According to “American species of Acacia by Lourdes Rico (2007) there are the following species of Acacai s.l. to be found in Costa Rica:

with thorns:

Myrmecophilous, spicate inflorescence:

Acacia collinsii (see also Yucatan)

Acacia cornigera

Acacia hindsii

Myrmecophilous, capitate inflorescence:

Acacia allenii

Acacia melanoceras

Acacia cookii

Acacia ruddiae

Non myrmecophilous

Acacia macracantha

Acacia farnesiana var. guanacastensis

with prickles:
capitate inflorescence:
Acacia polyphylla

Acacia riparia

Acacia tenuifolia

with spicate inflorescence:
Acacia hayesii

as well as two Acaciella species:
A. angustissima and A. villosa

In gardens you will also find some of the Australian phyllodineous acacias.