Metaphases from germinal tissue of eight males and seven females of Cicindelidia trifasciata from Cuba were analyzed. The species karyotype does not fit the pattern described for Nearctic cicindelids (2n = 18 + XXY): it has 11 autosome pairs and a sex chromosome system of the X1X2X3Y/ X1X1X2X2 X3X3 type, thus a diploid value of 2n = 26 in males and 2n = 28 in females. The first two autosome pairs were almost twice as large as the remaining chromosomes, and the sex elements were morphologically well differentiated. This population was found to be polymorphic for supernumerary chromosomes at both the intraindividual and interindividual levels. An extra small B chromosome was observed in all metaphases of one male (2n = 27), and every female showed metaphases with one to three small Bs, with a clearly higher frequency of cytotype 2n = 29.