(Gracilariales, Rhodophyta) is a common red (vm) marine macroalgae in the Northeastern coast of Brazil, which has been extensively harvested for the agar extraction. The aim of this study was to complete the life history of wild-type specimens (red color) and chromatic variants. Two variants were isolated besides the wild-type specimens collected in Paracuru beach, Ceará: i, greenish-brown (me), which was found in the natural population on Paracuru beach; ii, green (vd), which was obtained spontaneously in vitro from a tetrasporophyte branch. The culture conditions for both gametophytes and tetrasporophytes were: 25% von Stosch medium; 14L:10D (light: dark) photoperiod; irradiance of 100 µmol.m-2.s-1 and alternating 30 min aeration periods. Green, red and greenish-brown tetrasporophytes as well as green gametophytes were also cultivated in 10L:14D. The life history of Gracilaria sp. has been completed in vitro in 498 (vm), 523 (me) and 861 (vd) days, showing Polysiphonia-type. The tetrasporophytes produced tetraspores only at 10L:14D photoperiod, while green female gametophytes produced cystocarps only at 14L:10D photoperiod. However, the differentiation of verrucosa-type spermatangial conceptacles in green male gametophytes and spermatia liberation occurred in both photoperiods. Red male gametophytes showed henriquesiana-type spermatangial conceptacles and greenish-brown male gametophytes showed verrucosa and henriquesiana-type ones. Specimens of the three colors showed similar habit. Considering one color, specimens showed similar habit too, independently of the reproductive phase. Every tetrasporophytes showed in situ germination of tetraspores.
Gracilaria; life history; chromatic variants; reproduction
