Copiapoa humilis subsp. varispinata (Ritter) D. Hunt, Cact. Syst. Init. 13: 14 (2002).
Basionym: C. variispinata Ritter, Kakteen in Südamerika 3: 1070 (1980).
Synonym: C. paposoensis Ritter, Kakteen in Südamerika 3: 1068 (1980).

This is another Ritter discovery from the 1960s and described by him as Copiapoa variispinata in 1980. David Hunt corrected the spelling by replacing the ‘ii’ with a single ‘i’ when naming it as a subspecies of C. humilis. This is a very misunderstood taxon which Graham Charles discusses in some depth in his book Copiapoa. The recently named C. ahremephiana (the most northerly member of the Copiapoa cinerea group which grows near the Botija valley) was mistaken for this species for many years. It is a big mystery why Ritter did not discover that taxon too as it grows only a few kilometres further up the coast from the type locality of C. humilis subsp. varispinata. I am certain if he had found it he would have described it as a new species.

C. humilis subsp. varispinata grows in the vicinity of the Iscuña Valley, some 50km north of Paposo, as reported by Ritter. The plants I saw in habitat tended to be small squat plants, wider than high, growing among rocks and stones, distinctly ribbed with 15-18 ribs, forming small clusters. The spination  is variable, as alluded to in the name, although this appeared to have more to do with the size and age of the plants, as is typical in the C. humilis group. Smaller specimens with shorter spination immediately suggested to me a close relationship with C. humilis subsp. tenuissima, showing similar juvenile characteristics.

Larger plants had longer and more mature spination although somewhat variable. The distribution of the population we investigated was limited to 300m in altitude; no plants were found above that height. Unusually for C. humilis, the epidermis has a grey-grey colour in habitat. In cultivation, seed raised plants are green. The tubercles are of an identical size and structure to C. humilis subsp. tenuissima, particularly in smaller plants. Also similar is the spination, the radial spines are 4mm long, spreading evenly around areole, 10-14 in number. Central spines occur on larger plants and are 10- 15mm long and up to 5 in number. Flowers are approximately 30mm across, growing from the woolly apex, and have a reddish mid-stripe on the outside of the petals.

This taxon and C. humilis subsp. tenuissima are similar in many respects and more closely related to each other than to any other subspecies of C. humilis. However C. humilis subsp. varispinata seems to be selffertile, as observed in cultivation, whereas C. humilis subsp. tenuissima is self-sterile (J. Lüthy, pers. comm.). C. humilis subsp. tenuissima should be considered a fixed juvenile form which has adapted to grow at higher altitudes, in a drier environment. It has been reported from as far south as the Botija valley, which is perilously close to the habitat of C. humilis subsp. varispinata!

Figure 13 Copiapoa humilis subsp. varispinata PH443.01
(Quebrada Iscuña 200m)

I have been lucky enough to examine original Ritter material of C. humilis subsp. varispinata (FR1447) in cultivation. The plants, all over 30 years old, are much larger than I had observed in habitat and show very variable spination length, even in similarly sized specimens. I suspect that just like the case of C. humilis subsp. tenuissima, plants of this size do not exist in habitat. Copiapoa paposoensis is a taxon which Ritter discovered 20km north of Paposo. It grows high up in the hills,