Key to Malagasy Strumigenys

This worker key is based on: Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.

This key is from a revision that included the now synonymized genus Pyramica. Therefore there are two keys that treat two sets of Strumigenys species, the key found below and a key to Malagasy Pyramica.

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Strumigenys

1

 * With head in full-face view a preocular notch present, the ventrolateral margin of the head notched or indented immediately in front of the eye. With head in profile the preocular notch seen to continue vertically as a groove in the side of the head that extends towards the dorsal outline; in the same view preocular notch also seen to extend onto the ventral surface of the head as a transverse preocular groove that runs towards but does not reach the midline. An extremely deep and sharply defined post-buccal groove also present, extending across entire width of head immediately posterior of buccal cavity; postbuccal groove sharply separated from ventral preocular groove . . . . . 2


 * With head in full-face view a preocular notch absent, the ventrolateral margin of the head continuous to the anterior margin of the eye, without trace of a notch or indentation immediately in front of the eye. With head in profile side in front of eye without a vertical groove that extends towards the dorsal outline; in the same view without a transverse preocular groove on the ventral surface of the head. Postbuccal groove vestigial or at most a shallow transverse impression immediately posterior of buccal cavity . . . . . 23

2
return to couplet #1
 * With head in profile, upper scrobe margin ending, or at least becoming extremely indistinct, at about the level of the eye . . . . . 3


 * With head in profile, scrobe, and its dorsal margin, extending posteriorly well beyond level of eye . . . . . 9

3
return to couplet #2
 * Preapical teeth absent or at most a small spiniform denticle may be present immediately basal of apicodorsal tooth on right mandible. Apical fork of mandible subtended by a third, shorter spiniform tooth . . . . . 4


 * Preapical teeth present. Apical fork of mandible not subtended by a third spiniform tooth; at most the apicoventral tooth may have a minute spur or denticle at its ventral base . . . . . 7

4
return to couplet #3
 * With head in profile preocular groove meets and is interrupted by the upper scrobe margin before reaching the cephalic dorsum. Scapes relatively shorter, SI 78-86 . . . . . 5


 * With head in profile preocular groove extends uninterrupted to the cephalic dorsum, and is not interrupted by the upper scrobe margin. Scapes relatively longer, SI 91-132 . . . . . 6

5
return to couplet #4
 * Mesonotum with 1 pair of erect hairs on anterior margin. Cephalic dorsum with a transverse row of four erect hairs immediately in front of occipital margin . . . . . Strumigenys actis


 * Mesonotum with 2 pairs of erect hairs (can be worn). Cephalic dorsum with a transverse row of six erect hairs immediately in front of occipital margin . . . . . Strumigenys ampyx

6
return to couplet #4
 * Propodeal spines shorter, length of spine about equal to distance between bases of spines, distance between bases of spines measured distal to basal curvature. Dorsum of head sharply depressed behind vertex, forming a very shallow concave impression before occipital angles; in profile, outline of dorsal margin of occipital corners almost flat. Scapes relatively shorter, SI 91-106 . . . . . Strumigenys chilo


 * Propodeal spines long, much longer than distance between bases of spines. Dorsum of head evenly and gradually curved from vertex to posterior margin of occipital corner; in profile, outline of dorsal margin of occipital corners continuously and gradually curved, not flat. Scapes relatively longer, SI 115-132 . . . . . Strumigenys bibiolona

7
return to couplet #3
 * Large species, HL 1.25-1.45, HW 0.97-1.14. Mandible with truncated preapical teeth. Pronotal humeral hair absent. First gastral tergite and sternite without punctate sculpture or at most merely the extreme base of the tergite punctate, the sternite always smooth . . . . . Strumigenys grandidieri


 * Smaller species, HL 0.70-0.75, HW 0.55-0.59. Mandible with spiniform preapical teeth. Pronotal humeral hair present, stiff. First gastral tergite and sternite densely punctate over the anterior half or more of each sclerite . . . . . 8

8
return to couplet #7
 * Dorsum of petiole with at least 3 pairs of hairs. Propodeal spines broadly triangular. Propodeal declivity with a standing, posteriorly projecting hair at centre of lateral margin. Katepisternum smooth and shiny. Colour chocolate brown . . . . . Strumigenys dora


 * Dorsum of petiole with one pair of hairs. Propodeal spines narrowly triangular and almost spiniform. Propodeal declivity without standing hairs. Katepisternum reticulate-punctate. Colour orange brown . . . . . Strumigenys fanano

9
return to couplet #2
 * In full-face view apical portion of the inner margin of the mandible concave or scooped out. Mandible without defined preapical teeth; a rounded tumulus or rarely a minute acute denticle may be present on the proximal apex of the preapical concavity . . . . . Strumigenys dicomas


 * In full-face view apical portion of the inner margin of the mandible not scooped out or concave. Mandible with 1 or more sharply defined acute preapical teeth and/or denticles . . . . . 10

10
return to couplet #9
 * Left mandible with 2 preapical teeth and/or denticles . . . . . 11


 * Left mandible with 1 preapical tooth or denticle . . . . . 17