MADAGASCAR: Antsiranana: R.S. Manongarivo: -13.96167, 48.43333, 400m, rainforest, beating low vegetation, 18.xi.1998, B.L.Fisher.

holotype worker: pinned, CASENT0193889, BLF01998(12)-1; original locality label: MADG’R: Prov. Antsiranana: R.S. Manongarivo 10.8km 229°SW Antanambao 400m 13°57.7'S, 48°26.0'E, 18.xi.1998, B.L.Fisher#1998(12)-1; deposited at CASC.

(CASC)

MADAGASCAR: Antsiranana: R.S. Manongarivo: -13.96167, 48.43333, 400m (B.L.Fisher); Nosy Bé, R.N.I. Lokobé: -13.41944, 48.33117, 30m (B.L.Fisher et al.); Nosy Bé, Antsirambazaha: -13.41345, 48.31130, 143m (Lees & Ranaivosolo); Toamasina: F Ambohidena [Ile St.Marie]: -16.82433, 49.96417, 20m (B.L.Fisher et al.).

(n=4). Holotype: HW 0.61; HL 0.56; EL 0.11; SL 0.48; WL 0.65; SPL 0.06; PTH 0.15; PTL 0.22; PTW 0.19; PPL 0.13; PPW 0.21; LHT 0.46; CI 1.09; OI 0.20; SI 0.85; SPI 0.09; PTHI 0.69; PTWI 0.88; PPI 1.62; LBI 1.40.

HW 0.51–0.78; HL 0.51–0.78; EL 0.10–0.15; SL 0.43–0.54; WL 0.56–0.86; SPL 0.04–0.05; PTH 0.11–0.16; PTL 0.17–0.27; PTW 0.16–0.23; PPL 0.09–0.15; PPW 0.19–0.22; LHT 0.39–0.56; CI 1.02–1.04; OI 0.19–0.20; SI 0.72–0.85; SPI 0.06–0.07; PTHI 0.60–0.63; PTWI 0.87–1.03; PPI 1.46–2.03; LBI 1.42–1.52.

Workers of Crematogaster mpanjono are diagnosed from all Malagasy Orthocrema, except the closely related Crematogaster volamena, by a combination of the following: indistinct occipital carinae (Figure 14), non-protruding and small eyes and the absence of raised, sharp lateral carinae on the propodeum (Figure 15). All these characteristics are shared with the much more common Crematogaster volamena, from which it cannot be distinguished reliably based on the worker caste. Crematogaster mpanjono has slightly shorter propodeal spines than Crematogaster volamena, and often a long erect pilosity is present on the propodeum. The distributions of these two species (compare Figures 32F and 33D) aid in distinguishing between them, as they are not known to co-occur. Queens of Crematogaster mpanjono are easily separated from Crematogaster volamena queens by virtue of the scuto-scutellar suture that is acutely meeting the mesoscutum (Figure 23, compare with Figure 21) and the indistinct occipital carinae. From the remaining Malagasy Orthocrema queens, Crematogaster mpanjono queens are diagnosable by the absence of propodeal spines and by their larger size (HW 1.48, WL 2.70).

(Figures 33A–C).Very small to small species (HW 0.51–0.78, WL 0.56–0.86), with characters of the Crematogaster volamena-group, in addition to the following. Clypeus with or without several short vertical carinae.

Mesonotum usually denticulate, then weakly carinate until meeting metanotal groove; posterior face of mesonotum indistinct, gradually sloping into metanotal groove.

Head sculpture shiny to aciculate; propodeum often with longer erect pilosity. Color yellow to pale yellow.

(n=1). HW 1.48, HL 1.52, EL 0.42, SL 0.81, MSNW 1.04, MSNL 1.53, WL 2.70, SPL 0.00, PTH 0.39, PTL 0.51, PTW 0.51, PPL 0.39, PPW 0.53, LHT 1.07, CI 0.96, OI 0.27, SI 0.53, MSNI 1.77, SPI 0.00, PTHI 0.78, PTWI 1.01, PPI 1.35, LBI 2.52.

(Figures 33E–G). Medium-sized (HW 1.48, WL 2.70), with characters of the Crematogaster volamena-group, in addition to the following. Antennal scapes reaching to about level of lateral ocelli; occipital carinae indistinct; eyes larger (OI 0.27); head slightly longer than wider (CI 0.96).

Mesosoma slender (MSNI 1.77, WL 2.70); mesoscutum in dorsal view elongate; scuto-scutellar suture acutely meeting mesoscutum; dorsal face of propodeum about as long as posterior face, the latter sloping abruptly; petiole subquadrate.

Head sculpture mostly aciculate, carinulate below eyes. Color reddish brown.

Male unknown.

Only one nest collection of this species (a queen and a nanitic worker) from an arboreal root pocket exists. Therefore next to nothing is known about the biology of Crematogaster mpanjono. The known distribution records of this rare ant show a macrohabitat preference for lowland rainforests of the north-western Sambirano region (Nosy Bé, R.S. Manongarivo) or eastern littoral rainforest (F Ambohidena) (Figure 33D). These disjunct records from north-western Madagascar and the east coast island Ile St.Marie are peculiar and could point to incomplete distribution records for this species. In any case, although the Ambohidena population has not been sampled for nuclear genetic data, the conspecificity of these disjunct populations is supported by the COI barcoding data. Crematogaster mpanjono occurs in sympatry with the widespread Crematogaster rasoherinae and Crematogaster madecassa.

The Malagasy word “mpanjono” means “fisher “or “fisherman”. The name for this rare ant species is dedicated to B. L. Fisher and his ant diversity and conservation efforts in Madagascar. This name should be treated as a noun in apposition.