The genus Gracilariopsis (Rhodophyta, Gracilariales) in the Philippines: morphological and taxonomic confirmations

Abstract

Reports of the economically-important agarophytic seaweed genus Gracilariopsis Dawson from Philippine waters are verified for the first time. Cystocarpic, spermatangial and tetrasporic materials collected from various localities in eastern Panay and northwestern Negros islands conform to the circumscription of this recently reinstated genus. Materials are referred to Gracilariopsis heteroclada Zhang & Xia after morphological comparisons with type materials from southern China. In addition, a discussion of the complicated nomenclatural history of this species is included.

Another putative Gracilariopsis species is reported from Zamboanga City based on cystocarpic materials alone. This species differs from G. heteroclada with its smaller gonimoblast cells and larger height:width ratio of the gonimoblast mass. Vegetatively, the thallus is smooth, devoid of fine, determinate branchlets observed in G. heteroclada.