
Referencesto materialpresentinthe collectionof thefirstauthorareabbreviatedas
'V', followedby a collectionnumber. The pencil drawings have beenmadeby the first
author, with the aid of a Wild M8 stereo microscope with a camera lucida device.
Holotypes willbe depositedintheNationaalNatuurhistorischMuseum,Leiden(RMNH).
SYSTEMATICPART
Family Assimineidae H. & A.Adams, 1856
Acmella Blanford,1869
Vermeulen&Junau:Thesnailfauna ofßukit Sarang 211
Notes.- Acmella species are commoninsoilsamples fromBorneanlimestoneareas.
About15species havebeenidentified.Allbuttwoareendemictotheisland,and thetwo
widespread onesaretheonly namedso far: AcmellapolitaVonMoellendorff,1887,andA.
minutissima(Maassen, 2000).
Next tothe threespecies describedbelow, afourthoneoccurs onBukitSarang. Itis
distinctive, withaconicalspire andacancellatesculpture,butthematerialavailableistoo
poortoallowformaldescription.
Acmella caelataspec. nov. (fig. 1)
Material seen.- Malaysia, Sarawak, 2 div.:Lower TatauRiver valley, BukitSarang group (leg.
Serena Lee,V12641/1paratype,RMNH 109078/holotype).
Shell.- Shellminute,conical-ovoidwithaboutflatsidesandabroadly roundedapex,
slightly translucentwhite,somewhatshiny. Whorls3 1/8-33/8, moderately convex. Suture
impressed. Protoconchaboutsmooth at40 x magnification. Radial sculpture teleoconch:
growth linesonly, locally more distinctthanelsewhere. Spiral sculpture teleoconch: fine,
densely placed, flat spiral threads withshallow, narrow groovesinbetween. Umbilicus
open,narrow.Aperturesomewhatobliquelyovate, narrowly roundedabove,well round-
ed below,transitionfromparietal to columellarside gradual. Peristomesimple, reflected
onthecolumellarside,not so onthepalatal side.Height 0.80-0.95mm;widthc.0.7mm.
Apertural height c.0.40mm,width0.32-0.35mm.
Ecology. - Lowlandrainforestonandnearlimestonebedrock.
Distribution.- Malaysia, Sarawak,2 div.:TatauRiverBasin, BukitSarang.
Notes. - Acmella minutissima(Maassen, 2000), from Sumatraand Borneo, is wider
(0.8-1 mmwide),hasafinerspiral sculpture, andanaperturewithamoreangular transi-
tionfrom the parietal to the columellarside.An undescribed species fromSabahlooks
very similarin mostaspects, buthasamorecompressed spire (shellheight 0.65-0.75mm,
with3 1/2-37/8whorls).DiffersfromA. conica andA.obtusa,below, inhaving abroadly
roundedapexandanovateaperture.
Acmella conicaspec. nov. (fig.2)
Material seen.- Malaysia, Sarawak,2n<* div.:LowerTatau River valley, BukitSaranggroup (leg.
SerenaLee,V 12639/1paratype,RMNH 109079/holotype).
Shell. - Shell minute, conical with about flat sides and a rounded apex, slightly
translucentwhite,somewhatshiny. Whorls4-41/8,convex. Sutureimpressed.Protoconch
about smoothat40xmagn.Radialsculpture teleoconch:inconspicous growthlines only.
Spiral sculpture teleoconch:locally traces of a very fine, dense spiral striation, only just
visibleat40times magn.Umbilicusopen,narrow.Aperture aboutellipticwithaflattened
parietal side, rounded above, broadly roundedbelow, transitionfrom parietal to col-
umellarsidesomewhatangular. Peristomesimple, reflectedonthecolumellarside,notso
on the palatal side. Height c. 0.85 mm;width0.70-0.75mm. Apertural height 0.25-0.30
mm,width0.30-0.35 mm.
Ecology. - Lowlandrainforestonandnearlimestonebedrock.
Distribution.- Malaysia, Sarawak,2 div.:TatauRiverBasin, BukitSarang.
212 BASTERIA,Vol. 71, No. 4-6,2007
Figs 1-5.Acmella andJaponiaspec. 1.a,Acmella caelata spec. nov., holotype,Malaysia, Sarawak, Bukit
Sarang (RMNH, shellheight0.95mm),frontal view;b, do.,umbilical view;c, do.,paratypespecimen
from samelocality (V,shell height0.8 mm),frontal view ofaperture.2.a,Acmellaconica spec.nov., holo-
type, Malaysia,Sarawak,Bukit Sarang(RMNH, shellheight0.85mm),frontal view; b, do.,umbilical
view. 3.a,Acmellaobtusa spec. nov.,holotype,Malaysia, Sarawak,BukitSarang(RMNH, shellheight0.9
mm),frontalview; b, do.,paratypespecimenfromsamelocality(V), umbilical view.4.a, Japoniahyalina
spec. nov.,holotype,Malaysia, Sarawak,BukitSarang(RMNH, shellheight3.5mm),frontal view;b, do.,
umbilical view.5.a, Japoniaditropisspec. nov.,holotype,Malaysia,Sarawak,BukitSarang(RMNH, shell
height2.8mm),frontal view;b, do.,umbilical view.
Vermeulen&Junau:Thesnailfauna ofßukit Sarang 213
Figs6-7.Opisthoporusand Georissaspec.6.a,Opisthoporusserenaespec. nov.,holotype,Malaysia,Sarawak,
BukitSarang(RMNH, shell diameter17.2mm),frontalview;b, do.,umbilical view;c,do.,apicalview;
d,do.,operculum,outersurface;e,do.,operculum,lateral view.7.Georissa pachysomaspec.nov., holotype,
Malaysia, Sarawak,BukitSarang(RMNH, shellheight1.7mm),frontalview.
214 BASTERIA,Vol 71, No.4-6, 2007
Acmella obtusa spec. nov.(fig.3)
Material seen.- Malaysia, Sarawak,2nc' div.:LowerTatau Rivervalley, BukitSaranggroup, Bukit
Anyi,SE.side (V12760/>10paratypes,RMNH109080/holotype).
Shell.-Shellminute,conicalwithaboutflatsidesandabroadlyroundedapex,slight-
ly translucent white, somewhat shiny. Whorls 4 3/8-4 5/8, convex. Suture impressed.
Protoconchaboutsmoothat40x magn.Radialsculptureteleoconch:inconspicous growth
lines only. Spiral sculpture teleoconch: fine, densely placed spiral threads. Umbilicus
open, narrow. Aperture about elliptic with a flattened patieral side, rounded above,
broadly roundedbelow, transition from parietal to columellarside somewhatangular.
Peristomesimple, reflectedonthecolumellarside,not soonthepalatalside.Height 0.9-
1.0mm;width0.70-0.75mm. Apertural height0.25-0.30mm,width 0.30-0.35 mm.
Ecology. - Lowlandrainforestonandnearlimestonebedrock.
Distribution.- Malaysia, Sarawak, 2nc' div.:TatauRiver Basin, BukitSarang.
Notes.- A. conica, above, differs in having a somewhatless widetop, a less com-
pressed spire and atmosttracesofa spiralsculpture.
Family Cyclophoridae Kobelt, 1902
Japonia Gould, 1859
Japonia hyalina spec.nov.(fig. 4)
Material seen.- Malaysia, Sarawak, 2nc* div.:Lower Tatau River valley, BukitSaranggroup (leg.
SerenaLee,V12409/4paratypes);do.,BukitAnyi,NW.side (V12778/>10paratypes,RMNH109081/holo-
type);do.,BukitLebik,groundlevel (V12779/>10paratypes).
Shell.- Shellvery small, conicalwithconcave sides, translucentwhite,shiny. Whorls
4 1/8-45/8, thefirstwhorlsconvex, thelast distinctlykeeledattheperiphery, slightly con-
vex above and below. Sutureimpressed. Sculpture protoconch: surface minutely verru-
cate.Radialsculpture teleoconch:thefirstwhorlswithfine, densely placed andregularly
spaced riblets, later whorls with growth lines, only locally grading into riblets. Spiral
sculpture teleoconch: thefirst whorls with6-9 about equally strong spiralridges witha
minutelyerosecrest;inthelaterwhorlsthelowermostdevelopingintotheperipheralkeel
and above this 2-6continuing, thoseclosestto the periphery strongest, and leaving the
area below the suture withous spiral sculpture; below the periphery with c. 3 spiral
ridges: 2neartheperiphery and a third, very weak,basal. Umbilicusopen,0.7—0.9mm
diam.Aperture subcircular.Peristome triple;theinner two littlereflected, closetogether,
not reflected, a circularrim witha notch atthe level of thesuture; the outer distinctly
widenedand reflected, flator slightly convex, widening towardsthepalatal side, deeply
notched near the suture. Height 2.9-3.5 mm; width (excl. peristome) 3.6-4.4 mm.
Apertural height 1-1.2mm, width1.1-1.3mm. Periostracumvery thin,translucent,virtu-
ally withoutappendages.
Ecology. - Lowlandrainforestonandnear limestonebedrock.Aleaflitterdweller.
Distribution.- Malaysia,. Sarawak,2nc' div.:TatauRiverBasin, BukitSarang.
Notes. - Easily recognizable amongBorneanJaponiabecause by thefollowing com-
bination ofcharacters: shellsmall, glassy, whitewithoutany brownmarkings, peripheral
keel distinct, periostracumvery thin,translucent.TheshellsresembleCraspedotropis andrei
Vermeulen, 1999(Sarawak: GunungMuluN.P.)which, however,has amoreangular peri-
Vermeulen&Junau:Thesnailfauna ofßukit Sarang 215
stomeand weakerspiral sculptureabovetheperipheral keel.Inspiteoftheresemblance,
we think that both Japonia species presently described are, indeed, Japonia ather than
Craspedotropisbecausethey havea distinctnotchintheperistome, nearthesuture;achar-
actertypical forJaponiabutabsentin Craspedotropis. Thetwo generaalso differinopercu-
lumstructurebut, onfortunately,nooperculums areavailableofthetwospecies described
here.
Japonia ditropisspec. nov.(fig.5)
Material seen.- Malaysia,Sarawak, 2nc' div.:LowerTatau Rivervalley, BukitSaranggroup, Bukit
Anyi, NW. side (V 12780/>10paratypes); do., Bukit Anyi, SE-side (V 12781/10paratypes); do.,Bukit
Lebik, ground level (V 12782/>10 paratypes, RMNH 109082/holotype); do., Bukit Lebik, sediment
depositsc.40m abovegroundlevel(V 12783/3paratypes).
Shell.- Shellvery small,conicalwithconcavesides,slightlytranslucentpale corneous
to white, somewhat shiny. Whorls 3 3/8-4 1/2, the first whorls convex, the last keeled
slightly above and below the periphery, slightly convex above and below. Suture
impressed. Sculpture protoconch: surface minutely verrucate. Radial sculpture teleo-
conch;thefirstwhorlswithfine, densely placedandregularlyspaced riblets,laterwhorls
with growth lines, partly and sometimesat more or lessregular intervals grading into
riblets. Spiral sculpture teleoconch:thefirst whorls with4-6 aboutequally strong spiral
ridges witha minutely erose crest; in thelaterwhorls thelowermostdeveloping into a
supraperipheral keel, theother 3-5continuing asmuchweaker threads, thoseclosestto
the periphery strongestbut otherwisespread regularly from keel to suture; belowthis
keel 3—6spiralridges: two distinctin subperipheral andbasalposition, thesubperipher-
alslightlyless protrudingthanthesupraperipheral, 1-2thinthreadsabove,and0-3below
the subperipheral. Umbilicusopen, 0.4-0.7 mm diam.Aperture subcircular, butwith1-2
slight angles along thepalatal side.Peristomedouble;theinnerlittlereflected, a circular
rimwith anotchatthelevel of thesuture;theouter moderately widenedand reflected,
flat, not or hardly widening towardsthe palatal side, deeplynotched near the suture.
Height 2-2.9mm; width(excl. peristome)2.4-3.3mm.Aperturalheight 0.7-1.0mm,width
0.9-1.1 mm. Periostracum thin, pale grownish, with deciduous, small, semi-elliptic
appendages overthespiralkeels.
Ecology. - Lowlandrainforestonand nearlimestonebedrock.Aleaflitterdweller.
Distribution.- Malaysia, Sarawak, 2 div.:TatauRiverBasin, BukitSarang.
Notes. - SmallerthanJaponia hyalina, and withtwo conspicuous spiralridges onthe
lastwhorlinsteadof one.Thepristome isalsoless distinctlyprotruding.
Opisthoporus Pfeiffer, 1851
Opisthoporus serenaespec. nov. (fig.6)
Material seen.- Malaysia, Sarawak,2nc' div.:LowerTatau River valley, BukitSaranggroup (leg.
SerenaLee,V11678/9paratypes);do.,BukitAnyi,NW.side(V12787/>10paratypes,RMNH109083/holo-
type); do.,BukitLebik, groundlevel (V12788/9paratypes);do.,BukitLebik,sediment depositsc.40m
abovegroundlevel (V 12789/2paratypes).
Shell.- Shellmedium-sized, disc-shapedwithaflat uppersidebuta somewhatpro-
216 BASTERIA,Vol. 71, No. 4-6,2007
trading apex,whitishtopale brown,withnumerousvaguetosharply outlined, medium
to darkbrownzig-zag radialbands.Whorls4-45/8, convex. Sutureimpressed. Sculpture
protoconch: surface minutely ragulose. Sculpture teleoconch:irregularly spaced growth
lines, locallygrading intoinconspicuous, moreorless regularlyspaced, lowradialriblets,
spiral sculpture virtually absentexceptfor,insome shells, afew tracesof spiral grooves
onthe firstpart of theteloconch Umbilicuswide,0.33-0.40x theshell diam.Aretrorse
tubuleispresentnearthesuture,about1/8whorlbeforetheaperatre;beyond thisthelast
whorldescends slightly towards the aperture. Aperture circular. Peristome double;the
inner not reflected, athincircularrim with aslightnotch atthe level of the suture;the
outer widenedandreflected, narrowonthecolumellarside, wideningtowardsthepalatal
sideandflaring andwitharatherdistinct, downwardfoldontheupperpalatalside,cre-
ating a channelinbetweenthefoldandthesuture. Height 6.1-8.8mm;width(excl. peris-
tome) 13.3-18.0mm. Height andwidthaperture4.4-5.7 mm. Periostracumpalebrownish,
minutely wrinkly, overtheradialribletswithlowcrestswithanedge withshort, decidu-
ous hairs, slightly above theperiphery these are muchlonger, together forming aspiral
bandofhairaroundtheshell.Operculum calcareous, flat, edgesofwhorlsnotraised.
Ecology. - Lowlandrainforest onand nearlimestonebedrock.Aleaf litter dweller,
foundnearrock outcrops.
Distribution.- Malaysia, Sarawak, 2nc' div.:TatauRiver Basin, BukitSarang.
Notes.- OnBorneo, two more Opisthoporus occur witha similarly shaped, retrorse
tubule.Opisthoporus biciliatus (Mousson, 1849) differs in having asecond, subperipheral
row of hairs, inhaving fineand regularly spaced spiral groovesonthe firstpart of the
teleoconch. Opisthoporus latistrigus(vonMartens, 1864), differsinbeing smaller(diam. 9-
13mm), and not having any hairs aroundthe periphery. Inboth species the foldin the
outer peristome, on the palatal side and close to the suture, is (almost) lacking. The
peripheral hairsseem to provide theeasiest distinguishing characterbut, unfortunately,
they aredeciduousand mayfalloffeveninlivingadultspecimens.
Family Hydrocenidae Troschel, 1856
Georissa Blanford, 1864
Note.- The Borneo specieswererevised byThompson&Dance (1983)
Georissapachysoma spec. nov. (fig.7)
Material seen.- Malaysia, Sarawak,2nc* div.: LowerTatau River valley, BukitSaranggroup (leg.
SerenaLee,V12628/>10paratypes,RMNH109084/holotype);do.,BukitLebik,groundlevel(V 12837/2).
Shell. - Shell minute,conical with about flat sides and a rounded apex (juveniles
ovoid), opaque,orangeredturning tooffwhite,somewhatshiny. Whorlsup to3 1/8,con-
vex, the last rounded at the periphery but less so above and below. Suture deeply
impressed, bordered by a narrow shoulder.Protoconch aboutsmooth. Radial sculpture
teleoconch: growthlines, with (groups of)more distinctonesatirregularintervals.Spiral
sculpture teleoconch: the first whorl with 8-12 well-spaced, thin,low spiral threads, in
someshells disappearing aroundthestartofthesecond whorl,in othersonly disappear-
ing1/2 whorlbeforethe aperture.Umbilicusclosedandcoveredbythecolumellarperis-
tome.Aperture aboutsemi-elliptic. Peristomesimple, onthecolumellarsidewidenedand
flattenedto a callusborderedby a thin, low,erect ridge towards the parietal side,onthe
Vermeulen&Junau:Thesnailfauna ofßukitSarang 217
basal andpalatal sidenotthickenednor reflected.Height up to 1.9—2mm;width upto
1.4-1.6mm.Apertural height0.6-0.7mm, width0.7-0.8mm.
Ecology. - Lowlandrainforestonandnearlimestonebedrock.Onmossy rock faces.
Distribution.- Malaysia, Sarawak, div.:TatauRiverBasin, BukitSarang.
Notes.- AmongBorneanGeorissa, G. gomantongensis ismostsimilar. Itdiffersin hav-
ing a lemonyellow shell, a somewhatlarger aperture atthesamesize (c. 1mm across),
and spiral sculpture all over theshell, downtotheaperture.
Family Ariophantidae Godwin-Austen, 1888
Medyla Albers, 1860
Medyla decrespignyi (Higgins, 1868)(fig.8)
Nanina (Xesta) de-crespigniiHiggins, 1868: 179;holotype("Labuan")leg.DeCrespigny(notseen).
Material seen.- Malaysia, Sarawak, 2 div.:LowerTatau River valley, BukitSaranggroup (leg.
Serena Lee,V 11996/4);do.,BukitAnyi,NW.side(V 12874/6);do.,Bukit Anyi,SE.side(V12875/2);do.,
BukitLebik,groundlevel(V12876/7);UpperTatauRivervalley,upperKakusRiverlimestonescarps(leg.
K.F.Leong,V12881/1).
Ecology. - Lowlandrainforestonandnearlimestonebedrock. Active atnight, creep-
ing ontheforestfloorandonvegetation.
Distribution. - Malaysia, Sarawak, 2nc' div.: Tatau River Basin, Bukit Sarang, Ulu
Kakus. div.:TrusanRiver valley(1891). Sabah:Labuan (1868).
Notes.- So faronlyknown fromoldrecords. The Labuanpopulation is presumably
extinct; the Trusan Valley has not been explored malacologically in recent years. The
species seemsabsentfromwell-explored limestoneareas furthertotheWest:NiahCaves
N.P., and Gunung MuluN.R The new records in the TatauRiver basin show that the
species occurs inhighly localizedpopulations, apparently onand nearlimestonehills.
Family CamaenidaePilsbry, 1894
Amphidromus Albers, 1850
Amphidromus thalassochromusspec.nov.(fig.9)
Material seen.- Malaysia, Sarawak, 2nc' div., LowerTatau River valley, BukitSaranggroup (leg.
Serena Lee, V 120072/2 paratypes); do., Bukit Anyi, NW. side (V12898/>10 paratypes, RMNH
109085/holotype);do., Bukit Anyi, SE. side (V 12899/1 paratype); do., BukitLebik, groundlevel (V
12900/3paratypes.
Shell.- Shelllarge, sinistral, conical withflat sides, topwhorlswithcreamywhiteto
pale brownishground colour, withyellowish green,bleuish purple orbrownishpurple
radialcolourbandsthatbifurcateintheupperhalfofthewhorls, ground colourgrading
to pale blueishgreento purplishbrownonthelastworls, withapale yellow or whitish
peripheral band, abovethe periphery oftenwith a few radial colourbandsof irregular
outlineofthesamecolour, belowtheperiphery oftenwithafewscatteredtiny darkspots
218 BASTERIA,Vol. 71, No.4-6, 1007
Figs 8-11. Medyla, Amphidromus andTeracharopaspec. 8. a, Medyla decrespignyi(Higgins), Malaysia,
Sarawak,BukitSarang (V,shellheight17mm), frontal view;b, do.,umbilical view.9.Amphidromustha-
lassochromus spec. nov., holotype,Malaysia,Sarawak,BukitSarang(RMNH,shell height32mm),frontal
view.10.AmphidromuscoeruleusClench&Archer,Malaysia,Sarawak,BatuNiahNational Park (V,shell
height 33 mm), frontal view. 11. a,Teracharopa lenticula spec. nov., holotype, Malaysia, Sarawak,
BukitSarang(RMNH,shellheight2.3mm),frontal view;b,do.,umbilical view.