The phylogeny of the ant tribe Formicini (Hymenoptera: Formicidae) with the description of a new genus

Abstract. The holarctic ant tribe Formicini is revised, the new genus Bajcaridris described, and possible phylogenetic relationships are discussed. The subgenus Iberoformica is synonymized with Formica. A synopsis, diagnosis and keys to the genera are provided.


Introduction and History
Formicini ants are among the most dominant faunal elements within the holarctic region, and often display a decisive effect on the composition of the local fauna. Their dominance is due to their social and mainly predacious life style with often extensive colonies of nests which can include up to more than lOO0 nests and several hundred million ants within one locality (Holldobler Sr Wilson, 1990). This has not only resulted a wealth of publications on ecology and behaviour, but was the reason for the use of ants, especially of the Formica rufu group, in biological control. However, the systematics and taxonomy of this tribe remained utterly unresolved and has never been treated above the local fauna level.
The present study provides an historical review of the genus-level taxonomy of the Formicini, re-defines the tribe and the included genera, and provides a cladistic analysis of the tribe and a key to genera. A discussion of each genus includes synonymies, comments, distribution and biology. This study is the fourth step towards a generic revision and cladistic analysis of the formicine ants on a worldwide base (Agosti, 1990(Agosti, , 1991(Agosti, , 1992.
As conceived here, the tribe Formicini includes seven genera, all of which are limited to the northern temperate hemisphere, but only two of which have a holarctic distribution. Number of species included and ranges of the genera are given in the table below. The number of species represents described species only, and will certainly increase since species-level taxonomy remains utterly uninvestigated over the greater part of the ranges of these genera.
Y4 Dotiat Agostr Wilson (1990) adopted this system for their synopsis of the ant genera of the world. Furthermore, they included Bregmutomyrtna and indicated some doubt ilbout this system by listing this taxon as 'Formicini and Lasiini'. Agosti (1991), by describing new characters, proposed a new system. From Hiilldobler & Wilson's genera he included Cutaglyphis, Formica, Polyergus, Projormica, Ro,s.yomyrmex, Teruiornyrnrex in the Formicu gcnus group, Acunthomyops, Lusius and Myrmecocysriis in the Lusiu.s group, and Bregmatomyrma and Pseudolusiits in the Pseudolnsius genus group. Andrugnuthus had already been synonymized with Purutrechinu (Agosti L ! Bolton, 1990b). Thus, from Holldobler & Wilson's Lasiini and Formicini taxon, only the genera belonging to Agosti's Formica genus group are included in the tribe Formicini as it is diagnosed here. Terutomyrrnex is excluded because of its asepalous proventricule (Agosti, unpubl.). This makes a sister group relationship between Lasiini and Formicini highly unlikely (Agosti, 1991).
The following characters were used in thc study of formicini ants, but refer mainly to the tribal or higher level (see diagnosis of the tribe: Agosti, 1991, and in prcp.): the position of the antennal articulation (Forel, 1893); the structure of the clypeal and antennal groove (Emery, 1916), the propodeal spiracle, the male genitalia (Emery,19 16), and of the proventricule (Forel, 1912;Emery, 19 16, Eisner, 1957); the structure of the frontal canna, the position of the propodeal spiracle, the articulation of the petiole into the alitrunk, the relative position of the hind coxal cavity, the structure of the ventral surface of the petiole and the first gastral segment, and the pilosity of the hind tibia (Agosti & Bolton, 1990a).
Behavioural characters are not included in this study. However, a comprehensive synthesis of behaviour and ecology, including Formicini ants, which might be the starting point for comparative ethological studies, is given by Holldobler & Wilson (1990). The same publication also includes a synopsis of revisionary studies, regional faunas and distibution of all ant genera of the world, and thus does not need to be repeated here.
During this study it became evident that all the genera included are in need of a full-scale revision. Only Curugfyphis has recently been revised on a worldwide base (Agosti, 1990). The identity of almost all the subgenera and species can only be guessed from isolated descriptions, and monophyly has not been demonstrated for any of the subgenera. For the purpose of this study, all thc subgcnera were sunken into synonymy, and should await future cladistic analyses to establish their validity. Species groups have the further advantage of not being formally recopnized by the Code, and thus it is not as important whether the group is monophyletic or a mere operational taxon.

Measurements and indices
Morphological terminology in the text follows Holldobler & Wilson (1990). All measurements are given as a minimum, yaximum and, in parentheses, the median; the unit of measurement is mm: e.g. AL 1.23-1.45 (1.40).
Alitrunk length ( A L ) . The diagonal length of the alitrunk in profile from the point at which the pronotum meets the Phylogeny of the ant tribe Formicini 95

1s.
Diagnosis. Formicine ants with the following combination of characters (see discussion below): Mandible triangular and multidentate (except in Polyergus and large workers of some Cataglyphis spp. with falcate mandible) (Figs 2-9). Tentorial pit widely separated from the antennal socket ( Fig. 10). Antenna1 articulation of the lateral side of the corner formed from clypeus and frontal canna (Fig. 10). Frontal triangle at least indicated, mostly distinct and separated from the clypeus by a transverse suture (Fig. 10). Frontal carina always present and beginning as a distinct crest in front of the antennal articulation and passing medially of the toruli, divergent. Frontal carina never laterally extended and forming frontal lobes, nor bordering an antennal scrobe, but often forming distinct ridges (Fig. 10). Eye behind midlength of sides in full-face view. Foramen magnum closely set to the occipital margin of the head. Metanotum is a distinct part of the dorsal part of the alitrunk, on its sides two spiraculi which reach the dorsal outline viewed in lateral view . Metapleural gland slit-shaped, extended laterally ( Fig. IS). Emargination of petiolar articulation in the alitrunk does not surpass cranially a line spanned between the two anteriormost points of the two hind coxal cavities (Fig. 32). Propodeal spiracle slit-shaped or, if roundish, then the inner margin of the annular sclerite not parallel to the outer margin and the spiracle is minute (Fig. 18). Propodeal spiracle placed close to the metanotum, distinctly set apart from the declivitous face of the propodeum (Fig. 18). Shape of the alitrunk (Figs 18-24). Hind tibiae with a double row of bristles on the ventral side (except in some species of the Formica exsectugroup, but then the underlaying pubescence sparse (Fig. 33). Claw with one or two long bristles spanning from its base to its apex (Fig. 34). Formation of first gastral segment with the helcium enclosed by the tergite, and the ventral part separated from the sternite by a canna (Fig. 32). Karyotype either 2n = 52 or 2n = 54. Proventriculus long sepalous, not reflected distally. Lateral sides of the triangle constituted by the three ocelli each with a long distinct bristle, except in species with a reduced pilosity such as some species of the Formica exsecta-group. The metanotum is a part of the dorsal outline of the alitrunk with the spiracles not meeting dorsally but reaching to the dorsal outline in lateral view. Propodeum rounded, declivitous face never meeting the basal face in an angle. Propodeal spiracle oval to slitshaped, if oval then the annular sclerite never with parallel inner and outer margins; set close to the metanotum. Metanotal gland slit-shaped and extended iaterally; in Polyergus reduced but indicated by some pilosity on a bulge. Hind tibiae with a double row of bristles on the ventral surface, except in some species of the Formica exsecta-group, but then no thick appressed pubescence present. The emargination of the petiolar articulation never crossing a line spanning between the anteriormost points of the hind coxal cavities. Hind coxae closely set, meeting medially. in Bajcaridris slightly distant but never forming a U-shaped cavity as in Lasius (see Agosti,1YY2). Petiole ventrally keeled, never rounded in cross-section; nodiform or squamiform, the scale or node never inclined cranially but always upright. The construction of the first gastral segment with the helcium in the tergite separated from the sternite by a basal transversal suture, the first tergite and sternite fused only on the anteriormost part; first gastral tergite high, except in Polyergus and Rossomyrmex. Pubescence variable, pilosity variable in both density and shape. Individual hairs generally simple, thin and pointed to slightly keeled, in Formicu exsectoides-group, Polyergus and Rossomyrmex truncated thick bristles at least on the dorsum of the pronotum, and in some species of the Formica microgyna-group and all species of Bajcaridris at least the hairs on the petiole and o n the propodeum clavate.
Sculpture shining and smooth to dull and coarse, never either strongly rugose nor reticulate.
Wings usually present, often in the same species ergatogynes side by side with normal winged queens. Discoidal cell usually present, variable within some species of the C. bicolor-group.
MALES. As above but with the following modifications.
Mandible elongate triangular, falcate in Polyergus; masticatory margin of mandible with one apical tooth, rarely with a row of denticles as in Formica snnguinea and occasionally in some other species of the Formica fuscngroup. Frontal canna reduced to a bulge. Eye enlarged, as long as one fourth of the lateral side of the head, as in Catagfyphis, to almost two thirds as in Bajcaridris and Proformica occulatissima. Ocelli present, small and in the same plane as the surface of the head in Cataglyphis, large and forming a distinct socket in Bajcaridris and Proformica. Petiole low and a transversal node, in Catagfyphis somewhat squarniform. Genitalia large and either uniform and simple with an outer valve which is distinctly separated into stipes and squamula, a clasper-like median valve or volsella with a cuspis and digitus and an inner valve or sagitta with a distinctly serrated ventral surface. Bajcaridris, Cataglyphis and Proformica with additional appendices. Subgenital plate present but variable.
Males of the same size as females, distinctly larger than the workers, except in Bajcaridrk, some Catagfyphis of the bicolor and the bombycinus-groups with a large worker caste and some Formica of the exsecta-group.
Pilosity variable; a distinct dense long black pilosity in Proformica and otherwise generally a sparse pilosity with single, long acute hain.
Usually uniform black or shining blackish brown in Bajcaridris, Formica and Polyergus. Cataglyphis variable, either the ahtrunk yellow, yellow with three black longitudinal stripes or black and the gaster varying within the species-groups from brownish black to a yellowish red. The latter is also the case within Proformicu.
The diagnosis above is an attempt to separate all the seven genera of the Formicini from the rest of the Form.cinae. Thus any formicine species not showing all the characters in combination and failing to conform to the definition is excluded from the tribe.
The phylogenetic significance of the characters can only partially be assessed. because of the lack of adequate cladistic analyses of the whole subfamily.
Nevertheless, Melophorus from the supposed paraphy letic tribe Melophorini from the Formica genus group (Agosti, 1991) might be the candidate sister group of the Formicini. They share as unique characters the arrangements of the bristles on the hind tibia, and the slit-shaped prododeal spiracle, but both might be syrnplesiomorphies for the Formicinae. The low number of teeth on the mandible might be a synapomorphy, assuming the high number of mandibular teeth as it is represented in Nothomyrmeciu or in most of the dolichoderines, to be the plesiomorphic state for the Formicinae. The long, apically not reflexed. sepalous proventricule would in this case be an autapomorphy for the Formicini. The high chromosomal count (2n = 52 or 54) and male genitalia characters can not be assessed, as no data from Me[ophoru.s is available. However, the following ground plan is assumed for the male genitalia. Subgenital plate with a cranio-median appendage; apically simple, spade-shaped; stipes without a median appendage; sagitta without a big gap between the ergot and the beginning of the serrated face.
Within the tribe, the phylogenetic relationships have been completely resolved ( Fig. 1, Table 1 and Appendix). However, the paraphyletic genus Formicn and the sister group relationship between Polyergus and Rossomyrrnex need some explanation.
The paraphyly of Formica could have several reasons. This genus is easily recognized, and no-one has ever doubted its monophyly. However, it was always difficult to key this genus, because of the lack of autapomorphic characters. It thus seems that the paraphyly is an artefact, and further research will very likely reveal the missing characters. One particular characteristic of this genus is its highly diversified social behaviour which is not known from any of the other formicini genera. Characters involved in chemical communication, such as chemical compounds, might therefore be candidates. Further new characters might contribute to a resolution. Finally, the outcome of a molecular biological study of the subfamily (Agosti, in prep.) might yield some of the missing data. Therefore, although unsatisfactory at the moment, Formica is not fused with its sister group to resolve this unsatisfactory situation.
The sister group relationship of Polyergus and Rossomyrmen is supported by three synapomorphies, but doubts remain, despite the obvious confirmation of recent cladistic analyses of social parasites and their host relations within social Hymenoptera (e.g. Carpenter er al., 1993; Agosti. 1994). The lack of the male caste in Rossomyrmes is certainly an obstacle in accepting this sister group. How- Table 1. List of the apomorphies for the respective gcncra and nodcs ( Fig. 1). F, female: M, male: W. workcr: the numbers refer to the rcspective characters in the data matrix and in the list of charactcrs (Appendix). This list was compilcd using NONA (Goloboff. 1993  ever, based on the data available, the position of the two genera as sister group of Formica is the most parsimonious placement.
The autapornorphies of the genera are given in Table 1.
A catalogue of the Formicini species is only available for the nearctic region (Smith, 1979).
The Formicini are among the dominant ants in the holarctic region, with the few exceptions in marginal  (Farris,1XW) and NONA (Goloboff,1W3). Thiscladogram is stable to sueccssivc weighting. The consistcncy index is 0.97 and thc rctcntion indcx is 0.97. Node numbers correspond with thc variables in Tahlc 1.
habitats such as regions with permafrost or permanent ice. However, the genera seem to follow general patterns. On the one hand, the large genera seem to replace each other ecologically; on the other hand, the smaller genera are specialized, and are distributed alongside the species of the large genera. Formicu and Cutug!yphi.e have only a narrow zone of overlap, with Formica being abundant in the temperate vegetation zone with deciduous or coniferous forests, and Catagfyphis with their northern boundary either congruent with the evergreen, laurophyllous and sclerophyllous mediterranean vegetation zone or the steppe zone and open vegetation within the southernmost coniferous or deciduous forests. Formica find their southern boundary in the Northern Oases of the Old World desert zone.
The. smaller genera are either specialized as social patasites (Polyergus and Rossomyrmex), or seem to be confined to very restricted ecological niches (ANoformica. Bajacuridris and Proformica) and thus have a very local distribution, which does, however, not exclude a very large overall range of Proformica.
Behavioural and morphological variation is very uneven within the genera. Whereas Formica with well over 100 species has a tremendous variation in social behaviour, with almost all kinds of social parasitism to the very simple life style, with claustral nest foundation and small colonies to large homeostatic nest and colonies including several million specimens, the species show hardly any rnorphological variation. Catagfyphis is exactly the opposite, with an extreme variation especially in male genitalia but hardly any variation in social behaviour. The small genera show neither a great variation in morphological nor in behavioural characters.

Key to genera
Worker. femule 3 First maxillary palp segment flattened (Fig. 29); hairs at the base of the maxillary stipes longer than half the length of thc stipes (Fig. 29 6 Masticatory bordcr of mandible with a row of five teeth, with apically the largest and basally the smallcst tooth (Fig. 8); dimorphic worker cast (Figs 15, 17) ................... Proformica -Masticatory bordcr of mandible with five teeth or denticles, the three apical-most decreasing in size, the fourth distinctly largcr than the third and the fifth (Fig. 3) 1 Subgenital plate with a cranio-median appendage (Fig.38). Genitalia simple, without appendages of the stipes of the sagitta (Fig. 50) or a prolognation of the part between the ergot and the serrated ventral part of the sagitta (Fig. 52 (Fig. 56), a posterior projecting squamula (Fig. 45). and a prolongation of thc part between thc crgot and the scrratcd vcntral part of thc sagitta (Figs 43, 46.

Proformica
-Hcad, alitrunk and petiole without thick pilosity (Fig. 31); smooth and shining surface of head and alitrunk; subgenital plate with a median, distally truncated processus (Fig. 37); no lobe between stipes and volsella; volsella 90" rotated, pointing caudally (Fig. 48); ventral part of the sagitta acute (Fig. 49) Commenf. Afloformica includes three species, aberrans Mayr, flavicornis Kuznetsov-Ugamsky and nitidior Forel, all only known by their worker caste. In the ZMMSU are a few males collected by Dlussky but yet undescribed. My notes made on a visit concern only the genitalia and not the overall morphology, such as head shape or pilosity. Nevertheless, the few notes support Dlussky & Fedoseva (1988) to separate Alloformica as a good genus from Proformica.
WORKER. Formicini ant with the following combination of characters: 1 Monomorphic worker caste. 2 Mandible with a row of declining teeth (Fig. 2). 3 Scape with distinct long erect hairs (Fig. 10 Comparisons. This genus is unique in its domed eye in combination with long erect pilosity on the scape, the rough sculpture and the erect petiole. The domed eye and the rough sculpture are autapomorphies. Distribution and biology. The three species are only known from their type localities and a few additional localities. However, aberrans and flavicornis are the dominant ants in the herbaceous steppe on the foothills of the Zeravshanskiy mountains in Tadzhikistan, being important pollinators by visiting the flowers for nectar (Dlussky, 1981).
Bajcarickis -n. (Figs 3,14,23,31,37,(47)(48)(49) Type-species: Proformica theryi Santschi, 1936: 209. Comment. Bajcaridris includes the three species kraussi Forel, menozzii Santschi and theryi Santschi; the position of ocdatissima Forel, described from a single male, is uncerah, as the gaster of the type is lacking. It seems reasonable that it might be a male of an east mediterranean Proformica (see discussion under Proformica). The males described by Espadaler & Cagniant (1987) are the only males out of a complete series with workers. The male of kraussii has been related by both Emery (1899) and Forel (1902) to this species, obviously because no others had been described by then. Nevertheless it is easily distinguishable by its genitalia, in which the outer valve is not fused as in theryi but separated in a squamula which overhangs the stipes and by the stipes beeing caudally blade-shaped. B.rnenozzii is only known from one single worker.
WORKER. Formicini ants with the following combination of characters: 1 Small (TL <1.4mm), shining ants. 2 Mandible with 5 teeth, declining in size from apical t o basal with the exception of the third tooth, which is (17) Proformica sp., major worker.
distinctly smaller than the subsequent and the precedent (Fig. 3). 3 First funiculus segment longer than the two subsequent together.
MALE. Formicini ants with the following modifications: 6 Small males, of the same size as workers (TL < 1.4 mm).
7 Head compressed with a turban-like ocellar socket shining.
12 Volsella rotated about 90" caudally; digitus horizontal, the tip of the cuspis in situ as long as the stipes, dorsoventrally oriented (Fig. 48). 13 Sagitta with a ventrally elongated apex, in situ as long as stipes; ventral side with few distinct teeth, the lateral plate of the two-folded sagitta protruding almost as far as the median plate with the teeth (Fig. 49).
14 Few scattered long, erect hairs all over the body. 15 Dense pilosity on the dorsal surface of the wings.
Comparisons. The workers differ by the combination of the following three characters from all the other ants of the tribe: dentition of the mandible with a small third tooth, clavate hairs and the first funicular segment which is longer than the two subsequent. The males are unique in the following combination of characters: the same size as the workers, a compressed head with distinct, large ocelli forming a socket, a unique subgenital plate with an unpaired median, caudal process, and a long pointed sagi tta.
Distribution and biology. With the exception of Bajcaridris theryi, which has recently been rediscovered (Espadaler & Cagniant, 1987), all the three species have rarely been collected since they were described (kraussi: Forel, 1895, 1902, Emery, 1899 menozzii: (Santschi, 1923; theryi: Santschi, 1936). Their habitats are either in the oueds of the northern Sahara in Algeria (kraussii and menozzii) or in the meadows of the mountains of the Atlas in Morocco, where they are among the dominant ant species, building nests in the earth either below stones or with a distinct crater-shaped nest entrance (Espadaler & Cagniant, 1987).
3 Often a distinct psammophore formed by the macrochaetae on the stipes of the maxillae, the inner apical margin of the mandible and some long curved hairs on the third to fifth segment of the maxillary palps. 4 First maxillary palp segment compressed (Fig. 29). 5 Eye located distinctly behind the midlength of the head 6 Propodeal spiracles long and slit-shaped (Fig. 21). 7 Wings (female caste) with a straight frontal side and very few, short pubescence (length of the hairs << space between the hairs), hairs short and cone-shaped. Hind margin of front wings without a fringe of erect hairs. (Fig. 11).

MALES. As females, but with the following additions:
8 Body of the same size as the females.
9 Ocelli and eye only slightly enlarged in comparison to those in the female caste (Fig. 30). 10 Dorsal part of the ninth and tenth abdominal tergite sclerotized. 11 Subgenital plate three-lobed (Fig. 3.9, if seemingly truncated (Fig. 36), than the subgenital plate longitudinally stretched and thus forming a transversal opening between the subgenital plate and the genital capsule. 12 Stipes with a median appendage (Figs 41, 44). 13 The zone between the ergot and the beginning of the 14 Front wing in comparison to the alitrunk short (WI 15 Wings without dense pilosity on the dorsal surface. saggita stretched (Fig. 43).

XO).
Dimorphic worker castes are only present in C.bombycinus, lucasi and kurdistanicus; although there is an extensive size variation of the workers in some of the species, allometric growth is not preeminent. No workers are known for C.hannae, a supposed inquiline of bicolor (Agosti, 1994). the emmae group have been found in Morocco, Algeria and Tunisia on the southern side of the Atlas mountains (Delye, 1965), in Baluchistan (Agosti, 1990), and recently in the desert-like southeastern part of Spain ('l'inaut, 1993); the pallidus-group is restricted to the deserts of central Asia. The altisquamis-group has a range from the Iberian Atlantic coast to central Asia and from north of the Sahara and the Asir mountaines to central Asia via the southern side of the Mediterranean sea. Finally, the cursor-group is distributed from Portugal to eastern Mongolia along the north side of the Mediterranean sea, with the southernmost extensions on the Antiliban and the Brahui-Range in Pakistan. The species of the cursor-group are living in the most mesic habitats of all the Catuglyphis species, the species of the pallidus and the bombycinus group in the hottest areas (Agosti, 1990).
The biology of all the Catdgfyphis species is rather uniform and hardly known. The information points generally towards a mongynous, monoor oligocalic lifstyle, with independent nest founding and rather small colonies. The nests are always in the soil, often with only one entrance and a distinct crater made out of dug-out soil.
Comparisons. The workers and females of this genus differ from all the other formicini ants by the combination of a flat first maxillary palpal segment, the long and slitshaped propodeal spiracle, and the short wings with a very reduced pubescence; the males differ by the presence of a median appendix of the stipes, the 3-lobed subgenital plate (if it seems to be truncated then it is long and forming a distinct transversal opening between the subgenital plate and the genital capsule).
Distribution and biology. This genus is an inhabitant of the drier parts of the Palaearctic, such as the steppe, the savannah, the Mediterranean type ecosystem, and the deserts. Hardly any species are proper desert ants (such as bombycinus) but they live at the edge of the deserts in the wadis and the oases. Their habitats are from sea-level up to 2200m. The species of the bicolor-group have a range of distribution from the beaches of Ghana to Vienna and Central Asia, from Morocco to the plains of the Ghanges (Wehner et al., 1983), but not in Spain, and with a centre of diversity in the southeastern Mediterranean; the range of the bombycinus-group seems to be restricted to sandy deserts of North Africa and Middle East; the species of Thelytoky has been demonstrated in piliscupus (Cagniant, 1979). Channae, the only inquiline and social parasitic ant within Cataglyphis, was found in a nest of bicolor, which does not to appear to be its sister species (Agosti, 1994).
A summary of the biology of many of the Catagfyphis species is to be foulid in DIussky (1981).
Formica Linnaeus (Figs 6, 12, 18, 25, 26 Comment. The last full-scale revision of Formica (Wheeler, 1913b) included keys to all the species. A critical review of the systematics (only palaearctic species included), distribution and use in biological control of Formica has been compiled by Dlussky (1967). Gosswald's idiosyncratic view of the Formica rufa group includes an extensive list with many references from the very productive time in the 1970s and 1980s when a lot of attention was paid to the use of wood ants for biological control of pests and their conservation (Gosswald, 1989; see also the extensive bibliography in Cotti, 1963). Revisions of species groups were prepared by Yarrow (1954a, British fusca group;1955, British rufa group), Francoeur (1973, nearctic fusca group). Keys to the nearctic species are provided by Creighton (1950), andby Francoeur (1973) for the fusca group, and for the palaearctic region, or parts of it, by Dlussky (1967), Kutter (1977, Collingwood (1978a, b), Agosti & Collingwood (198%). Creighton (1950), Wilson & Brown (1954), Buren (1968) and more recently Tinaut (1990) discussed extensively the status of the subgenera within Formica. Their elevation of the palaearctic species of Proformica to generic level is here confirmed. The reconsideration of the status of species groups such as the sanguinea group must be subject of a revisionary study of the genus, including material from the whole holarctic region. As no sister groups of any of the subgenera are known, all the subgenera are suppressed and replaced by informal species groups (see above).
Generally, species groups can be defined by shared characters, such as the emarginate occiput or the toothless basal margin of mandible (exsecra group), the notch in the anterior margin of the clypeus (sanguinea group), or the life style such as the construction of large ant mounds (e.g. rufa or exsectoides group). But there are always some species whose placement remains doubtful. For example, should uralensis be included within the rufa group because of its lifestyle or within the fuscu group because of its WORKER. Formicini ant with the following combination of characters: 1 Mandible with a row of 7-10 teeth or denticles on the masticatory border. The apical tooth is the largest followed by 2 of decreasing size. The fourth is larger than the thrid, and the subsequent teeth. Basal face and masticatory border meet in a right-angle (Fig. 6). 2 Maxillary palps reaching behind the midlength of the buccal cavity and the foramen magnum (except in some species of the Formica exsecta-group). 3 Eye with more than 250 ommatidia, placed laterally, slightly behind the midlength of the head (Fig. 12).
FEMALE. As worker but with the following modifications: 4 All flight sclerites developed (except for some rare ergatogynes occurring some times in Formica sanguinea. 5 Distinct dimorphism between worker and female caste with distinctly larger females than the workers (except for some species in the exsecta-and the microgynagroup, where microgynes occur). 6 Wings with dense, short pilosity on the dorsal surface.
MALE. Formicini ant but with the following modifications: 7 Of the same size as the female. 8 Head approximately the same width as the alitrunk. 9 Mandible with a large apical tooth, sometimes followed 10 Frontal carinae reduced and not reaching far behind 11 Eye approximately one third of the head length. 12 OceUi slightly biased, forming a somewhat raised triangle on the frons (Fig. 26). 13 Subgenital plate with a median cranial and two lateral processes and a sclerite on each side, spade-shaped (Fig. 38). by a row of denticles (Fig. 26).
the posterior side of the toruli (Fig. 26).
14 Pygostyli developed. 15 Stipes and squamula fused, limits of the two segments medially indicated by a ridge; squamula never overhanging the blunt subparallel sided stipes caudally (Fig. 50). 16 Sagitta with a short interspace between the ergot and the dorsal beginning of the sagittate part which is shorter than the ergot (Fig. 52). 17 Wings with dense pilosity on the dorsal surface.
Comparisons. The presence of more than six denticles with the two apical being the largest, followed by a very small third and a row of at least four medium sized, but variable teeth on the mandible is unique among the Formicini. The male is different from all the other Formicini in the

109
presence of the basal appendix of the subgenital plate and the mandibles which meet medially and are never falcate.
Disrribution and biology. Formica is a holarctic genus. It is rarely found in zones with less than 250mm rainfall per year, and most of the species are found in the temperate zones in biotopes with deciduous or coniferous trees. In North America the distribution is extended further into subdesertic and desei-tic region than in the palaearctic region. In the latter, Formica spp. are often found in oases in the temperate zone, but not in subtropical deserts. The exsecta, exsectoides and rufa groups, with species building extensive and tall mounds in which they can maintain a homeostasis, are restricted even further North; the most southern parts are regions with winter rainfall, and only the timberline is than populated by Formica species.
Unlike all the other genera within the tribe, the species of Formica are quite variable in their behaviour. Behaviour patterns vary from simple life-style with claustral nest founding, small monogynous colonies, to very extensive polycalic, polygynous colonies with over 300 million workers in 45,000 interconnected nests (Higashi & Yamuchi, 1979), to slavemaking (e.g. species of the sunguinea group), social parasitic life-styles with or without workers, to an inquilinistic way of life (see Holldobler & Wilson, 1990). Another remarkable feature is the ability to maintain for days a mean temperature within the nest during phases with higher or lower outside temperatures. A compilation of the biology is included and compared with that of other ant species in Holldobler & Wilson (199 I).
The wood ants are of economic and conservational importance, especially species of the palaearctic ntfa group. Their economic impact is two-fold. On the one hand these species are important predators of forest insects; on the other hand they maintain extensive aphid colonies to yield honeydew. The presence of the latter is an important carbohydrate source for honey bees, and the presence of the wood ants can raise the yield of honey produced by bees by over 20%. An extensive bibiliography on wood ants was prepared by Cotti (1963).
The palaearctic wood ants are on IUCN's red data lists, as well as protected by many of the European governments (Day, 1991).

Comments.
Although probably the most prominent among the Amazon ants (dulotic ants; see Holldobler & Wilson, 1990), the taxonomy of the species is not well understood. The main problem might be the resolution of species specific character and those induced through different hosts. An old but still useful overview of the North American species is given by Creighton (1950) and Wheeler (1968); the male genitalia are described by Clausen (1938), Forbes & Brassel (1962) and Wheeler (1968.

WORKER. Formicini ant with the following combination of characters:
1 Head subquadrangular. eye in the posterior part of the midlength of the head (Fig. 13). 2 Mandible falcate, the masticatory border regularly and densely incised (Fig. 7). 3 PF 4,2, or 4,3, but the maxillary palps not reaching behind the midlength between the buccal cavity and the foramen magnum. 4 Clypeus compressed (Fig. 13). 5 Frontal carina reduced, but still beginning in front of the antennal articulation and at least as long as the posterior part of the torulus (Fig. 13). 6 Metapleural gland indistinct with a slit-shaped surface encircled by erect hairs on a bulla-shaped basal part of the propodeum (Fig. 19). 7 First gastral tergite very low (Fig. 19).
FEMALE. As worker but with the following modifications: 8 Either all flight sclerites developed or ergatogyne. 9 Wings without pilosity on the dorsal surface.
MALE. Formicini ant with the following combination of characters: 10 Mandible short (but meeting medially), falcate to 11 Antenna1 scape short, not extended beyond the occiput. 12 Pygidial gland present. 13 Subgenital plate with a short apico-cranial appendage 14 Sagitta without an extended space between the ergot 15 Wings without pilosity on the dorsal surface. pointed (Fig. 27).
Comparisons. This is an easily recognizable genus within Fomicini with all three castes having a falcate mandible. The falcate mandible has no preapical cleft as in the case of some Cataglyphis species. In addition, the males have a short antennal scape and they are always much smaller than the females.
Distribution and biology. This is a holarctic genus with three species in the palaearctic region and two species in the nearctic. The preferred habitats are open sunny places in meadows and in steppe within the forest and steppe vegetation zones where its hosts co-occur.
Polyergus is a very uniform genus, concerning both morphology and behaviour. All the species are obligatory dulotic ants, and the slave ants are always Formica spp., especially from the fusca group. Slave raids are usually carried out during day-time and in groups without prior recruitment by scouts. The nests include up to several hundred workers, and usually one queen. The queens are sometimes ergatogynes. Mating flight is generally in June and July. The freshly mated female needs to start the new colony by getting adopted by a colony of a Formica species, and by subsequent killing of the host queen.
A description of the raids is given by Forel (1874), and a synthesis and list of species and hosts is provided by Holldobler & Wilson (1990). Proformica Ruzsky (Figs 8,15. 17. 22,28,39,[56][57][58] Proformica Ruzsky, 1902:  Comrnetrts. This gcnus is hardly known and no complete series including all castes have been described (Dlussky, 1969). Approximatly fifteen species are included in Pruformica, which is in need of a revisionary study at species level. The species of the former Soviet Union have been described and revised by Dlussky (1969). Collingwood (197th) provided a key to fauna of the Iberian peninsula, and Agosti & Collingwood (1987a, b) a synonymic list and a key to the Balkan species.
The following diagnosis and descriptions are mainly based on loans of undescribed specimens or on recently collected material by C. A. Collingwood and D. Agosti. WORKER. Formicini ant with the following combination of characters: 1 Dimorphic worker caste, with larger workers with a subquandrangular head and minor workers with an elongate head (Figs 15, 17). 2 Second and third funicular segments shorter than the first. 3 Mandible with a row of teeth declining from apex to the base (Fig. 8).
FEMALE. As worker but with the following modifications: 3 Larger or of the same size as the large workers.
4 Ergatogyne, sometimes with an enlarged alitrunk and some additional sclerites, never seen with a full set of flight sclerites. 5 Wings with dense pilosity on the dorsal surface.
MALE. Formicini ant with the following cornbination of characters: 6 Of the same size as the females. 7 Head narrower or of the same width as the alitrunk (Fig. 28). 8 Alate, a full set of flight sclerites developed. 9 Subgenital plate with a transversal hole distal to the 10 Stipes an acute, apically rounded triangle (Fig. 56). 11 Sagittae apically rounded, the dorsal beginning of the sagittate part distinctly set apart from t h e ergot (Fig. 58). 12 Head, alitrunk and petiole covered with a thick, erect pilosity (Fig. 28). 13 Wings with dense pilosity on the dorsal surface. median apical appendage (Fig. 39).
Comparisons. The females and workers are different from Formicu in the teeth formula which is regularly declining in Proformica and with less than six teeth. The dimorphic worker caste and the short funicular segments separates Proformica species from the species of the Cafuglyphis genus complex. The combination of the small head (in comparison to the alitrunk), the very long and dense pilosity, the shape of the subgenital plate and the median lobe of the stipes is unique within the Formicini.
Distribution atid biology. Proformicu has a patchy distribution within the palaearctic region, from Mongolia through Central Asia, Caucasus, Balkans to Spain, but not in the Alps or the Apennines. The species are living in open habitats, such as grasslands above the timberline, the steppic zones or on the Mediterranean seashore. So far, all nests which have been dug out indicate a strict monogyny and ergatogynous queens. Closer examination nevertheless revealed some flight sclerites are developed, which could also be due to an allometric growth of the alitrunk, as the same development can be observed in the large workers of Cutaglyphis bombycinus or in those of the bicolor group, living in the same nest as proper females.

Rossomyrmex Arnoldi
WORKER. Formicini ant with the following combination of characters: 1 Shining and smooth surface. 2 Mandible subtriangular with a row of indistinct den-3 Maxillary and labial palps filiform. 4 Scapus clavate (Fig. 16). 5 Frontal carina reduced but present as a ridge medial to 6 Head with an emarginate occiput (Fig. 16). 7 Hind tibia with a dense pubescence; the double row of bristles on the ventral side present but hardly developed. 8 Petiole brick-like, with very distinct bristles on the dorsal anterior crest, pointing backwards (Fig. 24). 9 First gastral tergite low (Fig. 24).
FEMALE. As worker but with the following modifications: 10 All flight sclerites present. 11 Wings with dense pilosity on dorsal surface. 12 Wings long, WI >150.

MALE: unknown.
Comparisons. The worker and female are diagnosed by the combination of the emarginate occiput, the slender. long maxillary palps, the shining surface of alitrunk and head, and the teeth formula of the mandible.
Distribution and biology. The distribution areas of the two species as well as the one of their hosts (Proformica species) are widely separated. R.proforrnicarum (with P.epiwruli.r as slave) is distributed in south-east Kazachstan (Arnoldi, i92K; Marikovsky, 1974). and rnirzuchue (P. lorigisera) in the Sierra Nevada, Spain (Tinaut, 1981). R.proforrnicnrum is living in the transitional zone from the steppe to the desert, and minur~fzue is living in subalpine and alpine meadows.
Both the species are slave makers with small colonies with 20-200 ants and are monogynous. The slave raids differ from those of Polyergus. The recruited workers are carried to the nest to be raided, and not only pupae but larvae and eggs are taken. The description of a raid by Marikovsky (1974) indicates the use of polarized light in orientation. A detailed description and discussion of the biology, nest size and structure, foraging, diurnal and annual activity are given by Arnoldi (1932), Marikovsky (1Y74) and Tinaut (1981), and a comparison with other species is provided by Holldobler & Wilson (1990).