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Key to Nesomyrmex species of Neotropical region
Key to Neotropical species of Nesomyrmex based on Kempf (1959).
- The species Nesomyrmex tonsuratus and Nesomyrmex clavipilis are not included as they are known only from queens.
- Nesomyrmex iku, Nesomyrmex konina and Nesomyrmex xerophilus are not included as they were described after this key was published. See Arredondo & Guerrero's (2025) Key to Colombian Nesomyrmex species.
1
2
- Antennal scapes in repose attaining or surpassing the occipital margin; larger species, thorax length 1.4 mm or more => 3
- Antennal cales in repose failing to attain the occipital margin; smaller species, thorax length 1.3 mm or less => 5
3
- Humeri or pronotum obtusely angulate, almost rounded; petiolar and postpetiolar nodes lacking posterolaterally prominent spines or teeth => Nesomyrmex sculptiventris
- Humeri or pronotum sharply angulate or even dentate; petiolar and postpetiolar nodes posterolaterally with prominent spines or teeth => 4
4
- Mesonotum laterally projecting as a triangular lobe; thorax strongly constricted in front and behind of this lobe => Nesomyrmex pulcher
- Mesonotum lacking laterally a projecting lobe; thorax feebly constricted in front and behind of mesonotum => Nesomyrmex anduzei
5
- Head above longitudinally costate or rugose => 6
- Head above without longitudinal costate or rugose => 9
6
- Dorsum of thorax and postpetiole densely punctate with feebly raised longitudinal rugae; lateral lobe of mesonotum blunt; epinotal spines lacking erect or oblique hairs => Nesomyrmex itinerans
- Dorsum of thorax and postpetiole with strongly raised longitudinal or somewhat vermiculate costae; lateral lobe of mesonotum dentate; epinotal spines with erect or oblique hairs => 7
7
- Basal half of first gastric tergite finely and densely longitudinally striate; lateral border of dorsum of pronotum without a sharp continuous carina => Nesomyrmex schwebeli
- Basal half of first gastric tergite completely smooth and shining; lateral border of dorsum of pronotum a sharp continuous carina => 8
8
- Metasternal lobe dorsally dentate; intervals between costae on thoracic dorsum with miscrosculpture and subopaque => Nesomyrmex vicinus
- Metasternal lobe evenly rounded; intervals between costae on thoracic dorsum smooth and shining => Nesomyrmex costatus
9
- Dorsum of head with numerous shallow foveolae; epinotal spines as long as the distance between their apices => Nesomyrmex pittieri
- Dorsum of head without distinct foveolae; epinotal spines short and subconical, much shorter than the distance between their apices => Nesomyrmex brasiliensis
10
- Metasternal lobe posterodorsally produced, either angulate or subangulate; antennal scape in repose usually attaining the occipital margin => 11
- Metasternal lobe posterodorsally not produced, short and evenly rounded; antennal scape in repose failing to attain the occipital margin by a distance equal to its greatest width => 14
11
- Mandibles finely reticulate and subopaque at inner half of upper surface; sides of thorax rather coarsely and irregularly rugose => Nesomyrmex asper
- Mandibles smooth and shining at inner half of upper surface; sides of thorax with feeble rugosities or lacking them completely => 13
13
- Frons and vertex of head sculptured and opaque; legs lacking erect hairs => Nesomyrmex brimodus
- Frons and vertex of head smooth and shining; legs with long erect hairs => Nesomyrmex pleuriticus
14
- Anterior border of pronotum ecarinate; thorax completely smooth and shining => Nesomyrmex rutilans
- Anterior border of pronotum carinate; thorax always sculptured and opaque => 15
15
- Basal face of epinotum with a flattened, obtuse tooth at each side, separated from and projecting over, the spiracle, which is invisible from above; pronotum almost as long as broad at posterior corner, not conspicuously transverse => Nesomyrmex wilda
- Basal face of epinotum with a prominent lobe at each side, enclosing posterodorsally the spiracle which is always visible from above; pronotum much broader than long => 16
16
- Antennal scapes and extensor face of tibiae with a few short erect setae; sides of mesonotum broadly rounded and scarcely projecting laterad; epinotal spines very short and straight => Nesomyrmex argentinus
- Antennal scapes and extensor face of tibiae lacking standing ahirs; sides of mesonotum with a projecting angular or dentate lobe; epinotal spines much longer and curved => 17
17
- Dorsum of head completely reticulate-punctate, longitudinally rugose and opaque; color rather uniformly testaceous or yellowish-brown => Nesomyrmex spininodis
- Dorsum of head with at least the front and vertex partly smooth and shining; color always darker, at least head and gaster brown to piceous => Nesomyrmex echinatinodis