Key for species of the genus Microtityus (mainly females)

1. Basal middle lamella of the pectines conspicuously enlarged in both sexes (Fig. 12). ...................... M. vieques

– Basal middle lamella of the pectines not enlarged neither in female or male. ................................................................ 2

2. Female with pectinal basal plate wider than long, not spatulate (Fig. 13). ............................................ M. santosi

– Female with pectinal basal plate longer than wide, distally spatulate (Fig. 14). ...................................... M. borincanus