Crematogaster malahelo

Crematogaster malahelo is a rare species endemic to montane forest of the central highlands in Madagascar. It has been collected from only three locations, all of which harbor unprotected, rather disturbed forest fragments (SF Manjakatompo, Andranorovitra, Kaloy). Given this restricted distribution the species is exclusively sympatric with Crematogaster mafybe and allopatric with the rest of the C. degeeri-assemblage. The few collections have been made from dead twigs above the ground, indicating arboreal nesting preferences. (Blaimer and Fisher 2013)

Identification
Blaimer and Fisher (2013) - Crematogaster degeeri assemblage. Workers of Crematogaster malahelo can usually be distinguished from other species in the C. degeeri-assemblage given the characteristic promesonotal structure with a propodeum usually distinctly set off from the promesonotum in lateral view. Crematogaster alafara could cause possible confusion with this species, but C. malahelo bears sharp lateral margins on the pronotum (absent in C. alafara) and has shorter, triangular spines (SPI 0.03-0.07).

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Castes
Known only from the worker caste.

Nomenclature

 *  malahelo. Crematogaster malahelo Blaimer, in Blaimer & Fisher, 2013: 44, fig. 17 (w.) MADAGASCAR.

Worker
(n = 10) [holotype] HW 0.86-1.03 [0.93]; HL 0.80-0.94 [0.80]; EL 0.18-0.24 [0.20]; SL 0.63-0.71 [0.63]; WL 0.92-1.08 [0.94]; SPL 0.03-0.07 [0.05]; PTH 0.19-0.25 [0.21]; PTL 0.25-0.31 [0.29]; PTW 0.33- 0.43 [0.43]; PPL 0.15-0.20 [0.17]; PPW 0.28-0.37 [0.34]; LHT 0.64-0.77 [0.67]; CI 1.03-1.16 [1.16]; OI 0.22-0.26 [0.25]; SI 0.74-0.80 [0.79]; SPI 0.03-0.07[0.06]; PTHI 0.66-0.82 [0.72]; PTWI 1.24-1.52 [1.52]; PPI 1.71-2.04 [2.04]; LBI 1.36-1.53 [1.40].

Small to medium size (HW 0.86-1.03, WL 0.92-1.08). Masticatory margin of mandibles with four teeth; head shape fairly quadrate or slightly wider than long (CI 1.03-1.16); posterior margin of head in full-face view laterally subangular or rounded, sometimes slightly medially depressed; occipital carinae distinct; antennal scapes usually about reaching or surpassing head margin; midline of eyes situated at or slightly above midline of head in full-face view; eyes moderately large (OI 0.22-0.26), slightly protruding. Pronotum laterally angular, with sharp, raised margins; promesonotal suture indistinct, mesonotum more or less forming one plane with pronotum, but often the two separated by distinct variation in sculpture (see below); mesonotum usually without a distinct posterior face; laterally mesonotum angular to carinate, often with posterolateral denticles setting off the promesonotum distinctly from propodeum; metanotal groove fairly shallow, laterally constricted; propodeal spines very short (SPI 0.03-0.07), triangular dents or spines; dorsal face of propodeum distinct, convex; posterior face of propodeum steeply sloping; petiole in dorsal view from broadly to strongly flared and usually strongly concave, dorsolaterally carinate but without posterolateral tubercules or denticles; subpetiolar process usually present as small rounded tooth; postpetiole wider than long, very distinctly bilobed, with broad median impression; subpostpetiolar process absent. Head sculpture shiny to aciculate; pronotum dorsally costulate and contrasting abruptly with a shiny to aciculate mesonotum; dorsal face of propodeum carinulate or reticulate; rest of mesosoma, petiole and postpetiole aciculate to reticulate; face usually with < four erect, longer setae, and regular, shorter, appressed to suberect pubescence; promesonotum usually with < eight erect, long setae; otherwise promesonotum dorsally with sparse appressed to subdecumbent pubescence; petiole and postpetiole usually with a pair of short, erect setae posterolaterally, and shorter suberect, decumbent or appressed pubescence; abdominal tergites four to seven with sparse, short, erect pilosity, more abundant and longer on sternites four to seven, and regular appressed to decumbent pubescence throughout. Color reddish brown to dark brown.

Type Material
Holotype Worker: pinned, CASENT0317768, BLF17431, ex dead twig above ground [imaged on AntWeb]; original locality label: MADG’R: Kaloy, 1423 m, 18º35.39’S, 47º39.06’E, 27 Apr. 2007, disturbed montane rainforest, Fisher et al., BLF#; deposited at. Paratypes 4 workers, pinned. #1: CASENT0317767, deposited at. #2: CASENT0317769, deposited at. #3: CASENT0317770, deposited at. #4: CASENT0317771, deposited at. #1 and # 2 same collection and locality data as holotype. #3 and #4: BBB004, on tree trunk, Station Forestière Manjakatompo, -19.37083, 47.33900, 1575 m, disturbed montane rainforest, 31 Mar. 2007, B.B.Blaimer. MADAGASCAR: Antananarivo: Kaloy: -18.58998, 47.65102, 1423 m, disturbed montane rainforest.

Etymology
The Malagasy word malahelo means “sad.” This name alludes to the rather sad fact that all three of the montane rainforest locations where this species is known to occur is heavily disturbed. The name is treated as noun in apposition.

References based on Global Ant Biodiversity Informatics

 * Blaimer B. B., and B. L. Fisher. 2013. Taxonomy of the Crematogaster degeeri-species-assemblage in the Malagasy region (Hymenoptera: Formicidae). European Journal of Taxonomy 51: 1-64.