Microtis oblonga R.S.Rogers APNI*
Distribution and occurrence:
NSW subdivisions: CC, NT, CT
Other Australian states: Qld Vic. Tas. S.A.
Microtis oblonga and M. rara were treated as synonyms, see for example Bates (1984) and Jones (1988 p.327 'this species is identical with M. rara'), but Bishop (1996) recognised the two species as distinct. There are indeed two morphological forms subsumed within a broadly circumscribed M. rara, but they do not differ by the characters identified by Bishop (1996). Rather, the two morphotypes differ in the size and position of the apical labellum callus, with one having a large, elliptical and prominantly domed apical callus that overlaps the labellum margin in the labellum's apical notch; the other has a smaller cordate to rounded callus which is distant from the sinus apex and does not overlap the labellum margin, and the plants are generally smaller in flower size and stature. While I have not seen type specimens, the geographic distribution of these two morphotypes is compatible with the former being M. rara, and the latter being M. oblonga, which is provisionally accepted here as a result. The occurrence of M. oblonga in New South Wales can not be confirmed on the basis of specimens held in the New South Wales Herbarium, as at 5 November 2020.
Microtis oblonga could also be confused with M. unifolia but differs from that species by its widely spaced flowers at maturity, and by the long-rectangular labellum, which is around 4 times longer than broad rather than 1.5-2 times longer than broad as in M. unifolia.
Microtis oblonga could also be confused with M. arenaria, but M. oblonga has the labellum apical callus distant from the labellum margin, whereas in M. arenaria the callus may overlap the margin at the apex of the deep notch in the labellum apex, the depth of this notch being another distinguishing feature of M. arenaria. Microtis oblonga has widely spaced flowers at maturity, whereas in M. arenaria the flowers are closely spaced, as the type specimen (above) illustrates well.
Text by Matt A.M. Renner (5 November 2020).
Taxon concept:
APNI* Provides a link to the Australian Plant Name Index (hosted by the Australian National Botanic Gardens) for comprehensive bibliographic data
***The AVH map option provides a detailed interactive Australia wide distribution map drawn from collections held by all major Australian herbaria participating in the Australian Virtual Herbarium project.
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