SYSTEMATICS, GROWTH, AND DEVELOPMENT OF LAFOEINA MAXIMA(=KERATOSUM COMPLEXUM) (HYDROZOA, CAMPANULINIDAE)

¹ Department of Biology, Indiana University, Bloomington, IN 47405, and Marine Biological Laboratory, Woods Hole, MA 02543

Keratosum complexum Hargitt, 1909, is a junior synonym of Lafoeina maxima Levinsen, 1893. Several specimens have been collected from the type locality of K. complexum and compared with Hargitt's description and type specimen. These were compared with Levinsen's holotype of L. maxima and with another specimen of L. maxima from Greenland.

L. maxima superficially resembles a finger sponge. It has slightly branching stems which consist of many parallel tubes from which arise the hydranths, gonangia, and nematophores. With a height of up to 15 cm and a thickness of as much as 5 mm, the stems represent an extreme example of a fascicled hydroid stem.

Dormant hydroids were collected in the summer of 1975 off Cape Cod. Hyranths and nematophores developed in the laboratory at 5-7°C.

Some specimens sent out simple stolons which anastomosed to produce a reticulum, and hydranths developed from them. This condition, I believe, imitates a stage in the early development of the species. Later the hydrorhiza becomes a complex tangle of stolons making a mat as much as 0.5 mm thick.

The site of collection, 41°37N, is the most southern known for this northern species.