Key to Metapone of Asia

This queen key is based on: Taylor, R. W. and G. D. Alpert, G. D. 2016. The myrmicine ant genus Metapone Forel (Hymenoptera: Formicidae): a global taxonomic review with descriptions of twelve new species. Zootaxa. 4105(6):501-545.:

Nine nominal species are reported: two from Luzon, Philippines—one of them also from Negros, and one each from Sri Lanka, Taiwan, Sumatra and Great Nicobar Island, Sarawak, Sabah, Java, Bali and Lombok. Metapone hewitti (Sarawak) is male-based. Gynes are known for all species, workers additionally for four. Metapone is not (yet) known from subcontinental India, mainland Southeast Asia or China, though it is likely present in all three areas.

This key is of necessity based largely on the characters of gynes. It emphasizes features which we believe will also enable identification of worker specimens. The male-based M. hewitti is not included.

1

All body surfaces smooth, shining, very highly reflective, with at most a few extremely obscure, minute, generally ripple-like apparent vestiges of longitudinal striation. Head relatively broad (CI of only known specimen 91); clypeal outline in frontal view broadly semicircular. (Philippines: Luzon, gyne) . . . . . Metapone bakeri

Dorsal and lateral surfaces of head and mesosoma densely, finely, longitudinally striate. Known CI values less than 76. Clypeus differently structured . . . . . 2

2

return to couplet #1

Median section of clypeus extended forwards beyond the lateral sections to form a more-or-less proboscis-like structure which lacks median denticles (well-separated denticles at either end of the anterior border may be present) . . . . . 3

Median section of clypeus not protruding forward beyond its lateral sections, the anterior border with a pair of small approximate median denticles . . . . . 8

3

return to couplet #2

Head relatively narrow (HW 1.54, CI 68). Petiolar node in dorsal view more than twice as long as wide, with strong posterolateral tooth-like projections. Subpetiolar extension a long, low subrectangular, translucent lamina extending back almost to the subpetiolar angle; the latter acutely spine-like in lateral view. (Taiwan, gyne only) . . . . . Metapone sauteri

Species from distant other areas (Sri Lanka, Philippines, Indonesia). HW usually well less than in the alternative prescription and/or CI with a higher value. Petiolar proportions and subpetiolar configuration clearly dissimilar . . . . . 4

4

return to couplet #3

Subpetiolar process unusually configured. In lateral view the much-reduced longitudinal, acutely triangular posterior face (which lacks a framing lamella) so strongly inclined forwards that its profile almost aligns with the adjacent subpetiolar edge. The subpetiolar angle extended ventrally as a relatively large, acutely erect spine-like process, well separated from the more anterior, small, vertically tabulate, translucent subpetiolar extension, the posterior apex of which is hook-like, inclined posteriorly (Indonesia: Java, worker only) . . . . . Metapone javana

Petiolar sternite differently constructed: subpetiolar angle usually (not always) distinct, not spinosly extended; subpetiolar extension usually differently constructed: relatively large, or small and triangular . . . . . 5

5

return to couplet #4

Posterior face of subpetiolar process relatively large, with a translucent framing lamella clearly evident in profile view. Subpetiolar angle distinct, in lateral view slightly extended as a pointed process, partly including the framing lamella. Petiolar node in dorsal view approximately subquadrate . . . . . 6

Posterior face of subpetiolar process reduced; subpetiolar angle either rounded in lateral view, with the reduced profile of the posterior face grading smoothly into the profile of the subpetiolar edge; or without clear presence of a subpetiolar angle, so that the subpetiolar edge in effect continues directly to the posterior base of the sternites . . . . . 7

6

return to couplet #5

Subpetiolar extension relatively large, longitudinally subrectangular with minutely rounded corners; its base almost as long as the ventral subpetiolar edge. (Sri Lanka, gyne & worker) . . . . . Metapone greeni

Subpetiolar extension a small, sub-rectangular, barely translucent plate with its posterolateral corner extended to form a more-or less hook-like structure; its base about half as long as the ventral subpetiolar edge (Malaysia: Sabah, gyne & worker) . . . . . Metapone quadridentata

7

return to couplet #5

Anterior border of median clypeal projection subtended by a minute parallel groove bearing a rank of about 6 stout, forwardly-directed pale bristle-like hairs. Outline of anterior clypeal border above the groove shallowly rounded/convex in frontal view, the edge below the groove with a small tooth-like terminal angle on each side. Subpetiolar extension a dependant subrectangular, posteriorly inclined, relatively large tab, more-or-less transversely rectangular in shape. (Indonesia: Bali, gyne only) . . . . . Metapone balinensis

Anterior border of anteromedian clypeal process a single shallowly concave edge without an accompanying groove or hairline; anterolateral corners subdentate. Subpetiolar extension a small approximately right-angled triangle. (Indonesia: Lombok, gyne only) . . . . . Metapone wallaceana

8

return to couplet #2

Larger species, HW of 2 known gynes 1.00–1.04mm. (Indonesia: Sumatra, gyne only) . . . . . Metapone jacobsoni

Smaller species, HW of 2 known gynes 0.95, 0.98mm. (Philippines: Luzon, Negros, gyne only) . . . . . Metapone gracilis