Mystrium rogeri Forel, 1899

Yoshimura, Masashi & Fisher, Brian L., 2014, A revision of the ant genus Mystrium in the Malagasy region with description of six new species and remarks on Amblyopone and Stigmatomma (Hymenoptera, Formicidae, Amblyoponinae), ZooKeys 394, pp. 1-99: 45-51

publication ID

http://dx.doi.org/10.3897/zookeys.394.6446

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scientific name

Mystrium rogeri Forel, 1899
status

 

Mystrium rogeri Forel, 1899  Figs 4A, 8A, 9B, 9D, 12B, 29B, 37C, 38C, 39C, 40C, 41C, 43B, 43D, 44B, 44D, 45B, 45D, 46B, 46D, 47B, 47D, 48B, 48D, 49B

Mystrium rogeri  Forel, 1899 (in part: worker only, not male). MADAGASCAR. Syntypes: worker and male [The lectotype is designated below].

Mystrium rogeri  : Menozzi 1929.

Mystrium mysticum  [Not Roger, 1862]: Forel 1892, in part (worker only).

Mystrium stadelmanni  : Forel 1895, in part.

Lectotype

[here designated]. Worker: CASENT0101670, MADAGASCAR, Amparafaravantsiv Moramangoufer [MHNG: examined].

Worker.

Description. Measurements: lectotype. HL 1.87, HW 1.85, SL 1.13, ML 1.72, HD 1.24, WL 2.09, PnW 1.14, PpW 0.98, PtW 0.92, PtL 0.53, CI 98.7, SI 61.4, MI 93.3, PpI 86.5, PtI 174.6.

HL 1.19-2.27, HW 1.12-2.28, SL 0.70-1.37, ML 1.18-2.38, HD 0.83-1.47, WL 0.18-2.52, PnW 0.67-1.23, PpW 0.57-1.05, PtW 0.51-1.04, PtL 0.33-0.65, CI 93.9-101.4, SI 59.2-64.6, MI 90.9-105.7, PpI 79.3-90.1, PtI 153.1-182.6 (10 specimens measured).

Posterolateral corner of head strongly expanding posteriorly. Posterior face of vertex forming slightly blunt angle with dorsal face on median line of head, so that declivity of vertex on lateral part slightly steeper than on median part. Ventral half of vertex smooth and not sculptured. Eye small to moderately small. Anterior margin of clypeus straight or weakly concave and with small conical setae. Genal tooth of head undeveloped, but anterolateral corner of head angulate. Masticatory margin of mandible narrowly visible in full-face view, and difference in width of dorsal surface of mandible relatively small between mandibular shaft and distal portion. Second maxillary palpomere longer than third. First flagellomere (third antennal segment) as long as pedicel (second antennal segment). Shallow and fine longitudinal striae irregularly impressed on central part of pronotal dorsum, and sometimes shallowly reticulated around those striae. On lateral surface of pronotum, deep, fine longitudinal striae impressed and wide and deep punctures arranged on central horizontal line. Mesonotum differentiated from propodeum in dorsal view, length as long as that of propodeum in large individuals, shorter than propodeum in small individuals. Metanotal groove shallowly impressed, mesonotum in lateral view as high as pronotum in large individuals, higher than pronotum in small individuals. Metanotum weakly developed in largest individuals. Metapleural gland bulla developed, so that propodeal declivity in lateral view weakly convex posteriorly on ventral portion. Petiole in dorsal view moderately narrow, relatively narrower than that of Mystrium mysticum  .

Body color brown to black.

Queen.

Description. Measurements: HL 1.94-2.31, HW 1.99-2.40, SL 1.20-1.42, ML 1.87-2.48, HD 1.29-1.51, WL 2.78-3.31, MnW 1.42-1.83, PtW 1.03-1.32, PtL 0.61-0.78, CI 99.8-104.2, SI 58.1-62.8, MI 90.4-103.1, MnI 68.1-76.1, PtI 155.3-185.1 (10 specimens measured).

Wings usually present and well developed; but lacking in intercaste. Wing sclerites fully developed even if wings have dropped off in queen; developed to undeveloped in variable degrees in intercaste. Posterolateral corner of head strongly expanding posteriorly, expansion not differentiated from that of workers. Posterior face of vertex forming slightly blunt angle with dorsal face on median line of head, so that declivity of vertex on lateral part slightly steeper than on median part. Ventral half of vertex smooth and not sculptured. Eye well developed. Both anterior and lateral ocelli clearly present in queen; ocelli varied from absent to developed in intercaste. Anterior margin of clypeus straight or weakly concave with small conical setae. Anterolateral portion of head weakly to strongly angulate or with short spine. Masticatory margin of mandible narrowly, slightly visible in full-face view, dorsal surface on distal portion moderately wider than on mandibular shaft, difference in width much smaller than that in Mystrium mysticum  . Teeth always present on whole mandibular shaft. Spatulate seta present on basal side of each basal denticle on masticatory margin of mandible. First flagellar segment on antenna as long as pedicel. Setae on pronotum spatulate, widened distally with sharp or blunt apex. Propodeal declivity in lateral view almost straight and forming right to slightly obtuse angle with its dorsal margin, of which ventral portion with small convexity by metapleural gland. Petiole relatively long in dorsal view, about 0.6 × length of abdominal segment III.

Body color black.

Male.

Description. Measurements: HL 1.10-1.41, HW 1.43-1.85, SL 0.25-0.34, EL 0.59-0.76, WL 2.27-3.03, MnW 1.46-1.96, CI 127.9-132.0, SI 16.2-20.0, EI 49.9-54.1, MnI 101.4-107.6 (6 specimens measured).

Eye relatively small, occupying about half of head length. Ocelli relatively distant from dorsal margin of head in full-face view, or just failing to reach dorsal margin. Dorsal margin of head in full-face view rounded. Both anterior and lateral ocelli small. Distance between lateral ocellus and eye long, 3 × longer than diameter of lateral ocellus. Posterior half of vertex clearly differentiated from dorsal half, dorsal face almost as long as posterior face. Palpal formula 4,3. First segment of maxillary palp flattened and distinctly wider than second segment. Second maxillary palpomere longer than third. Notauli clearly impressed on mesoscutum. Petiole in dorsal view thin, its length about 0.5-0.65 × that of abdominal tergite III. Petiolar dorsum covered with rough, deep punctures. Abdominal tergum VIII roughly and deeply punctured.

Abdominal sternum IX punctured on its distal portion. Basal ring short, not extending basally. Telomere extending slightly further distally than digitus. Basoventral expansion of aedeagus less developed basoventrally, as long as dorsal extension. Ventral margin of aedeagus gently curved ventrally in lateral view. Aedeagus weakly narrowing distally, its distal portion widely rounded.

On forewing, cu-a located at junction of Media (M) and Cubitus (Cu).

Body color reddish brown to black.

Distribution.

MADAGASCAR and COMOROS: as in Figure 49B.

Additional material examined.

In addition to the type material, specimens from the following localities were examined in this study: MADAGASCAR. Diego-Suarez. Sakalava Beach [vegetated beach dunes] (-12.26278°, 49.3975°), across sandy trail in dwarf littoral forest, 10 m alt.; 7 km N Joffreville [camp 2 of Fisher] (-12.33333°, 49.25°), in dry forest, 360 m alt.; Parc National Montagne d’Ambre [lemur trail] (-12.51667°, 49.18333°), rainforest, 975 m alt.; Parc National Montagne d’Ambre [Petit Lac road] (-12.52028°, 49.17917°), rainforest, 1125 m alt.; Antsiranana. Parc National Montagne d’Ambre, Antomboka (-12.51269°, 49.17807°), montane rainforest, 970 m alt.; Parc National Montagne d’Ambre (-12.51389°, 49.17784°), montane rainforest, 984 m alt.; Pic Bades (-12.5186°, 49.18625°), montane rainforest, 900 m alt.; (-12.52306°, 49.17901°), montane rainforest, 1100 m alt.; Roussettes (-12.52574°, 49.17238°), montane rainforest, 1025 m alt.; Roussettes Camp 7 km SW Park entrance (-12.51444°, 49.18139°), rainforest, 960 m alt.; Mahasarika (-12.53176°, 49.17662°), montane rainforest, 1135 m alt.; (-12.53417°, 49.17607°), montane rainforest, 1325 m alt.; 3.6 km 235° SW Joffreville (-12.53444°, 49.1795°), montane rainforest, 925 m alt.; Petit lac (-12.53664°, 49.17412°), montane rainforest, 1130 m alt.; Lac Maudit (-12.58502°, 49.15147°), montane rainforest, 1250 m alt.; 12.2 km 211° SSW Joffreville (-12.59639°, 49.1595°), montane rainforest, 1300 m alt.; Forêt de Binara, 9.1 km 233° SW Daraina (-13.26333°, 49.60333°), rainforest, 800 m alt.; (-13.26333°, 49.6°), montane rainforest, 1100 m alt.; Nosy Faly (-13.3624°, 48.49101°), open secondary vegetation, 15 m alt.; Galoko chain, Mont Galoko (-13.58487°, 48.71818°), rainforest, 520 m alt.; Ampasindava, Forêt d’Ambilanivy, 3.9 km 181° S Ambaliha (-13.79861°, 48.16167°), rainforest, 600 m alt.; R.S. Manongarivo, 12.8 km 228° SW Antanambao (-13.97667°, 48.42333°), rainforest, 780 m alt.; 14.5 km 220° SW Antanambao (-13.99833°, 48.42833°), montane rainforest, 1175 m alt.; Parc National de Marojejy, Manantenina River, 27.6 km 35° NE Andapa, 9.6 km 327° NNW Manantenina (-14.435°, 49.76°), rainforest, 775 m alt.; 28.0 km 38° NE Andapa, 8.2 km 333° NNW Manantenina (-14.43667°, 49.775°), rainforest, 450 m alt.; Antranohofa, 26.6 km 31° NNE Andapa, 10.7 km 318° NW Manantenina (-14.44333°, 49.74333°), montane rainforest, 1325 m alt.; Betaolana Forest, along Bekona River (-14.52996°, 49.44039°), rainforest, 880 m alt.; Forêt Ambanitaza, 26.1 km 347° Antalaha (-14.67933°, 50.18367°), rainforest, 240 m alt.; Toamasina. Montagne d’Anjanaharibe, 18.0 km 21° NNE Ambinanitelo (-15.18833°, 49.615°), rainforest, 470 m alt.; Res. Ambodiriana, 4.8 km 306°Manompana, along Manompana river (-16.67233°, 49.70117°), rainforest, 125 m alt.; Réserve Spéciale Ambatovaky, Sandrangato river (-16.7633°, 49.26692°), rainforest, 520 m alt.; (-16.7702°, 49.26638°), rainforest, 470 m alt.; (-16.77274°, 49.26551°), rainforest, 450 m alt.; Manakambahiny, near Vavatenina Forest (-17.46667°, 49.35°), alt.; Parc National de Zahamena (-17.73359°, 48.72625°), rainforest, 950 m alt.; Tetezambatana forest, near junction of Nosivola and Manakambahiny Rivers (-17.74298°, 48.72936°), rainforest, 860 m alt.; Onibe River (-17.75908°, 48.85468°), rainforest, 780 m alt.; Reserve Betampona, Camp Vohitsivalana, 37.1 km 338° Toamasina (-17.88667°, 49.2025°), rainforest, 520 m alt.; Réserve Nationale Intégrale Betampona, Betampona 35.1 km NW Toamasina (-17.91801°, 49.20074°), rainforest, 500 m alt.; Réserve Naturelle Betampona, 34.08 km 332° Toamasina (-17.91977°, 49.20039°), rainforest, 525 m alt.; Reserve Betampona, Camp Rendrirendry 34.1 km 332° Toamasina (-17.924°, 49.19967°), rainforest, 390 m alt.; F.C. Sandranantitra (-18.04833°, 49.09167°), rainforest, 450 m alt.; Station forestière Analamazaotra, Analamazaotra 1.3 km S Andasibe (-18.38466°, 48.41271°), montane rainforest, 980 m alt.; Ankerana (-18.40062°, 48.81311°), rainforest, 865 m alt.; Ankerana (-18.4017°, 48.80605°), montane forest, 1035 m alt.; (-18.4061°, 48.82029°), rainforest, 725 m alt.; (-18.40829°, 48.82107°), rainforest, 750 m alt.; (-18.4104°, 48.8189°), rainforest, 855 m alt.; F.C. Andriantantely (-18.695°, 48.81333°), rainforest, 530 m alt.; Corridor Forestier Analamay-Mantadia, Tsaravoniana (-18.75641°, 48.42195°), rainforest, 1036 m alt.; (-18.75737°, 48.42302°), rainforest, 1018 m alt.; (-18.76124°, 48.42134 °), rainforest, 939 m alt.; (-18.76465°, 48.41938°), rainforest, 1039 m alt.; Ambohibolakely (-18.76087°, 48.37128°), rainforest, 1044 m alt.; (-18.76131°, 48.36437°), rainforest, 983 m alt.; (-18.77898°, 48.36375°), rainforest, 918 m alt.; Ambohibolakely (-18.77908°, 48.36628°), rainforest, 1014 m alt.; Ambatoharanana (-18.79956°, 48.4028°), rainforest, 1058 m alt.; (-18.80388°, 48.40506°), rainforest, 1013 m alt.; (-18.80398°, 48.40358°), rainforest, 1064 m alt.; (-18.80424°, 48.40081°), rainforest, 968 m alt.; (-18.80438°, 48.40735°), rainforest, 960 m alt.; Bevolota 17.1 km N Andasibe (-18.77071°, 48.43164°), montane rainforest, 995 m alt.; Analamay (-18.80623°, 48.33707°), montane rainforest, 1068 m alt.; Parc National d´ Andasibe-Mantadia, Forêt de Mantadia, 25.7 km 248° Moramanga (-18.81402°, 48.43028°), rainforest, 1040 m alt.; Ambatovy, 12.4 km NE Moramanga (-18.83937°, 48.30842°), montane rainforest, 1080 m alt.; Forêt Ambatovy, 14.3 km 57° Moramanga (-18.85083°, 48.32°), montane rainforest, 1075 m alt.; Torotorofotsy (-18.87082°, 48.34737°), montane rainforest, marsh edge, 1070 m alt.; Toliara. Réserve Spéciale d’Ambohijanahary, Forêt d’Ankazotsihitafototra, 35.2 km 312° NW Ambaravaranala (-18.26667°, 45.40667°), montane rainforest, 1050 m alt.; Makay Mts. (-21.20978°, 45.34184°), Gallery forest on sandy soil, 525 m alt.; (-21.21013°, 45.35462°), Gallery forest with bamboo, 540 m alt.; (-21.22336°, 45.32628°), Gallery forest on sandy soil, 480 m alt.; (-21.227°, 45.33222°), gallery forest on sandy soil, 475 m alt.; Forêt Ivohibe 55.6 km N Tolagnaro (-24.56167°, 47.20017°), rainforest, 650 m alt.; 11 km NW Enkara, Rés Andohahela (-24.56667°, 46.81667°), rainforest, 950 m alt.; Forêt Ivohibe 55.0 km N Tolagnaro (-24.569°, 47.204°), rainforest, 200 m alt.; 6 km SSW Eminiminy, Res. Andohahela (-24.73333°, 46.8°), wet forest, 330 m alt.; Rés. Andohahela, 6 km SSW Eminiminy (-24.73333°, 46.8°), rainforest, 330 m alt.; Parc National Andohahela, Col de Tanatana, 33.3 km NW Tolagnaro (-24.7585°, 46.85367°), rainforest, 275 m alt.; Manampanihy River, 5.4 km 113° ESE Mahamavo, 36.7 km 343° NNW Tolagnaro (-24.76389°, 46.76683°), rainforest, 650 m alt.; Col du Sedro, 3.8 km 113° ESE Mahamavo, 37.6 km 341° NNW Tolagnaro (-24.76389°, 46.75167°), montane rainforest, 900 m alt.; Forêt Mandena 8.5 km N Tolagnaro (-24.95267°, 47.0025°), littoral rainforest, 20 m alt.; Grand Lavasoa, 25.9 km W Tolagnaro (-25.08767°, 46.749°), rainforest, 450 m alt.; Toamasina. Res. Ambodiriana, 4.8 km 306° Manompana, along Manompana river (-16.67233°, 49.70117°), rainforest, 125 m alt.; Réserve Spéciale Ambatovaky, Sandrangato river (-16.7633°, 49.26692°), rainforest, 520 m alt.; (-16.7702°, 49.26638°), rainforest, 470 m alt.; (-16.77274°, 49.26551°), rainforest, 450 m alt.; Manakambahiny, near Vavatenina Forest (-17.46667°, 49.35°), alt.; Parc National de Zahamena (-17.73359°, 48.72625°), rainforest, 950 m alt.; Tetezambatana forest, near junction of Nosivola and Manakambahiny Rivers (-17.74298°, 48.72936°), rainforest, 860 m alt.; Onibe River (-17.75908°, 48.85468°), rainforest, 780 m alt.; Reserve Betampona, Camp Vohitsivalana, 37.1 km 338° Toamasina (-17.88667°, 49.2025°), rainforest, 520 m alt.; Réserve Nationale Intégrale Betampona, Betampona 35.1 km NW Toamasina (-17.91801°, 49.20074°), rainforest, 500 m alt.; Réserve Naturelle Betampona, 34.08 km 332° Toamasina (-17.91977°, 49.20039°), rainforest, 525 m alt.; Reserve Betampona, Camp Rendrirendry 34.1 km 332° Toamasina (-17.924°, 49.19967°), rainforest, 390 m alt.; F.C. Sandranantitra (-18.04833°, 49.09167°), rainforest, 450 m alt.; Station forestière Analamazaotra, Analamazaotra 1.3 km S Andasibe (-18.38466°, 48.41271°), montane rainforest, 980 m alt.; Ankerana (-18.40062°, 48.81311°), rainforest, 865 m alt.; Ankerana (-18.4017°, 48.80605°), montane forest, 1035 m alt.; (-18.4061°, 48.82029°), rainforest, 725 m alt.; (-18.40829°, 48.82107°), rainforest, 750 m alt.; (-18.4104°, 48.8189°), rainforest, 855 m alt.; F.C. Andriantantely (-18.695°, 48.81333°), rainforest, 530 m alt.; Corridor Forestier Analamay-Mantadia, Tsaravoniana (-18.75641°, 48.42195°), rainforest, 1036 m alt.; (-18.75737°, 48.42302°), rainforest, 1018 m alt.; (-18.76124°, 48.42134°), rainforest, 939 m alt.; (-18.76465°, 48.41938°), rainforest, 1039 m alt.; Ambohibolakely (-18.76087°, 48.37128°), rainforest, 1044 m alt.; (-18.76131°, 48.36437°), rainforest, 983 m alt.; (-18.77898°, 48.36375°), rainforest, 918 m alt.; Ambohibolakely (-18.77908°, 48.36628°), rainforest, 1014 m alt.; Ambatoharanana (-18.79956°, 48.4028°), rainforest, 1058 m alt.; (-18.80388°, 48.40506°), rainforest, 1013 m alt.; (-18.80398°, 48.40358°), rainforest, 1064 m alt.; (-18.80424°, 48.40081°), rainforest, 968 m alt.; (-18.80438°, 48.40735°), rainforest, 960 m alt.; Bevolota 17.1 km N Andasibe (-18.77071°, 48.43164°), montane rainforest, 995 m alt.; Analamay (-18.80623°, 48.33707°), montane rainforest, 1068 m alt.; Parc National d´ Andasibe-Mantadia, Forêt de Mantadia, 25.7 km 248° Moramanga (-18.81402°, 48.43028°), rainforest, 1040 m alt.; Ambatovy, 12.4 km NE Moramanga (-18.83937°, 48.30842°), montane rainforest, 1080 m alt.; Forêt Ambatovy, 14.3 km 57° Moramanga (-18.85083°, 48.32°), montane rainforest, 1075 m alt.; Torotorofotsy (-18.87082°, 48.34737°), montane rainforest, marsh edge, 1070 m alt.; Toliara. Réserve Spéciale d’Ambohijanahary, Forêt d’Ankazotsihitafototra, 35.2 km 312° NW Ambaravaranala (-18.26667°, 45.40667°), montane rainforest, 1050 m alt.; Makay Mts. (-21.20978°, 45.34184°), gallery forest on sandy soil, 525 m alt.; (-21.21013°, 45.35462°), gallery forest with bamboo, 540 m alt.; (-21.22336°, 45.32628°), gallery forest on sandy soil, 480 m alt.; (-21.227°, 45.33222°), gallery forest on sandy soil, 475 m alt.; Forêt Ivohibe 55.6 km N Tolagnaro (-24.56167°, 47.20017°), rainforest, 650 m alt.; 11 km NW Enkara, Rés Andohahela (-24.56667°, 46.81667°), rainforest, 950 m alt.; Forêt Ivohibe 55.0 km N Tolagnaro (-24.569°, 47.204°), rainforest, 200 m alt.; 6 km SSW Eminiminy, Res. Andohahela (-24.73333°, 46.8°), wet forest, 330 m alt.; Rés. Andohahela, 6 km SSW Eminiminy (-24.73333°, 46.8°), rainforest, 330 m alt.; Parc National Andohahela, Col de Tanatana, 33.3 km NW Tolagnaro (-24.7585°, 46.85367°), rainforest, 275 m alt.; Manampanihy River, 5.4 km 113° ESE Mahamavo, 36.7 km 343° NNW Tolagnaro (-24.76389°, 46.76683°), rainforest, 650 m alt.; Col du Sedro, 3.8 km 113° ESE Mahamavo, 37.6 km 341° NNW Tolagnaro (-24.76389°, 46.75167°), montane rainforest, 900 m alt.; Forêt Mandena 8.5 km N Tolagnaro (-24.95267°, 47.0025°), littoral rainforest, 20 m alt.; Grand Lavasoa, 25.9 km W Tolagnaro (-25.08767°, 46.749°), rainforest, 450 m alt. Mahajanga. Réserve Spéciale Marotandrano, Marotandrano 48.3 km S Mandritsara (-16.28322°, 48.81443°), transition humid forest, 865 m alt. Fianarantsoa. Ranomafana Nat. Park, Miaranony Forest (-21.25°, 47.41667°), montane forest, 700 m alt.; 7 km W Ranomafana (-21.26667°, 47.41667°), montane rainforest, 1000 m alt.; Parc National de Ranomafana, Vatoharanana River, 4.1 km 231° SW Ranomafana (-21.29°, 47.43333°), montane rainforest, 1100 m alt.; 7.6 km 122° Kianjavato, Forêt Classée Vatovavy (-21.4°, 47.94°), rainforest, 175 m alt.; Andrambovato along river Tatamaly (-21.50967°, 47.40762°), cultivated land (tavy), 984 m alt.; (-21.51089°, 47.40987°), rainforest, 994 m alt.; 2 km W Andrambovato, along river Tatamaly (-21.51167°, 47.41°), montane rainforest, 1075 m alt.; 45 km S. Ambalavao (-22.21667°, 47.01667°), rainforest, 785 m alt.; 43 km S Ambalavao, Rés. Andringitra (-22.23333°, 47°), rainforest, 825 m alt.; 9.0 km NE Ivohibe (-22.42667°, 46.93833°), montane rainforest, 900 m alt.; Parc National d’Isalo, 9.1 km 354° N Ranohira (-22.48167°, 45.46167°), gallery forest, 725 m alt.; R.S. Ivohibe 8.0 km E Ivohibe (-22.48333°, 46.96833°), montane rainforest, 1200 m alt.; Forêt de Vevembe, 66.6 km 293° Farafangana (-22.791°, 47.18183°), rainforest, transition to montane forest, 600 m alt.; Réserve Speciale Manombo 24.5 km 228° Farafangana (-23.01583°, 47.719°), rainforest, 30 m alt.; Parc National Befotaka-Midongy, Papango 27.7 km S Midongy-Sud, Mount Papango (-23.83517°, 46.96367°), rainforest, 940 m alt.

COMOROS. Mohéli, Ouallah (-12.32717°, 43.65952°), coastal scrub, 10 m alt.

Remarks.

The females of Mystrium rogeri  can be distinguished easily from other Mystrium  females by the combination of a distinct longitudinal carina on the central portion of the labrum (Fig. 8A) or a single lateral spine on abdominal sternum VII (Fig. 8C), and the straight anterior margin of the clypeus (Fig. 9D). In addition to these diagnostic characters, a combination of unsculptured and smooth areas on the ventral portion of the vertex (as in Fig. 11A) and the straight anterior clypeal margin separates Mystrium rogeri  from the other Mystrium  species workers; and a larger-sized alate queen (HW>1.99) with spatulate setae on the pronotal dorsum (Fig. 9B) separate Mystrium rogeri  from the queens of other species. For males, the small eye and small ocelli (as in Fig. 26B) that are separated from each other by a distance of more than 3 × the maximum diameter of lateral ocellus, petiolar dorsum (as in Fig. 28C) and abdominal tergum VIII (as in Fig. 28A) with rough and deep punctures, and less developed basoventral expansion of aedeagus (Fig. 29B) separate Mystrium rogeri  from the other Mystrium  males in the Malagasy region.

We propose a new set of diagnostic characters in this study to correctly identify Mystrium rogeri  . The diagnostic characters listed above are constant in females regardless of their body size. Because of the remarkable morphological variation in each species, most diagnostic characters for Mystrium rogeri  proposed in previous papers (e.g. Emery 1899; Menozzi 1929) cannot separate Mystrium rogeri  from the other Mystrium  species, especially from Mystrium mysticum  . Mystrium rogeri  also displays distinct variation in body size, color, relative mandible length, and shape of the petiole. The difference in the petiolar shape ( Emery 1899; Menozzi 1929) cannot be used for complete separation between Mystrium rogeri  and Mystrium mysticum  (PtI 153-183 vs. PtI 146-168). As mentioned in their discussion of Mystrium mysticum  , Molet et al. (2012) reported "mosaic monster" intermediates between queen and worker. The existence of this intercaste is not unique to Mystrium rogeri  , but rather a character of the mysticum species group that we confirmed in Mystrium mysticum  as well. In this study, the intercastes are keyed out with either of the workers or queens of each species.

As we discussed in Mystrium mysticum  , further studies are necessary to better separate the males of Mystrium rogeri  and Mystrium mysticum  . Here we propose only an aedeagal character to separate these very similar males (Fig. 29).

The lectotype for Mystrium rogeri  is designated. Mystrium rogeri  was described by Forel in 1899 using at least two workers and one male collected in Madagascar, and we confirm one worker and one male in his collection. Although we could not find any information to identify which type specimens were used in his original description ( Forel 1899), Forel mentioned that the workers he determined as Mystrium rogeri  were the same specimens he determined as Mystrium mysticum  ( Forel 1892), and which Emery had sent him. According to the description in Forel (1892), the worker of Mystrium rogeri  is smaller and stouter than the worker of Mystrium mysticum  ; however, we could not deduce how he determined the boundary of " Mystrium mysticum  " in the worker caste. To further complicate the story, when Forel described Mystrium rogeri  in 1899, he probably determined workers of actual Mystrium mysticum  as Mystrium stadelmanni  (see remarks for Mystrium mysticum  ). Moreover, once he determined Emery’s material as Mystrium rogeri  , the worker caste of Mystrium mysticum  should have been considered “unknown” once again. In addition to the misidentification of the worker caste, his description did not provide any details to identify which male specimens he studied. We also confirm Forel’s suspicions ( Forel 1899) that the male described as Mystrium rogeri  is not conspecific with the worker. We verify that the male specimen in his collection, which was probably used for the description of Mystrium rogeri  , is Mystrium oberthueri  .

Mystrium rogeri  is one of the most common Mystrium  species used in recent ecological and phylogenetic studies ( Molet et al. 2009; Molet et al. 2007a; Molet et al. 2012; Moreau et al. 2006; Saux et al. 2004). However, the identification of their voucher material is now reassessed: part of the material identified as Mystrium rogeri  in Molet et al. ( Molet et al. 2009; Molet et al. 2007a; Molet et al. 2012) is not Mystrium rogeri  (see remarks under Mystrium mysticum  ).

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Hymenoptera

Family

Formicidae

Genus

Mystrium