Key to Metapone of the Pacific Islands

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This worker 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.

Seven species are reported, with five described as new; four are from mainland New Guinea (one known also from New Britain and Micronesia) and one each from New Ireland, Guadalcanal (Solomon Islands), and Viti Levu (Fiji). Gynes and workers are known for one species, gynes alone for 4 and workers alone for 2. All Pacific records east of New Guinea are based on gyne specimens. Metapone truki is a possible tramp species, reported here from scattered localities in Micronesia, Indonesian West Papua, mainland Papua New Guinea and New Britain. This set includes both the gyne-based largest and smallest known Metapone species: Metapone titan and Metapone salomonis.

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Metapone

1

  • Subpetiolar extension a narrow, hook-like process, its base occupying less-than one-quarter of the subpetiolar edge in lateral view . . . . . 2
  • Subpetiolar extension an expansive triangular or rounded/subrectangular process, its base occupying at least half the subpetiolar edge in lateral view . . . . . 3

2

return to couplet #1

  • The largest known Metapone species (gyne HW 2.3–2.5 mm, TL ca. 14–16 mm). Clypeal rostrum relatively very large and broad, projecting ca 0.68x its apical width beyond the lateral sections of the clypeus in frontal view (Papua New Guinea: New Ireland, gyne only) . . . . . Metapone titan
  • Smaller species (known HW 1.28mm, TL ca 7.5 mm). Clypeal rostrum smaller, projecting ca 0.44x its apical width beyond the lateral sections of the clypeus in frontal view. (mainland Papua New Guinea, worker only) . . . . . Metapone philwardi
Taylor, Alpert 2016 Metapone-31 101.jpg
Taylor, Alpert 2016 Metapone-31 102.jpg

3

return to couplet #1

  • Clypeus apically rostrate, with a strong proboscis-like median extension projecting well beyond its lateral sections . . . . . 4
  • Clypeus projecting but barely rostrate, median apical section only slightly advanced beyond lateral sections, anterior border with an apical median, tab-like projection, a little narrower than the body of the sclerite, to which it is stepped on either side . . . . . 6

4

return to couplet #3

  • Smaller species (HW 0.87mm). (Solomon Islands: San Cristobal, gyne only) . . . . . Metapone salomonis
  • Generally larger species HW 0.85–1.22mm (Micronesia, New Guinea, New Britain) . . . . . 5

5

return to couplet #4 (In gynes & workers) Frons, cheeks, clypeus, promesonotal dorsum and sides of pronotum and petiole distinctly and regularly longitudinally or diagonally finely striate. Clypeal projection relatively a little shorter and narrower than in the alternative. Petiolar node relatively short and narrow. Apex of subpetiolar extension inclined posteriorly, broadly rounded (Micronesia, mainland New Guinea, New Britain, gyne and worker) . . . . . Metapone krombeini

Taylor,-Alpert-2016-Metapone-13-43-76.jpg
Taylor,-Alpert-2016-Metapone-27-77.jpg
  • (In gynes & workers) Striae in relevant areas less-strongly developed and less-regular; partly effaced, especially on frons and cheeks. Clypeal proboscis relatively short and broad. Petiole relatively short in lateral and dorsal view. Subpetiolar extension similar to alternative, but with its apex acutely pointed (mainland New Guinea, gyne and worker) . . . . . Metapone truki
Metapone truki casent0006672 head 1.jpg
Metapone truki casent0006672 profile 1.jpg

6

return to couplet #3

  • Larger species (HW 1.48 mm, TL ca 8.8mm (N=1). Subpetiolar extension subrectangular, ca twice as long as deep, the outer corners minutely rounded (New Guinea, Gyne only) . . . . . Metapone enigmatica
  • Smaller species (HW 1.02–1.09mm, TL ca 7.1–7.4mm). Subpetiolar extension an approximately equilateral triangle, inclined posteriorly (Fiji: Viti Levu, gyne only) . . . . . Metapone manni