Rhizome short-creeping to long-creeping; paleae pale brown, lanceolate, acute, 1.6-5.9 × 0.6-1.9 mm. Stipes pronounced, 1-18 mm long; stipe hairs whitish to pale red-brown, rare to common, 0.3-2.0 mm long. Lamina spathulate-oblanceolate to oblanceolate, obtuse to acute, (1.1—) 1.9—5,7(—9.9) × (0.3-)0.38-0.70(-1.0) cm; lamina hairs whitish, rare, on midribs only, more common in young fronds, to 1.2 mm long; texture coriaceous; veins invisible, endings not darkened; midrib somewhat raised below, ± concolorous with lamina. Sori subglobose to oblong, oblique, in upper ½ to 1/3 of frond, 1-10 pairs, 2.0-6.5 × 1,0-2.0 mm; soral vein ending within the sorus or extending a little beyond it, somewhat shorter than basiscopic vein, neither reaching the margin. Sporangia (190-)222.2-312.0(-390) mcm long; indurated cells of annulus (10-)11.0-13.6(-17). Spores (25-) 31.0-41.6 (-50) mcm diam.

G. armstrongii Tindale et G. billardieri Willd. affinis, sed a prima frondibus parum maioribus, praesentia stipitium cum pilis et plerumque maiore numero parium sororum; et a secunda rhizomate late repente, frondibus parvioribus et sporis maioribus. Rhizoma breviter vel late repens; paleae pallide brunneae, lanceolatae, acutae, 1.6-5.9 × 0.6-1.9 mm. Stipes manifestus, 1-18 mm longus; pili albidi vel pallide castanei, raro vel vulgares, 0.3-2.0 mm longi. Lamina spathulato-oblanceolata vel oblanceolata, obtusa vel acuta, (1.1-) 1.9-5.7 (-9.9) × (0.3-)0.38- 0.70(-1.0) cm; pili albidi, rari, solum in costa, frequentiores in frondibus juvenibus ,ad 1.2 mm longi; textura coriacea; venae non manifestae, extremae venarum non fuscatae; costa parum sub lamina procumbens, lamina ± concolor. Sori subglobosi vel oblongi, obliqui, in superiore \ vel J parte frondis, 1-10 pares, 2.0-6.5 × 1.0-2.0 mm; vena sori in sorum terminans vel parum ultra procurrens, parum brevior quam vena basiscopica, non ad marginem accedens. Sporangia (19O-)222.2-312.O(-390) /mi longa; cellulae induratae annuli (10—) 11.0-13.5 (—17). Sporae (25-)31.O-41.6(-5O) Mrn diametro.