Copiapoa humilis subsp. australis – a new subpecies

Towards the end of my first trip to Chile in the company of Alfred Lau, Clarke Brunt and Jean Ellwood we spent a day in the vicinity of Huasco where we discovered a small growing Copiapoa which we could not identify. We found only a few plants in a very limited area, and lack of time prevented us from exploring further.

I puzzled over its identity, and a study of the literature on our return did not throw up any suitable names. On a second trip to Chile, in November 2002, this time accompanied by Jonas Lüthy, Clarke Brunt and Simon Mentha, we planned to investigate this intriguing little plant further and to explore the habitat in more detail.

Figure 19 Copiapoa humilis subsp. australis PH472.07 (Huasco) –
a typical small clump

We also wanted to search in the surrounding area for other populations in an attempt to gain an understanding of its distribution. Our attempts at finding other populations were unsuccessful, but fortunately explorations at the original location revealed a larger number of plants than originally thought and a healthy viable population. We were also rewarded with a display of flowers during this visit; at the time of our first visit in February 2001 no flowers were in evidence. Studies indicated this taxon is most closely related to Copiapoa humilis and it is described here at the rank of subspecies. It is of particular note that this subspecies of C. humilis is the most southerly known at present and it extends the range southward by about 100km from Copiapoa humilis subsp. longispina, previously the most southerly recorded Copiapoa humilis taxon. Hence I have chosen the subspecies epithet australis to indicate its southern occurrence.

This taxon differs from Copiapoa humilis subsp. humilis in having smaller, conical bodies, smaller flowers with a distinct green ovary, a very large difference in dimensions between radial and central spines, and a very disjunct southerly distribution.

Figure 20 Copiapoa humilis subsp. australis PH472.07 (Huasco)
type plant prior to preservation, note the very long thin neck
between roots and body. The coin is 26mm in diameter.

Copiapoa humilis subsp. australis P. Hoxey subspecies nova

Differt a subsp. typica caulibus minoribus, conicis, floribus minoribus ovario viride, spinis conspicue dimorphis, marginalibus tenuibus et centralibus validis etiam patria disjuncta, australe.

Holotype: Paul Hoxey 472.07 (SGO 150209) Collected by Paul Hoxey, Clarke Brunt, Jonas Lüthy and Simon Mentha on 28th November 2002 and deposited at the Herbarium of the Museo Nacional de Historia Natural, Santiago (SGO), number 150209.

Figure 21 Copiapoa humilis subsp. australis PH472.07 (Huasco)
plant with juvenile and adult spination

Description:
Stem:- Mature heads 3-5cm across and 5-8cm tall, occasionally larger. Usually taller than broad. Strongly tuberculate, ribs very indistinct between 8 and 10 in number. Body soft to the touch, connected to the top of the root stock by a remarkably thin subterranean neck up to 50mm long and 3 to 4mm across. Initially soft, the neck matures to become brittle and is easily broken. It has small areoles along its entire length. Heads cluster readily, offsets forming from the top of the rootstock where they develop a neck to reach the surface, or from the basal areoles on a mature stem where they do not. Immature heads have distinct juvenile characteristics being smaller in all their parts without ribs. Specimens often offset prolifically, commonly having a combination of mature and juvenile heads. The epidermis is a dark grey-green colour, with a light whitish waxy coating. Seedlings in cultivation retain this colour. The tubercles are rounded and flattened to 8mm across and 5mm deep.

Root:- Large, tuberous and branching, to 150mm long and 30mm wide.

Spination:- Central and radial spines very distinct in mature growth, the central spines being much longer and thicker. Central spines up to 4, occasionally 5, straight, 15 to 25mm long, initially dark, almost black, ageing to grey with darker tip. Erect and spreading away from the plant body. Radial spines 6 to 8, 5 - 7mm long, initially dark, turning grey, much more slender than central spines, radiating in all directions around the areole, flattened to the plant body. The difference between the central and radial spines is much more pronounced in this subspecies than in any other, both in thickness and length.

Juvenile spine characteristics are observed in seedlings and new offsets from mature roots. Juvenile plants have weaker spination than mature heads as is typical in the Copiapoa humilis complex, central spines usually absent but occasionally 1 up to 5mm long. Radial spines 3mm long and flattened against the plant body.

Areoles:- 3mm in diameter and circular, initially covered in dense white wool which wears off with age. White wool very prevalent at the apex which covers the growing point. Areoles very easily detached along with spine cluster, leaving a clean 2-3mm diameter circular depression.

Flower:- Emerging one or two at a time from near the apex with the buds initially protected by the white apical wool. Opening during the day, 20mm across when fully open, by 25mm long. Outer perianth segments (approx. 12) green at base merging into yellow with a rose-red tip, fading into a faint mid-stripe. Petals (approx. 14) 20mm long and 4mm wide, golden yellow with a slightly darker mid-stripe. Ovary circular, 3mm in diameter. Pericarpel green without scales or hair. Style 12mm long, yellow fading to green at base. Stigma golden yellow, 6-7 lobes 2mm long. Pollen yellow. Stamens 10mm long, asserted just above stigma and surrounding it evenly. In habitat flowering was observed in November 2002.

Figure 23 Flower section of Copiapoa humilis subsp. australis
PH472.07 (Huasco)

Small beetles were observed eating the petals during our visit. It is not known if they are the pollination agent, as bees and hover flies are usually associated with pollination in the genus Copiapoa.

Fruit:- Globular, 5mm in diameter, green in maturity. Eventually dries, when it can be removed easily from the plant. Contains 10-15 seeds.

Seed:- Typical for a Copiapoa, testa black and glossy. Approximate dimensions 1.5mm x 1.2mm.Type location:- In the vicinity of Huasco in the province of Atacama (Region III), Chile. Growing on gently sloping to flat ground at an altitude of 400m, among small rocks and stones with a brown soil of a fine, powdery consistency.

Figure 22 Copiapoa humilis subsp. australis PH472.07 (Huasco)
plant with very heavy central spines. Can you see the tiny
radial spines?

Distribution:- The type locality is the only known population at present. Specimens were found over an area of about 1,000m, where they are fairly common. Plants of all ages were observed and the population appears stable and is reproducing well, with an estimated population size in the low thousands. There appears to be no natural threat to the plants with no evidence of animal predation, such as by guanaco or insect larvae. Man-made disturbance is also very limited at present so the plant should not be considered endangered, but could be susceptible due to its limited range. This region of Chile is often visited by cactus enthusiasts so it must be assumed that the distribution is small for it to have avoided detection until now.

Figure 24 Copiapoa humilis subsp. australis PH279.07 (Huasco)
seedling raised in cultivation just beginning to develop the heavy
cental spines

Material examined:- Paul Hoxey 279.07 (18th February 2001) and Paul Hoxey 472.07 (28th November 2002), both at the type locality.

Associated flora:- The area is rich in other cactus species with Copiapoa fiedleriana, Eriosyce villosa, Eriosyce napina, Eriosyce sp., Eulychnia acida and Echinopsis (Trichocereus) coquimbana growing in association.