Source: http://living-rocks.com/kaktusy.htm
Timestamp: 2019-04-21 06:49:05+00:00

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Presented here is the complete Kaktusy Special 2 2002 - Ariocarpus, reproduced with the kind permission of the Editor and the Authors:. Libor Kunte and Vladislav Šedivý. We would like to thank Kaktusy for providing us with the original text and images, we have presented the images here in uncropped format..
Kaktusy wishes to express many thanks to Roy Mottram for his assistance with the English text.
Ariocarpus, until recently a well defined genus of attractive Mexican cacti after numerous revisions, new descriptions and combinations of recent years seems to be for many of us, unintelligible or even confused.
The object of this special issue of KAKTUSY 2002 is to present a comprehensive circumscriptions of this genus without useless, contrasting opinions, which would just deepen the existing chaos even more. Should we manage to meet this target, at least partially, our basic aim will be considered fulfilled.
As initial data for this study, we used current opinions for the definition of individual taxonomic categories (in this case genus, species, subspecies and variety) which we applied to our suggested scheme for the genus. The scheme evolved by logical deduction, from discussions of each taxon. Our study also comes from first-hand experience gained by observing plants in the field and in culture and last, but not least, from the extensive literature, especially that published in recent years.
The limited space in this ‘SPECIAL’ does not allow us to provide detailed descriptions of individual taxa, and for the same reason- we do not intend to reiterate already known facts about the history and botanical development of the genus nor to repeat instructions on how to maintain plants in cultivation. We therefore concentrate on fundamental facts, which follow mainly from real life conditions of plants in nature, especially the inter-specific and intra-specific relationships.
Ariocarpus plants grow over a wide geographical range from southwest Texas (USA) to central Mexico (so far they have been reported in the states of Coahuila, Chihuahua, Durango, Zacatecas, San Luis Potosi, Nuevo Leon, Tamaulipas and Querétaro), which basically covers the Chihuahuan Desert and adjacent natural plant formations of semi-desert type at the margins, especially matorral xerofilo (semi-arid zones with low, shrubby vegetation, often caudiciform types, in which plants with succulent stems dominate), and its subtypes (matorral crassicaule, matorral desertico rosetofilo, matorral microfilo and matorral submontano).
Shrubby desert and semi-desert countryside therefore represent the majority of typical environments. Some Ariocarpus plants, however, also occur in high savannas (pastizal) or, conversely, in an environment of thin semi-deciduous or deciduous forests at lower altitude of almost tropical character (bosque espinoso, bosque tropical subcaudicifolio, bosque tropical caudicifolio).
In general, we observe that they mostly prefer central altitudes around 1000 metres above sea level, with extremes ranging from 200 metres to 2400 metres.
The genus as a whole is listed in Appendix 1 of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), thus, belonging to the category which needs the highest protection. Individual taxa are categorized by IUCN (International Union for Conservation of Nature) from LR - low risk, VU - vulnerable, EN - endangered to CR - critically endangered, and this will be discussed under the individual taxa. .The overall inclusion of all species of the genus Ariocarpus to Appendix 1 of CITES rates the degree of danger in a rather unbalanced and unfair manner, although this is probably not the main purpose of this international agreement.
The type species of the genus is Ariocarpus retusus, described in 1838 by Scheidweiler based on plants collected in the late 1830’s by Galeotti, most probably only a few kilometres east of the town of San Luis Potosi in the Mexican state of the same name. The way it is generally understood (as A. retusus subsp. retusus), it represents the most widespread taxon of the genus and the diversity of its forms is truly fascinating. Maybe this accounts for it being the first form discovered, and new forms are still being described under new names. Its distribution range takes in the northeast part of the state of Coahuila (with the northernmost occurrence near the town of Monclova), through the western tip of Zacatecas, the central part of Nuevo Leon up to San Luis Potosi (the most common occurrence), all the way down to southern Tamaulipas. The southernmost localities can be found in the vicinity of Rio Verde (San Luis Potosi).
In this huge area (distance from north to south equals approximately 500 km), countless populations of plants are encountered. The typical environment consists of a sloping rocky terrain of limestone or gypsum at altitudes up to 2400 metres above sea level, with desert and semi-desert formations of matorral xerofilo or pastizal type.
Because of the abundance of plants, and thanks to the specialized environments in which these plants in most cases live, A. retusus, as a whole, is not endangered in nature. Perhaps the only risk factor threatening some of its localities is the water erosion caused by irrigation for the pasture farming of goats and cattle. With respect listing of this species in CITES 1, there is no better option than to express its degree of danger in the lowest possible category, i.e. low risk - LR.
Considering the high variability of this species A. retusus lends itself to an infra-specific classification, ideally as subspecies, which are partially defined by their geographical locality. This should be possible with sufficient knowledge of the variability of the species over the entire range of occurrence. This, however, is not easy, in view of the lacks of uniformity of these forms (or ecotypes), at the individual localities. Rather different populations near the town of Matehuala may serve as a typical example. A. retusus plants sympatrically occurring with A. fissuratus subsp. hintonii are, with their keel-like tubercle, quite different from the not so far distant A. retusus, which presents a strange, mixed population of plants both with keel-like tubercles and tubercles of triangular profile. The second possibility is to choose the rank of variety and to divide the species according to minor differences, but this is problematic for the very same reasons. The well known A. retusus var. furfuraceus (S. Watson) Frank, especially at the border of Coahuila and Nuevo Leon, which contain numbers of imperceptibly different forms, can serve as an example. It seems that we still have to wait for a better understanding of the intra-specific natural relations of A. retusus and that more than a dozen existing names are meanwhile required to serve as a temporary compromise in price lists, catalogues and the collections of specialists.
These photos document the variability of populations of A. retusus subsp. retusus from the eastern part of San Luis Potosi.
Fig. 5: A. retusus subsp. retusus at San Francisco, San Luis Potosí (photo V. Zatloukal).
A diversity of forms of A. retusus subsp. retusus is concentrated on a relatively small area south of Matehuala, San Luis Potosi where they grow together with A. fissuratus subsp. hintonii.
Fig. 10: Fig. 11: Plants from La Luz (photo V. Zatloukal).
Fig. 16: From near Huizache, San Luis Potosí, the territory with an extreme variability of forms. In this photograph by P. Pavlíček is an old plant with elongated slim tubercles.
There are Ariocarpus populations in Aramberri (Nuevo Leon), whose taxonomic position has been the subject of guesswork by amateurs and professionals for several years. In appearance they resemble both A. retusus Scheidw. and A. trigonus (Weber) K. Sch. They flower red, but also in various shades of pink to white and yellow. They mostly grow solitary, although sometimes they also offset. Several known localities consist of plants with all possible permutations of tubercle shapes and flower colours. In 1997 they were described as Ariocarpus confusus Halda et Horácek, and, because of the character of the reproductive organs as mentioned in the commentary to the description, they appear close to A. scapharostrus, but their body form resembles A. retusus. This area, as well as the more distant neighbourhood of Aramberri, has in recent years become a place of interest to many specialists, who had the intention of shedding some more light on this problem than was possible by the authors of the original description. Their effort, however, did not bring about the desired result. North-eastern localities, in the direction of Lampacitos, are composed of a completely different type of plants than localities in the immediate vicinity of Aramberri. In the opposite direction, the distribution area of these "unclassifiable" plants continues, according to all available information, as far as to the La Escondida crossing, where populations, once again, consist of slightly different plants than in both previous cases.
Opinions on these plants differ too. One view is that they represent natural hybrids, supported by variability of some characters, such as the tubercles, branching type, variability in flower colour, and the occurrence of A. retusus and A. trigonus within the range of distribution. Another opinion is that they are only forms of A. retusus and A. trigonus, yet others believe, that they are the ancestral forms from which both taxa evolved by migration into distinct species. This last opinion led to the description of this peculiarity as a separate species.
To be able to reach a definite conclusion, a lot of detailed research from the disciplines of comparative morphology, chemotaxonomy, and further observations in the field including ecological studies are obviously still missing. Our own opinion is that the existence of the above-mentioned plants supports the statement that A. retusus and A. trigonus are conspecific (Anderson and Fitz Maurice, 1997) along with A. confusus Halda et Horácek, although this name is still only provisional.
Ariocarpus retusus subsp. trigonus (Weber) E. F. Anderson et W. A. Fitz Maurice is not a typical example of the flora of the Chihuahuan Desert. It inhabits Tamaulipas and Nuevo Leon states, and grows at altitudes with dispersion of 1200 metres (200 to 1400 metres above sea level) and in various types of natural formations. The centre of its range lies in the valley of the Rio Guayalejo and Rio Chihue rivers, which is called Valle de Jaumave (Tamaulipas), and to which the north-western part the Chihuahuan Desert partially extends.
In the south-eastern direction, the valley changes to lowland, and the landscape changes from subtropical semi-desert climate to almost tropical (around Llera, Tamaulipas). Plants usually occur in flat, rocky places or on low hills, most often under the protection of low bushes or sparse woodland. Localities at low altitudes and other more or less isolated places of its distribution in the central-northern parts of Tamaulipas and Nuevo Leon are areas, which are being gradually exploited for agricultural production, and that is why local Ariocarpus populations are more than likely condemned to eventual extinction. Fortunately, the majority of its area of occurrence consists of agriculturally unattractive land and so tens of thousands of specimens growing there provide a certain degree of safety for this taxon in nature. Variability is mainly in the shape of the tubercles, ranging from short and broad to long and narrow. The flower colour varies from pale yellow to deep yellow with occasional rare individuals with red flowers (do not confuse with A. confusus) a variation known also in other genera of cacti. The number of ecotypes in habitat is unusually large, especially in the Jaumave valley. Descriptions based on these ecotypes are of minimal botanical value (A. trigonus var. elongatus Backeb., or A. trigonus var. minor Voldan, redescribed as A. trigonus var. horaceki Halda), thanks to introgression of individual forms at different natural habitats. In the close vicinity of the village of San Antonio, the most famous site of occurrence for the so-called A. trigonus var. elongatus, we observed an unbelievable diversity of plants, from those with long tubercles to a very different form on a bare outcrop of disintegrating shale, which both by its geological preference and appearance resembled A. scapharostrus. We are convinced, that without a concept of these habitat forms, it is understandable why this extreme and evident type could be seen to represent a new species. We, however, see no value to mystify the professional public. It is worth adding that this change takes place within 50 to 100 metres of ordinary looking so-called A. trigonus var. elongatus!
A cross section of forms of A. retusus subsp. trigonus.
Fig. 25: Fig. 26: Two extreme forms with elongated tubercles from the vicinity of San Antonio, Tamaulipas, all within a distance of several tens of meters (photo L. Kunte, J. Bohata).
Fig. 27: Small form from the vicinity of Jaumave (photo V. Zatloukal).
Approximately 200 kilometres northeast of Jaumave an interesting natural formation may be found. This extremely arid area is called Rayones Valley. Here is a rare endemic species, the taxonomically and nomenclaturally unequivocal Ariocarpus scapharostrus Bod., standing virtually isolated systematically within our scheme of the genus. Its uniqueness is generated by adaptation to the specialized habitat. It prefers low shale hillocks, where it grows in crevices of grey, disintegrating shale, filled with yellowish clay. Rayones Valley occupies an area of about 50 square kilometres and Ariocarpus scapharostrus can be encountered at several localities in its northern, eastern and western parts at altitudes ranging from 800 to 1000 metres. We have received some indications suggesting other localities occur beyond the boundaries of the valley. Natural variability exists even within this more or less uniform Ariocarpus but it comprises minor differences in the shape of tubercles, which are so typical that gave this Ariocarpus its name (boat-beaked Ariocarpus). Inclusion of A. scapharostrus in the category of endangered plants (EN) is justified mainly because of its unique habitat.
Until recently, Ariocarpus agavoides had been considered as the most endangered Ariocarpus species. Its distribution range was formed only by very few limited and mostly devastated localities at the outskirts of the city of Tula (Tamaulipas) and its immediate vicinity. This species is really endangered in this area, mainly due to the undesirable effects of civilisation. In the recent past, however, two new localities have been discovered in the adjacent eastern part of San Luis Potosi. The countryside represents a type of peripheral formation of the Chihuahuan Desert and plants occur here under almost identical ecological conditions, that is, on limestone hillocks among low, xerophytic vegetation at altitudes of about 1200 metres. Minor differences compared to the Tamaulipas plants can be attributed to the slightly different ecological conditions at the each locality. This discovery has dramatically changed the degree of danger of A. agavoides and enabled the Mexican discoverers of these new localities (Sotomayor, Arendondo, Martinez) to suggest a reduction of its status on the IUCN scale from the highest possible rating of CR to EN. The populations in San Luis Potosi are quite large and sufficiently protected. The only known negative factor allegedly being wild goats and their trampling underfoot. This fact, however, does not change the need to protect the sites around Tula more effectively.
The extraordinarily attractive Ariocarpus kotschoubeyanus (Lem.) K. Sch., until the more recent serious exploration of Mexico considered as an extreme rarity, serves as a good example of how transient is the notion of scarcity. Today, it has been proved that it represents a widespread species with a range throughout the states of Querétaro, Tamaulipas, Nuevo Leon, San Luis Potosi and Coahuila, and also unconfirmed localities in Durango and Zacatecas. Compared with others this species prefers rather different conditions - flat, sandy-clayey deposits of limestone formations at altitudes ranging from 1200 to 1800 metres, situated, with few exemptions, in harsh conditions of the Chihuahuan Desert. Plants most often occur in nest-like places, frequently with enormous density of specimens. The best known localities are found in the eastern part of San Luis Potosi and the southern part of Coahuila in the area between towns of Saltillo and Torreon.
A. kotschoubeyanus var. macdowellii Backeb. occurs at several localities in the southern parts of Coahuila. The only reason for its description was its alleged dwarf stature. The miniature form is not, however, uniform, and the size of plants changes continuously in line with local climatic and soil conditions at each particular locality. A similar situation also appertains to A. kotschoubeyanus var. albiflorus (Backeb.) Krainz from the vicinity of Tula (Tamaulipas), described mainly for the difference in flower colour. The flower colour was described as white. However, at the same locality it varies from white to pink and even almost red, so the original author of this description was misguided. By the same token the recombination of both varieties to the subspecies is also untenable, since they are indistinguishable from populations in San Luis Potosi and Nuevo Leon. They are close morphologically and even geographically.
Slightly different conditions in several localities between Rio Verde and Las Tablas in San Luis Potosi subtle differences in the appearance of the plants were probably responsible for the recently published description of A. kotschoubeyanus subsp. sladkovskyi J. J. Halda et Horácek (these plants have been distributed under the appellation "San Francisco Form"). Other interesting sub-populations could also be classified in a similar manner, for example those plants found to the south-east of San Luis Potosi City. In our opinion, it would be possible to find or select dozens of similar forms and give them the status of variety or subspecies. Their taxonomic level should never go beyond that of form, cultivar or label name in specialized collections and in the price lists of cactus companies. Therefore it is much more valuable to identify plant by its known locality than to spread a taxonomic anarchy or superfluous names known locality, thus representing a strictly endemic element.
The form from the eastern part of San Luis Potosí that was described as A. kotschoubeyanus subsp. sladkovskyi J. J. Halda et L. Horáček.
Fig. 43: Las Tablas (photo V. Zatloukal) – details of the surrounding environment are very evident.
A. kotschoubeyanus subsp. elephantidens Skarupke ex J. J. Halda represents rather a different situation. It is the southernmost member of the genus and its localities in Querétaro are separated by approximately 150 kilometres from the nearest populations of A. kotschoubeyanus. It reaches nearly double the size of any other forms and its habitat is also different. It grows on stony slopes, often under the protection of shrubs, at altitudes of approximately 2000 metres. Despite the relatively minor differences in general appearance from typical A. kotschoubeyanus (deeper flower colour, size of the stem etc.), it is possible to consider this as a stable population and thanks to its geographical isolation, as a separate subspecies.
Tens of thousands of plants of A. kotschoubeyanus in known or yet unknown localities in nature cover an enormous area and make us sure that this beautiful species is not threatened with extinction. Large road and water works construction are the only serious threats. The degree of danger can thus be classified in the lowest possible category, which is low risk (LR).
Thanks to recently discovered taxa, A. fissuratus offers an interesting evidence of new developments in taxonomic concepts within the genus. Until recently it was only observed in its well known centre of occurrence in southwest Texas and southern parts of Coahuila. Last year’s surveys of central and northern parts of this Mexican state indicated an almost continuous cline of plants between two, so far isolated, areas. The discoveries of new taxa towards the end of the 20th century moved the species boundary almost 200 kilometres south to San Luis Potosi. The finding of intermediate forms in the area of the Sierra de la Paila mountain range and on the northern border of Coahuila made the intra-specific classification more difficult and led sometimes to an almost complete reclassification of the species as a single taxonomic unit (see for example E. F. Anderson and W. A. Fitz Maurice, 1997). We are convinced that the A. fissuratus - A. lloydii - A. hintonii - A. bravoanus is a continuum within the framework of a single species.
Natural conditions, where A. fissuratus occurs between Texas and San Luis Potosi, are very ecologically similar - Chihuahua Desert and its margins overlapping to semi-desert xerophytic vegetation, usually on the tops of low limestone hills or on plateau at altitudes from 500 to 1600 metres above sea level. Yet the typical variety prefers lower situations.
The northern limit of the range of A. fissuratus is is the area of Big Bend in Texas. Characteristic plants with rugged tubercles grow there.
Fig. 58: A miniature form from the vicinity of Terlingua (photo P. Pavlíček).
Fig. 60: A. fissuratus subsp. fissuratus, Cuatrocienegas, Coahuila, a typical form (photo V. Zatloukal).
Fig. 61: A. fissuratus subsp. fissuratus, El Hundido, Coahuila, an old plant (photo V. Zatloukal).
Fig. 62: A. fissuratus subsp. fissuratus, El Hundido, Coahuila, beautiful intermediate form (photo V. Zatloukal).
Fig. 63: A. fissuratus var. lloydii, Parras, Coahuila (photo P. Pavlíček).
Fig. 65: A locality A. fissuratus var. lloydii, Viesca, Coahuila (photo V. Zatloukal).
Fig. 66: An intermediate plant at Viesca (photo V. Zatloukal).
The typical A. fissuratus subsp. fissuratus is divided into two varieties, i. e. the northern form of the species (var. fissuratus), and, in a continuous movement southwards to Coahuila, and to Durango and Zacatecas (var. lloydii). At the imaginary border between these two varieties, they overlap, and both typical and intermediate forms exist together. A. fissuratus subsp. hintonii. (W. Stuppy et N.P. Taylor) Halda grows about 200 kilometres to the south, at several localities in the vicinity of Matehuala (San Luis Potosi). Even further south, A. fissuratus subsp. bravoanus (H. Hernandez et E. F. Anderson) J. Lüthy occurs, so far limited to the only known locality, thus representing a strictly endemic element.
The discovery of subsp. bravoanus is interesting, especially from the point of view of intra-generic links, because it represents a connecting line between the formerly recognised genera or subgenera Ariocarpus and Roseocactus, in particular between A. fissuratus and A. agavoides. According to present day knowledge, it is possible to classify subsp. hintonii as endangered (EN), and subsp. bravoanus as critically endangered (CR). Eventual corrections to the degree of danger will depend on them being found at other localities, especially for the latter subspecies (information about other localities of subsp. bravoanus not far from the type locality is already rumoured, although this information has not yet been verified). Although it is true that the long known northern varieties are indeed in danger because of the encroachment of arable land (near Cuatrocienegas, Coahuila), they mostly occur in highly arid localities or national parks, where this risk is very unlikely.
A. fissuratus subsp . bravoanus, El Nuñez, San Luis Potosí.
Fig. 73: Under shrubs (photo V. Zatloukal).
The search for intermediate forms, natural hybrids, and experiments with crossbreeding of individual taxa serves as supporting evidence for further argument toward the clarification relationships. In the case of the genus Ariocarpus, only limited results of crossbreeding experiments in cultivation so far exist (Lux, Stanik, 1983; Neuendecker, 1985). They indicate that all taxa of the genus known at that time were genetically compatible and that it is possible, without major difficulties, to cross-pollinate all species. A. scapharostrus constituted an exception since as the female parent it crossbred with other species only with some difficulties. The only, unfortunately very badly documented, case of natural crossing is the recent description of the hybrid A. retusus x A. kotschoubeyanus (A. x drabi J. J. Halda et J. Sladkovský 2000), coming from area near Dr. Arroyo, Nuevo Leon and having, allegedly, the appearance of a dwarf. A. retusus with a pink flower. It is not possible to glean more information because the Latin description is very brief, and it lacks any illustrations. Because of the absence of photographic material, we consider this information suspect. The plant from near Viesca, Coahuila, documented with success by P. Pavlícek, could also be a hybrid of A. fissuratus var. lloydii and A. kotschoubeyanus. Arguably, A. confusus could be yet another possible example of natural hybridisation. Sympatric occurrence of some Ariocarpus taxa in nature has been documented in the literature several times. An interesting form of A. retusus subsp. retusus grows with A. agavoides, A. fissuratus subsp. hintonii and A. fissuratus subsp. bravoanus, but transitional or hybrid specimens have never been observed in any of these cases.
Basically, it is necessary to state that Ariocarpus Scheidw. is a stable genus incorporated steadily and without any doubts into previous as well as present schemes of the Cactaceae with a relationship within the Thelocactus - Ariocarpus - Lophophora - Obregonia line. Basic common attributes are mainly the structure and character of the seeds, supported by the structure of the fruits and stems. There have been some attempts to combine all these genera into a bigger whole. The almost forgotten revision by W. T. Marshall of 1946, who incorporated Strombocactus Br. et R., Obregonia Fric and Encephalocarpus A. Berger into Ariocarpus, was developed again by J.J. Halda in 1998. In his revision he divided Ariocarpus into two subgenera and two sections. However, this old idea does not stand much of a hope for practical application and does not convince most botanists.
High variability within individual taxa and their relationships become the subject of an increasing interest among professionals and amateurs alike and presage further understanding, which will in turn refine opinions on the intra-specific arrangement of the genus. The sine qua non is, of course, further systematic research in the field. What may we expect from it?
1. Refinement of our understanding regarding the distribution and relationships between individual taxa of A. fissuratus. New findings are to be expected at the southern limits of A. fissuratus subsp. hintonii and A. fissuratus subsp. bravoanus in San Luis Potosi, and eventually also within A. fissuratus subsp. fissuratus in the northern parts of Coahuila.
2. Gradual clarification of the mysterious A. confusus including a more detailed overview of the variability and mutual relationships between A. retusus subsp. retusus and subsp. trigonus.
3. Confirmation of some historical locality data. For example, confirmation of the distribution of A. kotschoubeyanus to the west (Durango, Zacatecas) and in the north and south directions (Coahuila - San Luis Potosi - Nuevo Leon).
We are convinced there are still many more surprises awaiting lovers of Ariocarpus but we do not wish to speculate. Many distant or inaccessible localities are awaiting exploration, which may reveal perhaps, even such epochal break-throughs like the discovery of Geohintonia mexicana or Aztekium hintonii.
Stem usually single, 20-300mm broad, with underground part root-like and with both thickened and fibrous roots, the above ground part flattened to hemispherical, with truncate or convex apex, divided into spirally arranged, hard, more less triangular tubercles, which are flat, convex or fissured on top. Areoles consist of spiny and floral parts, which may be sometimes connected with a central, woolly furrow. Floral part close to the base of the tubercle. Spines usually absent, except at the seedling stage. Flowers develop at or close to the plant apex, bell-shaped, white, yellow, pink, red or magenta, 20-50mm broad, with filaments white to violet, stamens white to orange, and stigmas 5-10, white to yellow. Fruit fleshy, drying after maturity, round to oval, glabrous, whitish, green to slightly red, 5-39mm long, 2-12mm wide. Seeds black, spherical to ovate, 0.75-1mm long, with a large basal hilum.
Type species: Ariocarpus retusus Scheidweiler, Bull. Acad. Sci. Brux. 5: 491, 1838.
Ariocarpus fissuratus (ENGELM.) K. SCH.
Ariocarpus kotschoubeyanus var. elephantidens SKARUPKE, 1973 nom. inval.
Ariocarpus trigonus var. elongatus (S.-D.) BACKEB., 1961non sensu S.-D.
Ariocarpus elongatus sensu auct. (WETTSTEIN emend. HALDA) non sensu orig. S.-D.
Basic sources until 1989 are summarized in the appendix to the Chrudim Atlas of Cacti W 991 (V. Šedivý, Rod Ariocarpus Scheidw.).
E. F. Anderson and W. A. Fitz Maurice (Ariocarpus revisited. Haseltonia 5: 1-20. 1997).
Ríha, J. (2002). Rod Ariocarpus v údolí Aramberri, Nuevo Leon, Mexiko. Kaktusy 38:92-96.
Sotomayor, M., Arredondo, A., Martinez, M. (2001). Ariocarpus kotschoubeyanus (Lem.) K. Sch. - rozšírení, charakteristika nalezišt' a stupen ohrožení v prírode. Kaktusy 37:55-58.
Sotomayor, M., Gomez, A., Mendez, M. (2000). Neue Wuchsorte von Ariocarpus agavoides. KuaS 51:113-118.
Zachar, M., Verduzco, J. (1992). Ariocarpus kotschoubeyanus (Lem.) K. Sch. Cactaceae etc. 2: 74,107-108.
Worth mentioning are certain revisions of the genus and some new descriptions published continuously by J. J. Halda et al. (Acta Musei Richnoviensis,1998-2000). The Japanese book on Ariocarpus with almost 350 photographs (K. Suguri, Ariocarpus Hand Book, 1996, with text partly in Japanese) provides interesting comparative material with an incredible number of random mutations.

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