Observations on the acarofauna of fish aquariums. 11. A new oribatid and two new halacarid mites

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939
Bull. AnnIsSoc. r. beIgeEnt. 123(1987): 103-118'
Observations on the acarofauna of fish
aquariums. 11. A new oribatid and two
new halacarid mites
byA.FAIN°and L. LAMBRECHTSoo
Inthreepreviousnoteswedealtwithmitesfoundinfish aquariumsandassociatedor
notwithdiseases offish (FAIN& LAMBRECHTS, 1985 and 1986and FAIN& BELPAIRE,
1985).
In this paperwe describe anew oribatid mite, TrimaIaconothrusmanicuIatussp. n.
(Ma1aconothridae),anewsubgenus(AmlimnohaIacarussubg.n.)andtwonewspeciesin
thegenusLimnohaIacarusWALTER,1917(Ha1acaridae):L.(L.)mamillatussp.n.andL.
(A.)inopinatussp.n.
These mites were found in four aquariums containing two different species offish
(DiscusandSca1aria).Nopathologicalactionhasbeenobservedinthefishesinrelation
with the presence ofthese mitesin the aquariums.
Allour measurements aregiveninmicrons (j1m).
Material examined
ThespeciesthatwedescribehereinwerefoundinfouraquariumsinAntwerp,Belgium.
Table1givesthevariationsinthenumberofmitesinthevariousaquariums. Aquarium
M2is thesame as M1 butthe samplewas taken one month later. All these aquariums
belongto thesame owner.
N° of aquarium pH and mineral content tempera- Mite fauna
pH mS KH Nitrites Nitrates ture Oribatid Halacarids
-------------------------------------------------------------------------------
M1 6,5 700 0,5 0,0106 200 25· C ++++ ++++
M2 6,5 700 0,5 0,0106 200 25· C ++++ ++++
M3 7,8 600 7 0,0146 10 25· C + +
M4 7,5 850 3,5 0,0058 60 25· C + +
M5 6,4 850 0,5 0,0255 300 25· C ++ ++
TABLE 1:Variations ofthe mite populationinthevarious aquariums
Itappearsfrom theseobservationsthatmiteswerethemostabundantinslightlyacid
waters(pH6,4to 6,5)withalowlevel ofKH.
o Institutroyal desSciencesnatureilesdeBelgique, rueVautier29,B-1040Bruxeiles
Veterinarysurgeon,KoninginElisabethstraat8,B-2610Antwerpen
00
Manuscritacceptele 18mars 1986.
104 Bull. AnnIsSoc. r. beIgeEnt. 123, 1987
Study ofthespecies
Family Malaconothridae
Genus TrimaIaconothrus BERLESE, 1916
Themitesofthegenus TrimaIaconothrusaregenerallyfoundinverydamporevenin
subaquatichabitats. Theyarefrequently encounteredin moist moss or Sphagum.
Anunidentifiedspecies attributedtothisgenushasbeenrecordedfromaquariumsin
GermanybyGESCH (1982) and UNTERGASSER(1984).
Thenewspeciesthatwedescribehereinwasfoundinseveralaquariumsbelongingto
thesame ownerin Antwerp.
TrimaIaconothrusmaniculatusspec. novo
Adult(figs1-4):Colouryellowish.Holotype560longand300wide(maximum).Length
and width of4paratypes: 570 x 285, 555 x 290, 552x 270, 540 x290. The tegument
comprizes a thin granularcerotegument and afinely punctate cuticledevoid ofpits or
reticulate pattern. Prodorsum: Lateral angulation between legs I and Il conspic,uous.
EachsidewithaS-shapedpoorlysclerotizedridge. Rostralsetaeabout45long,theyare
piloseintheirbasalhalf. Lamellarsetaewithathickbasalhalfandwithafewbarbules,
theyare60to70longandare55to60apart,theyaresituatedclosetothelateralmargins
of the body at about 30 from the rostral setae and 108 from the interlamellar setae.
Interlamellarsetae 105long, 90 apart and situated at 135from the anteriormargin of
body.Exobothridialsetaeverythinandshort.Notogaster.Posteriorregionslightlyscaly.
Apairofpigmentedeyesarepresentinfrontofsetaecl.Allthesetaearesmooth.Length
ofsetae:c215;cl,dl,d220-25;c3,elandf230-35; e270;h160;h2105;psI25-30.Mostof
the long setae are curled. Orifices ofthe oil glands very small situated inside setae f2.
Venter. Absence ofthick transverse sclerite in the anterior region ofthe anal groove.
Epimeralsetae:3-1-2-3,all,thesesetaeareveryshort.Analandgenitalslitsofaboutthe
samelength.Thereare6pairsofthingenitalsetae(25to30long).Onepairofanaland3
pairsoflongeradanalsetae.Lengthofsetaeh325-30,ps260andps320-25. Legs:Tarsi
tridactyle, themedianclawthickerbutshorterthanthelaterals.TarsiIandIlwithlong
and very unequal setae ft, oneis smooth and thin, the otheris thick, flattened and its
lateralmarginsbearnumerouslongandthinbarbules.TarsiIIIwithbothsetaeftthick
andbarbulate. TarsiIVwithonlyonepilosesetaft. Setae tcoftarsiIandIllong, bare
with hooked apex. Setae u, p and pvare unequal flattened spines bearingfinger-like
projections(hencethenameofthespecies:manicuIatus). OntarsiIIIandIVthesesetae,
aswellasthesetaesaredentateratherthanfinger-like; thesetae tcareveryunequal,the
longest bearingbarbules onlyinits basalthird, theshorteris barbulateinitsbasaltwo
thirds. Solenidiotaxy: TarsusIwithalongthicktvldirectedbasally,2thinandparallel
tv2and tv3. Thefamulus isaconicalspine.
Remarks:
This species is easily recognizable by the combination ofthe following characters:
Bull. AnnIsSoc. r. beIgeEnt. 123, 1987 105
1
(
0
,,
I,}
\ c:::?
Fig1. TrimalaconothrusmanicuJatussp. n. Adultindorsalview.
106 Bull. AnnlsSoc. r. beIgeEnt. 123, 1987
o
3
3
Fig2. TrimaJaconothrusmanicuJatussp. n. Adultinventralview.
Bull. AnnlsSoc. r. beIgeEnt. 123, 1987 107
Shapeofthetarsalchaetotaxy(veryunequalsetaeft, modifiedaspectofspines u,pand
pv), epimeralformula 3-1-2-3, absence ofpits orreticulation onthecuticle, sixpairs of
relativelyshortgenital setae.
Thegenus Trimalaconothruscomprizesuntilnowmorethan40species,mostofthem
tcI
et
Figs3-7.Figs3-4: Trimalaconothrusmaniculatussp.n. Adult:apicalpartoftarsiI(3)andIV(4).
Figs 5-7: Trimalaconothrusglaber(MICHAEL, 1888). Adult(type specimen): apical partof
tarsusIdorsally(5) andventrally(6)and oftarsusIV(7).
108 Bull. AnnIsSoc. r. beIgeEnt. 123, 1987
beingdescribed from countries outside Europe. KNllLLE (1957) listed 16 species from
Europe and more recentlytwo newspecies havebeen added to this list. Mostofthese
species have been inadequately described and KNULLE in his key retained only seven
species as valid: T. gIaber (MICHAEL, 1888), T. tardus (MICHAEL, 1888), T. novus
SELLNICK,1921,T. vietsi(WILLMANN,1925),T.foveoIatusWILLMANN,1931,T.scuIptus
KNULLE, 1957 and T. saxosus KNULLE, 1957. To this list should be added T. buresi
KUNST, 1959. Another species T. scutatus MIHELIC, 1959, described from Austria,
probably does not belong to the genus TrimaIaconothrus owing to the fact that it
possesses asensillus.
Atfirst aspect ournewspecies resembles T. gIaber, howeverexaminationoftypical
material(slides nOs 1930.8.25 1106and 1108)showsthat bothspecies differfrom each
otherbythefollowingcharacters: 1)Chaetotaxyoftarsiverydifferent. In T. gIaberthe
twosetaeitoftarsiItoIIIareverythick,conical,bareandsubequa1,andthesetae u,p
andpvaredevoid offinger-likeprojections;ontarsiIIIandIVthesetae tcareequalin
lengthand bare(figs 5-7); 2) Absence ofsclerotized transversecushioninthe anterior
region ofthe adanal plate. This sclerite is present in T. gIaber(see KNULLE, 1957); 3)
Interlamellarsetaeshorter(inT.gIabertheyareincompleteandmeasureatleast140)and
closertoeachother(inT.gIaberthesesetaeare120apart);4)Only6pairsofgenitalsetae
(7pairsinT.gIaber). OwingtothedorsalmountingofthetypesofT.gIaber(inbalsam)it
was notpossibleto studythe analand the epimera1setae.
T. manicuIatusdiffersfrom T. tardus, T. novusand T.ioveoIatusbytheaspectofthe
tarsalchaetotaxyandtheabsenceofpitsorreticulationonthecuticle.FromT.scuIptusit
differsbythesmoothaspectofthedorsalsetae,thesmalleradanalsetae,thepresenceof
only2pairsofepimeralsetaeIll,theabsenceofsclerificationsonthedorsum,thelarger
sizeofthebody.FromT.saxosusitdiffersbythemuchthinnerandshorteradana1setae,
thesmoothaspectofthedorsalsetae,theequallengthofbothanalandgenitalplates.Itis
distinguishedfrom T. vietsibythemuchlargerbodysize,theequallengthsofanaland
genitalplates,the presenceof2pairs ofsetaeonepimeresIII(see KNULLE, 1957).
Habitat
Holotype and 40 mounted paratypes, all adults, and numerous immatures, from 2
aquariumsM1 (=M2)andM5,containingtwodifferentfishes (DiscusandScalaria),in
Antwerp,on3Januaryand6February1986.Ho1otypeintheInstitutroyaldesSciences
naturelles de Belgique. Paratypes in the British Museum (Nat. Hist.) London, in the
Museum National d'Histoire naturelle, Paris and in the D.S.National Museum, Was
hington.
Family Halacaridae
Genus LimnohaIacarus.WALTER, 1917
With the new subgenus and the two new species that we describe herein, the genus
LimnohaIacaruscomprizesnowthreesubgenera, 12species and onesubspecies.
1. LimnohaIacarus s. str. WALTER, 1917. Pa1ps with trochanter much narrower than
Bull. Ann1sSoc. r. be1geEnt. 123, 1987 109
genu-femurandarticulatingataboutarightanglewiththelatter;tibiaeoflegsIand11
withoutbarbedspines, ontibiaeIIIspinesareeitherpresentorabsent.Allclawswith
longcombs.TarsiI-IVwith9-8-6-5setae(characterobservedonlyinL,mamillatus).
Typespecies: Ha1acarus wackeriWALTER, 1914.Thissubgenusincludes eightother
species.AllthegroupisconfinedtotheOldWorld(Europe,AsiaandTropicalAfrica),
it includes the following species: L, mauritziROMIJN & VIETS, 1924; L, africanus
WALTER,1935;L. fontina1isWALTER&BADER,1952,L,portmanniBADER,1967;L,
majorBADER,1968;L,capernaumiPETRoVA,1967;L,lanaeGREEN,1976;L,mamil
latussp. n.
2. Stygoha1acarusVIETS, 1934. Palpswithtrochanteras wide as genu-femur(inlateral
view)andnormallyarticulatedwiththelatterwithoutforminganangle.Allthetibiae
oflegswith2apicalbarbedspines;genuaIand11with2apicalandgenuaIIIandIV
withoneapicalbarbedspines.
Typespecies:Limnoha1acarus(Stygoha1acarus)scupiensisVIETS,1934.Thissubgenus
is monotypic. Describedfrom Europe.
3. Am1imnoha1acarussubg. n.: Palp-t,rochanterasinLimnoha1acarus.Legs:GenuaI-IV
without barbed spines; tibiae I-Illwith 1-1-2-1 barbed,spines, tibiaIVwith athick
ratherlong, subapicalbarbedseta. Claws Iwithonlyafew apicalshortand narrow
spines,therestoftheconcavityoftheclawwithoutsuch'spines. ClawsII-IVwithshort
combsformedof4to5narrowspines.Legchaetotaxy:TarsiI-IVwith7-6-6-5setae,in
the typespecies.
Typespecies:Limnoha1acarus(Amlimnoha1acarus)inopinatussp. n. Foundinaqua
riumsinBelgium.Asecondspecies,L,(A.)cultellatusVIETS,1940hasbeendescribed
fromSouthAmerica.
Most ofthe species ofLimnoha1acarusliveinfreshwater, especiallyinsubterrlj.nean
waters(PETROVA, 1967).Theyhavebeenrecordedfromdeepwells,lakes, marshesand
springs.Threespecieswerefoundinbrackishwater(e.g.L,portmanniandL,majorfrom
theLakeTanganikaand L, fontinalisfrom awellwithslightlybrackishwater.)
The two species recorded herein were found in fish aquariums in Antwerp. The
presenceofhalacaridmitesinaquariumshadalreadybeenreportedbyGensch(1982)in
Germanybutthemiteswerenotidentifiedatthegenericorspecificlevel.Webelievethat
thesespeciesfound inaquariumsarenotlocalspecies. Probablytheyhavebeenintrodu
ced in Europe with the tropicalfishes or plants. One can surmize that the ecological
conditionsexistingintheseaquariumsandwhicharesuitableforthetropicalfishes(high
temperature,goodaerageand abundantfood supply)arealsoveryconvenientforthese
mites.
1. Limnoha1acarus(Limnoha1acarus)mamillatusspec. novo
Female(figs8-12): Lengthandwidthoftheholotype(idiosoma)306x201.Itcontainsa
roundeggof72diameter.Totallengthincludinggnathosoma345.Lengthandwidthin3
paratypes: 310 x 200; 309 x 190; 295 x 210. Posterior margin ofidiosoma with small
rounded projections (mamillate). Dorsum: Anterior plate 75 long and 90 wide (maxi
mum)bearinganetworkpatterninitsposteriorhalf;afewdarkgranules(eye)andapair
110 Bull. Ann1sSoc. r. beIgeEnt. 123, 1987
9
Figs8-9. Limnohalacarusmamillatussp.n.Femaleindorsalview(8);posteriorregionofdorsum,
enlarged(9).
Bull. Ann1sSoc. r. be1geEnt. 123, 1987 111
ofmicrosetaearepresentintheanteromedianpart;acrestislacking;theanteriormargin
bearstwolateralpores. Posteriorplateellipsoidal,withbroadlyroundedextremities,it
bears a network moredeveloped anteriorlyand is219long and 128 wide(ratio length:
=
width 1,7to 1,71in3paratypes). Ocularplatestriangular,longer(84)thanwide(45);
bearing anteriorly a number ofdark granules, larger than those ofthe anterior plate
(eyes); they also bear a poorly developed network, one small pore and a lyrifissure.
Postocularplates absent. Lateralplatesdevoid ofnetworkbutbearingalongseta. All
theseplatesareseparatedfromeachotherbysoftstriatedskin. Excretoryporeteminal
asmallpunctateplatebearingtwomicrosetae. Venter: Mostoftheventer
punctateplatebearing6to8suckers.Behindthisplatearethetwo
Figs10-12.Limnohalacarusmamillatussp.n.Femaleinventralview(10);tarsusI(11)andpalp(12)
inlateralview.
112 Bull. Ann1sSoc. r. be1geEnt. 123, 1987
paramediangenitalplatesseparatedbythevulvaandcarryingeachathinseta. Gnatho
soma: Length,includingrostrum60,widthofthebase51.Itbears2pairsofthin·setae.
Chelicerae68long. Palps:Trochanter6longand 14wideinlateralview;genu-femur30
longand23wideinlateralview.Theaxis ofbothsegmentsformanangleofabout60°.
Thegenu-femurbears2inequaldorsalsetae,onesubapical,thinand45long,theothervery
shortandsituatedinthebasalthird ofthesegment.Tibia20longand 18wideinlateral
view,bearingastrongventralsubapicalspine.Tarsusl2longand10wideinlateralview,
itbearsastrongapicalspine(18long),onelongandthindorsalseta,threelongandthin
ventralsetaeandtwolongdorsalsolenidions.Legs:LegsItoIVinsertedlaterally,butlegs
1-11 are slightly ventral whilst legs Ill-IV are distinctly dorsal. Coxae rudimentary.
Lengths ofsegments (legs I to IV): Trochanters 22-22-45-45; Basifemora 33-33-27-25;
Telofemora 57-57-45-45; Genua 42-40-42-42; Tibiae 60-60-75-84; Tarsi 57-57-66-65.
Chaetotaxy oflegs (number of setae, including solenidions and spines): Trochanters
1-1-1-0;Basifemora4-4-2-1;Telofemora4-4-3-3;Genua6-6-4-3;Tibiae9-7-7-6or9-6-7
6;Tarsi9-8-6-5.Onlythetibiaebearbipectinatespines(onesubapical,18long,theother
prebasa126long).Claws:Alltheclawswithalongcombofthinspines,theclaws11toIV
arebifid attheirapex.
ThenatureofthesetaeoflegsandpalpshassofarnotbeenstudiedintheHalacaridae.
Thesolenidionsaredifficulttorecognizeinthesemites.ThetarsiIbear7,thetarsi116
andthetarsiIIIandIV2cylindricalsetaewhichcouldbeeithersolenidionsoreupathi
dias. The palp-tarsus bear2dorsalsolenidions.
Nymph11: Length ofidiosomaoftwo paratypes261 and 255. Dorsumas inthefemale
exceptthatthereisapostscapularplate.Venterwith4largeplates,twomedianandtwo
lateral.Theposteromedianplatebears7pairsofsuckers.Legsasinthefemale. Pigmen
ted eyes not observed.
NymphI:Idiosoma150longinaparatype.Sameaspectoftheidiosomaasinthenymph
11butthereare5pairsofsuckers.LegsItoIIIwith6freesegmentsasinnymph11;legsIV
with only 5free segments, the basi and telo-femur being fused. Chaetotaxy oflegs;
FemoraIVwith2setae;Tibiae6-5-5-5; Tarsi7-6-6-5.
Larva: Length and width of idiosoma in one paratype 165 x 108. Dorsum as in the
nymphs.Venter:thereisno'posteromedianplate,theidiosomabeingstriated.Legs:Inall
thelegsthebasifemuris'fusedwiththetelofemur,thisfusionisnotcompleteintarsusI.
Legchaetotaxy:Trochanters1-1-1;Femora4-4-3:Genua4-4-3;Tibiae5-5-5;Tarsi7-6-6.
Male: unknown.
Habitat
Holotypeand20paratypesfemale, 18paratypesnymphs(7nymphsI,llnymphs11)and
6paratypeslarvae, allfrom aquariumnOMl,Antwerp,3.1.1986. Otherparatypesfrom
thesame aquariumbutonFebruary 1986(25females, 20nymphs11,7nymphs Iand 5
larvae)andfromaquariumsM3andM4(5femalesand6nymphs)andM5(16females, 10
nymphs)from the samelocality. Types deposited asfor T. manicu1atus.
Remarks:
ThisspeciesisveryclosetoL.lanaeGREEN, 1976,describedfromacraterlakeinJava.
WehaveexaminedtheholotypeofL.1anae.Thisspecimensisdeeplystainedinredand
rather opaque. L. mamillatusdiffers from thatspeciesbythefollowingcharacters: