Crematogaster rasoherinae Forel

Blaimer, Bonnie B., 2012, Taxonomy and species-groups of the subgenus Crematogaster (Orthocrema) in the Malagasy region (Hymenoptera, Formicidae), ZooKeys 199, pp. 23-70 : 31-38

Crematogaster rasoherinae Forel Figures 2426

Crematogaster rasoherinae Forel, 1891: 194. Worker syntype(s) from MADAGASCAR: Tamatave ( O’swald) [Naturhist. Mus. Hamburg, not examined, destroyed during WWII]. Forel, 1912: 164. Queen, male described. Combination in Crematogaster ( Neocrema ): Santschi, 1918: 182; in Crematogaster ( Crematogaster ): Wheeler, W.M. 1922: 1023; Combination in Crematogaster ( Orthocrema ): Emery, 1922: 131; Combination in Crematogaster ( Mesocrema ): Santschi, 1928: 33.

= Crematogaster ( Orthocrema) rasoherinae var. brunneola Emery, 1922: 131. Replacement name for Crematogaster rasoherinae var. brunnea Forel, 1907: 79. Worker and queen syntypes from Madagascar: Andranohinaly (SW Madagaskar) (Voeltzkow) [MHNG, examined]. [Junior primary homonym of brunnea Smith, F. 1857: 75.]. Lectotype worker by present designation: top specimen of 2 workers on one pin, CASENT0101836 (image on AntWeb). Combination in Crematogaster ( Mesocrema ): Santschi, 1928: 33. Syn. n.

= Crematogaster voeltzkowi Forel, 1907: 78. Worker syntypes from Comoros: Anjouan (Voeltzkow) [MHNG, examined]. Lectotype worker by present designation: top specimen of 2 workers on one pin, CASENT0101615 (image on AntWeb). Combination in Crematogaster ( Neocrema ): Santschi, 1918: 182 (misspelled as woelzkowi); Comb. in Crematogaster ( Crematogaster ): Wheeler, W.M. 1922: 1024; Comb. in Crematogaster ( Orthocrema ): Emery, 1922: 131. Syn. n.

Type material.

Syntypes not available for examination; these specimens were housed in the collection of the Naturhistorisches Museum in Hamburg and were destroyed during World War II (confirmation obtained 19.vii.2011, via e-mail communication with F. Wieland).

Neotype worker, by present designation: pinned, CASENT0120911, BLF16755, ex dead twig above ground; original locality label: Prov. Toamasina, Tamatave, 20m, 18°09.28'S, 49°24.76'E, 16.ii.2007, urban gardens, Fisher et al. BLF16755; deposited at CASC.

Other material examined

(BBBC, CASC, MHNG, NHMB, PSWC, ZMBH, MCZC). MADAGASCAR: Antsiranana: Baie Sakalava: -12.27330, 49.39064, 10m (B.L.Fisher et al.); Montaigne Français: -12.32278, 49.33817, 180m (R. Harin’Hala); 7 km N Joffreville: -12.33333, 49.25000, 360m (R. Harin’Hala); 2km S Joffreville: -12.47639, 49.22222, 500m (G.Alpert); 7km SE Antsiranana: -12.31670, 49.33330, 80m (G.Alpert); R.S. Ambre: -12.46889, 49.24217, 325m (B.L.Fisher et al.); P.N. Montagne d’Ambre: -12.50035, 49.17500, 885m; -12.53444, 49.17950, 925m; -12.52028, 49.17917, 1125m (B.L.Fisher et al.); Nosy Bé, R.N.I. Lokobé: -13.41944, 48.33117, 30m (B.L.Fisher et al.); Nosy Bé, Lokobe Forest: -13.41640, 48.30720, 50m (G.Alpert); Nosy Bé, 5km E Marodokana: -13.36670, 48.30000, 50m (G.Alpert); R.S. Manongarivo: -13.93153, 48.45213, 370m (B.B.Blaimer); Ambondrobe: - 13.71533, 50.10167, 10m (B.L.Fisher et al.); P.N. Ankarana: -12.90889, 49.10983, 80m; -12.86361, 49.22583, 210m (B.L.Fisher et al.), P.N. Ankarana: -12.90056, 49.14722, 150m (G.Alpert); F Andavakoera: -13.11833, 49.23000, 425m (B.L.Fisher et al.); Rés. Analamerana: -12.74667, 49.49483, 60m (B.L.Fisher et al.); F Binara: -13.26333, 49.60333, 650-800m (B.L.Fisher et al.); 6.3 km S Ambanizana: -15.68131, 49.9580, 25m (B.L.Fisher et al.); 5.3 km SSE Ambanizana, 425m, -15.66667, 49.96667 (B.L.Fisher et al.); Nosy Mangabe: -15.49730, 49.76223, 5m (B.L.Fisher et al.); -15.50000, 49.76670, 200m (P.S.Ward); P.N. Marojejy: -14.43333, 49.78333, 450m (B.L.Fisher et al.); P.N. Masoala: -15.71333, 49.97167 (B.L.Fisher et al.); -15.72667, 49.95667, 150m (A.Dejean et al.); 84km SW Sambava on road to Andapa: -14.57730, 49.73940, 160m (W.L.&D.E.Brown); Vohemar: -13.35967, 50.00390, 16m (B.L.Fisher et al.); F Analabe: -13.08333, 49.90833, 30m (B.L.Fisher et al.); Forêt d’Ampondrabe: -12.97000, 49.70000, 175m (B.L.Fisher et al.); F Orangea: -12.25889, 49.37467, 90m (B.L.Fisher et al.);F Ampombofofo: -12.09949, 49.33874, 25m (B.L.Fisher et al.); Ampamakiambato: -13.97545, 48.15929, 145m (B.L.Fisher et al.); Forêt d’Anabohazo: -14.30889, 47.91433, 120m (B.L.Fisher et al.); Ankobahoba: -13.39166, 48.48249, 40m (B.L.Fisher et al.); 14km W Cap Est, Ambato: -15.29128, 50.33803, 150m (B.L.Fisher et al.); Andranomatàna: -13.14965, 48.91765, 28m (B.L.Fisher et al.); Tsihombe: -25.31833, 45.48367, 30m (B.L.Fisher et al.); Antalaha: -14.90130, 50.28095, 24m (B.L.Fisher et al.); 55km S Antalaha, Nosy Ngontsy: -15.26440, 50.48930, 50m (G.Alpert); 55km S Antalaha, Cap Est: -15.25640, 50.47940, 1m (G.Alpert); Ambohitsara, 10km SW Antalaha: -14.95000, 50.26670, 50m (G.Alpert); Antananarivo: R.S. Ambohitantely: -18.19800, 47.28150, 700m (B.L.Fisher et al.); Fianarantsoa: P.N. Ranomafana: -21.26650, 47.42017, 1020m (B.L.Fisher et al.); 3km W Ranomafana, nr Ifanadiana: -21.25000, 47.41670, 950m (P.S.Ward); Ranomafana, nr. Ifanadiana: -21.26670, 47.45000, 650m (P.S.Ward); 10km E Ranomafana: -18.99972, 48.95000, 50m (G.Alpert); R.S. Manombo: -23.01580, 47.71900, 30m (B.L.Fisher et al.); -23.02183, 47.72000, 36m (R. Harin’Hala); Mahabo [ Rés. Forestière d’Agnalazaha]: -23.19383, 47.72300, 20m (B.L.Fisher et al.); F Ampitavananima: -23.12972, 47.71700, 34m (B.L.Fisher et al.); 8km E Kianjavato: -21.38860, 47.94360, 145m (G.Alpert); Mahajanga: PN Ankarafantsika (F Tsimaloto): -16.22806, 47.14361, 135m (B.L.Fisher et al.); PN Ankarafantsika: -16.31670, 46.81670 (L.A. Nilsson); Ambolomaiky: -15.85410, 46.74663, ca. 80m (B.L.Fisher et al.); Forêt Ambohimanga: -15.96267, 47.43817, 250m (B.L.Fisher et al.); PN Baie de Baly: -16.01000, 45.26500, 10m (B.L.Fisher et al.); P.N. Namoroka: -16.37667, 45.32667, 100m (B.L.Fisher et al.); P.N. Tsingy de Bemaraha: -19.13222, 44.81467,100m; -18.70944, 44.71817, 150m (B.L.Fisher et al.); Mahavavy River: -16.05167, 45.90833, 20m (B.L.Fisher et al.); Rés. Forestière Beanka: -18.02649, 44.05051, 250m (B.L.Fisher et al.); F Tsimembo: -19.02139, 44.44067, 20m; -18.99528, 44.44350, 50m (B.L.Fisher et al.); S.F. Ampijoroa: -16.31944, 46.81333, ca. 40m; -16.31670, 46.81670, 80m; F Asondrodava:: -17.96533, 44.03550, 6m (R. Harin’Hala); 3km S Namakia: -15.95611, 45.83556, 40m (G. Alpert); Toamasina: RS Ambatovaky: -16.81739, 49.29402, 360m (B.L.Fisher et al); F Ambatovy: -18.85083, 48.32000, 1075m (B.L.Fisher et al.); Rés. Betampona: -17.92400, 49.19967, 390m (B.L.Fisher et al.); 11km SE Ampasimanolotra (=Brickaville): -18.90000, 49.13330, 5m (P.S.Ward); 10km N Brickaville: -18.79194, 49.08667, 100m(G. Alpert); F Kalalao [Ile St.Marie]: -16.92250, 49.88733, 100m (B.L.Fisher et al.); F Ambohidena [Ile St.Marie]: -16.82433, 49.96417, 20m (B.L.Fisher et al.); F Ampanihy [Ile St.Marie]: -16.91117, 49.93917, 10m (B.L.Fisher et al.); F Sahafina: -18.81445, 48.96205, 100m; -18.81445, 48.96205, 140m (B.L.Fisher et al.); Mahavelona (Foulpointe): -17.66667, 49.50000, (A.Pauly); Manankinany: -17.03330, 49.53330 (L.A.Nilsson); Tanambao Nosibe: -17.89117, 49.45617, 15m (Blaimer&Raharimalala); Antaratasy: -17.76733, 49.47767, 25m (Blaimer & Raharimalala); Ampasina-Maningory: -17.21467, 49.40550, 20m (Blaimer & Raharimalala); Anosintany: -16.91117, 49.58867, 10m (Blaimer & Raharimalala); Maitsokely: -16.90617, 49.58683, 10m (Blaimer & Raharimalala); Fenoarivo: -17.38117, 49.41500, 10m (Blaimer & Raharimalala); Antetezambaro: -17.05283, 49.56700, 10m (Blaimer & Raharimalala); Mahambo: -17.48933, 49.45167, 10m (Blaimer & Raharimalala); Tamatave: -18.15467, 49.41267, 20m (B.L.Fisher et al.); Brickaville: -18.82183, 49.07017, ca. 25m (B.L.Fisher et al.); Analalava: -17.7095, 49.45400, 50m (B.L.Fisher et al.); Mahanoro: -19.89933, 48.80883, 15m (B.L.Fisher et al.); Vatomandry: -19.33283, 48.97950, 16m (B.L.Fisher et al.); Forêt d’Analava Mandrisy: -16.48567, 49.84700, 10m (B.L.Fisher et al.); S.F. Tampolo: -17.28250, 49.43000, 10m (B.L.Fisher et al.); Analalava: -17.693194, 49.46027, ca. 20m (R. Harin’Hala); Toliara: Mahafaly Plateau: -24.65361, 43.99667, 80m (B.L.Fisher et al.); F Mikea: -22.90367, 43.47550, 35m (R. Harin’Hala); Libanona Beach: -25.03883, 46.99600, 20m (B.L.Fisher et al.); F Petriky: -25.06167, 46.87000, 10m (B.L.Fisher); Ranobe: -23.03975, 43.61090, 30m (Frontier Project, MGF); Rés. Berenty (F Bealoka): -24.95694, 46.27150, 35m (B.L.Fisher et al.); Rés. Berenty (F Malaza): -25.00778, 46.30600, 40m; Rés. Berenty (F Anjapolo): -24.92972, 46.20967, 65m (B.L.Fisher et al.); Rés. Berenty: -25.02100, 46.30550, 35m, -25.00670, 46.30330, 85m (R. Harin’Hala), -25.01670, 46.30000, 35m (P.S.Ward), -24.98330, 46.30000, 30m; Miandrivazo: -19.52317, 45.4575, 80m (B.L.Fisher et al.); Morondava: -20.29650, 44.28150, ca. 10m (B.L.Fisher et al.); F Beroboka: -22.23306, 43.36633, 80m (B.L.Fisher et al.); F Tsinjoriaky: -22.80222, 43.42067, 70m (B.L.Fisher et al.); PN Tsimanampetsotsa: -24.10056, 43.76000, 25m; -24.04722, 43.75317, 40m (B.L.Fisher et al.); Ejeda: -24.3505, 44.51600, 250m (B.L.Fisher et al.); F Tsivory: -24.07083, 46.07533, 400m (B.L.Fisher et al.); Manatantely: -24.9815, 46.92567, 100m (B.L.Fisher et al.); 6.1 km 182°S Marovato: -25.58167, 45.29500, 20m (B.L.Fisher et al.); 3.4 km 190° S Marovato: -25.55972, 45.28250, 160m (B.L.Fisher et al.); 3.5 km 236° SW Marovato: -25.55389, 45.25583, 230m (B.L.Fisher et al.); P.N. Andohahela: -24.81694, 46.61000, 150m (R. Harin’Hala); -24.93683, 46.62667, 180m (R. Harin’Hala); -24.75850, 46.85370, 275m; -24.93000, 46.64550, 300m (B.L.Fisher et al.); P.N. Andohahela/parcel3: -25.01366, 46.64650, 160m; -25.01790, 46.65175, 170m; P.N. Andohahela/ parcel1: -24.94713, 46.67312, 400m; -24.94683, 46.67625, 440m (B.B.Blaimer); 5km NNW Isaka-Ivondro, Rés. Ando hahela: -24.75000, 46.85000, 280m (P.S.Ward); (P.S.Ward); 7km NW Ranopiso: -25.01670, 46.63330, 100m (P.S.Ward); 2.7km WNW 302 º St.Luce: -24.77167, 47.17167, 20m (B.L.Fisher et al.); F Mandena: -24.95167, 47.00167, 20m (B.L.Fisher); Rés. Cap St.Marie: -25.58767, 45.16300, ca. 35m; -25.59444, 45.14683, 160m, -25.58167, 45.16833, 200m; (B.L.Fisher et al.); SW Madagaskar, Andranohinaly: -23.27500, 43.97500 (Voeltzkow).

SEYCHELLES: Mahé Island: Morne Blanc: -4.65988, 55.43743, 480m; -4.65740, 55.43325, 660m (B.L.Fisher et al.); Petite Congo Rouge: -4.64514, 55.43364, 745m (B.L.Fisher et al.); Mont Copolia: -4.65121, 55.45835, 520m (B.L.Fisher et al.); Silhouette Island: Mont Dauban: -4.48126, 55.22641; 735m (B.L.Fisher et al.); Aldabra Atoll: Grande Terre Isl.: -9.43453, 46.45767, ca. 5m (S.M.Goodman); COMOROS: Mohéli: Ouallah: -12.30668, 43.66407, 275m; -12.30353, 43.66827, 500m; -12.29696, 43.67392, 680m; -12.29600, 43.67600, 750m (B.L.Fisher et al.); Madahali: -12.37421, 43.86857, 50m (B.L.Fisher et al.); Lac Boundouni: -12.37915, 43.85165, 25m (B.L.Fisher et al.); Grande Comore: Goudjoulachamle: -11.44826, 43.27373, 80m (B.L.Fisher et al.); Grillé: -11.47578, 43.34669, 805m; -11.47578, 43.34669, 995m (B.L.Fisher et al.); Karthala: -11.82699, 43.42950, 1000m (B.L.Fisher et al.); Domani: -11.51778, 43.28000, 5m (B.L.Fisher et al.); Itoundzou: -11.63136, 43.30434, 635m (B.L.Fisher et al.); Trou du Prophete: -11.38087, 43.31335, 10m (B.L.Fisher et al.); Anjouan: -12.22265, 44.28820, 10m; -12.25764, 44.38915, 20m; -12.18771, 44.35929, 65m; -12.29311, 44.51090, 440m; -12.30537, 44.45031, 500m (B.L.Fisher et al.); Anjouan (Voeltzkow); Hajoho: -12.12195, 44.48795, 10m (B.L.Fisher et al.); Lac Dzialandée: -12.22474, 44.43121, 900m (B.L.Fisher et al.); Mt. Ntringui: -12.19865, 44.41866, 740m; -12.22043, 44.42924, 1225m (B.L.Fisher et al.); MAYOTTE: Reserve forestière Majimbini: -12.76796, 45.18615, 525m (B.L.Fisher et al.); Mont Combani: -12.80632, 45.15314, 370m (B.L.Fisher et al.); Baie de Tsingoni: -12.79260, 45.10764, 5m (B.L.Fisher et al.); Hajangoua: -12.85492, 45.19889, 10m (B.L.Fisher et al.); Mont Benara: -12.87585, 45.15672, 425m (B.L.Fisher et al.); Sazile: -12.97839, 45.17261, 35m (B.L.Fisher et al.); Tanaraki: -12.75754, 45.0678, 10m (B.L.Fisher et al.); Reserve forestiere Sohoa: -12.80586, 45.10054, 20m (B.L.Fisher et al.); Gorgora Kandza: -12.86735, 45.20827, 65m (B.L.Fisher et al.).

Worker measurements

(n=28). Neotype worker: HW 0.64; HL 0.61; EL 0.15; SL 0.45; WL 0.68; SPL 0.07; PTH 0.17; PTL 0.25; PTW 0.18; PPL 0.14; PPW 0.19; LHT 0.44; CI 1.05; OI 0.25; SI 0.74; SPI 0.10; PTHI 0.67; PTWI 0.73; PPI 1.41; LBI 1.53.

Other material.

HW 0.51-0.63; HL 0.49-0.62; EL 0.12-0.15; SL 0.38-0.46; WL 0.52-0.65; SPL 0.00-0.10; PTH 0.11-0.16; PTL 0.16-0.24; PTW 0.13-0.19; PPL 0.10-0.14; PPW 0.14-0.21; LHT 0.35-0.44; CI 0.99-1.07; OI 0.21-0.27; SI 0.71-0.82; SPI 0.00-0.17; PTHI 0.60-0.72; PTWI 0.65-0.93; PPI 1.21-1.62; LBI 1.26-1.56.

Diagnosis.

Workers of Crematogaster rasoherinae can be distinguished from all other Malagasy Orthocrema by the presence of small anterolateral denticles on the petiole and the rectangular shape of the same. Queens are distinct from all other species by their rectangular petiole shape. In addition, the absence of propodeal spines distinguishes Crematogaster rasoherinae queens from Crematogaster madecassa and Crematogaster razana , whereas very small size (HW 0.80-0.89, WL 1.50-1.63) and large eyes (OI 0.30-0.34) easily separate them from Crematogaster volamena and Crematogaster mpanjono .

Worker description

(Figures 24 A–F).Very small species (HW 0.51-0.64, WL 0.52-0.68). Masticatory margin of mandibles with 4 teeth; clypeus with several weak vertical carinae; posterior margin of head in full face view usually laterally rounded, sometimes medially slightly depressed; occipital carinae well pronounced; antennal scapes usually just reaching, but not surpassing posterior margin of head; midline of eyes situated well above midline of head in full face view; eyes flush with head, not notably protruding.

Promesonotum laterally subangular, with mesonotum posterolaterally slightly marginate and metanotal groove bordered by weak carinae; in lateral view outline of promesonotum moderately convex; promesonotal suture usually absent; mesonotum with or without a distinct posterior face; metanotal groove with 2-3 median carinae of varying prominence; propodeal spines short (SPI <0.17) or absent (most Comoros Isl. material), if present straight or upwards curved, in lateral view directed upwards, in dorsal view almost parallel and not diverging; dorsal face of propodeum very short; petiole in dorsal view rectangular, with dorsolateral margins weakly carinate or angular and small antero- and posterolateral denticles; subpetiolar process mostly developed as broad, rounded protuberance, sometimes as small angular dent; postpetiole more or less globular, merely impressed posteriorly, or with faint median impression; subpostpetiolar process often present as small, angular protrusion.

Head sculpture reduced, aciculate; mesosoma with promesonotum dorsally aciculate; meso- and metapleuron aciculate to areolate; propodeum with dorsal face carinulate or reticulate, posterior face shiny; dorsal face of petiole mostly reticulate; helcium dorsally finely areolate; postpetiole dorsally feebly reticulate; lateral and ventral face of petiole and postpetiole areolate or reticulate; face with 2-4 erect flexuous setae, and abundant short, subdecumbent pubescence; pronotum with 0-4 (most often 2) erect, stiff humeral setae, and 0-4 (usually 2) erect, stiff lateral setae on mesonotum, rarely also 2 erect setae present dorsally; mesosoma with scattered decumbent pubescence; petiole with a single stiff, erect seta on each posterolateral tubercle; postpetiole with a pair of erect dorsoposterior setae; abdominal tergites and sternites 4-7 with fairly abundant short erect pilosity (> 20 setae), which is more sparse on tergite 4 and usually present only towards posterior end, and with decumbent pubescence throughout.

Several color variants. Most widespread in Madagascar is a light to dark brown form; less common is a bicolored form with light brown or reddish head and mesosoma and dark gaster. On the Comoros islands, the Seychelles and Mayotte, Crematogaster rasoherinae is most often yellow or pale yellow colored, often with the posterior half of the gaster black. The typical brown Madagascar color form seems to be only present on the Seychelles.

Intermediate worker measurements

(n=10). HW 0.73-0.84, HL 0.72-0.83, EL 0.18-0.23, SL 0.49-0.56, WL 0.83-1.03, SPL 0.06-0.15, PTH 0.18-0.23, PTL 0.29-0.37, PTW 0.23-0.30, PPL 0.18-0.23, PPW 0.27-0.34, LHT 0.50-0.57, CI 1.00 -1.05, OI 0.24-0.30, SI 0.65-0.75, SPI 0.08-018, PTHI 0.56-0.67, PTWI 0.74-0.88, PPI 0.43-0.53, LBI 1.59-1.84.

Intermediate worker description

(Figures 25 A–E). Intermediate between workers and queens in size. Head, petiole and postpetiole characters similar to queens; ocelli present, but smaller than in queens; the mesonotum is to various extent raised and fused dorsally over pronotum and has wing attachment sutures; otherwise mesosomal characters more similar to worker characters, especially propodeum, and propodeal spines are present.

Queen measurements

(n=10). HW 0.80-0.89, HL 0.79-0.88, EL 0.26-0.28, SL 0.51-0.56, MSNW 0.62-0.85, MSNL 0.70-0.90, WL 1.50-1.63, SPL 0.00, PTH 0.20 -0.24, PTL 0.35-0.43, PTW 0.26-0.31, PPL 0.21-0.28, PPW 0.31-0.37, LHT 0.62-0.70, CI 0.99-1.02, OI 0.30-0.34, SI 0.62-0.66, MSNI 1.72-1.91, SPI 0.13-0.16, PTHI 0.49-0.63, PTWI 0.62-0.75, PPI 1.30-1.63, LBI 2.19-2.48.

Queen description

(Figures 26 A–C). Very small (HW 0.80-0.89, WL 1.50-1.63). With worker characters, except as follows. Masticatory margin of mandibles with 5 teeth. Antennal scapes not surpassing posterior margin of head, reaching only to about level of lateral ocelli; eyes large (OI 0.30-0.34), situated at midline of head in full face view; head shape quadrate (CI 0.99-1.02), posterior margin of head straight.

Mesosoma slender (MSNI 1.72-1.91, WL 1.50-1.63); mesoscutum in dorsal view oval, about half as wide as long; dorsal face of propodeum distinct, about half as long as posterior face; propodeal spines absent; petiole and postpetiole as in worker; anteroventral subpetiolar tooth present, but reduced with respect to worker.

Sculpture smooth and shiny throughout; erect pilosity generally more abundant, but finer than in workers: face with 4-6 longer erect setae and abundant shorter erect to suberect pilosity; mesonotum with abundant short, and scattered longer erect setae; petiole with one pair of long flexuous setae posterior to posterior denticles; postpetiole with flexuous pair of dorsoposterior setae and 2-4 additional long setae; petiole and postpetiole with abundant shorter pilosity throughout. Body color similar to respective workers.

Male measurements

(n=5). HW 0.43-0.48, HL 0.34-0.37, EL 0.19-0.22, SL 0.05-0.08, MSNW 0.43-0.53, MSNL 0.38-0.49, WL 0.64-0.80, SPL 0.00, PTH 0.11-0.13, PTL 0.15-0.19 PTW 0.10-0.14, PPL 0.15-0.19, PPW 0.15-0.19, LHT 0.31-0.34, CI 1.19-1.33, OI 0.54-0.59, SI 0.15-0.21, MSNI 1.56-1.80, SPI 0.14-0.17, PTHI 0.64-0.74, PTWI 0.54-0.83, PPI 1.38-1.55, LBI 2.07-2.42.

Male description

(Figures 25 F–H). Very small (HW 0.43-0.48, WL 0.64-0.80). Masticatory margin of mandibles with 2 teeth; eyes very large (OI 0.54-0.59) and protruding, covering most of gena, and reaching anteriorly almost to clypeal margin; antennae 9-10-segmented (separation between 3rd and 4th funicular segment often absent or incomplete), scapes very short (SI 0.15-0.21), 2nd funicular segment globular, last 2 or 3 funicular segments compressed (this may be post mortem); head strongly wider than long (CI 1.19-1.33), mostly due to lateral extent of eyes; ocellar triangle extending to posterior head margin in full face view as a crown; occipital carinae distinct.

Mesosoma fairly slender (MSNI 1.56-1.80, WL 0.64-0.80); mesoscutum in dorsal view slightly wider than long; scutellum with two distinct faces: anterior face short and steeply sloping from mesoscutum, posterior face long and flat; scutellum in dorsal view oval and posteriorly rounded, but dorsoposterior margin carinate; dorsal face of propodeum about as long as posterior face; propodeal spines absent; petiole in dorsal view more or less rectangular, but carinae or denticles absent and all margins rounded, in lateral view petiole anteriorly tapering; anteroventral subpetiolar tooth absent; postpetiole globular, but dorsally somewhat compressed and flat, median impression absent; wings clear.

Sculpture smooth and shiny throughout; face with 2 longer erect setae close to ocelli and sparse short suberect pilosity; mesoscutum with scattered short erect or suberect pilosity; longer erect pilosity present on posterior part of scutellum; petiole with one pair of fine, erect setae; postpetiole with fine dorsoposterior setae. Head medium brown, mesosoma pale yellow, metasoma light brown.

Distribution and biology.

Crematogaster rasoherinae is the most widespread species of the Malagasy Orthocrema , and in fact it is one of the most abundant Crematogaster species in Madagascar and on a number of Indian Ocean islands (Figures 26 D–F). The species is distributed throughout all native forest habitats in Madagascar - rainforest, dry or spiny forest alike - and is also found in disturbed habitats and urban areas. It has been collected at elevations up to 1225m, but appears to be more common at lower elevations. In natural habitats this species is predominantly arboreal nesting, both in dead twigs as well as in live plant parts. However, ground nesting in rotten logs or branches does occur occasionally.

Biologically Crematogaster rasoherinae is interesting because of the presence of intermediate workers (i.e., individuals intermediate between workers and queens) (Figures 25 A–E) of unknown function in the colony. I have found intermediates in all four colonies that I collected of this species, with the highest number hereby being eight individuals in one nest. In all cases a normal, dealate queen also was present in the nest. None of the intermediates observed was winged and it seems likely that they are either entirely wingless or brachypterous. Scanning electron micrographs of the lateral mesosoma (Figures 25 C and D) show the presence of a rudimentary suture above the mesopleuron where in a normal queen the forewing attaches.

Discussion.

An intriguing characteristic of Crematogaster rasoherinae is the morphological variability of this species on the Comoros Islands compared to the remainder of its distribution range. In Madagascar, the Seychelles and Mayotte this species always possesses propodeal spines. On the Comoros Islands in contrast, propodeal spines can be present (as in Figure 24B), reduced or entirely absent (as in Figure 24E). More specifically, all specimens examined from the island of Grand Comore have no, or very reduced propodeal spines, whereas on Anjouan and Moheli propodeal spines are mostly reduced or absent and present only in fewer individuals. This spine-polymorphism was presumably the basis of the description of the here synonymized Crematogaster voeltzkowi . Anjouan is the type locality for this species name and the syntype specimens represent the morphological form lacking the propodeal spines. Analysis of DNA sequence data from both the nuclear markers (see Figure 1) and ancillary mitochondrial data however clearly shows a lack of genetic divergence between the ‘armed’ and ‘unarmed’ forms in Crematogaster rasoherinae . The cause and maintenance of this intraspecific polymorphism remains to be investigated.

The syntype specimens of Crematogaster rasoherinae have been lost or destroyed during the times of World War II. Confirmation for this has been obtained via e-mail communication with the Naturhistorisches Museum Hamburg (F. Wieland, 19.vii.2011). I designate a neotype in this study to unequivocally ascertain the identity of the species Crematogaster rasoherinae , hereby selecting a worker specimen from or close to the original type locality in Madagascar, Tamatave [Toamasina, town]. In a large and taxonomically difficult genus such as Crematogaster type material is indispensable to clarify species identities. Although no closely resembling species is currently known, it is likely that a morphologically similar species could be discovered in the future, either in Madagascar or on the African mainland.