Morphology and life history studies of Endarachne binghamiae (Scytosiphonaceae, Phaeophyta) from the Azores

First reported for the Azores in 1994, Endarachne binghamiae is commonly found throughout the year on hard substrates in the upper mid-tidal region of the exposed Azorean shores. Morphological and culture studies of this species were carried out based on material collected from six localities on the island of São Miguel. Erect thalli collected in the field are dorsiventrally flattened and arise from an encrusting base or small discoid holdfast. The erect blades, up to 13 cm long and 2 cm wide, are lanceolate or obovate, simple, solid and thin, gradually tapering at the base. The plurilocular sporangia lack paraphyses and are positioned in continuous sori covering most of the surface area of the blades. Reproductive plants, with plurilocular sporangia, occurred all year round. In culture, spores released from the plurilocular sporangia developed into small knot-filaments, which upon squashing exhibited a three-dimensional representation of a typical multistratose crust. These prostrate knot-filaments gave rise directly to new erect blades. No unilocular sporangia were seen and no evidence of sexuality was observed. These results are similar to those reported of Californian plants, indicating that the Azorean Endarachne have a monophasic heteromorphic life history. © 2003 Elsevier Science B.V. All rights reserved.