If you come across very small specimens, it can be helpful to have a leght list in order to identify them quicker. Here are the smallest species by length of adults(!) (only less than 4mm)

2,5-2,9mm
Eugerax poecilum (Panama, Costa Rica)

3,0mm
Eugerax poecilum (Panama, Costa Rica)
Pseudovostox myrmecus (Java)
Eugerax salcedoi (Venezuela)

3,0-3,5mm
Eugerax poecilum (Panama, Costa Rica)
Eugerax salcedoi (Venezuela)
Cosmogerax diagonale (Venezuela)

3,5mm
Eugerax salcedoi (Venezuela)
Cosmogerax diagonale (Venezuela)
Cosmogerax formica (Venezuela, Guatemala, Panama, Brazil)
Paralabella maeklini (Brazil)
Marava minuscula (=unidentata?) (Venezuela)
Caecolabia gomyi (Mascarene Islands: Réunion)
Pseudovostox africanus (Sudan, Tanzania, Congo, DR Congo, Angola)

3,5-4mm
Marava minuscula (=unidentata?) (Venezuela)
Caecolabia gomyi (Mascarene Islands: Réunion)
Pseudovostox africanus (Sudan, Tanzania, Congo, DR Congo, Angola)
Carcinophora minima (Brazil)
Cosmogerax magicum (Guatemala)
Brachylabis lenkoi (Brazil)
Eugerax semiapterum (Venezuela)