Crematogaster malala, Blaimer, Bonnie B., 2010

Blaimer, Bonnie B., 2010, Taxonomy and Natural History of the Crematogaster (Decacrema) - group (Hymenoptera: Formicidae) in Madagascar, Zootaxa 2714, pp. 1-39 : 24-25

Crematogaster malala NEW SPECIES

( Fig. 36 & 42 )

Holotype worker. MADAGASCAR: P.C. Ankazomivady, -20.79751, 47.17910, 1782m, ex dead twig above ground, disturbed montane rainforest, B.L.Fisher et al. #20466 (CASENT0140925, specimen image on Antweb) (deposited in CASC).

Paratypes. 4w, P.N. Befotaka-Midongy, -23.84080, 46.95750, 1250m, ex dead twig above ground, montane rainforest, (B.L.Fisher et al. #15029: CASENT0193561 and CASENT0193562; #15041: CASENT0193559 and CASENT0193560) (deposited in MCZC, SAMC, MHNG, UCDC).

Material examined. ( CASC) MADAGASCAR Fianarantsoa 36km S Ambalavao, Rés. Andringitra (=P.N. Andringitra): -22.23333, 47.00000, 1925m (B.L.Fisher); P.N. Andringitra: -22.18767, 46.90083, 2150m (B.L.Fisher et al.); P.N. Befotaka-Midongy: -23.84080, 46.95750, 1250m (B.L.Fisher et al.); 28km SSW Ambositra, Ankazomivady [=P.C. Ankazomivady]: -20.77500, 47.16833, 1680m (B.L.Fisher et al.); P.C. Ankazomivady: -20.77667, 47.16500, 1780m; -20.79751, 47.17910, 1782m (B.L.Fisher et al.); R.S. Ivohibe: -22.49667, 46.95500, 1575m (B.L.Fisher et al.).

Worker measurements (n=10). HW 0.89–1.09; HL 0.80–0.99; EL 0.21–0.25; SL 0.73–0.82; WL 0.97– 1.16; SPL 0.18–0.27; PTH 0.20–0.24; PTL 0.23–0.28; PTW 0.29–0.41; PPL 0.17–0.21; PPW 0.26–0.36; LHT 0.70–0.88; CI 1.05–1.17; OI 0.24–0.28; SI 0.81–0.91; SPI 0.17–0.25, PTHI 0.84–1.00, PTWI 1.18–1.64, PPI 1.43–1.72; LBI 1.23–1.39.

Worker description. Small to medium species (HW 0.89–1.09, WL 0.97–1.16).

Masticatory margin of mandibles with 4 teeth; posterior margin of head laterally forming round corners; antennae with scapes reaching or just surpassing posterior margin; midline of eyes situated just above midline of head in full face view.

Promesonotum with laterally rounded shoulders; promesonotal suture weakly impressed, usually complete; outline of promesonotum convex in lateral view, sometimes broken by mesonotum which is often slightly raised over pronotum and forming a small antero-medial tubercle; mesonotum postero-laterally rounded or angular; propodeal spines medium sized (SPI 0.17–0.25), less than half the width between their bases, evenly tapering, from straight to weakly curved, and in dorsal view weakly diverging; petiole in dorsal view trapezoidal, anteriorly flared into rounded lobes, dorso-lateral margins carinate, terminating in a small postero-lateral tubercle; subpetiolar process present as a long, moderately acute antero-ventral tooth; postpetiole distinctly bilobed and broadly medially impressed.

Head sculpture reduced, usually aciculate; mesosoma with meso-and metapleuron carinulate or costulate; dorsal face of propodeum weakly costulate to reticulate; posterior face largely shiny; rest of mesosoma including legs largely aciculate; dorsal face of petiole mostly shiny; postpetiole dorsally feebly reticulate; lateral and ventral face of petiole and postpetiole coarsely rugulose-reticulate; helcium dorsally carinulate; face with 2–4 erect setae; pilosity on dorsum of mesosoma 2–4 erect humeral setae, rarely one pair of erect setae at base of mesonotal tubercules; a pair of stiff, long, erect setae present on postero-lateral tubercles of petiole; dorso-posterior erect setae also present on postpetiole; abdominal tergites 4–7 with scattered erect pilosity.

Colour light to dark brown, mesosoma usually lighter coloured than head and metasoma.

Variation. Workers from the Midongy region are darker coloured than from P.C. Ankazomivady and P.N. Andringitra localities and have a denser appressed pubescence. The mesonotum is often more prominently raised over the pronotum in the P.C. Ankazomivady and P.N. Midongy material, than in workers from the other locations.

Comments. Crematogaster malala is characterized by a combination of the following features. The petiole has postero-lateral tubercles that each bear a single, stiff and long erect seta. The postpetiole is distinctly bilobed and broadly medially impressed and also bears a pair of dorso-posterior stiff, long erect setae. These characters, together with the erect pilosity on abdominal tergites 4–7 and the 4 mandibular teeth, are shared with C. grevei . In distinction to C. grevei however the lateral portions of the promesonotum in C. malala are not raised with respect to the median portion and are postero-lateral rounded or angular. The metanotal groove further lacks lateral carinae and the promesonotum forms a convex outline in lateral view. In molecular phylogenetic analyses this species is well supported as a distinct clade by both nuclear and mitochondrial data, and results suggest it is the sister taxon to the rest of the Malagasy Decacrema species.

Distribution and biology. Collections of this species are rare, with a few colonies from three locations of higher elevation rainforests (> 1250m) in the Ankaratra (Ankazomivady), Andringitra and Midongy massifs ( Fig. 56 ). The isolated, montane distribution invites speculation that glacial cycles have played an important role in shaping this species’ evolutionary history and distribution, as has been suggested for other taxa in Madagascar (for an overview see Vences et al., 2009). Next to nothing is known about the biology of this species. Fisher’s collections of C. malala workers document these ants as nesting in dead twigs (n=4) and in carton nests (n=1); queens or males of this species have not yet been discovered. A recent search for C. malala in the P.N. Andringitra at about 1800m, not far from where it had been collected before, was unsuccessful and suggests that these ants might be highly restricted in habitat and possess inconspicuous life habits.

Etymology. This species’ name is derived from the Malagasy adjective “ malala ”, meaning “the beloved one”, inspired by happiness about the discovery of its morphological distinctness compared to the other species in the group.

Figures

FIGURES 32 – 37. Malagasy Crematogaster (Decacrema) species; a: full-face view, b: lateral view, c: dorsal view. 32: C. nosibeensis; 33: C. sisa; 34: C. sabatra; 35: C. mahery; 36: C. malala; 37: C. grevei.

FIGURES 38 – 43. Malagasy Crematogaster (Decacrema) species; a: petiole & postpetiole in dorsal view, b: petiole & postpetiole in lateral view. 38: C. nosibeensis; 39: C. sisa, 40: C. sabatra; 41: C. mahery; 42: C. malala; 43: C. grevei.

FIGURES 54 – 57. Distributions of Malagasy Crematogaster (Decacrema). 54: C. grevei; 55: C. mahery; 56: C. malala; 57: C. nosibeensis.