Lepanthes cactoura is a medium-sized to large epiphytic orchid of the genus, caespitose, with fine roots and slender, erect secondary stems (ramicauls) 6–10 cm long, enclosed by ten to fifteen minutely ciliate, long-acuminate lepanthiform sheaths — the funnel-shaped, fringed sheaths characteristic of the genus. Each ramicaul bears a single erect, thinly coriaceous, more or less reticulate, narrowly ovate leaf with an acute, acuminate apex, 5–7 cm long and 1.5–2.2 cm wide, the base broadly cuneate into a petiole 1 mm long.

The inflorescence is a very congested, successively many-flowered raceme up to 10 mm long, borne on the dorsum (upper surface) of the leaf by a filiform peduncle 15–25 mm long; the floral bracts are 1.5 mm long; the pedicel 4 mm; the ovary lightly crested, 2 mm long. The sepals are translucent white, minutely denticulate; the dorsal sepal is broadly ovate, obtuse, 3.5 mm long and 3 mm wide, connate to the lateral sepals for 0.5 mm; the lateral sepals are ovate and oblique, 3.5 mm long and 1.75 mm wide, connate 1 mm, each with two veins. The petals are cream with brown tips and a red-brown inner margin, microscopically pubescent, transversely bilobed, 1 mm long and 3 mm wide, with a minute process on the lateral margin near the middle; the upper lobe is suboblong and truncate with a minutely erose upper edge; the lower lobe is triangular, acute, obtusely angled on the outer margin and shorter than the upper lobe. The lip is red-brown with a white stripe on each side, bilaminate; the blades are thin and microscopically pubescent, semiorbicular with rounded apices and obtuse bases, 1.4 mm long, adherent over the column; the connectives broadly cuneate; the body narrow, connate to the column at the base; the appendix thick, pubescent, terete to subconical, with a small, similar, apical segment — the "cactus-like tail" from which the species takes its name. The column is slender, 1.5 mm long, with a dorsal anther and a ventral stigma.

Flower characteristics at a glance: the flower is small (sepals 3.5 mm long) but distinctive, with translucent white sepals providing a pale background, cream petals marked by dark red-brown tips and inner margins, and a boldly striped red-brown lip with white longitudinal stripes projecting forward from the column. The overall effect is considerably subtler in colour than the vivid yellow-and-magenta of several congeners, and the diagnostic thick cylindrical appendix that gives the species its name is not visible without dissection. The short raceme and dorsal peduncle place the open flower on the upper surface of the leaf, in the pattern typical of the genus.

The morphological characters described here follow Luer & Escobar (1991); the description is reproduced with minor modernization by Luer & Thoerle (2012) in Icones Pleurothallidinarum XXXII.

The published literature describes Lepanthes cactoura from a single collection, at the type locality in the municipality of Mesopotamia (Antioquia), "epiphytic in cloud forest between La Unión and Sonsón," at approximately 2,400 m (Luer & Escobar, 1991). No subsequent ecological or habitat observations for this species have been published in the intervening decades.

In La Honda, L. cactoura has been observed as an epiphyte within the forest interior of mature secondary cloud forest — consistent with the habitat described in the protologue. Flowering has been observed only sporadically, and the species is not encountered frequently during walks through apparently suitable habitat. Given that La Honda sits within the same eastern-Antioquia cordillera corridor as the type locality, its occurrence here extends the documented presence of the species by only a short distance but provides the first post-protologue field observation of the species in its natural habitat that we are aware of.

Lepanthes cactoura is endemic to Colombia, known only from the department of Antioquia (POWO, 2026). The holotype was collected in the municipality of Mesopotamia, "epiphytic in cloud forest between La Unión and Sonsón," at 2,400 m (25 August 1984; L. de Posada, C. Head & F. López) and published by Luer & Escobar (1991). No additional localities for the species are documented in the published literature.

The La Honda record documents a newly-confirmed locality approximately 6 km northeast of the type locality, in an adjacent municipality within the same eastern-Antioquia cordillera corridor. Given that the species has not been the subject of ecological or population-level study since its original description in 1991, this observation constitutes a modest but meaningful extension of the documented presence of the species.

Flowering has been observed in La Honda only sporadically, on a limited number of occasions. The available data do not support a reliable characterisation of the species' phenology at this site; systematic observation across a full annual cycle would be required to describe the flowering period of the local population. No seasonality data have been published elsewhere for this species.

Recognition rests on the combination of the medium-to-large ramicauls (longer than in many sympatric Lepanthes), the narrowly ovate reticulate leaf, the translucent white sepals, the cream petals with brown tips and red-brown inner margins, and the distinctive red-brown lip marked by a white stripe on each side. The overall colour palette — muted whites, creams, and red-browns — distinguishes the flower from the more brightly coloured yellow-and-magenta congeners common in the region. The eponymous thick cylindrical pubescent appendix of the lip, which gives the species its name, is a dissection character and not visible in the living flower without manipulation. The genus Lepanthes is diagnosed as a whole by the lepanthiform sheaths on the ramicauls, visible with a hand lens.

Lepanthes cactoura has not been evaluated globally on the IUCN Red List (status NE, Not Evaluated, as of the date of this sheet). At the national regulatory level in Colombia, the species is not listed in Resolución 0126 de 2024 of the Ministry of Environment; it is therefore not classified as threatened under current Colombian environmental law.

"Not Evaluated" is not a statement that the species is safe — it is a statement that no formal assessment has been made. Lepanthes cactoura has not been the subject of ecological or population-level study since its original description in 1991, and the La Honda record reported here appears to be the first field observation of the species in its natural habitat to be made public since then. A species that is known from a narrow geographic range, has not been restudied in over three decades, and belongs to a genus actively targeted by specialist collectors merits conservative treatment regardless of its formal IUCN status.

For these reasons, the specific location within La Honda where L. cactoura has been documented is not published, and elevation data are redacted from this sheet. Requests for further locality detail from researchers or conservation practitioners with a legitimate scientific or institutional purpose may be directed to [email protected].