Hibiscus krichauffianus

McLay, Todd G. B., Barker, Robyn M. & Albrecht, David E., 2023, Morphological and environmental variation within Hibiscus krichauffianus (Malvaceae), and the recognition of two new species, H. verecundus and H. calcareus, Australian Systematic Botany 36 (6), pp. 457-477 : 461-465

Environmental variation within H. krichauffianus sens. lat.

PCA ( Fig. 5) shows a clear segregation of morphotype B samples (orange triangles) from morphotype A (grey squares), C (blue circles) and D (black crosses) samples. Morphotypes A, C and D largely occupy the same space within the PCA and the environmental variables used in the final dataset do not differentiate the climate envelopes of those morphotypes. Given the association of morphotype C with calcrete or limestone soils, edaphic variables may be more suitable for discriminating this species but were not included due to the lack of a comprehensive soil dataset for Australia (though see https://portal.tern.org.au/metadata/ 22160, accessed July 2023) .

Taxonomic implications

We have shown that there is considerable morphological variation within H. krichauffianus and that four morphotypes can be distinguished.

After reviewing the putative type material (including the collection localities of specimens), we determined that morphotype A correlates with H. krichauffianus sens. strict. An amended description of H. krichauffianus , designation of a lectotype and identification of possible syntypes are presented below. The status of the name H. krichauffianus var. chippendalei Fryxell was investigated and is discussed below under excluded taxa.

Morphotype B can be distinguished from the other three morphotypes on the basis of several morphological characters and has a distinct environmental envelope relative to the other three morphotypes ( Fig. 5). This morphotype is described below as the new species H. verecundus McLay & Albr.

Morphotype C is similar to morphotype A ( H. krichauffianus sens. strict.), differing in the shorter stature and growth form, smaller and often more deeply toothed leaves and seeds with an indumentum of short appressed hairs ( Fig. 2–4). The consistent morphological differences between morphotype C and H. krichauffianus sens. strict., and the association of this morphotype with finer-textured calcareous soils (e.g. Milthorpe & Cunningham 1928, NSW 624403; Symon NYPE-1300, AD 98805401), indicates that this entity is worthy of formal recognition and is described below as H. calcareus McLay & Albr. The environmental variables we used did not capture the association of this taxon with calcareous soils ( Fig. 5).

Morphotype D is tentatively recognised as distinct on the basis of the ferruginous indumentum, petals longer than 39 mm long and geographic separation from other H. krichauffianus sens. lat. taxa. We have given morphotype D the

2

0

Morphotype A B C –2 D –4 –2 0 4 6

informal phrase name H. sp. Belele (D. W.Goodall 3417). Further collections are required to confirm the morphological and environmental differences identified in this study that were based on limited material (five sheets in total).

Informal conservation assessments were made using International Union for Conservation of Nature (2012) criteria, though this should be more rigorously considered, and assessments also made against the threat classification system in use for each Australian state in which the taxa occur.