Morphological description (show/hide)
| Thinly to thickly encrusting, or bulbous-encrusting, 2-14 mm thick, forming small to very extensive growths over the coral substrate (12-135 mm in maximum diameter). | | Live colouration was consistently and evenly | | Large oscules are situated on the points of bulbous lobes, 0.4-1.6 mm in diameter, with a very slightly raised and membranous lip. Minute pores, up to 150 ﾵm in diameter are scattered over the surface. Pores and oscules were not observed in exposed intertidal (desiccated) material. | | The texture is firm, barely compressible, but easy to crumble when alive. No mucous is produced upon exposure to the air. | | The surface is optically smooth, irregularly bulbous, and usually mostly clear of silt in situ. Surface lobes may collapse upon desiccation or preservation in thinly encrusting material, but thicker specimens usually retain their shape. | | The choanosomal skeleton consists of several components. There is a basal layer of spongin, 60-240 ﾵm thick, lying on dead coral or on other sponges (sometimes with foreign sponge spicules protruding into the basal skeleton), and with an erect basal layer of smooth choanosomal principal styles and echinating acanthostyles standing perpendicular to the substrate, which together form a leptoclathriid structure. Intermingled with, or overlaying the erect basal skeleton is a regularly renieroid reticulation of acanthostrongyles in pauci- or multispicular (vaguely ascending) and uni- or paucispicular (irregularly transverse) tracts. Meshes are triangular to rectangular, 60-150 ﾵm maximum diameter, without any obvious spongin fibre component, lined by abundant but virtually unpigmented interfibril spongin, and with circular to oval choanocyte chambers 63-95 ﾵm in diameter. The mesohyl matrix of the basal skeleton (i.e. point of attachment to the substrate) and peripheral skeleton is more heavily pigmented than spongin in the choanosomal region, and microscleres appear to be more abundant near the surface. At the major nodes of the renieroid skeleton are echinating acanthostyles, occurring singly or in plumose brushes, and these may form irregularly plumose, usually discontinuous ascending tracts. In addition to the renieroid skeleton is a subisodictyal extra-fibre skeleton of choanosomal and subectosomal megascleres. Those spicules originate and extend from the erect leptoclathriid basal skeleton, often ascending all the way to the surface. Extra-fibre tracts become increasingly plumose and dendritic towards the periphery, sometimes forming a subisodictyal reticulation, but those megascleres only form clearly continuous tracts in thicker sections, whereas in thinly encrusting specimens extra-fibre spicules may be more irregularly dispersed throughout the choanosomal skeleton. | | The ectosomal skeleton is microscopically hispid, with the points of smooth choanosomal principal styles protruding through the surface. Detritus is usually absent from the surface, although thinly encrusting specimens may contain isolated arenaceous particles. The projecting principal megascleres are surrounded at their bases by plumose brushes of mostly small ectosomal auxiliary subtylostyles, although larger subectosomal megascleres may also participate in ectosomal brushes. The subectosomal region is structurally variable. In thinly encrusting sections the peripheral skeleton is not clearly delineated from the choanosomal skeleton, containing only thick tangential to paratangential tracts of larger subectosomal auxiliary subtylostyles, with tracts measuring up to 140 ﾵm thick in some sections. In thicker bulbous sections the subectosomal region is relatively cavernous, containing numerous plumose, stellate brushes of choanosomal and subectosomal megascleres, and that region is clearly differentiated from the renieroid choanosomal skeleton. Subectosomal megascleres also commonly occur in the deeper choanosomal skeleton, together with smooth choanosomal principal styles, and those spicules may form vaguely ascending, multispicular, extra-fibre tracts, 25-65 ﾵm in diameter, or they may be irregularly dispersed throughout the skeleton. | | Choanosomal principal styles are fusiform, slightly curved, thick, with rounded or slightly subtylote, smooth or less commonly with lightly microspined bases. Length 183-(317.9)-561.8 ﾵm, width 6.5-(14.8)-25 ﾵm. Acanthostrongyles of the renieroid skeleton are short, thick, straight or slightly curved, with either symmetrical and subtylote, or asymmetrical extremities (subtylote bases, rounded or slightly subtylote points, most are evenly microspined on base, apex and shaft. Length 98.6-(120.6)-142 ﾵm, width 4.5-(10.1)-15.1 ﾵm. Subectosomal auxiliary subtylostyles are long, thin, fusiform, straight, with prominent tylote, subtylote or polytylote, and microspined or less commonly smooth bases. Length 231.4-(372.9)-472.9 ﾵm, width 2.5-(5.9)-12.6 ﾵm. Ectosomal subtylostyles are smaller but identical in geometry to larger auxiliary megascleres, with tylote or subtylote, smooth or microspined bases. Length 100-(192.7)-251.7 ﾵm, width 1.1-(3.3)-6.3 ﾵm. Echinating acanthostyles are long, thick, fusiform, slightly curved, with subtylote and lightly microspined bases, and with entirely smooth shafts or with the proximal half of shafts covered with spines, these spicules are probably merely smaller morphs of principal styles. Length 107-(194.1)-247.6 ﾵm, width 5-(10.1)-14.8 ﾵm. | | Palmate isochelae are abundant, of one size category, and unmodified. Length 18.1-(2.5)-18.9 ﾵm. Toxas are incompletely differentiated into two size classes: the smaller forms are thin, with extensive rounded central curvature, and straight or rarely slightly reflexed points. Chord length I 21.4-(44.3)-85.7 ﾵm, width 1-(1.9)-4.1 ﾵm. The larger forms are thick, with sharply angular or rounded central curvature, long, straight or very slightly reflexed points which characteristically bear a terminal bulbous swelling and an apical spine surrounded by smaller spines. Chord length II 62.9-(169.2)-354.3 ﾵm, width 2-(4.7)-10.6 ﾵm. |
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