Luzarinae

In the four analyzed species of Luzarinae, we found the karyotype with 2n = 11♁ in I. puri, 2n = 12♁ in L. susurra, 2n = 13♁ in M. ornata, and 2n = 18♀ in L. lata (Figs 1–4). All of them presented X0♁-XX ♀ sex-determining system, except L. susurra with the Neo-XY♁-XX ♀; the X (and Neo-X) chromosomes are metacentrics with the same size of the largest bivalents of the karyotype; the Neo-Y chromosome of L. susurra is a small acrocentric (Fig. 5, Tabs 1–2).

Izecksohniella puri and M. ornata showed symmetrical karyotypes with all M/SM chromosomes, and FN = 20 and 24, respectively. In M. ornata both bivalents of the pair 1 presented chromosomes with secondary constriction and sattellite (Fig. 3, arrow). Luzaridella susurra has an irregular karyotype, with FN = 16, composed of two pairs of large submetacentrics (1 and 2), but the pair 1 with CI closer to the limit for an acrocentric chromosome; both twice the size of the pairs 3 (small metacentric), 4 and 5 (small acrocentrics). Luzarida lata presented asymmetric karyotype, with FN = 28, composed of six pairs of M/SM chromosomes, and two pairs of acrocentrics (pairs 7 and 8). In the last two species, acrocentric bivalents are among the smallest chromosomes of the complement (Figs 1–4, Tabs 1–2).

Meiosis. We did not obtain meiotic divisions in I. puri and L. lata, since all analyzed specimens were adult females; we found metaphases I in L. susurra, with a pair of heteromorphic homologues that represent the Neo-XY chromosomes, both connected by a terminal chiasma (Fig. 5); in M. ornata we found diplotenes with all metacentric bivalentes (ring-shaped) joined by a terminal chiasma, and the X chromosome differing from bivalentes by its rodshaped (Fig. 6).