Drosera arenicola — 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 perennial rosette plant of the sandstone plateaus, with leaves densely set with tentacles that turn red in full sun. As in several other sundews of the Guiana Highlands, the plant may form a short stem of old leaves over the years. Reliable measurements and a confirmed flower colour from the original description or the Flora of the Venezuelan Guayana could not be checked here; anyone wishing to identify the species should consult those sources.

Similar species

Several sundews on and around the tepuis are hard to separate in the field: Drosera roraimae with long-petioled leaves, Drosera hirticalyx with a hairy calyx, Drosera kaieteurensis and Drosera felix as tiny red rosettes, and Drosera esmeraldae of the lowland white sands. The name refers to the sandy habitat, but that is no distinguishing feature: almost all species in the region grow on sand.

The trap and how it works

An active flypaper trap. The tentacles catch small insects walking over the sand or flying low above it; the surrounding tentacles then bend towards the prey. On the bare, nutrient-poor sandstone plateaus animal prey is one of the few sources of nitrogen and phosphorus.

Habitat and ecology

Sandy, acid and extremely nutrient-poor soils on and around the table mountains: bare sandstone and sand flats on the plateaus, and wet sandy ground in open, marshy vegetation (R5, D2, W4). The climate on the tepuis is cool and very wet.

Distribution and elevation

The Guayana Highlands of Venezuela, in the states of Bolívar and Amazonas. As far as known confined to Venezuela; records from neighbouring countries are unconfirmed. A reliable altitudinal range could not be checked.

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 cells are 8 one-degree squares — 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: the locality of poached species is obscured at source. At this scale that obscuring disappears into the noise. The cells show where it has been seen, not where it occurs: an empty square means nothing.

Forms and variation

Besides the typical form a variety has been described from tepuis in the west of the Guayana region (var. occidentalis); whether that distinction will hold in a modern revision is unknown. The Guiana sundews as a group have never been fully revised, and several names may merge or split on closer study.

Where and when to see it

Tepuis can be reached only with guides, permits and often by helicopter; spontaneous fieldwork is out of the question. Anyone on an expedition would do well to photograph every sundew with flower, leaf base and calyx in view, and to record the exact habitat. Such data are scarce and valuable.

Conservation status

Not assessed for the global IUCN Red List and not listed in CITES. The table mountains lie largely in national parks and are hard to reach, so direct threats are slight. Climate change and growing tourism on a few popular tepuis are the main risks; nothing is known about population size or trends.

Scientific name

Drosera arenicola | Steyermark, 1952

Described by Julian Alfred Steyermark in 1952, in Fieldiana, Botany, volume 28, p. 243. The precise type locality could not be established. The species is endemic to Amazonas and Bolívar states, Venezuela, and occurs above 1200 m elevation, including on tepui plateaus. From the Latin arena ("sand") and -cola ("dweller") — "sand-dwelling", consistent with the species' sandy/rocky tepui habitat.

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