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| Macrosolen zamboangensis Mazo, Nickrent & Pelser, in Mazo, Nickrent & Pelser, 2022. |
Abstract
Macrosolen zamboangensis, a new mistletoe species from the Zamboanga peninsula of the island of Mindanao (Philippines), is described. The new species is a member of the widespread M. melintangensis species complex, but differs from the previously described species in this complex in having a conspicuously papillose corolla head. It is also the only species in this complex that displays a combination of papi-lose pedicels, calycula and fruits, at least 3–4 inflorescence axes grouped at a node, and relatively small flowers that are clustered at the apex of a raceme (a subumbel) instead of being more evenly distributed along the inflorescence axis. The conservation status of this new species is considered Vulnerable (V).
Keywords: hemiparasitic plants, Macrosolen melintangensis, mistletoe, species com-plex, taxonomy, western Mindanao.
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| Morphological features of Macrosolen zamboangensis. A. Habit of mistletoe. B. Leaf variation, adaxial surfaces above, abaxial sur-faces below. C. Inflorescence. D. Closer view of flowers in bud stage and at anthesis. E. Infructescences emerging from swollen node. F. Closer view of calyculus/ovary, subtending bract, and pedicel. G. Seed removed from fruit. H. Mature fruit with scale insects on pedicel. |
Macrosolen zamboangensis Mazo, Nickrent & Pelser, sp. nov.
Diagnosis: Macrosolen zamboangensis is similar to species of the M. melintangensis complex, but unique in having conspicuously papillose flowers and fruits in combination with relatively short corollas (i.e. less than 20 mm in mature flower buds) of flowers that are clustered in subumbels. The inflorescences are generally 3–4 per axil, more numerous than in other members of the complex.
Etymology: The specific name refers to the Zamboanga peninsula of the island of Mindanao, Philippines, where this species was discovered.
Distribution and habitat: Thus far, M. zamboangensis is only known from its type locality, which is in a disturbed lowland tropical rain forest and at 320–350 m elevation. Macrosolen zamboangensis was observed growing on Mangifera sp. (Anacardiaceae), Palaqium sp. (Sapotaceae), and species of Sapindaceae.
CONCLUDING REMARKS:
Naming a new species in a mistletoe genus such as Macrosolen presents a number of challenges. These include the absence of type specimens associated with various names, variations in descriptions of the same taxa by different authors, and weighing the extent of polymorphism present within a taxon prior to considering it a species. Although photographs of herbarium specimens provide invaluable data for this type of work, the quality of specimens varies considerably and crucial details (e.g. of flowers) are not always visible. For the Philippine flora in particular, specimens (including types) were destroyed in WWII and no collections currently held in PNH and various in-country university herbaria are digitized and available for viewing on the internet. To fully explore species boundaries in Macro-solen, the morphological character variation should be examined in the context of a molecular phylogeny, but currently no such data exist. As discussed here, the M. melintangensis complex may contain as few as four and as many as 13 species. All of these taxa can be characterized, more or less, by unique combinations of characters. For the 39 morphological characters considered here, we propose that M. zamboangensis shows sufficient phenotypic differences from other members of the complex to be considered a distinct species.
Kean Roe F. Mazo, Daniel L. Nickrent and Pieter B. Pelser. 2022. Macrosolen zamboangensis (Loranthaceae), A New Mistletoe Species from Zamboanga Peninsula, Philippines. Webbia. Journal of Plant Taxonomy and Geography. 77(1); 127-134. DOI: 10.36253/jopt-12339
