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A large colony, strongly polysiphonic and fragmented. Colony polysiphonic throughout, with the exception of the most distal, youngest branches. Polysiphony due to numerous and thin secondary tubes. Basalmost stem fragment (ca 0.5 cm thick and 19 cm long, including hydrorhiza) completely polysiphonic, provided with a large rhizoidal hydrorhiza (ca 5 cm long)
spreading on a calcareous bryozoan; originally hydrorhiza could have been discoidal, later, while the colony was growing the hydrorhiza may have developed strong hydrorhizal stolons for the attachment to less firm substratum. Hydrorhizal stolons polysiphonic, consisting of a large number of thin tubes like those giving rise to polysiphony of stem. Stem forking at 9 cm height, though previously with a few small, simple branches. Following stem fragment, ca 10.5 cm long, branched, giving rise to several polysiphonic lower-order stems. Branching irregular and in several planes, sometimes with more or less spiral arrangement. Branches originating laterally at the hydrothecal base, decreasing in diameter distally; plane formed by hydrothecae of lower-order branch perpendicular to that formed by hydrothecae of previous branch. Branches divided into short hydrothecate internodes; one hydrotheca per internode. Hydrothecae alternately arranged in one plane, though with a spiral variation of that plane along the branches. Hydrotheca slightly abcaudally directed. Adcauline wall adnate to internode for approximately two-thirds of its length; free part of adcauline wall straight or slightly
convex. Abcauline wall straight or slightly concave. Hydrothecal aperture provided with three cusps separated by deep embayments. Rim of hydrothecal aperture with numerous renovations, even in the distalmost hydrothecae. |