Yungasocereus
From M&J Cactus Wiki
| Yungasocereus | |
|---|---|
| File:Yungasocereus inquisivensis.jpg | |
| Kingdom | Plantae |
| Family | Cactaceae |
| Subfamily | Cactoideae |
| Tribe | Cereeae |
| SubTribe | Trichocereinae |
| Genus | Yungasocereus |
| Species | |
| Notes | Taxonomy follows Joël Lodé (2015) with molecular insights from Arakaki (2008), Schlumpberger (2012), and Franck (2012). |
Etymology
Named after the Yungas region (La Paz, Bolivia), where the genus was first discovered.
Description
Yungasocereus is a monotypic genus of columnar cacti with uncertain phylogenetic placement.
- Habit: Shrubby to tree-like; branching; columnar; up to ~4–5 m tall.
- Stems: Erect, with weakly defined ribs.
- Ribs: 6–10, straight, slightly tuberculate; with transverse grooves above areoles.
- Areoles: Close-set.
- Spines: 4–12, short, aciculate; radials and centrals not clearly differentiated.
- Flowers: Nocturnal, remaining open during the day; small, narrowly funnel-shaped, slightly zygomorphic, white.
- Floral tube: With imbricated, woolly scales.
- Pollination: By bats.
- Fruits: Small, broadened at the base; with numerous fleshy scales; partially retaining floral remains.
- Seeds: Elongated, shiny, dark brown to black.
Habitat
Endemic to the Bolivian Yungas:
- humid tropical montane forests
- warm, moist environments
Altitude range: approximately 1450–2550 m.
Distribution
Bolivia:
- La Paz
Taxonomy
The genus has a highly uncertain and debated placement.
Key points:
- Originally described as Samaipaticereus inquisivensis (Cárdenas, 1957)
- Transferred to Yungasocereus by Ritter (1980)
- Temporarily included in Haageocereus (Hunt & Taylor)
- Later restored as a separate genus
Molecular insights:
- Arakaki (2008): places it within or near Weberbauerocereus
- Schlumpberger (2012): includes it in a "Cleistocactus clade"
- Franck (2012): groups it with Cleistocactus and Samaipaticereus
Interpretation:
- Possibly derived from reticulate evolution
- Phylogenetic position remains unresolved
The genus is therefore considered provisionally accepted.
Species
Monotypic genus:
Notes
- One of the least clearly resolved genera in Trichocereinae.
- Shows affinities with multiple genera (Weberbauerocereus, Cleistocactus, Samaipaticereus).
- May represent a lineage shaped by hybridisation.
- Restricted to a very specific ecological zone (Yungas forests).
