Calymperes tahitense (Sull.) Mitt.

Plants robust, apparently yellow-green when fresh, terrestrial. Stems c. 10–35 mm, with moderately conspicuous, brown, smooth rhizoids in lower portions. Leaves loosely contorted when dry, erect-spreading when moist, linear from a slightly broader base, tubulose, the lamina abruptly tapered at apex to a well-developed proboscis, coarsely toothed at apex by multi-cellular teeth, unistratose except at the thickened margins, 6–7 × 1 mm; cancellinae extending ¼ to nearly ⅓ the leaf length, rounded distally, with files of hyaline cells interdigitating among the green cells of the upper lamina, with cells rectangular and mostly c. 45–75(–90) × 25 µm; leaf margins very strongly thickened and winged (in cross-section) throughout, with well-developed teniolae extending ⅓ or more the leaf length; upper laminal cells ± isodiametric, somewhat irregular, dark green, mostly 3–5 µm diam., appearing smooth in surface view, in cross-section bulging on adaxial surface. Costa stout, mostly short-excurrent (nearly filling the proboscis and usually extending slightly beyond the "lamina" of the proboscis), not tapered and somewhat swollen at apex, bearing clusters of gemmae on the adaxial apical surface, in cross-section protruding strongly and rounded abaxially, with median guide cells and 2 stereid bands. Gemmae not forming spherical clusters, the individual morphology not clearly seen in N.Z. material.

Presumably dioicous; male plants only (with numerous perigonia) seen in N.Z. material.

Not illustrated here; Whittier 1976, fig. 41; Reese et al. 1986, fig. 21.

In a N.Z. context, C. tahitense is remarkably distinct. The cancellinae and gemmae are obvious even with a hand-lens and clearly distinguish it as belonging to the Calymperaceae. It is a more robust species than C. tenerum. The restriction of the gemmae to the adaxial surface of the costal apex, the well-developed teniolae, and the highly distinctive interdigitated files of hyaline and chlorophyllose cells at the distal margin of the cancellinae distinguish this poorly documented (in N.Z.) species.

The sole Kermadec Is collection was made by P. de Lange and D. Havell in May 2009. According to their field notes it grew "on humus and leaf litter overlying hard breccia rock in [a] deep gorge". According to Reese & Stone (1995) this species grows on "tree trunks and boulders in rainforest along streams" in northern Queensland. They also describe it as "dark green to blackish"; this does not accord with the Kermadec Is collection.

Reese & Stone (1995) briefly discussed an intergradation between this species and the pantropical C. afzelii.