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Species: Tetramorium forte   Forel, 1904 

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Taxonomic History (provided by Barry Bolton, 2015)

Tetramorium caespitum var. forte Forel, 1904c PDF: 371 (w.q.m.) FRANCE. Palearctic. AntCat AntWiki

Taxonomic history

Subspecies of Tetramorium caespitum: Forel, 1905: 173; of Tetramorium ferox: Santschi, 1936c PDF: 203.
Raised to species: Collingwood, 1978 PDF: 71; Casevitz-Weulersse, 1990b: 420.
[Name misspelled as Tetramorium jorte by Ruzsky, 1905b: 534.].


South European part of former USSR, Crimea Caucasus in Europe Romania, former Czechoslovakia, former Yugoslavia, Bulgaria


nesting in dry warm habitats

Taxonomic Treatment (provided by Plazi)

Güsten, R., 2006:
(Figs 2-6, 11, 16)
Material examined
New records: France - [[workers]], Dept. Gard , banks of Rhone river 7km n Avignon , 03.V.1992 , leg. A. Schulz ; [[workers]], [[queens]], Dept. Vaucluse , banks of Rhone river near Avignon, 100m , 05- 11.V.1992 , leg. A. Schulz ; [[workers]], Dept. Herault , Bois Noir n of Vailhauques, ca. 15km nw Montpellier , 21.III.1995 , leg. Windschnurer ; [[workers]], Dept. Bouches-du-Rhone , St. Martin-de-Crau, ca. 12km e Arles , 23.III.1995 , leg. Windschnurer ; [[workers]], Dept. Loire , above Malleval , VI.2002 and 02.V.2003 , leg. R. Guesten . Spain - [[workers]], Prov. Badajoz , Presa, near Embalse de Orellana , 22.I.1989 , leg. D. Wrase ; [[workers]], S side of Sierra Nevada, 2200m , 06- 18.V.1991 , leg. A. Schulz ; [[workers]], Prov. Cadiz , Sierra Ubrique, between Benaocaz and Grazalema , 28.VIII.1991 , leg. A. Buschinger & P. Douwes ; [[workers]], [[queens]], Prov. Granada , Sierra Nevada, rd GR 420, ca. 3rkm nw Sierra Nevada, ca. 1900m , 22.V1995 , leg. T. Assmuth & M. Sanetra ; [[workers]], [[queens]], Prov. Jaen , se Desfiladero de Despenaperros, Puerto de los Jardines, 870m , 26.V1995 , leg. T. Assmuth & M. Sanetra ; [[workers]], [[queens]], [[males]], Prov. Cuenca , ca. 2rkm e Villalba de la Sierra, ca. 20km n Cuenca, ca. 1200m , 26.V1995 , leg. T. Assmuth & M. Sanetra ; [[workers]], Prov. Cuenca , 2rkm n rd Beamud-Buenache, dir. Embalse de la Toba ne Cuenca, ca. 1400m , 27.V1995 , leg. T. Assmuth & M. Sanetra ; [[workers]], [[queens]], Prov. Teruel , Guadalaviar river, 5rkm ne Albarracin, ca. 1200m , 29.V. 1995 , leg. T. Assmuth & M. Sanetra ; [[workers]], Prov. Cordoba , Sierra de Hornachuelos, Cortijo de Spinola , 23.II.1999 , leg. D. Wrase ; [[workers]], Com. de Madrid , Boadilla del Monte, ca. 10km w Madrid , 25.II.1999 , leg. D. Wrase ; [[workers]], Prov. Toledo , Quero , 08.III.1999 , leg. D. Wrase . Portugal - [[workers]], Distr. Viseu , Caldas da Felgueira, 600m , 22.VI.2000 , leg. A. Schulz & K. Vock ; [[workers]], [[queens]], [[males]], Distr. Guarda , Serra da Estrela, n slope of Torre, 1500m , 23.VI.2000 , leg. A. Schulz & K. Vock ; [[workers]], [[queens]], Distr. Castelo Branco , nr. Monsanto, 400m , 25.VI.2000 , leg. A. Schulz & K. Vock ; [[workers]], Distr. Viseu , Serra de Montemuro, 1100-1300m , 26.VI.2000 , leg. A. Schulz & K. Vock ; [[workers]], Distr. Braganca , nr. Macedo de Cavaleiros, 600m , 27.VI.2000 , leg. A. Schulz & K. Vock ; [[workers]], [[queens]], [[males]], Distr. Braganca , Parque natural de Montesinho, 700-900m , 29.VI.2000 , leg. A. Schulz & K. Vock ; [[workers]], [[queens]], [[males]], Distr. Braganca , Parque natural de Montesinho, 700-800m , 30.VI.2000 , leg. A. Schulz & K. Vock ; [[workers]], Distr. Braganca , Parque natural de Montesinho, 1000-1300m , 01.VII.2000 , leg. A. Schulz & K. Vock . Morocco - [[workers]], [[queens]], Reg. Ifrane, Moyen Atlas , rd 3325, 6rkm n rd S 309, 6rkm se Ifrane, ca. 1800m , 25.IV1995 , leg. R. Guesten, M. Sanetra & R. Schumann ; [[workers]], Reg. Meknes, Moyen Atlas , rd S 303, ca. 24rkm s Ain Leuh, ca. 1300m , 12.V1995 , leg. T. Assmuth, R. Guesten, M. Sanetra, A. Schulz & R. Schumann ; [[workers]], Reg. Meknes, Moyen Atlas , rd 3211, 14 rkm n rd 3485, ca. 40rkm s Ain Leuh, ca. 1100m , 12.V1995 , leg. T. Assmuth, R. Guesten, M. Sanetra, A. Schulz & R. Schumann ; [[workers]], Reg. Kenitra , Foret de la Mamora, 2 rkm n Ain-Johra, 100m , 19- 20.V1995 , leg. T. Assmuth, M. Sanetra & A. Schulz ; [[workers]], Moyen Atlas, Reg. Meknes , Aguelmame Azigza, 1500m , 19.II.1999 , leg. D. Wrase .
Other examined specimens: 1 [[worker]], lectotype of T. caespitum forte Forel (hereby designated, Fig. 2): „ T. caespitum L. [[worker]] v. forte Forel , type, AlbaronCamargum / Lectotype Poldi 74 / LectotypusTetramorium caespitum forte Forel des. R. Guesten, A. Schulz & M. Sanetra 2005“ ( MHNG , together with 2 paralectotype [[workers]] on same pin, lectotype marked by red cardboard square) ; 34 paralectotype [[workers]], Albaron ( Camargue ) ( MHNG , 2 of these on same pin as lectotype) ; 2 paralectotype [[workers]], same data as previous ( MCSN ) ; 3 paralectotype [[workers]], same data as previous ( NHMB ) ; 2 paralectotype [[workers]], same data as previous ( DSTA ) ; 11 [[workers]], FRA , Camargue ( MHNG ) ; 3 [[workers]], same data as previous ( NHMB ) ; 1 [[worker]], same data as previous ( DSTA ) ; 5 [[workers]], FRA , Albaron , 23.I.1925 , leg. A. Chobaut ( DSTA ) ; 5 [[workers]], FRA , Banyuls , leg. Saulcy ( MCSN ) ; 1 [[queen]], FRA , Var , Cavalaire-sur-Mer , VI.1922 , leg. L. Berland ( NHMB ) ; 6 [[workers]], syntypes of T. caespitum ruginode Forel : „ Spanien , Cordova , Lehmann / Tetramorium caespitum L. v. ruginode Stz. [this label only with one of the syntypes ] / Type / Zool. Mus. Berlin” ( ZMHB ) ; 5 [[workers]], POR , Viana Castells ( DSTA ) ; 1 [[worker]], ESP , Barcelona , Certellas , VIII.1921 , leg. Xaxars ( DSTA ) ; 24 [[workers]], 1 [[queen]], ESP , Pozuelo de Calatrava , leg. La Fuente ( DSTA ) ; 5 [[workers]], same data as previous ( MCSN ) ; 1 [[worker]], same data as previous ( NHMB ) ; 1 [[worker]], ESP , Venta de Cardenas , 27.VII.1879 , leg. L. Bleuse ( MCSN ) ; 1 [[worker]], ESP , Chamartin , 15.IV1900 ( MCSN ) ; 4 [[workers]], ESP , Puig , 13.I.1923 ( MCSN ) ; 4 [[workers]], ESP , Montsiak , 15.I.1923 ( MCSN ) ; 1 [[worker]], ESP , Cuenca , Belinchon , 08.VII.1925 , leg. J.M. Dusmet ( NHMB ) ; 3 [[workers]], 1 [[queen]], ESP , Villalba near Madrid , 28.III.1926 , leg. H. & H. Lindberg ( NHMB ) ; 2 [[workers]], ESP , Sta Morena Sta Helena , 04- 08.IV.1926 , leg. H. & H. Lindberg ( NHMB ) ; 1 [[worker]] [not [[queen] as stated by Emery 1909], lectotype of T. caespitum hispanicum Bondroit (hereby designated): „ EspagnePer[?] / LectotypusTetramorium caespitum hispanicum Bondroit des. R. Guesten, A. Schulz & M. Sanetra 2005” ( MCSN ) ; 1 paralectotype [[worker]] (of T. c. hispanicum ), same data as previous ( MCSN ) ; 2 paralectotype [[workers]] (of T. c. hispanicum ), leg. Cabrera ( MCSN , together with 1 paralectotype [[worker]] of T. c. hispanicum on same pin which is not T. forte ) ; 1 paralectotype [[worker]] (of T. c. hispanicum ), ESP ( MHNG ) ; 2 paralectotype [[workers]] (of T. c. hispanicum ), ESP , Carmona ( DSTA ) ; 1 [[queen]], lectotype of T. maurum tingitanum Santschi (hereby designated): „ Maroc , Rabat , Thery / T. caespitum st maura v. tingitana , Santschi det. 1920 / Naturhist. Museum Basel / Sammlung Dr. F. Santschi, Kairouan / LectotypusTetramorium maurum tingitanum Santschi des. R. Guesten, A. Schulz & M. Sanetra 2005“ ( NHMB , together with paralectotype [[queen]] on same pin, lectotype marked by red cardboard square) ; 1 paralectotype [[queen]] (of T. m. tingitanum ), MAR , Rabat , leg. A. Thery ( NHMB , on same pin as lectotype) ; 1 [[worker]], lectotype of T. maroccanum De Haro & Collingwood (hereby designated): „ Ain Leuh 103 / 17 / 41[?] / Tetramorium caespitum v. marocane Sants ., Santschi det. 19 / Sammlung Dr. F. Santschi, Kairouan / Naturhist. Museum Basel / Lectotypus Tetramorium maroccanum De Haro & Collingwood des. R. Guesten, A. Schulz & M. Sanetra 2005” ( NHMB ) ; 1 paralectotype [[worker]] (of T. maroccanum ), MAR , Ain Leuh ( NHMB ) ; 1 [[worker]], MAR , Ain Leuh , leg. A. Thery ( NHMB ) ; 2 [[workers]], MAR , Rabat , leg. A. Thery ( NHMB ) ; 1 [[worker]], MAR , Tanger , 1901 , leg. G. Buchet ( NHMB ) ; 2 [[workers]], MAR , Larache , III.1907 ( NHMB ) ; 1 [[worker]], MAR , Ben-Slimane (formerly Boulhaut) , leg. A. Thery ( NHMB ) ; 2 [[workers]], MAR , Khenifra near Azrou , leg. A. Thery ( NHMB ) ; 11 [[workers]], MAR , Foret de Zaer ( DSTA ) .
Description of worker
Measurements and indices (n=34): HL 0.824±0.057(0.725-0.936)mm,
HW 0.783±0.059(0.680-0.906)mm, HS 0.804±0.056(0.702-0.921)mm,
SL 0.631±0.038(0.563-0.728)mm, ML 0.986±0.111(0.831-1.194)mm,
MW 0.529±0.046(0.456-0.637)mm, PSL 0.104±0.016(0.076-0.143)mm,
PEL 0.328±0.033(0.247-0.385)mm, PEW 0.290±0.030(0.219-0.342)mm,
PEH 0.271±0.026(0.238-0.323)mm, PPL 0.208±0.017(0.171-0.238)mm,
PPW 0.335±0.037(0.257-0.404)mm, HW/HL 0.951±0.022(0.912-1.020),
SL/HS 0.786±0.026(0.727-0.840), MW/ML 0.560±0.032(0.509-0.675),
PSL/ML 0.110±0.012(0.085-0.130), PEH/PEL 0.826±0.048(0.750-1.019),
PEW/PEL 0.868±0.078(0.742-1.192), PEW/HS 0.360±0.019(0.311-0.402),
PPL/PPW 0.622±0.044(0.553-0.688), PPW/HS 0.419±0.021(0.365-0.466),
PEW/PPW 0.860±0.044(0.813-1.033), WI-A 0.322±0.019(0.269-0.359),
WI-B 0.390±0.018(0.338-0.430).
Measurements and indices of the lectotype (Fig. 2): HL 0.906mm, HW 0.891mm, HS 0.898mm, SL 0.675mm, ML 1.102mm, MW 0.618mm, PSL 0.143mm, PEL 0.385mm, PEW 0.328mm, PEH 0.323 mm, PPL 0.238 mm, PPW 0.394mm.
Larger Palaearctic Tetramorium worker with subquadrate head. Preoccipital margin nearly straight to concave, genae more or less straight, outlines convergent (Fig. 11). Head widest behind the eyes. Mesosoma robust, broad, with pronounced pronotal angles (Fig. 2). Mesopropodeal suture shallowly depressed. Propodeal spines moderately long and straight. Petiole robust, node in lateral view rather rounded, outline anterior of node concave. Petiole and postpetiole broad in relation to mesosoma, postpetiole with laterally prominently protruding angles (Figs 2, 16). Dark brown to blackish, appendages lighter, orange-brown. Head, dorsal parts of mesosoma, petiole and postpetiole entirely carinate or rugose. Frontal area of head with 14-16 even rugae which diverge slightly towards the preoccipital margin, converging into a conspicuously arcuate pattern in lateral view (see Schulz 1996, p. 407). Genae and surface of occipital corners rugose (Fig. 11). Dorsal surface of head with reticulate microsculpture, but with few more conspicuous anastomoses between principal rugae. Ventral head surface longitudinally striate without any microsculpture. Scapes usually smooth and shinning, sometimes with diffuse microsculpture, and with an inconspicuous anterio-dorsal carina at the base which may grade into the trace of a transverse extension but not into a conspicuous dorsally projecting flange. Dorsal surface of mesosoma rugose with variably developed reticulate microsculpture, on the propodeum evenly and roughly reticulate, especially between the spines. Dorsal part of petiole and postpetiole longitudinally to concentrically, often rather irregularly rugose with reticulate microsculpture, no weakening of sculpture on dorsalmost surfaces (Fig. 16). Ventral parts of petiolar nodes heavily reticulate. Polygonal microsculpture on the first gaster tergite never absent, rarely covers the whole surface of the tergite (in some Moroccan specimens). On the anteriormost part of the tergite, this microsculpture can appear striated in some specimens. Frequency of the latter feature within the same nest series increases towards the south of the species´range.
Description of gyne
Measurements and indices (n=23): HL 1.064±0.073(0.842-1.293)mm,
HW 1.127± 0.096(0.891-1.391)mm, HS 1.096±0.080(0.866-1.330)mm,
SL 0.791±0.044(0.634-0.861)mm, ML 1.762±0.101(1.391-1.879)mm,
MW 1.082±0.074(0.830-1.196)mm, PSL 0.147±0.022(0.105-0.181)mm,
PEL 0.467±0.029(0.380-0.504)mm, PEW 0.559±0.047(0.418-0.618)mm,
PEH 0.460±0.034(0.371-0.518)mm, PPW 0.711±0.054(0.556-0.817)mm,
HW/HL 1.060±0.060(1.000-1.326), SL/HS 0.723±0.034(0.602-0.763),
HS/ML 0.622±0.028(0.581-0.727), MW/ML 0.614±0.019(0.568-0.653),
PSL/ML 0.083±0.011(0.062-0.102), PEH/PEL 0.984±0.059(0.902-1.111),
PEW/PEL 1.194±0.097(1.000-1.383), PEW/HS 0.511±0.037(0.421-0.569),
PPW/HS 0.650±0.045(0.525-0.712), PEW/PPW 0.787±0.042(0.630-0.855),
WI-A 0.360±0.017(0.324-0.392).
Medium-sized Palaearctic Tetramorium gyne, generally with rather robust appearance. Head with rather rounded preoccipital corners and straight to slightly convex, somewhat convergent genal outlines (Fig. 3). Scape relatively short and broad. Mesosoma short and robust, with flat (not bulging) dorsal outline. In dorsal view the pronotal angles are fully visible (Fig. 5). Propodeal spines broadly attached, triangular with pointed tips, orientation subcaudate. Petiole and postpetiole very wide, lobe-like, the petiole medially emarginated. First gaster tergite with at least a few erect hairs. Colour as in workers. Frons rugose, the rugae divergent and curving towards the occipital corners with little or no anastomosing (Fig. 3). Genae rugose, ventral head surface longitudinally striate. On the genae and near the occipital corners, a fine reticulate microsculpture occurs between the main rugae. Sides of mesosoma and petiolar segments mainly longitudinally carinate, restricted parts only rugose. In dorsal view, pronotum with rugose sculpture, mesonotum longitudinally rugose but more weakly so laterally, with a very small smooth and shining spot anterio-medially, scutellum rugose except for narrow smooth median part (Fig. 5). Sculpturing between the spines variable, principally longitudinally rugose. Sculpture of dorsal surface of waist segments also variable, diffusely rugose to rugulose, to concentrically striate. Individuals with more pronounced sculpturing have the rugose portion more strongly developed. Polygonal microsculpture covers small spots on the first gaster tergite, appearing longitudinally striate on the anterior part (0.150-0.250mm) of the tergite.
Descriptions of T. forte gynes have been published by Bondroit (1920, as T. hispanicum ), Santschi (1921b, as “ T. caespitum st. maura var. tingitana ”), Santschi (1932, as “ T. caespitum st. hispanicum var. ruginodis ”) and Cagniant (1997, as T. ruginode marocana ), the latter providing a drawing of the petiolar segments. The gynes from Spain studied by Santschi (1932) are present in NHMB.
Description of male
Measurements and indices (n=22): HL 0.738±0.019(0.702-0.770)mm,
HW 0.752±0.043(0.687-0.891)mm, HS 0.745±0.025(0.695-0.800)mm,
SL 0.344±0.011(0.323-0.361)mm, 2FL 0.406±0.018(0.361-0.428)mm,
ED 0.278±0.012(0.257-0.304)mm, ML 2.028±0.064(1.891-2.135)mm,
MW 1.210±0.064(1.098-1.318)mm, PEW 0.482±0.048(0.390-0.589)mm,
PPW 0.637±0.046(0.570-0.722)mm, HW/HL 1.020±0.059(0.959-1.255),
SL/HS 0.462±0.022(0.421-0.501), SL/2FL 0.847±0.041(0.778-0.925),
MW/ML 0.597±0.037(0.538-0.663), PEW/HS 0.647±0.057(0.529-0.772),
PPW/HS 0.854±0.051(0.778-0.934), PEW/PPW 0.758±0.056(0.661-0.848),
WI-A 0.276±0.017(0.236-0.311).
Small Palaearctic Tetramorium male, with broad head and relatively large eyes (Fig. 4). Mesonotum and scutellum bulging. Propodeal spines well visible, but short and more or less triangular, tooth-like. Petiole and postpetiole very broad (Fig. 6), petiole on each side with two laterally oriented processes and a distinctly emarginate median part. Isolated erect hairs on first gaster tergite. Colour dark brown, appendages yellowish orange. Sculpture on head, mesosoma and waist dense. Head largely rugoreticulate (Fig. 4), pronotum and lateral parts of mesosoma chiefly longitudinally striate with reticulate microsculpture, mesonotum longitudinally to concentrically striate but with extensive parts laterally and anterio-medially smooth and shining (Fig. 6). Scutellum completely striate, propodeum diffusely striate to reticulate, waist segments reticulate, gaster without sculpture.
The male of T. forte had hitherto only been described by Cagniant (1997, under the name T. ruginode marocana ), based on one specimen. This work included detailed drawings of genitalic characters.
Phylogenetic relationships and similar species
Tetramorium forte belongs to the caespitum-group of species in the sense of Bolton (1977), which is (except for some peripheral species) the only Palaearctic one out of 40 largely provisional species-groups defined by Bolton (1976, 1977, 1979, 1980) in the genus Tetramorium . Few studies have addressed phylogenetic relationships in this group and in particular the position of T. forte . Palomeque et al. (1989) studied the karyotype of T. forte , which proved to be of little interest for phylogeny as all Palaearctic Tetramorium species hitherto studied have a haploid chromosome number of n=14 with few differences in chromosome morphology (Lorite et al. 2000; Sanetra, unpubl.). Based on allozyme electrophoresis, Sanetra and Buschinger (2000) found T. chefketi (see Appendix A) to be very closely related to T. forte , a finding corroborated by mtDNA studies (Schlick-Steiner et al. 2005). The position of T. moravicum was ambiguous, as it constituted a clade with T. forte and T. chefketi in some but not all data analyses (Sanetra & Buschinger 2000; Schlick-Steiner et al., 2006).
Tetramorium forte is a member of a morphologically defined assembly of species in which the workers are dark and strongly sculptured, with no unsculptured surface areas on the waist segments. While not all these species are necessarily closely related, the allopatric T. chefketi , found to be related to T. forte in phylogenetic studies, is also the most similar species. Tetramorium moravicum is also closely similar and sympatric with T. forte in southeastern France (see below). One other species sharing the lack of smooth and shining areas on the petiolar nodes, T. alternans Santschi , 1929 (see Appendix A), is sympatric with T. forte in North Africa. The other Tetramorium taxa sympatric with T. forte in Europe, which are T. caespitum s.l. (see Appendix A), T. semilaeve and T. meridionale , belong to other species complexes and show more divergent morphological characters. Tetramorium maurum (see Appendix A), which may be sympatric with T. forte in the Maghreb, is anomalous as the gynes are very similar, even though based on the workers the species should rather be assigned to a widely conceived T. semilaeve complex.
Differentiation of workers
In workers, T. forte is most readily distinguishable from other dark, strongly sculptured Palaearctic Tetramorium species by its wide petiolar nodes. While this is not as obvious as in gynes, the postpetiole shows a conspicuously angular lateral outline in dorsal view (compare Fig. 16 with Figs 17-19), and the values for WI-A and WI-B are larger while that for PPL/PPW is smaller than in the most similar species, with some overlap (Table 1).
Except for this character, workers of T. chefketi are very similar to T. forte , though the mesosoma is narrower (Table 1) and the sculpture overall more strongly rugose, particularly near the occipital corners where there is also some anastomosing of the rugae (Fig. 12). Tetramorium moravicum workers are also similar -they may be identified by a more prominent anterio-dorsal carina at the base of the scape than in T. forte and T. chefketi , which extends into a conspicuous dorsally projecting flange (Fig. 13). Also, in contrast to T. forte , the scape is reticulate or faintly longitudinally rugose in T. moravicum , and the occipital corners are quite prominent with the main rugae on the head running parallel throughout their length and not converging into an arcuate pattern in lateral view as in T. forte (see Schulz 1996, p. 407). Tetramorium alternans is a smaller species than T. forte (Table 1) with a lighter, reddish-brown colour. The scapes are shorter with a densely striate to granulate sculpture. While there are no smooth and shining spots on the waist segments, densely reticulate microsculpture predominates with only a sparse weak rugosity (Fig. 19). In this character, T. alternans recalls T. brevicorne Bondroit , 1918 from the Tyrrhenian Islands (see Sanetra et al. 1999) rather than T. forte , T. chefketi or T. moravicum .
Workers of T. caespitum s.l. strongly differ from those discussed before by conspicuous smooth and shining medial areas on the petiolar segments (which, however, may greatly vary in width), and the head surface has a much more weakly developed rugosity, appearing shining through the lack of microsculpture (Figs 15, 20). The waist segments are a lot narrower than in T. forte (Table 1). The workers of T. semilaeve , and many ill-defined species similar to it, are even more weakly sculptured, yellowish to light reddish-brown and much smaller than T. forte (nest means of ML always <0.800mm, HS <0.730mm). Workers of T. meridionale have petiole and postpetiole at least as broad as T. forte , but in other characters generally resemble T. semilaeve .
Differentiation of gynes
In gynes, T. forte is easily distinguished from T. chefketi , T. moravicum and T. alternans by the very broad waist segments (compare Fig. 5 with Figs 7-8, see also Table 2).
Tetramorium chefketi gynes are otherwise very similar, particularly in dorsal surface sculpturing (Fig. 7), but the mesosoma is somewhat more slender (only slightly narrower numerically, Table 2) and the rugosity is more pronounced. The latter is most obvious on the head with a rugoreticulum developed near the hind margin, even extending anteriolaterally beyond the eyes (see Schulz 1996, p. 407), whereas few anastomoses between the longitudinal rugae are evident in T. forte (Fig. 3). Tetramorium moravicum gynes differ in the structure of the scape base in a similar way as workers do; in most populations they are much larger than T. forte but microgynes are the size of large T. forte gynes (Table 2). The only known gyne of T. alternans has the mesonotum more tapering anteriorly, and narrower (Table 2) than in T. forte and less than half of its surface (medio-posteriorly) is longitudinally rugose to striate.
The gynes of T. caespitum s.l. are much larger than those of T. forte (Table 2), which is associated with a relatively smaller head and a bulging mesonotum completely concealing the pronotal corners in dorsal view, and the mesosoma is smooth and shining over two thirds of its surface or throughout (Fig. 9). Tetramorium semilaeve gynes are also weakly sculptured (usually few shallow striae on the mesonotum), and are more lightly brownish than those of T. forte , while they are of similar size. Those of T. meridionale are even more yellowish, have a conspicuous transverse striation on the occipital margin and enlarged petiolar nodes though somewhat less than T. forte (Fig. 10).
Even though the workers of T. maurum are very dissimilar to those of T. forte and indicate the affiliation to a different species complex, the gynes surprisingly were found to be closely similar. No morphometric characters have been detected that reliably differentiate the gynes of the two species. However, T. maurum gynes are lighter in colour (reddish-brown), the dorsal border of the petiole is not emarginated medially, the rugae on the head are less pronounced, and a larger medial unsculptured surface (> 50%) occurs on the scutellum, sometimes small unsculptured areas are also present on the petiolar nodes.
Differentiation of males
In males, much as in gynes, T. forte is characterized by a wider petiole and postpetiole (WI-A: 0.236-0.311) than T. chefketi and T. moravicum (nest means of WI-A always <0.240, compare also Schulz 1996, p. 412).
In most populations, T. moravicum males are larger (ML> 2.200mm) but where microgynes occur, the size is about the same as for T. forte males. In T. forte the scutellum is clearly striate (Fig. 6), whereas T. moravicum has a more diffuse often striolo-reticulate sculpture with sometimes a shining median part. Tetramorium alternans males are unknown.
Males of T. caespitum s.l. are much larger (nest means of ML always> 2.500mm) than those of T. forte with narrower waist segments (nest means of WI-A always <0.240), the latter also applies to those of T. semilaeve . The male of T. meridionale has not been described.
Distribution and biology
Lopez (1991) compiled the first comprehensive list of collecting localities of T. forte on the Iberian Peninsula (also presented as a distribution map in Lopez Gomez 1988). From these data it is evident that T. forte occurs throughout Spain up to the extreme northwest, although the species might be absent from the north coast beyond the Cantabrian Mts. There is no obvious preference for areas with a stronger Mediterranean climatic influence. In the Sierra Nevada, the species occurs at least up to 2200m. Many additional Spanish records (e.g. Tinaut 1991; De Haro & Collingwood 1991, 1992; Espadaler & Suner 1995; Espadaler 1997b; Espadaler & Roig 2001; Reyes Lopez & Garcia 2001) confirm the ecologically generalistic occurrence of the species, which also holds true for the distribution pattern in Portugal (Paiva et al. 1990; De Haro & Collingwood 1992; Tinaut & Ruano 1994; Cammell et al. 1996; Way et al. 1997; Salgueiro 2002b, 2003; present study). Menozzi (1926) and Wheeler (1926) reported T. forte from Mallorca, but its presence on the Balearic Islands should be reconfirmed due to the commonly dubious application of the name.
Abundant samples compiled from Morocco (Cagniant 1997, collecting localities not specified) show T. forte to occur in diverse habitats from sea-level up to 2000m in the north of the country (especially in the Middle Atlas), much as in southern Spain (Fig. 21). In the south, however, it appears much more localized at higher elevations of the High Atlas. According to Csosz (in litt.), a few samples from Algeria have been traced in collections. Three workers from Ponta Delgada (Sao Miguel, Azores, leg. W.M. Wheeler) in NHMB had previously been determined as T. forte , but proved to belong to T. caespitum s.l. upon investigation. The ant fauna of the Azores, largely or entirely introduced, is well known (Yarrow 1967; Heinze 1986; Salgueiro 2002a) and it seems certain that no other Tetramorium species of the caespitum-group occur. On the Canary Islands, T. forte has likewise not been recorded.
The range of T. forte extends into France along the Mediterranean coast, but except for one sample in the extreme southeast (Sommer & Cagniant 1988), no reliable records other than the original description had been published prior to this study. As Bernard´s (1967) understanding of T. forte was evidently insufficient, his locality citings from the Iles d´Hyeres and the Cote d´Azur need to be re-investigated. Consequently, a gyne from Cavalaire-sur-Mer (Var) in NHMB currently represents the easternmost confirmed record. The northernmost locality in the Dept. Loire indicates an inland extension along the Rhone river for more than 200km. Only recent investigations (Schulz 1996; Schlick-Steiner et al., in press; Guesten, unpubl.) have shown that the distribution of T. forte in southern France is entwined with that of T. moravicum , which is very similar in the worker morph. Current data suggest that T. moravicum occurs at xerothermic localities with less overt Mediterranean influence compared with those of T. forte (Fig. 22). Tetramorium moravicum is usually found above 600m where its range approaches the coast, although it may inhabit lower elevations in the Dept. Alpes-Maritimes where the ocurrence of T. forte is not confirmed. The overall distribution pattern of T. forte (Fig. 21) renders likely the postglacial recolonization into its present range from an atlanto-mediterranean refuge. Resulting contact with the ecologically similar T. moravicum progressing from a pontomediterranean refuge (Schlick-Steiner et al., in press) might have impeded further spreading of both species, but this needs additional investigation.
As stated above, records of T. forte from Corsica (Casevitz-Weulersse 1974, 1990a, 1990b) were based on a different concept of the species. Our study of comprehensive samples from Corsica and Sardinia indicated that the true T. forte is not present on the Tyrrhenian Islands.
Apparent polygynous colonies have been observed in T. forte several times throughout its range (e.g. near Avignon, France; near Ifirane, Morocco), and the functional status as queens has been confirmed by dissection in one instance (five inseminated egg-laying queens: Sierra Nevada, Spain). Winged sexuals were recorded in T. forte colonies during late May in Spain, but during late June in the mountains of northern Portugal. The lepismatid silver-fish Proatelurina pseudolepisma (Grassi, 1887) is a generalistic myrmecophile commonly found inhabiting nests of T. forte (Molero-Baltanas et al. 1998). Astenus (Eurysunius) alcarazae Assing, 2003 and probably other species of the subgenus also occur with T. forte ; these are myrmecophilous staphylinid beetles specialized to live in the colonies of ants of the genus Tetramorium in the western Palaearctic (Assing 2003). However, no records of ant social parasites collected together with T. forte are available, including the inquilines Strongylognathus testaceus (Schenck , 1852) and Anergates atratulus (Schenck , 1852), which are known to use a relatively broad range of hosts in the genus Tetramorium (e.g. Sanetra et al. 1999; Sanetra & Buschinger 2000). Polygyny in a potential host species might be seen as a critical barrier for colony-founding queens of socially parasitic ants (see also Sanetra & Guesten 2001).
worker (Figs 11, 16), male (Figs 4, 6): Portugal , Distr. Braganca , Montesinho
gyne (Figs 3, 5): Portugal , Distr. Viseu , Serra de Montemuro
France , Dept. Vaucluse , 7 km nAvignon ; Spain , Prov. Cuenca , 2 km eVillalba de la Sierra ; Spain , Prov. Jaen , Puerto de los Jardines ; Spain , Prov. Granada , Sierra Nevada (2200m) ; Spain , Prov. Badajoz , Embalse de Orellana ; Portugal , Distr. Viseu , Caldas da Felgueira ; Portugal , Distr. Castelo Branco , nr. Monsanto ; Morocco , Reg. Kenitra , Foret de la Mamora ; Morocco , Reg. Meknes , Aguelmame Azigza

Specimen Habitat Summary

Elevations: collected at 230 m

Type specimens: Lectotype of Tetramorium forte: casent0911249; Lectotype of Tetramorium maurum tingitanum: casent0911252; syntype of Tetramorium caespitum ferox marocana: casent0915010; syntype of Tetramorium caespitum maura tingitana: casent0915029; syntype of Tetramorium forte: casent0909101; syntype of Tetramorium caespitum caespitum hispanica: casent0904805; syntype of Xiphomyrmex fuscipes ruginodis: casent0915042

(-1 examples)

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