Sunday, October 28, 2018

[Botany • 2018] Acropogon horarius (Malvaceae, Sterculioideae) • A Very Rare and Threatened New Microendemic Species of Acropogon from New Caledonia [Novitates Neocaledonicae X]


Acropogon horarius Gâteblé & Munzinger

in Gâteblé & Munzinger, 2018.
 Novitates neocaledonicae X.

Abstract
A new species, Acropogon horarius Gâteblé & Munzinger, sp. nov. (Malvaceae, Sterculioideae), is described from New Caledonia. It is known only from two very small subpopulations in the rainforests of the Petchécara Pass between Thio and Canala, in the southeast of Grande-Terre, New Caledonia’s main island. This shrub to small tree has hastate leaves and minute sessile tubular whitish-yellowish flowers and is strikingly different from all other members of the genus. The type locality is geologically complex and located within one of only four amphibolite lenses known in New Caledonia. A line drawing and colour photos are provided for the new species, along with a preliminary risk of extinction assessment, which indicates that the species is Critically Endangered.

Keywords: Acropogon, geology, Malvaceae, New Caledonia, new species, Sterculioideae, taxonomy, threatened species

Figure 2. Acropogon horarius Gâteblé & Munzinger sp. nov. A flowering branch B inflorescence and a zoom on stellate trichomes of the flower tube C female flower D male flower E infructescence F detail of erect stellate trichomes on the follicle’s surface G detail of an open follicle H close-up of the abaxial leaf reticulum.
Drawings by Laurence Ramon (A–H Gâteblé et al. 806).

Figure 3. Acropogon horarius Gâteblé & Munzinger sp. nov. A overview of a single mature shrub in habitat B juvenile plant C leaf D flowering branch E inflorescence F male flower G female flower H follicles. Photographs by G. Gâteblé
 (A Gâteblé et al. 803 B Gâteblé et al. 804 C–H Gâteblé et al. 806).

Acropogon horarius Gâteblé & Munzinger, sp. nov.

Diagnosis: Acropogon horarius Gâteblé & Munzinger differs from all other members of the genus by the combination of its long and thin petioles, hastate and cordate leaves and minute sessile tubular whitish-yellowish flowers.
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Distribution and ecology: The new species is only known from the south-eastern part of the Grande-Terre, at the Petchécara Pass between Thio and Canala (Fig. 1), where it grows on slopes in rainforest on a soil of complex geological origin.
  
Etymology: The plant is named after the last of New Caledonia’s scheduled roads or “route à horaire” along which it grows.


 Gildas Gâteblé and Jérôme Munzinger. 2018. Novitates neocaledonicae X: A Very Rare and Threatened New Microendemic Species of Acropogon (Malvaceae, Sterculioideae) from New Caledonia. PhytoKeys. 110: 1-8.  DOI: 10.3897/phytokeys.110.27599