Neoteny in Turbinicarpus

So what is neoteny ? Neoteny can be defined as follows:
Retaining juvenile or embryonic characteristics throughout the life-span; becoming fertile when still showing juvenile characteristics (always in comparison with related taxa)

The example of neoteny that most people have encountered is exhibited by the Axolotl. The Axolotl is the usually permanent larval form of the Mexican Salamander, Ambystoma mexicanum. It resembles a large, fully grown tadpole, up to about 30cm long, but it also reaches sexual maturity in this state. The Axolotl has the external gills of the Salamander larva and because of this it must live in water, unlike the normally amphibious Salamanders.

Ok, but what has this got to do with Turbinicarpus ? I hear you ask. Well it is believed that the genus Turbinicarpus sensu Glass and Foster, i.e.. Turbinicarpus and Normanbokea, but excluding Gymnocactus, are a group of plants that constitute neotenous forms of the genus Gymnocactus. In that they are smaller, generally solitary or not as offsetting and having spination reminiscent of juvenile Gymnocactus species.

This is best illustrated with a few photographs of seedlings and the most obvious example of neoteny in Turbinicarpus.

[Two month old lophophoroides seedling] [Close-up of adult valdezianus] [Adult valdezianus]

The photograph on the left is of a two month old seedling of T. lophophoroides, about 8mm high. It shows the typical characteristics of Turbinicarpus species in the early seedling stage, i.e.. plumose or feather-like spination and low rounded tubercles. The photo on the right is of an adult plant of T. valdezianus, this is about 2cm high and the middle photo is a close-up of the spination of the T. valdezianus. It is obvious that the spination of the seedling and of the adult valdezianus are identical (the adult valdezianus also has the low rounded tubercles, but these are not clear on the photo).

Note:I have not been able to find much information on neoteny in Turbinicarpus, if you know of any sources of information on this subject, whether it is with regard to Turbinicarpus in particular or plants in general, please let me know.

List of sources used to compile this text.

  1. A revision of the genus Neolloydia by Edward F. Anderson, Bradleya 4:8, 1986.
  2. Glossary of botanical terms with special reference to succulent plants by Urs Eggli.
  3. Plant and animal biology by A.E. Vines and N. Rees.
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