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Pinguicula imitatrix
This is the ghost among Mexican butterworts. Pinguicula imitatrix is known from a single collection made in 1939 in the state of Guerrero, and no one has since refound the plant with certainty — not even the expeditions that travelled to Guerrero specifically to look for it. The name, 'the imitator', refers to its resemblance to other species, and that is exactly why it is so hard to find again.
No photograph of this species under a Creative Commons licence or in the public domain is in the guide yet.
Identification
An honest account begins here with what is missing. The species was described by the German Pinguicula specialist S.J. Casper on the basis of herbarium material, and we have been unable to trace any testable measurement or colour statement from that description; every measurement field on the fact card has therefore been left empty. What can be said: it is a Mexican butterwort with the usual build of the genus — a flat rosette of sticky entire leaves with a glistening glandular coating, and scapes each carrying a single two-lipped flower. The epithet indicates that in the herbarium the plant closely resembles another, commoner species; that is precisely the sort of resemblance that lets a rare species go unnoticed for decades.
Similar species
The name is the key here: this species was described because it imitates another butterwort, and Guerrero holds several large-flowered species of section Orcheosanthus side by side — Pinguicula moranensis, P. orchidioides and P. zecheri are all known from the mountains around Puerto del Gallo and Chilapa. Anyone who finds in that country a butterwort that fits none of those three properly has something worth documenting. One caution: resemblance alone is not an identification. Without comparison against Casper's type material, any field determination of this species remains provisional.
The trap and how it works
About the trapping there is no doubt, because it is constant within the genus. The upper leaf surface carries stalked glands exuding a viscous clear droplet, and sessile glands that release digestive enzymes only once prey is lying on them. An insect landing on the glistening surface sticks fast and, through its own movements, touches ever more droplets; at the same time the plant starts a slow growth response in which the leaf margin bends over the prey and holds the digestive fluid. What this species catches exactly has never been studied — that would require living plants that can be watched in the field.
Habitat and ecology
Here too we must keep to what is on record. The only collection comes from the highlands of Guerrero, a landscape of pine-oak forest and montane cloud forest between roughly two thousand and two and a half thousand metres, with damp mossy banks along the mountain roads where the district's other butterworts grow (B5). We can offer no more than that general indication: there is no published habitat description, no elevation figure we could verify and no documented living population. Whoever refinds the species will make their most important contribution with exactly those data.
Distribution and elevation
Endemic to Mexico and, as far as known, to the state of Guerrero. The range rests entirely on one collection from 1939; there are no later finds that we could confirm. A targeted expedition to the mountains of Guerrero in 2006, which did encounter three other butterwort species, failed to find this one. That can mean two things: the species survives somewhere in the vast, poorly explored highlands of Guerrero where nobody has yet looked, or the original material was gathered at a site that has since gone. Both possibilities are real.
- Recorded (one-degree cells)
Forms and variation
No forms or varieties are recognised, and none can be: a species known from a single collection offers no material in which to establish variation. Indeed, even the normal range of variation of the species — how large the leaves can become, how much the flower colour shifts, whether there is a distinct winter form — is wholly unknown. That is no detail: in a species that by its own name resembles others, ignorance of its range of variation is the chief reason it is not refound. Natural hybrids are, logically, equally unknown.
Where and when to see it
This is a species you stumble on, not one you find. Anyone searching for butterworts in the highlands of Guerrero would do well to document every population fully — flower from the front and the side, spur to scale, summer rosette from above, winter rosette if present, plus altitude, rock and date — and not only the individuals that are immediately recognisable. The chance that a rediscovery comes out of such a series of photographs is greater than the chance that someone names the species in the field. Do not collect plants; a good photographic series with locality data is worth more to this question than a herbarium sheet.
Conservation status
The species has not been assessed for the global IUCN Red List and is not listed in CITES. What is known amounts to one collection from 1939 and no confirmed record since — a file too thin for a formal assessment, and worrying for that very reason. Guerrero has lost much of its mountain forest since 1939 to logging, coffee growing and conversion to pasture, and it cannot be ruled out that the only known site went with it. As long as nobody refinds the species, whether it still exists remains undecided. For this page, then: no category, no data, and one collection to build on.
Scientific name
Pinguicula imitatrix | Casper, 1963
Described by Siegfried Jost Casper in 1963. The species occurs in north-eastern Mexico. The species name imitatrix is Latin for "female imitator" and refers to this species' strong resemblance to another, closely related Pinguicula species with which it was initially confused.
World Checklist of Vascular Plants (WCVP), via Plants of the World Online (POWO), Royal Botanic Gardens, Kew.