Tetraplasandra

Tetraplasandra is an obsolete genus of flowering plants in the ivy family, Araliaceae. They are small to medium trees, (rarely shrubs or large trees) of mesic to wet forests.
Some authors have recognized as many as 19 species in "Tetraplasandra", while others have recognized as few as six. In 2007, the authors of a scientific paper recommended that the genus be divided into nine species. In 2010, all of these nine species were included in "Polyscias" subgenus Tetraplasandra, a subgenus of 21 species in the large genus "Polyscias", which will comprise about 250 species, when about 90 undescribed species are published.
The range of variation in "Tetraplasandra" is unusually large for a genus in Araliaceae Most of the species were originally described in other genera which were later merged with "Tetraplasandra".
The type species for the genus is "T. hawaiensis".
As defined by in 1970, "Tetraplasandra" is endemic to Hawaii and occurs on six of the eight main islands. Niihau and Kahoolawe are low-lying and dry; consequently, they do not support "Tetraplasandra". "T. oahuensis", "T. kavaiensis", and "T. hawaiensis" are found on six, five, and four of the islands, respectively. The other species are single-island endemics.
"T. oahuensis" and "T.kavaiensis" have done well in cultivation in Southern California. They are sensitive to heat, but very tolerant of shade, and they need some wind protection. In horticulture, "T. kavaiensis" has often been misidentified as "T. meiandra". True "T. meiandra" is now treated as a synonym of "T. oahuensis".
"T. gymnocarpa", a rare tree of Oahu, is considered an oddity, since it is the only species in Araliaceae whose flowers have a completely superior ovary.
The genus "Tetraplasandra" has long been known as a close relative of the obsolete genera "Gastonia", "Reynoldsia", and "Munroidendron". This was confirmed by a pollen study in 1971. In 2010, "Arthrophyllum", "Cuphocarpus", "Gastonia", "Reynoldsia", "Munroidendron", and "Tetraplasandra" were all sunk into "Polyscias", raising the number of species in that genus from about 100 to 159.
Four Hawaiian names are applied to groups of "Tetraplasandra" species. "T. hawaiensis" is known as ohe. "T. kavaiensis" and "T. gymnocarpa" are called oheohe. "T. waimeae" is called ohe kikoola. "T. oahuensis" and "T. lydgatei" are called ohe mauka. The related name, ohe makai, is applied to "Polyscias sandwicensis", formerly known as "Reynoldsia sandwicensis". These names closely correspond to clades currently recognized within "Tetraplasandra".
Species in "Polyscias" subgenus Tetraplasandra.
Most of the information in the species list is from Lowry and Plunkett (2010). Synonyms are names of species accepted by Sherff (1955) or by Frodin and Govaerts (2003), except for "Tetraplasandra lydgatei" and "Tetraplasandra bisattenuata", which were resurrected after 2003. For complete synonymy and distribution within the Hawaiian Islands, see Lowry (1990).
History.
The genus name was erected by Asa Gray in 1854, in his account of the botany of the U.S. Exploring Expedition (1838-1842). The name is derived from Greek, "tetraplasios", "fourfold", and "andros", "male, stamen".
Asa Gray named only one species, "T. hawaiensis", in "Tetraplasandra". The tree that was later known as "Tetraplasandra oahuensis" (now "Polyscias oahuensis"), he named "Gastonia oahuensis", but with considerable doubt about its placement.
In 1867, Horace Mann Jr. named two new species, "H. kavaiensis" and "H. dipyrenum" in "Heptapleurum", a genus that Joseph Gaertner had named in 1791, in "De Fructibus et Seminibus Plantarum". Mann created a new section in "Heptapleurum" for the two Hawaiian species. He named the new section "Pterotropia". "Heptapleurum" is no longer recognized and its type species is now known as "Schefflera stellata". Earl Edward Sherff did not consider the two species named by Mann to be truly distinct. He included both in "Tetraplasandra kavaiensis", which he divided into eight varieties, including "T. kavaiensis" var. "dipyrena".
From 1864 to 1868, Berthold Carl Seemann published a series of articles in the "Journal of Botany, British and Foreign", all of which were entitled "Revision of the natural order Hederaceae". In 1868, he published a book by the same title. He divided what later became Hawaiian "Tetraplasandra" into four genera. He maintained "Tetraplasandra" for "T. hawaiensis" and created two new genera; "Triplasandra", for Asa Gray's "Gastonia oahuensis" and "Dipanax" for Mann's "Tetraplasandra dipyrena". He placed Mann's "Tetraplasandra kavaiensis" in "Agalma", a genus that Friedrich A.W. Miquel had established in 1856.
In 1873, Heinrich Wawra von Fernsee named a new species from Kauai as "Tetraplasandra waimeae".
In 1888, in the first flora of the Hawaiian Islands, Wilhelm B. Hillebrand raised Horace Mann Jr's "Pterotropia" to generic rank as "Pterotropia". He added to it, a new species from Oahu, which he named "Pterotropia gymnocarpa". This work was published posthumously by his son, William Francis Hillebrand to whom the name "Pterotropia" is often incorrectly attributed. The name "Pterotropia" is now considered illegitimate because, while "Pterotropia" is an older name, "Dipanax" is older at generic rank and therefore has priority.
Wilhelm B. Hillebrand put two species in "Tetraplasandra": "T. hawaiensis" and "T. waimeae". He placed four species in "Triplasandra": "Tri. oahuensis", "Tri. meiandra", "Tri. lydgatei", and "Tri. kaalae". Three of these were newly named. "Tetraplasandra waimeae" is now known to be closer to "T. oahuensis" than to "T. hawaiensis".
In 1898, in a monograph on Araliaceae for "Die Natürlichen Pflanzenfamilien", Hermann Harms adopted Hillebrand's "Pterotropia", but sank "Triplasandra" back into "Tetraplasandra". Harms accepted the six species that Hillebrand had placed in "Triplasandra" and "Tetraplasandra". He also included in "Tetraplasandra", the Malesian species that was later called "Gastonia serratifolia" and then "Polyscias serratifolia".
In 1913, Joseph F.C. Rock described a new species from Kauai, and named it "Tetraplasandra waialealae".
In 1917, Charles Noyes Forbes named another species from Kauai as "Tetraplasandra racemosa". Both of these are still recognized as distinct species, but in 1952, Earl Edward Sherff erected the new genus "Munroidendron" for "T. racemosa".
In 1955, Sherff wrote a revision of the Hawaiian species of "Tetraplasandra". It included a detailed taxonomic history. Sherff considered "Tetraplasandra" to consist of three species from Malesia and 19 from Hawaii. In this treatment, he named several new species and included others that had been named by Joseph F.C. Rock, Otto Degener and Carl J.F. Skottsberg. Of all of the species named by Sherff, only "T. bisattenuata" is still recognized today.
Sherff recognized the uniqueness of "T. hawaiensis", a judgement that was corroborated by subsequent evidence. He understood that "T. waimeae" and "T. waialealae" are closely related and that these two belong in a group with "T. oahuensis", "T. lydgatei", and "T. bisattenuata". He placed "Pterotropia" in synonymy under "Tetraplasandra", writing that "a monographic study of "Tetraplasandra" reveals so much interlocking and overlapping of characters between "Tetraplasandra" and the species assigned to "Pterotropia" as to remove all warrant for their segregation".
In 1990, "Tetraplasandra" was covered in a flora of Hawaii. Only six species were recognized, pending further study. These were "T. gymnocarpa, T. hawaiensis, T. kavaiensis, T. oahuensis, T. waialealae," and "T. waimeae". A detailed description and full synonymy were given for each species.
In 2000, a new species from the island of Kauai, "Tetraplasandra flynnii", was described in Novon. At that time, it was known from only three individuals. "Tetraplasandra lydgatei" was resurrected in 2005 in a paper in Pacific Science. At that time, it was known from only six individuals on the island of Oahu.
In 2007, a molecular phylogenetic study compared by cladistic methods, the DNA sequences of two regions of nuclear DNA for eight species of "Tetraplasandra" and their close relatives. The two DNA regions, known as Internal transcribed spacer and non-transcribed spacer are adjacent to genes for Ribosomal RNA. In this study, the former genus "Tetraplasandra" was resolved as monophyletic and consisting of three clades.
"T. hawaiensis" was found to be sister to the rest of "Tetraplasandra". "T. kavaiensis", "T. flynnii", and "T. gymnocarpa" formed a strongly supported clade. The remaining clade consisted of "T. bisattenuata", "T. oahuensis", "T. waimeae", and "T. waialealae". "T. bisattenuata" was found to be distinct and the authors recommended that it be reinstated.
"Tetraplasandra oahuensis" is heterogeneous and probably polyspecific, but the authors recommended that further studies be conducted before any attempt to divide it.
"Polyscias" subgenus Tetraplasandra.
In 2010, a molecular phylogenetic study was published for the seven genera which at that time constituted the pinnate Araliaceae. It was found that the six smaller genera are all embedded in the large genus "Polyscias". In a companion paper, published simultaneously, the six smaller genera ("Arthrophyllum, Cuphocarpus, Gastonia, Reynoldsia, Munroidendron," and "Tetraplasandra") were placed in synonymy under "Polyscias", thereby raising the number of species in that genus from about 100 to 159. About 80 species from Madagascar and ten from New Caledonia are known from recently collected specimens. They will be named and described in forthcoming papers. Many of these were photographed during field work.
"Polyscias" has been divided into 11 subgenera, with seven species placed incertae sedis, that is, without decision on which part of "Polyscias" they should belong to. "Polyscias" subgenus Tetraplasandra comprises 21 species, consisting of the former genera "Tetraplasandra", "Munroidendron", and "Reynoldsia", as well as the two Malesian species that were in "Gastonia", and four of the six species that Philipson had placed in "Polyscias" section Eupteron.
"Polyscias acuminata" might also belong to "Polyscias" subgenus Tetraplasandra. It was placed incertae sedis, but has characters resembling those of subgenus Tetraplasandra. In other ways, however, it resembles "Polyscias nodosa", the sole member of "Polyscias" subgenus Eupteron.
The former genus "Tetraplasandra" is a monophyletic group and is sister to a clade consisting of only two species: "Polyscias racemosa" and "Polyscias sandwicensis". The former had constituted the monospecific genus "Munroidendron" and the latter is the type species for the previously accepted genus "Reynoldsia". This "Hawaiian clade" of 11 species consists of all of the native Hawaiian members of "Polyscias".
The former genus "Reynoldsia" turned out to be diphyletic, with its single Hawaiian species not forming a clade with the four species from Samoa, Tahiti, and the Marquesas. Basal relationships in "Polyscias" subgenus Tetraplasandra remain obscure because of insufficient taxon sampling in phylogenetic studies.
Sources.
Gregory M. Plunkett, Jun Wen, Porter P. Lowry II, Murray J. Henwood, Pedro Fiaschi, and Anthony D. Mitchell. accepted, undated. Araliaceae, pages ??. In: Klaus Kubitzki (editor); ?? (volume editor). "The Families and Genera of Vascular Plants" volume ??. Springer-Verlag: Berlin; Heidelberg, Germany. ISBN ??