Novon 14: 377, fig. 1. 2004.
Plants in slender strands, green to yellow-brown. Stems 3–6 cm, stiff, sparingly branched. Leaves erect- to wide-spreading, often transversely attached to stem, strongly contorted when dry, 2–2.5 mm; margins entire or obscurely serrulate; apex gradually long-acuminate; costa 50–75 µm wide at base; alar region not differentiated; basal laminal cell walls firm; distal cells 70–120 × 6–7 µm. Sporophytes unknown.
Elevation: moderate elevations
Leptodictyum wallacei is known only from Hext Spring in San Saba County. The species is distinguished from the variable aquatic ecotypes of L. riparium by its stiff stems, smaller size, and absence of alar cell elaboration. L. Hedenäs (pers. comm.) has examined an isotype and suggested that the specimen fits well within the variation of L. riparium.