Orthocrema

This is currently a subgenus of Crematogaster. Blaimer (2012) revised the Malagasy species in this subgenus, dividing the species into two species groups.

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Crematogaster madecassa-group

 * Crematogaster madecassa
 * Crematogaster telolafy
 * Crematogaster razana

Worker diagnosis of the Crematogaster madecassa-group: Very small species (HW 0.48–0.60, WL 0.44–0.69). Masticatory margin of mandibles with 4 teeth; posterior margin of head in full face view usually laterally rounded, sometimes medially slightly depressed; occipital carinae well pronounced; antennal scape length variable; midline of eyes situated well above midline of head in full face view; eyes large (OI 0.22–0.28) and distinctly protruding.

Pronotum laterally subangular; mesonotum laterally with distinct, raised carinae that are confluent with lateral carinae bordering metanotal groove and propodeum; in lateral view outline of promesonotum moderately convex; mesonotum transversely concave, without a distinct posterior face and gradually sloping into metanotal groove; metanotal groove in dorsal view constricted by bordering lateral carinae, propodeal spines short to medium-sized (SPI 0.10–0.26), form variable; dorsal face of propodeum very short; petiole in dorsal view ovo-rectangular, with dorsolateral margins increasingly carinate posteriorly, ending in small posterolateral denticles; subpetiolar process variable: from small, but distinct and acute tooth to reduced angular dent; postpetiole globular, faintly impressed posteriorly, no trace of median impression; subpostpetiolar process present or absent.

Sculpture overall reduced; head shiny; mesosoma dorsally mostly shiny, carinulate laterally; meso- and metapleuron mostly shiny, with some reticulations; dorsal face of propodeum carinulate, posterior face shiny; dorsal face of petiole shiny; helcium dorsally carinulate; postpetiole dorsally feebly reticulate; lateral and ventral face of petiole and postpetiole reticulate; face with 4–8 erect, long flexuous setae, and abundant shorter, subdecumbent pubescence; promesonotum usually with 4–6 erect, long flexuous setae: 2 humeral setae, and 2 setae at anterior and usually also 2 setae at posterior end of mesonotal carinae; additional long erect setae, and scattered shorter erect setae may be present dorsally on promesonotum; 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, erect long pilosity (> 20 setae) and sparse decumbent pubescence throughout. Color pale to medium yellow, or yellowish-brown.

Queen diagnosis of the Crematogaster madecassa-group: (C. telolafy unknown) Very small (HW 0.80–1.10, WL 1.28–1.74). With worker characters, except as follows. Masticatory margin of mandibles with 5 teeth; antennal scapes not, or just reaching posterior margin of head; eyes large (OI 0.29–0.37) and protruding, situated slightly above midline of head in full face view; head wider than long (CI 1.11–1.21) and widest just posterior to eyes, posterior margin of head straight.

Mesosoma more compact (MSNI 1.55–1.82, WL 1.28–1.74); mesoscutum in dorsal view almost or as wide as long; dorsal face of propodeum absent, and posterior face very sharply and almost vertically sloping; propodeal spines present, much shorter than in workers (SPI 0.02–0.14), sometimes reduced to minute dents; petiole and postpetiole as in workers.

Sculpture smooth and shiny throughout, except metapleuron and anteriormost part of propodeum carinulate; erect pilosity very abundant on head, dorsal side of mesosoma and on metasoma, but finer and shorter than in workers; petiole with 1–3 pair(s) of long flexuous setae posterior to denticles; postpetiole with abundant erect pilosity. Color similar to respective workers, but often metasoma darker.

Crematogaster volamena-group

 * Crematogaster volamena
 * Crematogaster mpanjono

Worker diagnosis of the Crematogaster volamena-group: Very small to medium sized species (HW 0.51–0.98, WL 0.56–0.92). Masticatory margin of mandibles with 4 teeth; clypeus with or without several irregular vertical carinae; posterior margin of head in full face view laterally subangular, often medially slightly depressed; occipital carinae indistinct; antennal scapes just barely (small workers) or not reaching (larger workers) posterior margin of head; midline of eyes situated well above midline of head in full face view; eyes small (0.18–0.22) and fairly flush with head.

Pronotum laterally subangular; in lateral view, anterior part of mesonotum often angular or denticulate, posteriorly at least weakly carinate until meeting metanotal groove; in lateral view outline of promesonotum fairly flat; dorsal face of mesonotum flat, posterior face distinct or indistinct; metanotal groove very constricted by bordering lateral carinae, a third as wide as pronotal width; propodeal spines short (SPI 0.06–0.12), upwards directed sharp points; length of dorsal face of propodeum about a third of posterior face; petiole in dorsal view ovo-rectangular, dorsolateral margins angulate, ending in small posterolateral denticles; subpetiolar process variable, from well pronounced acute tooth to reduced angular dent; postpetiole short and broad, appearing bilobed, with diffuse, broad median impression; subpostpetiolar process absent.

Sculpture overall reduced; head shiny to aciculate; mesosoma dorsally mostly shiny, meso- and metapleuron mostly shiny, rugulose in some parts; dorsal and posterior face of propodeum shiny with some carinulae; dorsal face of petiole shiny to carinulate; helcium dorsally reticulate; postpetiole dorsally shiny; lateral and ventral face of petiole and postpetiole feebly reticulate; face with very abundant silken erect to suberect pilosity of variable length, usually hereof 6–12 longer setae; promesonotum with at least 6 erect, long flexuous setae: 2 humeral setae, 2 setae at anterior end of mesonotum and 2 setae on mesonotal tubercles or denticles; additional long erect setae, and scattered shorter erect setae may be present dorsally on promesonotum; longer, erect pilosity present or absent from propodeum; petiole with a single flexuous setae on each posterolateral tubercle; postpetiole with a pair of long flexuous dorsoposterior setae, and several shorter setae dorsally and laterally; abdominal tergites and sternites 4–7 with dense erect pilosity (> 50 setae) of medium length, interspersed with a subdecumbent shorter pubescence. Color, pale or golden yellow, or medium brown.

Queen diagnosis of the Crematogaster volamena-group: Large (HW 1.48–1.72, WL 2.61–2.70). With worker characters, except as follows. Masticatory margin of mandibles with 5 teeth. Antennal scapes not surpassing posterior margin of head, reaching to about level of median or lateral ocelli; occipital carinae well pronounced or indistinct; eyes medium-sized to large (OI 0.23–0.27), situated at midline of head in full face view; head wider than long or slightly longer than wide, posterior margin of head straight.

Mesosoma compact to slender (MSNI 1.64–1.77, WL 2.61–2.70); propodeal spines absent; petiole oval or subquadrate and lacking denticles; postpetiole broad, but lacking median impression; broad subpetiolar process present, but lacking distinct tooth.

Head sculpture aciculate or carinulate-aciculate; sculpture on mesosoma and metasoma aciculate, except dorsal face of propodeum transversely carinulate and metapleuron carinulate. Erect pilosity somewhat less abundant than in workers, but denser on mesoscutum and scutellum; petiolar and postpetiolar pilosity as in workers. Color brown with yellow markings on meso-, metasoma and legs, or reddish brown.

Nomenclature

 *  ORTHOCREMA [subgenus of Crematogaster]
 * Orthocrema Santschi, 1918d: 182 [as subgenus of Crematogaster]. Type-species: Myrmica sordidula, by original designation.
 * Orthocrema raised to genus: Soulié, 1964: 398.
 * Orthocrema junior synonym of Crematogaster: Hölldobler & Wilson, 1990: 13.
 * Orthocrema subgenus of Crematogaster: Bolton, 1995b: 40.
 * APTEROCREMA [junior synonym of Crematogaster (Orthocrema)]
 * Apterocrema Wheeler, W.M. 1936c: 45 [as subgenus of Crematogaster]. Type-species: Crematogaster (Apterocrema) atitlanica, by monotypy.
 * Apterocrema junior synonym of Orthocrema: Blaimer 2012: 52.
 * EUCREMA [junior synonym of Crematogaster (Orthocrema)]
 * Eucrema Santschi, 1918d: 182 [as subgenus of Crematogaster]. Type-species: Formica acuta, by original designation.
 * Eucrema junior synonym of Orthocrema: Blaimer 2012: 52.
 * [Emery, 1919b: 62, Emery, 1922e: 137, Soulié, 1964: 389 and Soulié, 1965: 78 incorrectly treat Eucrema as a junior synonym of subgenus Crematogaster sensu stricto. This stems from Emery's (1912d: 272) unjustified subsequent designation of Formica acuta as type-species of Crematogaster; see above under that genus.]
 * MESOCREMA [junior synonym of Crematogaster (Orthocrema)]
 * Mesocrema Santschi, 1928b: 33 [as subgenus of Crematogaster]. Type-species: Crematogaster rasoherinae, by subsequent designation of Donisthorpe, 1943f: 661.
 * Mesocrema junior synonym of Orthocrema: Blaimer 2012: 52.
 * NEOCREMA [junior synonym of Crematogaster (Orthocrema)]
 * Neocrema Santschi, 1918d: 182 [as subgenus of Crematogaster]. Type-species: Crematogaster distans, by original designation.
 * Neocrema junior synonym of Orthocrema: Emery, 1922e: 130.
 * Neocrema raised to genus: Soulié, 1964: 398.
 * Neocrema junior synonym of Crematogaster: Hölldobler & Wilson, 1990: 13.
 * Neocrema subgenus of Crematogaster: Wheeler, W.M. 1922a: 662; Kempf, 1972a: 82; Bolton, 1995b: 39.
 * Neocrema junior synonym of Orthocrema: Blaimer 2012: 52.
 * RHACHIOCREMA [junior synonym of Crematogaster (Orthocrema)]
 * Rhachiocrema Mann, 1919: 318 [as subgenus of Crematogaster]. Type-species: Crematogaster (Rhachiocrema) wheeleri, by original designation.
 * Rhachiocrema raised to genus: Soulié, 1964: 398.
 * Rhachiocrema junior synonym of Crematogaster: Hölldobler & Wilson, 1990: 13.
 * Rhachiocrema subgenus of Crematogaster: Bolton, 1995b: 45.
 * Rhachiocrema junior synonym of Orthocrema: Blaimer 2012: 52.
 * TRANOPELTOIDES [junior synonym of Crematogaster (Orthocrema)]
 * Tranopeltoides Wheeler, W.M. 1922e: 10. Type-species: Tranopelta huberi, by original designation.
 * Tranopeltoides junior synonym of Crematogaster: Kempf, 1960c: 173.
 * Tranopeltoides junior synonym of Orthocrema: Blaimer 2012: 52.

Orthocrema Diagnosis
Blaimer (2012): Diagnosis of the subgenus Orthocrema in the Malagasy region

Workers
1. Very small to medium-sized (HW 0.43–0.98, WL 0.44–0.95).

2. Antennae 11-segmented, antennal club 2-segmented.

3. Promesonotal suture absent.

4. Lateral margins of promesonotum with at least 4 long, erect setae.

5. Propodeal spiracle circular or subcircular (Figure 2).

6. Petiole in dorsal view rectangular (Figure 3) or ovo-rectangular (Figure 4A).

7. Petiole with dorsoposterior lateral denticles or tubercules that each bear an erect seta (Figures 3 and 4A).

8. Postpetiole either more or less globular (Figure 4B), without median longitudinal impression, or weakly bilobed with a broad impression (Figure 5).

9. Postpetiole with at least one pair of long, dorsoposterior setae (Figure 4B).

10. Subpetiolar process present (form variable).

11. Sculpture overall reduced, mostly aciculate, small regions areolate or reticulate.

Minimal diagnosis

A combination of characters 6, 7, 8 and 9 will unequivocally separate workers of Orthocrema species from the remaining Crematogaster species in the Malagasy region.

Queens
1. Very small to large (HW 0.73–1.72, WL 0.83–2.70).

2. Antennae 11-segmented, antennal club weakly 2-segmented.

3. Occipital carinae mostly present (Figure 6).

4. Propodeal spiracle circular (Figure 7) or subcircular.

5. Petiole in dorsal view rectangular (Figure 8A), ovo-rectangular (Figure 9A), oval (Figure 10A) or subquadrate (Figure 11A).

6. Postpetiole more or less globular, without distinct median longitudinal impression (Figures 8–11B).

Minimal diagnosis

A combination of characters 3, 5 and 6 will unequivocally separate queens of Orthocrema species from the remaining Crematogaster species in the Malagasy region.