Association of uropodid, prodinychid, polyaspidid, antenno- phorid, sejid, microgynid, and zerconid mites with ants
PEKKA T. LEHT]NF,N
Lehtinen. Pekka T.: Association of uropodid, prodinvchid, prolyaspidid, antennophorid, sejid. microgynid, and zerconid mitcs with ants. [Myrgaster inom kvatsterfamil jema Uropodidae, Prodinychidae, Polyaspididae. Antennophoridae, Sejidae, Microgynidae och Zcrconidac.]- Ent. Tidskr. 108: 13-20. Unei, Sweden 1987. ISSN 0013-886x,
The obligatorily myrmecophilous fauna of North Europe include one species of. Anten- nophorus (Antennophoridae) and about 20 species of Uropodidae, representing the sub- families Oplitinae ( Oplitis and Urodiscel/a), Trachyuropo dinae (Urotrachytes and U rojanetia), and a few species in other subfamilies (Phaulodinychus in Uropodinaeland Uroobovella, Oodinychtts, ar,d Trematurella in Trematurinae). Polyaspidid taxa are represented only by deviating populatbns of Dipolyaspis trsracezs. while various generally non-myrmecophilous prodinychids have invaded ant nests locally (Prodinychus flagelliger, Dinychus carinatus, D. arcuutut). and in some case formed huge populations (Trachyxenura pyriformis, Dinychus septentionalit).
Many zerconids are numerous in ant nests, but only Prozercon traegardhi anda new species from SW Finland show a distinct preference.
Morphological adaptations concerning mouthparts and larval design for ant symbiosis are found in Antennophoridae and in the uropodid subfamilies Oplitinae and Trachyuropodinae.
These two subfamilies share only a few parallel adaptations, and they have evolved from differ- ent uropodid groups. Most myrmccophilous mite species of Nonh Europe prefer a single ant host. Nests of Formicinae, esp. Ltr;ius (Chthonolastus, Cqutolasius & s.str.), Dendrolasius, Csmponotus, and Formica are distinctly preferred to Myrmicinae (except Tetamorium\.
Both ants and mites have seemingly isolated populations, which could be classified as species in stalu nascendi. Many of these mite populations with different ant hosts are also allopatric ard here trcatcd as subspecies. All European species of the Oplitis ovalala-group live in myr- micine nests ( Ierramoium, Messor, and Myrmica). A detailed analysis of the taxonomy of thc uropodid guests of different populations of Formica er.recra most probably will help in the taxonomic reevaluation of the latter.
The names used in this paper are based on a recent revision of these groups, including also the checking of all Berlese types.
Pekko T. Lehtinen, Zoological Museum, Department of Biology, University of Turku,
S F-205 00 T urk u, Finland.
Introduction
The presence of a ich mite fauna in the nests of various European ants was wcll documented by numerous authors ca. 100 years ago and first men- tioned by Forel (1874) without identification of
the mitcs. Michael (1894b) and Wasmann (1899) suggcsted that many of these mites are dependent on certain ant species or at least strongly prefer their nests as the microhabitat.
Basic data for myrmecophilous Uropodoidea was presented by Haller (1877 & 1882), Lubbock (ltt8l ). Berlese (1881, 1882-1892, 1904 a & b), G.
Canestrini & R. Canestrini (1882), G. Canestrini
& Berlese (1884), G. Canestrini (1884), Michael (1891 & 1894 a & b), Karpelles (1891), Moniez (1892 & 1894), Wasmann (1894, 1897 a-b, 1898, I tt99 & 1902), Leonardi ( 1895 & 1896), Trouessart (1U96 & 1902), Janet (ltt97 a & b), Karawaicw (1906), and Kneissl (1907, 1908).
Although myrmecophilous species of mites wcre described by many acarologists, the main opus is Berlese's Acari Mirmecophili (1904b), at least as far as the Uropodina is concerned - the
main group discussed here. Later, Donisthorpe
14 Pekka T. Lehinen
(1927: British Isles), Balogh (1938: Hungary), Storkan (1940) and Pecina (1980: Czecho- slovakia), Greim (1952: S Germany) and Wis- nicwski (1979c: Poland), have published locallists of myrmecophilous mites. North European myr- mecophilous uropodids and polyaspidids havc been recentlv described by Greim (in Hirschmann 1957), Hirschmann & Zirngicbl-Nicol (1961), Wisniewski (1979a. 1980a & b), Pecina (191t0),
and Hirschmann (1984). Krasinskaya (1961) studied the tife historics of some of the species dis- cussed here.
The European uropodids have not been
taxonomically revised so far. Names used here are based on a recent. as yet unpublished revision that also includes checking of all Berlese types of thc mite groups discussed here.
The published information about North Euro- pean myrmecophilous mites is scanty, and the majority of the common widespread species were never reported from any of the North European countries. Thor (1900) dcscribed a new species, Uropotla formicarum from Norway. It has not
bccn cited by Central European authors and it is hcrc synomymize d with Oodinychus ovalis (C . L.
Koch). Triigirdh (1942) described a new uropodid species. Trematttrella stylifera, and stated (1945) that it is associated with a species of the Formica ruft-group from Sweden. Hc also proposed a new family, Trematurcllidac (1944), for the species.
TrigArdh (1943) also presented a review, where
thc family Antennophoridae was discussed in morc detail, however, with most examples from tropical and other non-European genera. Hc mentioned the phoretic dispersal of uropodid
deutonymphs, but exemplified from other insects.
mainly Coleoptera. No mesostigmatid mite from
^nt n€sts is previously known from Finland.
"I r.c cvaluation of thc descriptions of the associ- ations between different species of mites with the ant spccies were affected by the obscurity of both mitc and ant taxonomy at the time of the pionccrs
of this field (Leonardi 1896, Wasmann 1t199,
Donisthorpe 1927). Thc current specific concepts of the Formica rufa grorp date back only to Yar- row (1955), and, in my opinion, there are still many unsolved problems. The yellow species of /,asius have quite often been misidentified, not only by acarologists, but also by myrmecologists.
There are also two additional sources of error in the published data about the association between mite and ant specics. First, a sample from under a
single stone or any other limited area may include small nests of many Myrmica, Leptothorax, and lasius spp. In this way, thc guests of different ant species may become mixed in the sample.
Secondly. many authors have listed the host species of ditferent mites without any quantitative information. Let's take an illuminating examplc.
If we have an old large anthill of Formica exsecta.
throughout crowded with the very striking, nicc red uropodid Urojunetia coccinea (500-15(X) speci- mens per liter), it is likcly that single specimens are accidentally transported by the ants to the neighbourhood. When we then find single speci- mens of U. coccinea within the closeby anthill of Formica aquilonia or under the stones. where Ior-
mica ftt^sca or Lasiu.c riger happen to have their ncsts. these observations don't prove that the species belong to the local host species of U. coc- cinea. Third, dead specimens of many arthropod species are actively transported to the nest hy the ants.
Dispersal and feeding of myrmecophilous mites The mode of living and dispersal of myrmecophil- ous mites is realized according to three differcnt strategies.
1. Phoretic dispersal of adult specimens, Adult specimens of Oplitis and Urodiscella are regularly attached to thc protibial comb of their host ant, both workers and alates. This behaviour was first dcpicted by Janet (1897a). Adult specimens of
Antennophorus are regularly attached below or on the head of the ants, and are dispersed in this way.
Both the oplitine species and Antennophorus make use of this close attachment for their feeding and are more generally classified as commensals.
What they eat is subject to opinions, but Oplitis spp. are usually regardcd mainly as feeding of the minute skin particlcs and other organic debris combed by their brushlike, strongly specialized mouth parts.
2. Phoretic dispercal by deulonymphs. Many adults of myrmecophilous and non-myrmecophil- ous species of the uropodid subfamilies Uro- podinae and Trematurinae and the nominate polyaspidid subfamily are never attached to in- sects. Most of them, however, have a phoretic deutonymph that is firmly attached to a flying in-
sect to secure an effective dispersal.
Phaulodinychus hamulifer, the oddJooking guest
of Lasius niger, throughout covered by club-
shaped strong setae, can easily be collected by sweep-netting at the swarming of its host. Work- ers. most probably. play no role in the dispersal of this species. The mode of dispersal of the myr- mecophilous populations of Dipolyaspis testaceus
and Oodinltchus spatuliferus has not been ob- served, but most probably their deutonymphs arc phoretic on swarming Camponotus herculeanus.
These specialized populations most Iikely repre- sent evolving new taxa, although no undisputed morphological differences are present.
Manv species of these subfamilies have two types of deutonymphs, phoretic and sessile. The common uropodid species of various special habi- tats. Oodittychus ovalis, uses various insects for dispersal by its phoretic deutonymphs, but sessilc deutonvmphs are often found in large numbers to- gether with adults and protonymphs in a suitable
h abita t.
A special group consists of the myrmecophilous species ofthc genus Uroseius. Adults ofthis genus are rarely collected on mammal carcasses, while phoretic deutonymphs are relatively common in some of the non-myrmecophilous species. For Uroseius koe hleri Wisniewski, 1979, onlv a few deutonymphs are known from an anthill of For- mica polyctena in Poland and from two anthills of
F. rufa in southern Finland.
3. Neither adults nor deutonymps of ohligatory myrmecophilous groups are regularly attached to anls. Uroobovella obovata is an example of this strategy, other can be found in the subfamily Trachyuropodinae.
Species of Urotrachytes, Urojanetia, and Uroobovella obovata are often found in huge numbers within ant nests! whilc solitary specimens are found in the surroundings outside the nests.
Most probably they are accidentally attached to the workers of ants. and this is sufficient for their dispersal. The same is true for all zerconid, sejid, and prodinychid species. present in ant nests.
Categories of myrmecophilous mites
Wasmann (1894) first classificd myrmecophilous arthropods into synoects, synocoets, symphiles
(: m)'rmecoxenes), and, ectoparasires. These categories wcrc discussed in detail by Donisthorpe (1927: xv-xxiii). The first and last categories are not represented in the mite groups discussed here, although uropodids as parasites wcre still listed by Sellnick (1939).
Association of mites with ants 15 Synocoets were originatly defined as guests tol- erated by ants, while symphiles as guests actively and friendly treated by ants. Much additional data about reciprocal relations of different arthropod groups have been accumulated since Wasmann's time, and the relationships are best described in general terms of cocvolution.
The term myrmecophilous is now used as a gen- eral term for organisms distinctly preferring ant nests, but this term doesn't describe thc mode of
association in detail. All authors that have made exact observations about the habits of mites in ant nests, have regarded most ofthem as commensals.
Our knowledge today is not sufficient for the final classification of symbionts and pure commensals among the myrmccophilous mites, but most prob- ably all groups of mites that are obligatory myr- mecophilous (Antennophorus, Oplitis, Urotlis-
cella, Urotrachytes, Urojanetia and Phaul-
odinychus (Uropolyaspis) spp., Oodinychus spatuliferus & Uroobovella obovata) are sym- bionts. A part of the facultative myrmccophilous species may also belong to this category.
All zerconids, preferring to live in or regularly prescnt in ant nests live there probably simply be- cause these microhabitats are rich in organic deb- ris or afford an optimal microclimate for hiberna- tion. Many of thesc mitcs most probably are fungi- vores as many other debris living ones. Hyphae of numerous species of fungi are regularly present in ant nests, and they are most probably as important to the myrmecophilous mites as the ants them- selves are.
The mite fauna of difrerent ant species
Most Finnish species of myrmecophilous mites are associated with only one or two host species (Tab.
1). Their more detailed distribution will be discus- scd elsewhere (Lehtinen. in preparation). Old ob- servations from othcr European countries were summarized without revision of neither ant nor mite species by Bernard (1968). These data cannot be compared with the data in Tab. 1.
Members of Lasius s.lat. have the highest number of mites associated with a single species of ant. In addition. the genus Antennophorus with five European specics is completely restricted to nests of Lcsius, and the oplitine generaOplitis and Urodiscella are nearly so restricted. Thc nests of
Lasius (Chthonolasius) are quite difficult to find,
as they are 3M0 cm deep in the ground (L. mixtus
16 Pekku T. Lehtinen
Tab. 1. Checklist of Finnish myrmccophilous mites; Antennophorina, Uropodina, Sejina & Zerconina. The column A givcs the type of relationship as: (l) dependent on onc/two closely related ant speices, (2) abundant in ant nests, but several common hosts, (3) occasionallv very abundant in anthills. (4) myrmecophilous populations <lf non-myr- mecophikrus spccies. and (5) common non-myrmecophilous spccies. also regular in anthills. In column B, (l ) denoles species with parthenogenetic populations only in Dorthern Europe, and (2) specialists of decaying wood, often in
nests of ants. Thc C column givcs distributional data as: (1) not previouslv rccordcd from continental nonhern Euro- pe, (2) recorded from Finland, and (-j) not previously recorded from Finland. Thc column to the right lists the host spccies. the ones with disdnct correlations are given in bold types.
Mite species Host species
Aniennophorina Camin & Gorirossi. 1955
Anlennophoridae Berlese, 1892
A nlerutop ho rus pubescerrs Wasmann. 1897 Uropodina Kramer. 1881
Uropodidee Kramer. 1881
Oplitinae Hirschmann & Zirngiebl-Nicol, 1962 Oplitis pandata (Michael, 1894)
O. pandaru (Michael. 1894)ssp. n. "A"
O. pandam (Michael. 1894) ssp. n. "B"
O. uillosel/a (Berlese- 1904) O. villosella ssp. n.
O. ouarr./a (tserlese. 1903)
O. stamncriGretm in Hirschmann 1957
Urodisce llu ( U ro pectinis) philocten o (lanet. I 897) U. (Uropectiniu) wasm anni (Kneissl, 1907) U. (Urodiscellu) uloplzora (Berlese, 1903) Trachyuropodinae Berlese, l9l7
Urotrochytes lbtmicaria ( Lubbock. l88l ) Uroj ane tiu coccinea (Nlichael, 1891 )
U. excavata (Wasmann, 1899) U. wasmanniana (Berlese. 1903) U. hirschrnanni (Pecina, 1980) Uropodinae Kramer. 1881
Uroseius koehleriW isniewski, 1979 (D only) M ic rocy I li ha min ima (Kramer, I 81,12)
Phaulodinychns ( P haulo dinychus) sp . n.
P. (Uropolyaspis) hamulikr (Michael. 1894) P. ( U.) spin<tsulus (Kneissl, 1916)
Trcmalurinae tserlese. I 917
O odittyc hus spotuliJeras (Moniez. I 892) ssp. bectwirhi Wisniewski, 1979 O. ovalis (C. L. Koch,1839)
I pi duro p odo di a lveolara (Hirschmann & Z. -Nicol.
I. interstructura (Hirschmann & Z.-Nicol. l96l) Trematurella elegans (Berlese, 191 6)
Uro dias pis tcct a (Kramer. 1876)
Uroobovclla obovara (Canestrini & Berlese, 1884) Dinychopsis canla (Hull, 1918)
Prodinychidae Berlese, I 9 I 7
Trac hy xenura pyriforzri (Berlesc. I 920)
I
I t I
Lasius umbralus
Lasius niger
Formica rula (inland),
f. e.rrccla (inland bogs) Camponoltu herculeanas (SW) Lasius llavus (Ostrobothnia) Lasius meridionalis Teiramodum caespitum Dendrolasius fu liginosus Lasiusmixtus
Lasiusflavus (S Finland)
Dendrolasius fuliginosus & Lasius mixlus Lasiusflavus
Fomicr exsecta (meadows &
archipelago), F. sazguinea, [;. (Servi- formica) spp .
Telr8morium caespitum Lasius mixtus
Lasius meridionalis
Formica rufa
Camponotus herculeanus Lasius niger
Lasius mixtus
Camponotus herculeanus & C. vagas Formico, Camp onotus, La.riu;r- spp.
Dendn usius luIiginosus. Lasius mcn- 422
t96r)2 2
'!2 25l
1
2
dionalis & 1,. Jlavus
I Formica pratensis
3 Fonnico polvctena, L. niger 2
1 Formica flsca, Lasius niger
| l.'ormica polyctena
I Formicaexsecta, F. aquilonia, D. fuliginosus
3 Fonnicafusca
3 Formica pol.yctena
3 Formica polyctena 1 Losius & Myrmicaspp.
P rodi ny chus (A I lodi nychus) flagel liger (Berlese, l9l0)
Diny chus a rcuatus (Tragardh. 1943) D, septentrionalis (Triigirdh, 1943) D. ca r inut us Be rlese, 1903
3
32
332
2
Associati<ttt <tf mites with ants 77
Mite species Host species
Polyaspididae Berlesc, l9 I 3
Discourella (D.) morlesta (I-eonardi. 1899) 'frachytes aeg1ota (C. L. Koch, l84l)
T. ninima Trigitrdh. l91O
Dipolyaspls testaceus (C. L. Koch, 1836) spp. criocephaliW isnicwski, I 979 Sejina TriigArdh. I 93tt
SejidaeBerlese,lS95
^Sejas togatu.r C. L. Koch, 1836 Microgynidae Triigdrdh, 1942 M icrosejus t runcicola T r i\gir dh, 1942 ZerconinaTragArdh. 1946
Zerconidae Canesrini. l89l
Para z e rcon (Para ze rc on) radi atus (Berlese. 1910) Pro ze rco n trae ga rdhi (Halbert. 1915)
P. lochiSellnick.l943 Zercon solenites Haarlav , \942 Z. lindrothiLundqvist & Johnston, 1986 Z. spatulatus(C.L. Koch, 1939)
Z. sp. n. (aff. Z. spatulatus) Z. airiosusTriigirdh, 1910
Camponons ligniper da, Formica fusca, Lasius
all ants
Formica rufu-gr<lup, M yrmicq Camponoaus herculeenus
2 Formica polyctena
3 Formica aquilonia, F. rufa, F. fusca, Leptothorax s?p.
2 allants
3 Lasius flavus, L. niger
2 all ants 3 Formico spp .
3 Lasius spp., Fonnico fusca
I all southern ants
I Camponotus ligniperdu. Losius niger.
L. Jlavus
3 Formica, Lasius, Camponotus, Myrmica
& Leptothot0x spp.
2
2 2
1
4
5 5
4 I
I
I 2
2
2
I
5 2 5 5 5 3 2
5
& L. umbrdus) or thc species itself is rare
(L. meridionalis). Only onc nest of each of these species was checked in Finland for this study. re- sulting in four taxa present only in the nest of
L. rnixttrs'. namely Urodiscella philoctena, Phaulodinychus spinosulus, Urojanetia w sman- niana, an<l a parthenogenetic population of Mit'
rocylliba minimq.'lhe single nest of L. umbratus yietded the only northern European species of Antennophoridae. Anlennophorus pubescens, and the nest of L. nreridionuhs the second known locality of Urojanetiu hirsthmanni, a new suh- species of Oplitis villosella. and the only myr- mccophilous Ipiduropodu, l. dialveolata that was
also found in a closeby nest of Dendrolasius fttliginosus. The nests of the latter species are al- ways founded through a previously existing ncst of a Chthonolasius. This sccms to explain the pres- cnce of .{. tlialveolutu and, Urodiscella alophora in ncsts oI holh suhgenera. Oplitis stummeri is con- fined to nests of D . fttliginosus. and most probably some old records of U/odricella ricasoliana (W as-
mann, i899. Donisthorpe 1927) refer to this species.
The common spccies of lasias also have several specialized mites. Nests of L. (Cautolasius) flavus
in southern Finland are inhabited bv Urotrachfies formicarius and Urodiscella n'usmunni, but a few
isolated populations of L. Jlavus in the small is- lands of thc Bothnian Gulf havc 0 . villosella asthe oplitinc guest. U. wasmunni may be dependent
alsct on IJ. formicarius, as it has never been found as tlrc single uropodid guest of an L. flavus-nesl.
Thc only zerconid species that could be classified as a gucst of mainly one species of ants is Prozer- con taegardhi, found sparingly mostly with L.
llavus. Large, old nests of Lasits (L.) niger are
regularly inhabited by Oplitis pandata and
Phaulodin-v-chus hamulifer wilhin thc more or less continuous range of this ant in southcrn Finland' often also by Uroobovella ohovutu.
In Finland, nests of Oatr4tonolus herculeanus arc richcr in specialized uropodid species than those of C. ligniperda. especially when the com-
mon central European guest of the latter,
IJrojanetia cristiceps obviously is lacking in Fin- land. However. the majoritv of younger nests of C. herculeantts are poor in uropodid miles, except Oodinvchur olafis. Thc lirt of its Suest was mar- kcdly increased through examination of two very old nests, both quite exceptional in regard to their arthropod fauna. The first nest was found in the
18 Pekka T. Lehtinen
floor of a since long unused barn in the Seitsemi- nen National Park, central Finland. The barn had been used to store grass from the surrounding
fields. A new species of Phaulodinychus was found in this ncst together with the only Finnish
inland population ol Ephippiochthonius tet- rachelatus, a pseudoscorpionid common in the outer and middlc zoncs of the SW archipclago.
The second ncst was found in the Saaristomeri Na- tional Park (SW archipclago). This huge nest in- cluded the remaining spccialist species of C. fter- culearurs: Oplitis pandata n.ssp. "B". Oodinychus sparuliferus bcckwithi and Dipolyaspis testaceus criocephali. Wisniewski & Hirschmann (19U3) de- scribed a species Dinycllrrs camponoti based only on larval stage. As long as most larvae of the Di- rryclrus spp.. preferring decaying wood, have never been described. it is impossible to know with which spccics it will bc synonymized, but the strongest candidalcis D.t'arinatus Berlese, a rcgu- lar but not abunclant spccies in SW-Finland.
Old records from othcr parts of Europe arc thc least reliablc among Fornr'r'a spp.. The most intcr- esting specics is f'. (()tptoformica) exseoa. lt is the main host ol Urojanetia cocclnea for the island and coastal populations and for the meadow popu- lations with flat anthills in the inland. The inland bog populations of F. exsecta usually have quite rich populations of a new subspecies of Oplilis pandata. These populations of F. exserta often build high. relatively narrow anthills, and the pos- sibility docs cxist that wc arc dealing with differcnt ant taxa, as is now gcncrally accepted for tho tradi- tional F. rufu. Scvcral local non-myrmecophilous specics of Uropodidac and Zerconidae and numc-
rous othcr nresostigmatid. prostigmatid, tar- sonemid, astigmatid. and oribatid mites are often present in old anthills of the southern type of F. e-rr-
secta. This seems to be the most common "nat- ural" habitat of Traclty-tcnura p,vriforntis, a com- mon species in man-made habitats rich in organic debris.
Nests of the other species of the P. exsecto-group have not bccn sufficicntly invcstigatcd. Most of them may sxceptionally bc accepted as thc host of U. coccinea. Apart from this group, nests of F:
(Raptiforntica) sanguirtea and its slavcs (Servifor- ,r1ica spp.) sometimes have a rich population of U.
coccinea.
Most nests of Formiut aquilonia, F. rufu, F.
polyctena, aruJ F. prutensis are verv rich in a fcw
common spccics of Laclaptidae, espccially
Hypoaspis myrmecophilus and Cosmolaelaps cuneifer. Locally common zerconids (Prozercon kochi, Parazercon radiattts, Zercon curiosus, Z.
spatulatus and, Z- so/enrles, the latter only in north-
crn and central Finland) may be abundant- Uropodids are most often represented only by the non-hostspecific Oodinychus ovalis. In E Finland, however, Oplitis punduta ssp. "A" may be locally abundant in anthills of F. rula, and the Finnish deutonymphs ol Uroseius koehleri are all from nests of that species. An anthill of F. polyctena from Kankaanpdii, inland of W Finland, had the highest density of uropodid mites, almost 7000 specimens in a sample of less than two liters. The species composition was quite exceptional, with Ditryclrus septentrionalis and Sejus togatus ir.huge numbers, Dinychus arcuatus and Dinychopsis rutula among the abundant species, together with the very abundant myrmecophilous Oplitis pan- ddtu spp. "A", and a fcw Ootlinychus oyalrs and Urojanetia coccineu. A rich sample of lre-
muturella elegans was collcctcd from an anthill of f. polyctena-
Anthills of F. polyctena havc been thoroughly investigated in Poland (Wisniewski 1979a, b, ctc).
and most Polish uropodid species are recorded
from these. Unfortunatel)', the nests of other species of the F. rufa group are practically unin- vestigated in the same area, and generally no in- formation has been given as concerns numbers of spccimens of diffcrcnt mitos. A dircct comparison of thc guests of this spccics bccomes difficult also l;ccausc the concept of F. polyctena may bc slightlv different in thcsc two countries.
Ncsts of Formica (ServiJitrmit'a) ilsr:a undcr stones and in thc soil rnostly sharc the myr- mecophilous species Uroobovella obot,ata and common zerconids with nests of Lasius niger in similar habitats. The nests of l. (Sen,iformica) in decaying tree stumps are preferred localities for the r are P rodiny c hus fl age ll ige r in E Finland. This is repeatedly confirmed from nests of F. /&sca, but apparently many .rf thc trce trunks wcrc inhabited l'ty F. gagatoides. P. J'lagelliger and Serviformica spp. prefer decaying tree trunks of birch. willow, aspen, and alder in virgin forests, and it is hard to dccidc whether the association is due to common preference of this special habitat of decaying wood or of true reciprocal dcpcndcncc.
The mite fauna of the ncsts of Finnish Myr- micinae is generally poor, with the exception of 'l'etramorium caespitttttt. Large nests of this
