Acanthomyrmex basispinosus

The type material was found in rotten wood in a rainforest.

Identification
Moffett (1986) - Propodeal spines of both castes with distinctive widened bases; postpetiole narrow, much wider than long in dorsal view.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia, Sulawesi.

Nomenclature

 * . Acanthomyrmex basispinosus Moffett, 1986c: 67, figs. 8A, 9-14 (s.w.) INDONESIA (Sulawesi).
 * Type-material: holotype minor worker, 2 paratype major workers, 5 paratype minor workers.
 * Type-locality: holotype Indonesia: SE Sulawesi, 1-2 km. E Wolasi, 42 km. S Kendari, ca 350 m., 13-14.vii.1972, W-46, rotten wood, rainforest (W.L. Brown); paratypes with same data.
 * Type-depository: MCZC (holotype); BMNH, MCZC (paratypes).
 * Status as species: Bolton, 1995b: 53; Yamada, Ito, et al. 2018: 10.
 * Distribution: Indonesia (Sulawesi).

Worker
Minor. Holotype (HW 1.08) and five minor worker paratypes measure HW 0.98 to 1.13, HL 0.95 to 1.08 (CI 103 to 105), ML 0.18 to 0.19 (MI 72 to 77), SL 1.06 to 1.20 (SI 97 to 115), EL 0.21 to 0.23, HFL 1.28 to 1.39 (FLI 124 to 136; EWI 16 to 17) mm. Head strongly concave across posterior margin in full-face view, and thus similar in shape to Acanthomyrmex luciolae and concavus, except less broad (CI < 120), and lateral margins relatively more convex; widest above eyes. Head with rounded, thick-walled foveae (although foveae near scrobe, on side of head and on vertex with thinner walls, and thus approach the condition described for Acanthomyrmex ferox). Dorsum of head with longest hairs extending about 0.18 mm. As in Acanthomyrmex notabilis, short but conspicuous wide sulcus present mesad between the eyes above the frontal area (traces of such a sulcus present in some A. luciolae, Acanthomyrmex crassispinus and Acanthomyrmex concavus specimens). Clypeal index 102 to 110. Lobe to each side of medial clypeal hair moderately to strongly produced; lateral clypeal hairs in a completely enclosed fovea. Rugum extending back across clypeus from each of these medial clypeal lobes present, though poorly developed. Mandibles lacking a ventral tooth.

Spines on trunk virtually straight. Propodeal spines somewhat longer than those on pronotum; in the two largest specimens (HW for both 1.13 mm) propodeal spines considerably longer, as pronotal spines are very short and stubby. Propodeal spines with a distinctive widened base in profile. Pronotal spines without conspicuous hairs. Pronotal angle abrupt but not forming a feeble tooth. Propodeal declivity bordered on each side by two adjacent rugae, which extend down from base of each propodeal spine (second rugum feeble).

Node of petiole as in figure, without sharp lateral denticles; PWI intermediate (79 to 84). Anterior peduncle of petiole long and narrow, with the lateral hairs present and sublateral hairs lacking; subpetiolar declivity absent. Postpetiole narrow, almost twice as wide as it is long in dorsal view, and with a high, narrow node; thus the postpetiole resembles that of A. notabilis. Femora with scattered hairs, and conspicuously concave beneath; hind femora relatively slender (FWI < 18). Color orange yellow or reddish yellow, legs lighter yellow.

Major. The two paratypes measure HW 2.10 to 2.18, HL 2.17 to 2.24 (CI 97), SL 1.18 (SI 54 to 56), EL 0.28, HFL 1.40 to 1.44 (FLI 64; FWI 16) mm. Foveae on head denser, more deeply impressed, and somewhat larger than in A. crassispina and Acanthomyrmex dusun. Without a distinct cephalic hollow. Long feeble darkly pigmented medial streak dorsad on head; wide medial sulcus conspicuous on frons. Clypeal index larger than in minors: 126 and 139. Forward margin of clypeus lacking a medial projection (but with two feeble, rounded lobes medially). Propodeal spines as described for minor worker.

Type Material
Holotype. Minor worker deposited in from Indonesia: S.E. Sulawesi: 1-2 km east of Wolasi, 42 km south of Kendari, ca. 350 m, rotten wood in rainforest, W-46, 13-14 July 1972 (W. L. Brown, Jr. [examined]). Paratypes. Two majors and five minors, same date and collection number as holotype (MCZ, ).

Etymology
Name derived from Latin basis + spina, referring to the widened bases of the propodeal spines.

References based on Global Ant Biodiversity Informatics

 * Janda M. Personal communication. 20 August 2010.
 * Moffett, M. 1986. Revision of the myrmicinae genus Acanthomyrmex (Hymenoptera: Formicidae). Bulletin of the Museum of Comparative Zoology 151(2): 55-89
 * Moffett, M. 1986. Revision of the myrmicinae genus Acanthomyrmex (Hymenoptera: Formicidae). Bulletin of the Museum of Comparative Zoology 151(2):55-89.
 * Moffett, M. W. 1986. Revision of the myrmicine genus Acanthomyrmex (Hymenoptera: Formicidae). Bulletin of the Museum of Comparative Zoology 151:55-89.
 * Woodcock P., D. P. Edwards, T. M. Fayle, R. J. Newton, C. Vun Khen, S. H. Bottrell, and K. C. Hamer. 2011. The conservation value of South East Asia's highly degraded forests: evidence from leaf-litter ants. Phil. Trans. R. Soc. B. 366: 3256-3264.
 * Woodcock P., D.P. Edwards, T.M. Fayle, R.J. Newton, C. Vun Khen, S.H. Bottrell, and K.C. Hamer. 2011. The conservation value of South East Asia's highly degraded forests: evidence from leaf-litter ants. Phil. Trans. R. Soc. B 366: 3256-3264.