Homalomena lingua-felis

Homalomena lingua-felis is a species of flowering plant in the family Araceae endemic to North Sumatra, Indonesia.^[1] This species belongs to the Homalomena Chamaecladon supergroup and was formally described in 2026 through a publication in the journal PhytoKeys.^[2][3]

The species is known for the upper surface of its leaves being covered in dense hairs with a rough texture resembling a cat's tongue, which is its primary distinguishing feature and the origin of its name.^[4][5]

The species was first described by Muhammad Rifqi Hariri and colleagues in the scientific paper entitled "A new densely-haired aroid species of Homalomena (Araceae) from North Sumatra, Indonesia", published in PhytoKeys, volume 271 (2026).^[1] The study was conducted through a collaboration involving the National Research and Innovation Agency (BRIN), Bandung Institute of Technology (ITB), Sebelas Maret University, IPB University, University of Lampung, and other botanical institutions.^[2][4]

The specific epithet lingua-felis is derived from Latin, where lingua means "tongue" and felis means "cat". The name refers to the adaxial (upper) leaf surface, which is covered in dense hairs and has a rough texture resembling a cat's tongue.^[6]

Homalomena lingua-felis is a small lithophytic herb, reaching approximately 9.5 cm in height and up to about 21 cm in canopy width. It grows attached to rock surfaces in humid environments.^[1]

• Stem: Short and compact, about 2 cm long and approximately 0.5 cm in diameter, reddish in colour and covered by the bases of the leaf sheaths.
• Petiole: 1.2–4.5 cm long, greenish-red to dark red, with a papillose (minutely bumpy) surface.
• Leaf blade: Elliptic, cordate, to ovate, measuring approximately 1.35–16.0 × 0.8–7.6 cm.

The adaxial (upper) leaf surface is dark green and densely tomentose, with hairs having bulbous green bases and white tips. The abaxial (lower) surface is pale greenish-white and papillose.^[1]

• Number: 3–7 inflorescences per sympodium, opening sequentially and lacking a noticeable odour.
• Peduncle: Pendulous, 6–8 mm long, pale red and papillose.
• Spathe: 9.7–19.0 mm long, not constricted at the middle; externally green to reddish-brown or orange-red.
• Spadix: 7.1–15.4 mm long; the staminate (male) zone narrowly shaped, measuring 5.3–11.4 mm.

Floral morphology, particularly the conical shape of the staminate zone, is a key diagnostic feature of the species.^[1]

Homalomena lingua-felis is an endemic species known only from Central and South Tapanuli, North Sumatra, Indonesia. Its natural habitat consists of vertical rock faces near waterfalls at elevations of approximately 15–50 m above sea level.^[1]

As a lithophyte, the species is adapted to environments with constant water spray. Its thick leaves and dense indumentum on the adaxial surface are thought to reduce the mechanical impact of water droplets and protect leaf tissues.

In its natural habitat, the species has been reported growing alongside other species such as Homalomena anthurioides and Homalomena plicata.

Morphologically, Homalomena lingua-felis resembles Homalomena pexa, particularly in the presence of leaf trichomes. However, several key differences distinguish the two species:

• Dense hairs are confined to the adaxial (upper) leaf surface (in contrast to H. pexa, where hairs occur on both surfaces).
• The petiole is shorter.
• The staminate (male) zone is conical (as opposed to ellipsoid in H. pexa).

Molecular analysis based on the internal transcribed spacer (ITS) region indicates that H. lingua-felis belongs to the Chamaecladon clade, together with H. atrox and H. humilis. In contrast, H. pexa is placed in a different lineage within the genus Homalomena.

These findings demonstrate that morphological similarity does not necessarily reflect close phylogenetic relationships.

The species was discovered during a field expedition in January 2024 in the Batang Toru area, South Tapanuli, North Sumatra, Indonesia. The study involved specimen collection in its natural habitat, detailed morphological analysis, and comparison with herbarium collections.^[7]

The identification was further supported by DNA-based molecular analyses. Prior to its formal scientific description, the species was already informally known among ornamental plant enthusiasts and had been traded without a confirmed taxonomic identity.^[8]

Homalomena lingua-felis has been proposed as Vulnerable (VU) under the criteria of the International Union for Conservation of Nature (IUCN), particularly criteria C1, C2(i), and D2.^[1]

This assessment is based on several factors, including:

• An estimated mature population of fewer than 1,000 individuals
• An Area of Occupancy (AOO) of approximately 8 km²
• A highly restricted geographic distribution

The main threats to the species include:

• Habitat degradation due to land-use change
• Forest fires
• Illegal collection for the ornamental plant trade

Pressure from the ornamental plant market, particularly through online platforms, is considered a significant factor that may accelerate population decline in the wild.^[1]