(Carter in Higgin, 1886)
Species Overview
Heteropia ramosa (Carter in Higgin, 1886) is a whitish yellow group of cylindrical hollow, thick-walled branches. Microscopic examination is needed to establish its identification.
Taxonomic Description
Colour: Whitish-yellow.
Shape, size, surface and consistency: Small, cylindrical, branched, sessile; branchlets more or less acuminated, horn-shaped. Oscules single, at the end of each branch, naked, i.e., without spicular fringe. Size under 2 mm in the diameter of the stem; length up to 1.5 cm; thickness of the wall, including the cortex and the atrium, about 3 mm. Surface even.
Spicules: Calcareous. Of three kinds, viz., oxeas, triactines, and tetractines.
Triactines, small and large, the latter averaging 150 x 15 µm inch in the shaft, and the arms respectively 100 x 15 µm; larger triactines are confined to the wall, and the smaller, which are chiefly sagittal, to the outer and inner surfaces.
Tetractines, of the same size as the large triactines with the addition of the fourth ray which is short and curved, about 45 µm long. Tetractines are confined to the inner part of the atrium, where they are formed by the addition of the fourth arm to the apical rays of the large triactines of the wall which abut against this part; thence projecting into the cavity of the atrium.
Oxeas very large, long, fusiform, slightly curved, and often lance-pointed anteriorly, averaging 2600 x 110 µm in its greatest transverse diameter. Oxeas are confined to the surface.
Skeleton: Ectosomal : consisting of long, large, fusiform oxeas arranged parallel to each other and closely approximated, on the same plane, more or less covered by small sagittiform triactines. Pores situated in the interstices between the arms of the triactines, along the intervals of the large oxeas. Choanosomal : oscules leading into a cylindrical atrial cavity, about the same shape as the sponge, and equally branched; presenting on its surface a great number of circular holes in juxtaposition, rendered more or less polygonal by the intercrossing of the rays of the tri-and tetractines that form the skeletal structure of the atrium, which is sparsely echinated by the fourth ray of the tetractines. Wall consisting of organic choanoderm traversed horizontally, at intervals, by the shafts of large, sagittal triactines which, coming from opposite sides and overlapping each other, have their apical rays in the internal surface of the cortex and that of the atrium respectively.
Ecology: No data.
Distribution: Collected at Holyhead, Wales.
Type specimen information: Original in the Liverpool Free Museum under registration number L. F. M., No. 22. 4. 74. 7.
Remarks
This species in spiculation is very much like Leuconia gossei , but the structure is syconoid, and thus belongs to Heteropia .
Source: Carter in Higgin, 1886