Pinguicula hondurensis — Vorstman's Guide to the Carnivorous Plants

No photograph of this species under a Creative Commons licence or in the public domain is in the guide yet.

Identification

A loose rosette four and a half to eight, sometimes ten centimetres across, with four to eight obovate leaves three to six centimetres long and one and a half to three and a half wide. Each plant carries one to three scapes twelve to sixteen centimetres tall, green or purple-tinged. The flower is three to a little over four centimetres long including the spur: purple, with white lines and a white throat, a two-lobed upper lip and a three-lobed lower lip whose middle lobe is clearly larger. The spur is straight, cylindric to awl-shaped and only four to eight millimetres — strikingly short for such a long corolla tube. The long corolla tube combined with a short spur means something to pollinators: nectar sitting deep in the tube is reachable only by long-tongued insects, which limits the number of visitors.

Similar species

The species stands closest to Pinguicula utricularioides and P. rzedowskiana, both Mexican, and differs from them in keeping the same leaf type all year and in its purple flowers. The first point is the more useful in the field: many Mexican butterworts alternate between large summer leaves and a compact winter rosette, while this species forms no winter rosette. Within Honduras there are hardly any alternatives — a large purple-flowered butterwort on a rock face in the mountains is unmistakable here.

The trap and how it works

The leaves carry the usual two-part glandular coat: stalked glands with a sticky droplet and sessile glands releasing digestive enzymes once prey rests on them, after which the dissolved food is absorbed through the leaf skin. On an exposed, wind-swept rock face drying out is the biggest risk for such a trap, and it is no accident that the species grows precisely on the side struck by the moist north-easterly wind. There the air is laden with moisture and the droplets stay effective.

Habitat and ecology

Exposed rock slopes and walls swept by the north-east wind, in the transition from cloud forest to montane forest, with Clusia, cypress, sweetgum and pine in the surrounding vegetation. So this is not deep forest but the openings within it: rock ribs, cliffs and steep edges where trees gain no foothold and the moist sea wind has free play. The elevations given run from about fifteen hundred to over two thousand metres. In Honduras that north-eastern side is no arbitrary direction: it is the side on which the trade wind brings moisture in from the Caribbean all year, and on which cloud is forced up against the first ridges. It is precisely there that the permanent mist this species lives on forms.

Distribution and elevation

Endemic to Honduras. The original description names the centre and south-east of the country; type material in the international database additionally comes from the ridge of Pico Bonito in Atlántida department on the north coast, at about two thousand one hundred and fifty metres. The picture is therefore of a species occurring on a few isolated peaks and ridges in Honduras, each time in the narrow altitudinal belt where cloud runs against the slopes.

Recorded (one-degree cells)

Distribution based solely on records at GBIF (Global Biodiversity Information Facility), not on TDWG regions — those are often far larger than the actual range. The light halo is the area around a record, the dark core the record itself. The darker square is the only one-degree cell — roughly a hundred and ten kilometres — in which the species has been recorded, from all GBIF records. This is coarser than for most species because hardly any record of this plant carries an accurate coordinate. It shows where the species has been seen, not where it occurs: an empty square means nothing.

Forms and variation

No wild subspecies or varieties are recognised. One property of the species itself is worth noting, though: it is homophyllous, meaning it carries the same leaf type all year and forms no compact winter rosette as many of its Mexican relatives do. The variation set out in the description — four to eight leaves, one to three scapes — is limited and rests on a small number of collections. That homophyllous behaviour says something about the climate: where a dry season is sharp enough it pays to make a compact overwintering rosette, and where the slopes receive moisture from cloud all year it is unnecessary.

Where and when to see it

April and May are the months: the species has been found then in flower and with summer leaves. Search the open rock along ridges and on cliffs facing north-east, in the belt where cloud forest gives way to lower montane forest. That means climbing: the known sites lie high and are reached only by mountain trails. Photograph flower and spur in profile — the ratio between the long corolla tube and the short spur is the character here. Bear in mind that rock faces in this climate are slippery with moss and algae; work from a safe position and use a telephoto lens rather than climbing.

Conservation status

The species has not been assessed for the global IUCN Red List and is not listed in CITES. What is known: a Honduran endemic, described only in 2019, known from a few high rock habitats. The documented site on the Pico Bonito ridge lies inside a national park, which is favourable; beyond it the montane forests of Honduras are under pressure from felling, fire and conversion to farmland, and the narrow altitudinal belt this species inhabits shifts upward with warming. The absence of a category follows directly from the recent description.

Scientific name

Pinguicula hondurensis | Zamudio & Vega, 2019

Described by Sergio Zamudio and Ricardo Vega in 2019. The species is endemic to Honduras. The species name hondurensis refers directly to Honduras, the country where the species is endemic.

World Checklist of Vascular Plants (WCVP), via Plants of the World Online (POWO), Royal Botanic Gardens, Kew.