Key to Atta by Borgmeier (1959)

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Thanks to Marc Van der Stappen (Teleutotje) for the translation.

This is a translation in English of the German determination keys in :

Revision der Gattung Atta Fabricius ( Hymenoptera , Formicidae ) .

[ Revision of the genus Atta Fabricius ( Hymenoptera , Formicidae ) . ] .

Thomas Borgmeier , 1959 , Studia Ent. , vol. 2 , fasc 1 - 4 , pp. 321 - 390 .

The keys to the subgenera are on pages 335 - 336 and to the soldiers , males and queens on pages 337 - 339 .

T. Borgmeier recognizes the following 14 species in the genus Atta Fabricius 1804 :

Subgenus Atta Gonçalves 1942 s. str. : A. cephalotes ( Linn. 1758 ) , A. colombica Guérin 1845 .

Subgenus Archeatta Gonçalves 1942 : A. insularis Guérin 1845 , A. texana ( Buckley 1860 ) , A. mexicana ( Fr. Smith 1858 ) .

Subgenus Neoatta Gonçalves 1942 : A. sexdens ( Linn. 1758 ) , A. laevigata ( Fr. Smith 1858 ) , A. opaciceps Borgmeier 1939 , A. robusta Borgmeier 1939 , A. capiguara Gonçalves 1944 , A. vollenweideri Forel 1893 .

Subgenus Palaeatta Borgmeier 1950 : A. bisphaerica Forel 1908 , A. goiana Gonçalves 1942 and A. saltensis Forel 1913 .

Since then , according to the catalogue of Barry Bolton , one dubious species is poorly described but nobody , except the author , has seen the types of this species !

T. Borgmeier gave keys to the subgenera ( based on males ; less elaborated version in the key to the males . ) , to the soldiers , to the males and to the queens . I have combined the keys to the subgenera and to the males .

Soldiers :

1. Frontal area on both sides with wooly hairs ; head shining or dull ; head width 5;5 - 6;4 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cephalotes ( Linn. )
- Frontal area without wooly hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. The whole body with light colored , against the body lying pubescence ; as good as without hairs ( except clypeus , frontal carina and underside ) ; head width 4.2 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . colombica Guérin
- Body without light colored , against the body lying pubescence ; thorax always , although sometimes thinly , hairy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3. Stigmata ( tracheal openings ) on both sides of the petiole protruding , visible from above . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
- Stigmata ( tracheal openings ) on the petiole not protruding . . . . . . . . . . . . . . 6

4. Occipital lobes and first gastral segment nude , shiny ; occipital grove shallow , corner between sides more than 90 degrees ; head width 4.6 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mexicana ( Fr. Smith )
- Occipital lobes and first gastral segment with hairs ; deeper occipital grove , sides meeting less than 90 degrees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5. Thorns on mesonotum cylindrical , not pointed , shorter than those on the epinotum ; thorns on epinotum curved to the ground ; head width 5 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . insularis Guérin
- Thorns on mesonotum sharp pointed , longer than those on the epinotum ; thorns on epinotum horizontal ; head width 4.1 mm . . . . . . . . texana ( Buckley )

6. Head width 6 - 7.7 mm , length 13 - 16 mm . . . . . . . . . . . . . . . . . . . . . . . . . . 7
- Head width 4.8 - 5.4 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

7. Head polished and strongly shiny ; head width reaches 7.7 mm , total length reaches 16 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . laevigata ( Fr. Smith )
- Head not polished , weakly shining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

8. Occipital grove very deep ; head width reaches 6.4 mm . . . bisphaerica Forel
- Occipital grove shallower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

9. Gaster dull , with hairs , clearly wider than ½ head width ( 54:80 ) ; head width 6.2 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . robusta Borgmeier
- Gaster shiny , short pubescence , around ½ head width ( 45:80 ) ; head width reaches 6.2 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . opaciceps Borgmeier

10. Upper part of the head with hairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
- - Upper part of the head nude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

11. Head normally very hairy , dull ; head width 5 mm . . . . . . . sexdens ( Linn. )
- - Head with only a few hairs , almost nude , normally a little bit shiny ; head width 5.3 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . capiguara Gonçalves

12. Occipital lobes without tubercules ; postpetiole rounded , without a sharp ridge or tooth ; head width 5 mm . . . . . . . . . . . . . . . . . . . . . . . . . . saltensis Forel
- - Occipital lobes with tubercules ; postpetiole with a sharp ridge . . . . . . . . . 13

13. First gastral segment polished , practical without hairs ; head width 5.4 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vollenweideri Forel
- - First gastral segment dull , very hairy ; head width 4.8 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . goiana Gonçalves

Males :

A combination of the keys to the subgenera and to the males .

1. Stipes and squamula with an elbowed articulation , not grown together ; ventral middle ridge of the sagitta with teeth ( forming a pair of rows , they are curved and dorsal oriented ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
- Stipes and squamula fixed together , forming one structure ; ventral side of the sagitta in the middle without teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2. Frontal carina with a tooth . Squamulae dorsal , in the middle , not grown together ; sagitta on both sides with a sharp ( vertical ) ridge along its length and alongside it a curved hook or hooks . . . . . . . . . . . . . . . ( subgenus Atta s. str. ) 3
- Frontal carina without a tooth . Squamulae dorsal , in the middle , grown together ; sagitta on the sides without ridge or hooks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ( subgenus Archeatta Gonçalves ) 4

3. Squamula , seen from above , on both sides longer than broad . Side hooks of the sagitta long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cephalotes ( Linn. )
- Squamula , seen from above , on both sides as long as broad . Side hooks of the sagitta shorter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . colombica Guérin

4. Dorsal borders on the inside of the squamula straight , not curved outward . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mexicana ( Fr. Smith )
- Dorsal borders on the inside of the squamula curved outward . . . . . . . . . . . . 5

5. Outer border of the strongly downward sloping apical area of the volsella stretched out like a ridge to the back . . . . . . . . . . . . . . . . . . . . texana ( Buckley )
- Outer border of the strongly downward sloping apical area of the volsella not stretched out to the back . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . insularis Guérin

6. Sagitta with broadenings to the sides ; side borders of the sagitta turned up or folded over to the inside ; apex narrowly convex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ( subgenus Neoatta Gonçalves ) 7
- Sagitta without broadenings to the sides ; side borders of the sagitta not turned up or folded over to the inside ; apex widely convex , turned over to the front , on both sides with a fingerlike extension . . ( subgenus Palaeatta Borgmeier ) 12

7. Sagitta , seen from above , sheath-like , side parts vertical . . sexdens ( Linn. )
- Sagitta , seen from above , looking almost like a spoon , side parts forming an obtuse angle with the middle part , top borders folded over to the middle . . . . . 8

8. Apex of the sagitta not stretched out to the back above the folded-up side borders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
- Apex of the sagitta stretched out to the back above the folded-up side borders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

9. The folded-up sides borders of the sagitta short and small . Subgenital plate at the distal end curved to the inside . . . . . . . . . . . . . . . . . . . . . . robusta Bogmeier
- The folded-up sides borders of the sagitta longer and broader . Subgenital plate at the distal end straight and strongly sloping downward . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . laevigata ( Fr. Smith )

10. Sagitta broad , seen from above strongly diverging to the base ; the folded-up side borders of the sagitta on the inside not curved in . . . vollenweideri Forel
- - Sagitta smaller and longer , less strongly diverging to the base ; the folded-up side borders on the inside curved in . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

11. The folded-up side borders of the sagitta short and small ; tip of the middle part only a little protruding . . . . . . . . . . . . . . . . . . . . . . . . . opaciceps Borgmeier
- - The folded-up side borders of the sagitta long ; tip of the middle part more strongly protruding to the rear . . . . . . . . . . . . . . . . . . . . . . capiguara Gonçalves

12. Stipes , seen from above , very broad ( subapically ½ times as broad as long ) , at the apex strongly sloping downward . . . . . . . . . . . . . . . . goiana Gonçalves
- - Stipes small , apically pointed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

13. Stipes as long as the volsella ; fingerlike extensions on both sides of the apex of the sagitta short . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bisphaerica Forel
- - Stipes much shorter than the volsella ; extensions on the sides of the sagitta longer and broader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . saltensis Forel

Queens :

The queen of A. goiana Gonçalves is unknown .

1. Wing at the side of the costa with brown lines . . . . . . . . . . . . . . . . . . . . . . . . 2
- Wings at the side of the costa without brown lines . . . . . . . . . . . . . . . . . . . . . 6

2. Occipital corners without a tooth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
- Occipital corners with a tooth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3. Head width 5.2 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cephalotes ( Linn. )
- Head width 4.2 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4. Body rust yellow , with against the body lying pubescens . . colombica Guérin
- Body dark brown , with outward projecting hairs . . . . . mexicana ( Fr. Smith )

5. Scutellum with a grove . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . insularis Guérin
- Scutellum without a grove . . . . . . . . . . . . . . . . . . . . . . . . . . texana ( Buckley )

6. Gaster smoothly polished , heavily shining ; head and thorax weakly shining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . saltensis Forel
- Gaster dull or weakly shining ; head and thorax dull . . . . . . sexdens ( Linn. ) , capiguara Gonçalves , vollenweideri Forel , laevigata ( Fr. Smith ) , opaciceps Borgmeier , robusta Borgmeier and bisphaerica Forel ( T. Borgmeier didn’t succeed in the dichotomous differentiation of the queens of these species ! ) .

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