Mycoheterotrophic Plants

How many of them are there?

Thismia guangdongensis X.J. Li, A.Liu & D.X. Zhang

Thismia guangdongensis is described in Li et al. (2023) from Huaiji County, Guangdong Province in China, so far the only location of this species. It is very similar to T. javanica, T. arachnites, T. brunonis, T. gardneriana, T. bokorensis and T. breviapendiculata due to its heteromorphic tepals and connective structures. The authors state that the closest affinity exists in comparison with T. breviappendiculata and they list some convincing differences to it (appendage shape, colour of transverse bars on the inner surface of the floral tube, color of the outer corolla tube). However, the distinctions mentioned in comparison with the other Thismia species are less plausible:
1. The color of the annulus is yellow also in T. arachnites and T. bokorensis, in T. javanica it has an orange tinge according to Smith (1910), and neither Griffith (1844, 1845) nor Miers (1847) nor Hooker (in Thwaites 1861 or Hooker 1888) nor Trimen & Hooker (1898) say much on the annulus color on T. brunonis and T. gardneriana, exept for yellowish or yellow as the color for the flower as a whole.
2. The coloration of the floral tube is also ornamented with orange longitudinal streaks in T. arachnites (Chantanaorrapint 2018) and explicitly in T. javanica (Smith 1910, p.33).
3. The orange transver bars inside the tube are yellow in T. arachnites (Chantanaorrapint 2018) and also present (no statement on color) in T. javanica (Smith 1910).
4. The color of the appendages vary between reddish and yellow in T. arachnites (Chantanaorrapint 2018) and again is described explicitly as orange in T. javanica (Smith 1910).
In summary, T. guangdongensis seems to be closer to T. javanica and T. arachnites than to T. breviappendiculata. Moreover, while reading the detailed description of J.J. Smith (1910) on Thismia javanica and simultaneously regarding the images of T. arachnites (in Chantanaorrapint 2018), I can not find any difference between the two species except for the length of the tepal appendages (9,25 - 13,5 mm in T. javanica after Smith (1910) vs. 12 - 25 mm in T. arachnites after Chantanaorrapint (2018)). Hence, conspecificity of T. arachnites, T. javanica and T. guangdongensis can not be ruled out, a notion that may also include T. gardneriana and T. brunonis. Unfortunately, the location of the type specimen of T brunonis is unknown (according to Jonkter 1938) and none of the mentioned Thismia species could yet be included in the molecular phylogenetic study of Li et al. (2023). It would be great to compare Chantanaorrapints (2018) T. arachnites and several of the T. javanica collections (e.g. Siti-Munirah & Dome 2019) as well as the new T. guangdongensis in a molecular based study.

Nevertheless, until more information is gathered, we include Thismia guangdongensis in this list.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith