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| Argyreia gyrobracteata Traiperm & Chitchak
in Chitchak, Traiperm, Staples, et al., 2018.
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ABSTRACT
Argyreia Lour. is one of the most taxonomically complex genera of the morning glory family (Convolvulaceae). The number of named species is now 135, and new species are regularly being described. There are several species complexes that are morphologically similar and difficult to tell apart. Therefore, the aim of this study is to explore the species identification criteria for Argyreia, especially new sources for taxonomically informative characters. Ten accessions representing three morphologically similar Argyreia operational taxonomic units (OTUs) were collected and their anatomical characters were investigated using the leaf peeling technique and paraffin sectioning method. Anatomical character states were analyzed using two phenetic analysis methods: clustering analysis (CA) and principal component analysis (PCA). Three distinct clusters were clearly separated in both PCA and CA at the internal similarity coefficient of 0.48 with a high R-value of 0.89757. Nineteen effectively distinguishable character states were derived from the high loadings of the first two components. In conclusion, two of the separated groups were matched with known species, and the third separated group is here delineated as a new species. Therefore, a new species, Argyreia gyrobracteata Traiperm & Chitchak, is described and illustrated together with ecological data and a preliminary conservation assessment.
Keywords: cluster analysis, cryptic species, morphometrics, principal component analysis, species delimitation
Argyreia gyrobracteata Traiperm & Chitchak, sp. nov. Argyreia Lour. is one of the most taxonomically complex genera of the morning glory family (Convolvulaceae). The number of named species is now 135, and new species are regularly being described. There are several species complexes that are morphologically similar and difficult to tell apart. Therefore, the aim of this study is to explore the species identification criteria for Argyreia, especially new sources for taxonomically informative characters. Ten accessions representing three morphologically similar Argyreia operational taxonomic units (OTUs) were collected and their anatomical characters were investigated using the leaf peeling technique and paraffin sectioning method. Anatomical character states were analyzed using two phenetic analysis methods: clustering analysis (CA) and principal component analysis (PCA). Three distinct clusters were clearly separated in both PCA and CA at the internal similarity coefficient of 0.48 with a high R-value of 0.89757. Nineteen effectively distinguishable character states were derived from the high loadings of the first two components. In conclusion, two of the separated groups were matched with known species, and the third separated group is here delineated as a new species. Therefore, a new species, Argyreia gyrobracteata Traiperm & Chitchak, is described and illustrated together with ecological data and a preliminary conservation assessment.
Keywords: cluster analysis, cryptic species, morphometrics, principal component analysis, species delimitation
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| Fig. 7. Argyreia gyrobracteata Traiperm & Chitchak sp. nov.: (A) flower in front view; (B) flower in side view; (C) interaction with an insect visitor, oriental carpenter bee (Xylocopa nasalis); (D) plant habit
(all photos taken by P. Rattanakrajang from live plants vouchered as P. Rattanakrajang et al. 104).
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TYPE: Thailand. Ubon Ratchathani, Sirindhorn district, ..., in the edge of dipterocarp forest, August 2016, P. Rattanakrajang, N. Chitchak & P. Traiperm 110 (holotype BKF!; isotypes K!, QBG!)
DIAGNOSIS: The new species is similar to A. mekongensis in having a white campanulate corolla, but differs from that species by the linear-oblong to narrowly lanceolate bract shape (versus lanceolate or oblong-lanceolate), the curly or twisted bract orientation (versus falcate), the larger sepals, and the multicellular, uniseriate, villous trichomes restricted to a small, dense, triangular patch on the adaxial side of the filaments, above the insertion point of the filaments on the corolla tube (versus dispersed in a band 3–5 mm wide surrounding the free filament, above the insertion point on the corolla tube).
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DISTRIBUTION: Known so far from discrete populations in two different districts within Ubon Ratchathani province, Thailand. One population is close to the border of Thailand–Laos and possibly A. gyrobracteata occurs across the border in Laos.
ETYMOLOGY: The specific epithet refers to the curly/twisted bracts of this species, which have not been observed in any other known species of Argyreia.
Natthaphong Chitchak, Paweena Traiperm, G. Staples, Pantamith Rattanakrajang and Pirada Sumanona. 2018. Species Delimitation of Some Argyreia (Convolvulaceae) Using Phenetic Analyses: Insights from Leaf Anatomical Data Reveal A New Species. Botany. 96(4); 217-233. DOI: 10.1139/cjb-2017-0108
