Pinguicula olmeca

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

Identification

A uniform rosette of 6 to 8(16) leaves 20 to 55 mm long, with the usual sticky glandular droplets. The most striking character of the species is what it lacks: unlike Pinguicula moranensis, P. zecheri and the other members of its section, it has only one leaf type all year, without the fleshy non-carnivorous winter rosette that belongs to almost every Mexican butterwort. The flower is purple and carries an extraordinarily long spur: 40 to 60 millimetres, nearly as long as the scape itself. That spur makes the flower unmistakable from a distance — a purple cup with a thin straight tail projecting far behind it. Flowering runs from August to November.

Similar species

Among the large-flowered, long-spurred Mexican species the spur length is decisive here: forty to sixty millimetres is exceptional even for this group. More telling still is the combination with the absence of a winter rosette, which gives a plant away at once in the dry months from December to March: if it is still growing with trapping leaves then, it is not P. moranensis. The habitat helps too: this species grows at eight hundred metres in the warm Gulf-coast zone, whereas most relatives begin only above fifteen hundred. Confusion is therefore unlikely in practice.

The trap and how it works

The trapping leaves are permanently in service, and that is what makes this species interesting. Stalked glands carry a clear sticky droplet; the sessile glands between them release digestive enzymes as soon as prey lies on the leaf, after which the margin bends slowly over the catch. Because there is no resting period the plant feeds all year round — possible in a rainforest with more than three metres of rain a year and a nearly constant temperature. The longest spur of this set, incidentally, has nothing to do with catching: it serves pollination, and points to pollinators with a very long tongue, such as hawkmoths or hummingbirds.

Habitat and ecology

Rocky limestone outcrops in the transition between montane cloud forest and tropical rainforest, at 800 to 865 m. The plants sit on permanently moist limestone faces (R2, R1) in the company of orchids, begonias and ferns, under a semi-warm climate with rain throughout the year and more than 3200 mm of annual precipitation (B2). It is that very constancy that explains the plant's build: where there is no dry season and temperature hardly fluctuates, a protective winter bud is superfluous, and a butterwort can afford permanently sticky, vulnerable leaves.

Distribution and elevation

Endemic to the Mexican state of Tabasco, at Ejido Villa de Guadalupe in the municipality of Huimanguillo — the southern, hilly part of the state where the last remnants of humid forest lie. This agrees with the entry in our species list. The known range is extremely small and appears limited to a few limestone outcrops within that one municipality. Tabasco is otherwise a flat, heavily cleared state with little suitable habitat, so a wider distribution is unlikely; the adjoining mountain zone of northern Chiapas, however, remains insufficiently explored botanically.

• Native

Forms and variation

No wild varieties have been described, which goes without saying for a species known from a few rocks in one municipality. The variation recorded in the protologue lies mainly in the number of leaves per rosette, from six to sixteen, and in spur length (forty to sixty millimetres). Both will track the conditions of the particular rock: light, water supply, thickness of the moss mat. The absence of a winter rosette is a character of the species, not a form. No natural hybrids are reported; no close relatives grow nearby.

Where and when to see it

Go between August and November, when the species flowers; the rain in this country is heavy then, but the plants are at their best. Seek out the limestone outcrops of southern Huimanguillo and look at the vertical, permanently wet faces carrying orchids, begonias and ferns — that plant company is the best guide. The purple flower with its five-centimetre spur is recognisable from a distance. Take rain gear and protect your equipment; the climate here is humid and warm and gear fogs up at once. Leave the plants alone and keep off the faces.

Conservation status

The species has not been assessed for the global IUCN Red List and is not listed in CITES. What is known is the profile of a highly vulnerable species: described in 2018, confined to a few limestone rocks within one municipality in a state whose original forest has largely gone. Tabasco has been heavily cleared for cattle, oil palm and petroleum infrastructure, and the last remnants of humid forest on the southern limestone hills are under pressure. Limestone is quarried as well. A species with so small a range and so specific a habitat would almost certainly fall into a threatened category on assessment; that the assessment is missing is a gap in the file.

Scientific name

Pinguicula olmeca | Zamudio, Burelo & Gonz.-Aguilar, 2018

Described by Sergio Zamudio, C.M. Burelo-Ramos and L. González-Aguilar in 2018, in Botanical Sciences 96(2): 359–365, based on material (C.M. Burelo-Ramos 530) collected on 10 July 2016. The type locality lies near Ejido Villa de Guadalupe, Huimanguillo municipality, in the Mexican state of Tabasco, at 800 metres altitude, on a limestone rocky outcrop in the transition zone between cloud forest and tropical evergreen forest. The name refers to the Olmec civilisation, regarded as the "mother culture" of Mesoamerica, whose religious and cultural centre was at La Venta, in the same Huimanguillo municipality where the species was discovered.

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