Rhodophyta, Red Algae
Halopithys incurvus (Hudson) Batters
Rhodophyta, Order: Ceramiales; Family: Rhodomelaceae.
The generic name of the Halopithys genus means ‘sea pine’. The name of the species incurvus describes the shape of the branches, and means ‘bending inwards’, ‘bowed'.
The Halopithys incurvus is an erect, tubular alga (polysyphonic) with cylindrical branch edges, usually pointed towards the thallus. The connection to the substrate is through a round holdfast measuring less than 1 cm in diameter. Microscopic examination, even using a magnifying glass, reveals the polysyphonic structure that characterizes the family: thin, dark lateral rings with wider rings in between them. The structure of the rings is easily construed in the upper parts of the thallus, compared to those in the lower parts, in which the cells of the outer layers (cortex) are thicker.
The alga is about 10 cm in length. The width of the branches is around 1 mm.
The alga is coloured bright red which can fade to yellow.
The Halopithys incurvus can easily be confused with the Rytiphlaea tinctoria, since they both grow more or less in the same habitat, are similar in size and are both hooked at the edge. Upon further inspection, though, one discerns the difference in branch structure: the Rytiphlaea tinctoria has symmetric branches on both sides, and the Halopithys incurvus’s branches are rounder. The most obvious difference is that the Halopithys incurvus does not colour paper red when dried.
The Halopithys incurvus is to be found in potholes and tidal pools within the intertidal zone. There are little data from Israeli coasts. In other places worldwide the alga has been reported in both shallow waters and up to a depth of 3 m.
Biology and reproduction
The Halopithys incurvus - like the Polysiphonia -has a three stage life cycle. The male reproductive cells (antheridia) are arranged in a row and develop at the edges of young branches. The reproductive stages are similar to those of the Rytiphlaea.
Seasonality and distribution
The alga is quite rare, but may be found throughout the year.
Halopithys incurvus -The thallus is characterized by the edges of the branches, which are bent inwards.
An additional species reported in the area is Halopithys pinastroides (S. G. Gmelin) K.tzing; however, this seems to be a synonym for the species described herein (Halopithys incurvus).