Lepanthes acarina is a minute, epiphytic, caespitose orchid with slender roots. The ramicauls are slender and erect, 10–35 mm long, enclosed by 3–8 closely fitting, microscopically scabrous lepanthiform sheaths. The single leaf is erect and coriaceous, elliptic-ovate, subacute to obtuse, 7–10 mm long and 4–6 mm wide, with the rounded base contracted into a petiole approximately 1 mm long.

The inflorescence is a subdense, successively few- to several-flowered raceme 3–10 mm long, borne beyond the apex of the leaf on a capillary peduncle up to 10 mm long; floral bracts muricate, 1 mm long; pedicels 1 mm; ovary 1.5 mm. The sepals are yellow or red, minutely serrulate-ciliate on the margins and carinate externally. The dorsal sepal is broadly ovate-triangular, subacute, 2–2.5 mm long and 2.5 mm wide, 3-veined, fused to the lateral sepals for 1 mm. The lateral sepals are ovate, oblique, acute and diverging, 2.5 mm long and 2.5 mm wide together, each 2-veined, fused for 1 mm. The petals are red, microscopically pubescent, transversely bilobed, 0.5 mm long and 1.75 mm wide, with the upper lobe oblong, oblique, obtusely angled and truncate, and the lower lobe smaller, narrowly oblong, subfalcate and obtuse. The lip is red, bilaminate, with the blades ovate and subacute, microscopically pubescent, 1 mm long; the connectives cuneate; the body narrow, fused to the base of the column; the sinus obtuse with the appendix bisegmented and pubescent, constricted above the middle, with the apical portion deflexed and the basal portion concave. The column is stout, 1 mm long, with a dorsal anther and ventral stigma.

Flower characteristics at a glance: very small (sepals 2–2.5 mm; total flower 3–4 mm across at full opening), with the dorsal sepal broadly triangular and the spreading laterals likewise broadly built, all minutely serrulate-ciliate on the margins — the "prickly" character that the species's mite-allusion name evokes. The diagnostic floral signature is delivered by the lunate red lip blades and the proportionally large, pubescent appendix between them, deflexed at its midpoint, giving the lip a layered, knotted appearance under magnification despite the diminutive overall size.

The morphological characters described here follow Luer (1983), as reproduced in Luer & Thoerle (2012) in Icones Pleurothallidinarum XXXII.

The published literature describes Lepanthes acarina as an epiphyte of montane and cloud forest across the tropical Andes. Luer (1983) cited paratype collections from elevations ranging 1,600–2,800 m across multiple Antioquian municipalities in Colombia, with the type itself from cloud forest at approximately 2,000 m near Río Silante in Pichincha, Ecuador. POWO (2026) characterises the species's habitat as primarily the wet tropical biome, consistent with mature Andean cloud forest. Luer & Thoerle (2012) note that the species characteristically grows on mossy twigs, often in association with other small pleurothallids — a microhabitat pattern that holds at La Honda.

In La Honda, L. acarina has been observed as an epiphyte on mossy twigs at approximately 2,300 m, in association with other small pleurothallids exactly as the literature anticipates. The species is not perceived as common at the site, but this assessment may be partly an artefact of the plant's miniature stature: a 10–35 mm ramicaul bearing a 7–10 mm leaf and a 3–4 mm flower disappears into the moss-and-litter background to all but the closest inspection. Luer & Thoerle (2012) themselves observe that the species is usually overlooked or ignored on account of its size, and the question of true local abundance at La Honda accordingly remains open pending dedicated micro-survey of the relevant twig microhabitat.

Lepanthes acarina has a broad tropical-Andean distribution, native to Bolivia, Colombia, Ecuador, and Peru (POWO, 2026). It is recognised in the Colombian Lepanthes treatment of Luer & Thoerle (2012) and in Idárraga-Piedrahita et al. (2011), Flora de Antioquia. The type locality lies in Ecuador (Pichincha, ca. 2,000 m), making L. acarina the first species documented in this book whose type locality is outside Colombia — a small but meaningful editorial milestone after the long sequence of Antioquian endemics described by Luer, Escobar, and their co-authors at the Sociedad Colombiana de Orquideología.

In Colombia, the protologue (Luer, 1983) cites paratype collections distributed across the Cordillera Central in Antioquia: from Mun. Cocorná at 1,600 m, Mun. Frontino (Alto de Cuevas) at 2,050 m, Mun. Jardín (Alto de Ventanas) at 2,800 m, Mun. Sonsón (Tres Cruces) at 2,750 m, Mun. Yarumal (Alto de Ventanas) at 2,100 m, and forest east of Santo Domingo at 2,170 m. The Cocorná and Sonsón records are notably proximate to La Honda within eastern Antioquia, and the documented elevational span — from 1,600 m at Cocorná to 2,800 m at Jardín — places this among the broadest paratype-elevation ranges for any Lepanthes recorded in the book.

The La Honda record at approximately 2,300 m sits squarely within the centre of the species's documented Antioquian elevation band and, more broadly, within the tropical-Andean montane corridor across which L. acarina has been reported.

Flowering has been observed in La Honda. Luer & Thoerle (2012) note that the racemes of L. acarina frequently bear capsules and flowers simultaneously — an architectural consequence of the successive few-to-several-flowered raceme, which produces flowers in sequence rather than synchronously and often retains older fertilised pedicels alongside newer buds. The available data do not yet support a precise characterisation of the local phenology; systematic observation across a full annual cycle would be required to confirm flowering peaks or quiescent periods at the site.

Recognition rests on the combination of vegetative habit and floral architecture, both of which speak to the same theme: smallness as the species's defining character. Vegetatively, the very small ramicauls (10–35 mm) and small elliptic-ovate leaf with a rounded base contracted into a 1 mm petiole place L. acarina among the smallest plants in this book.

Florally, the diagnostic features are the subdense, successively few- to several-flowered raceme borne above the apex of the leaf on a capillary peduncle; the deep-red minute flowers with minutely serrulate sepal margins — the prickly, mite-evoking character that gave the species its name; and the lunate red lip blades with the proportionally large, pubescent appendix between them, deflexed at the midpoint. Luer & Thoerle (2012) note that the racemes characteristically present flowers and ripening capsules together — an extra confirming detail when the plant is found in the field. The combination of tiny ramicaul, elliptic-ovate leaf, and minute red prickly flower borne above the leaf apex is unambiguous in the field once the search image has been acquired — though, as already noted, acquiring that search image is itself the primary challenge given the species's stature.

Lepanthes acarina 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. L. acarina's broad documented range — across the tropical Andes from Bolivia and Peru through Ecuador to Colombia — distinguishes it from the narrow endemics that have dominated the Lepanthes sheets in this book. A wide-range species is, in general, less vulnerable to localised threats than a single-municipality endemic. But range-scale resilience does not confer microsite security: the cloud-forest mossy-twig microhabitat on which L. acarina depends is sensitive to canopy thinning, microclimate change, and the loss of mature substrate trees, all of which are operative in eastern Antioquia. Locally — at La Honda and elsewhere within the species's range — persistence depends on the continuity of mature montane forest and intact moss-bearing twig substrates at approximately 2,200–2,400 m elevation.

For these reasons — and to maintain consistency with the locality-redaction practice applied to the other Lepanthes sheets in this book — the specific location within La Honda where L. acarina has been documented is not published, and precise elevation data beyond the approximate 2,300 m tier 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].