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Nanodeaceae Nickrent & Der

Family Description

Distribution Map

List of Genera

Phylogeny & Classification

Photographs

Mida

  1. Mida salicifolia

The Enigmatic Taxon Mida fernandeziana

This plant was known only from the Juan Fernandez Islands off the coast of Chile. It was originally named Santalum fernandezianum F. Phil. in 1892.  Sprague and Summerhayes (1927), based on the presence of a short, cupular perianth tube and a sessile stigma, suggested a relationship to Mida salicifolia from New Zealand. Accordingly, they transferred the taxon to this genus, thus creating the name Mida fernandeziana (Phil.) Sprague & Summerhayes. Unfortunately, the last known tree of this species from the island of Masatierra died between 1908 and 1916. Skottsberg (1930) looked into the taxonomic issues surrounding this plant and others related to the sandalwood genus Santalum.  At that time, Skottsberg supported the concept of the genus Eucarya that we know today is a component of Santalum. Regarding Mida salicifolia, he said

"Mida differs from Santalum and Eucarya as well as from most Santalaceous genera by its remarkable tepals. DeCandolle (4, p. 686) remarked on their structure: "lobis a tubo basi bene distinctes et facile segregatis" ['with lobes distinct to the tube base and well separated']. Apparently Sprague and Summerhayes did not pay any attention to this character or they would not have brought Santalum fernandezianum to Mida. They do not even mention the tepals."

The "tepals" (now considered petals) of S. fernandezianum are indeed remarkable. As illustrated well by Cheeseman (1914) and the University of Aukland website photos, they are cordate, narrowing almost to a "claw" (as seen in Malpighiaceae) when they insert on the perianth tube (or hypanthium).  Between the petal lobes at the rim of the hypanthium are bulges. These bulges were equated with a calyculus by Bhatnagar (1960), a term also used in Nickrent et al. (2010).  Kuijt (2015) disputed the existence of a calyculus in Mida, claiming that the illustration by Cheeseman (1914) showed "nothing of the sort". Looking at Cheeseman's illustration, one can see that he accurately drew the bulges present between the petals. Moreover, he shows a rim of tissue at the top of the (immature) fruit.  Looking at the photo of mature, bright red fruits from the Univ. of Aukland website, one can see that after the petals dehisce, a dark rim of tissue remains that encircles the fruit apex. In my estimation, this represents a calyx vestige, i.e. a calyculus.

In addition to recognizing that the Juan Fernandez Island taxon was a Santalum, Skottsberg went on to compare it with species of Santalum that have short perianth tubes and sessile stigmas, such as S. insularis (= S. insulare, Sect. Polynesica) and S. (Eucarya) acuminata. You can see his illustrations of flower longitudinal sections HERE.

So is the Juan Fernandez Island taxon really a Santalum or Mida? Enter molecular phylogenetics! Harbaugh and Baldwin (2007) sequenced the chloroplast gene 3' trnK intron and found that S. fernandezianum came out with S. acuminata, very close to what Skottsberg (1930) had suggested. Biogeographically, this also suggests a dispersal from Australia to Juan Fernandez Islands. These authors state "... evidently, Sprague and Summerhayes (1927) were not so far off after all", but I would argue that Skottsberg was closer to the mark. Recall that Sprague and Summerhayes placed the Juan Fernandez taxon in Mida.  Skottsberg (1930) said "I cannot even suggest where Mida comes in", which is certainly understandable now because Mida is not closely related to Santalum.  Molecular phylogenetic data (see Der & Nickrent 2008Nickrent et al. 2010) show that Mida (from New Zealand) and Nanodea (from Patagonia of South America) are in a family distinct from Santalaceae sensu stricto, i.e. Nanodeaceae. These taxa likely represent a Gondwanan lineage that share an ancient ancestor dating to the time the southern continents were more proximal.

Nanodea

  1. Nanodea muscosa


References

 



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