Dyckia joanae-marcioi P J Braun, Esteves & Scharf
Literature references:
Comments:
- Distr. To date, Dyckia joanae-marcioi is recorded only from the type locality near Mato Verde, northern Minas Gerais, Brazil. Only one large population is situated at a slightly rocky place. The new species is not accompanied by other bromeliads or cacti. Indeed, other bromeliads and cacti occur several kilometers away at different elevations. Dyckia joanae-¬marcioi grows at that remote place.
Discovery
One of the most interesting areas to dis¬cover cacti in Brazil is the mountain chain near Mato Verde in the North of the state of Minas Gerais. In 1971, for the first time, Leopoldo Horst travelled the region in search of cacti and discovered close to Mato Verde new taxa in addition to representa¬tives of known species. Some of the new species from that area are Micranthocereus albicephalus (Buining & Brederoo) Ritter, Melocactus robustispinus Buining & Bre¬deroo, and Arrojadoa eriocaulis Buining & Brederoo. As a result, this region became a standard travel stop for all cacti-scientists travelling in Minas Gerais. New discoveries in the close surroundings followed. These included Arrojadoa horstiana P.J. Braun & Heimen and Arrojadoa rosenbergeriana (van Heck & Strecker) P.J. Braun, Esteves & van Heck.
In the 1980s, researchers began taking a special interest in the terrestrial bromeliads of this region. In several journeys near Mato Verde, Rauh (& Leopoldo Horst) and Braun & Esteves were able to add several species of Aechmea, Dyckia, Encholirium, Hohen¬bergia, Orthophytum, and Vriesea. Eventu¬ally, in 1999, Braun & Esteves studied a reddish-leaved, succulent Orthophytum growing there. On their way back into the valley, in a deeply sunken path full of red dust, they spotted small, reddish-orange, typical Dyckia-flowers high up between the rocks. Even at that time, this region seemed to have been well explored for three decades, so they didn't expect something new. But in spite of this, they became curi¬ous and they climbed the slope just to see what the plant looked like and to take some photos.
On reaching the plants, they were greatly surprised to discover a large popu¬lation of white lepidote, highly succulent Dyckia. Plants like this had not been known to grow in this region in Minas Gerais, and to the knowledge of the authors, none of the other travellers discovered this population. Interestingly, no other species of bromeliads or cacti occurred at this location. Maybe, this explains why it was not found until then.
Obviously, the species described here, is not identical to any Dyckia known to date. The authors propose a name for this new conspicuous, succulent species.
Species delimitation and characteristic features
After discovering this species in 1999, both E. Esteves in Brazil and P.J. Braun from Euro¬pe tried to solve the enigma of this Dyckia. Besides the discussion regarding the name "Dyckia argentea" (see below), no earlier collections at that site or of that population or publications regarding the as yet unknown plants from Mato Verde could be found.
In 2002 the locality was revisited to collect more data in situ. Further populations could not be found. It is likely that the population is a remainder of a largely isolated branch of the relationship close to Dyckia marnier-lapostol¬lei. Nevertheless, all known species occur far away in the state of Goias in central Brazil.
1. Dyckia marnier-lapostollei L.B. Sm. (see Smith 1966, Rauh 1985, Braun & Este¬ves 2005) from south-eastern Goias exposes a clearly different habit. Dyckia marnier-lap¬ostollei is a much bigger plant, the leaves are longer, broader, and recurved; frequently, the apex even curls up backwards. In addition, the scales are loosely arranged across the surface. The dense marginal teeth are covered with white scales and the inflorescences are more stout and longer.
2. Dyckia lindevaldae Rauh (see Rauh 1988, Braun & Esteves 1990) from northern Goias grows in groups (gregarious) and forms small, apparently "dichotomous" branching rosettes. The leaves are clearly different, less succulent, and diffusely lepidote too.
3. Dyckia braunii Rauh (see Rauh 1990a, 1990b, Braun & Esteves 1990, 2002, 2006) from northern Goias is probably the closest relative. Regarding their morphology in veg¬etative state D. joanae-marcioi and D. braunii are very similar. In habitat, it is as easy to distinguish both species as in cultivation when several plants of both species stand close to each other. Distinguishing between individual plants can be a challenge even to the trained eye. To compare fruits and seeds, the vouchers Braun 3038 (HAL) for D. braunii and Braun 2384 (HAL) for D. joanae-marcioi were deposited.
Taxonomic problems
The greyish-silvery leaves might lead one to misidentify this species as the lost "Dyckia argentea". The name was used by G. Nicholson in 1885 for his combination Dyckia argentea (Baker) G. Nicholson. The species he was working on came from Mexi¬co. Nowadays, it has been renamed Hechtia argentea Baker and is widely cultivated in botanical gardens (in Europe).
Hechtia argentea Baker in W.B. Hemsley, Biol. Cent.-Amer., Bot. 3: 317 (1884).
Syn.: Dyckia argentea (Baker) G. Nicholson, 111. Dict. Gard. 1: 497 (1885).
Distribution: Mexico, Queretaro.
The collection locality is situated in the Serra do Lenheiro near Sao Joao del Rei in Minas Gerais, thus at least c. 700 km south of Mato Verde, the collection site of Dyckia joanae¬rnarcioi. Braun & Esteves visited the moun¬tain ranges near Sao Joao del Rei many years ago without recognising plants similar to those from Mato Verde. Studying both the old description in Flora Brasiliensis and the her¬barium vouchers in B and C (type collections online) didn't reveal any relationship to the plants from Mato Verde. Just the leaf length of 30 cm in the collections of Glaziou descri¬be much larger plants with a diam. of about 50-60 cm, which is not consistent with the compact, succulent features of the plants from Mato Verde. Dyckia joanae-marcioi is clearly different to the still lost "Dyckia argentea Mez". For taxonomic reasons, the name is not applicable. —See Die Bromelie
