Rhytidoponera castanea

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 * . Rhytidoponera castanea Crawley, 1925b: 589 (w.) AUSTRALIA (New South Wales).
 * Type-material: syntype workers (number not stated).
 * Type-locality: Australia: New South Wales, Derby, no. 398 (J. Campbell).
 * Type-depository: OXUM.
 * Junior synonym of rufiventris: Clark, 1936: 83; Taylor & Brown, 1985: 47; Taylor, 1987a: 70; Bolton, 1995b: 378.
 * Status as species: Heterick, 2021: 5.
 * Senior synonym of carinata: Heterick, 2021: 5.
 * Distribution: Australia.
 * carinata. Rhytidoponera carinata Clark, 1936: 54, pl. 4, fig. 32 (w.) AUSTRALIA (Northern Territory).
 * Type-material: holotype (?) worker.
 * [Note: no indication of number of specimens is given.]
 * Type-locality: Australia: Northern Territory, Borroloola, 1911 (G.F. Hill).
 * Type-depository: MVMA.
 * Status as species: Brown, 1958g: 202; Taylor & Brown, 1985: 41; Taylor, 1987a: 67; Bolton, 1995b: 378.
 * Junior synonym of castanea: Heterick, 2021: 5.

Taxonomic Notes
Heterick (2021): Reichel (2003) removes R. castanea from synonym under Rhytidoponera rufiventris, and I agree this is justified; hence R. castanea is given revived status in this work. However, I can also see no clear distinction between R. castanea and R. carinata. Colour alone seems to be the reason the two taxa are separated and unless some other character can be found, or molecular evidence proves otherwise these seem very feeble grounds to posit two distinct species. The morphometrics supplied by Reichel all overlap considerably for both putative species, and colour variation among specimens in the WAM, ANIC and JDM collections is huge across a continuous spectrum — from a pin of light yellow-orange specimens identified by P. S. Ward as ‘R. carinata’ to dark reddish-black workers. Most are bicoloured (fitting castanea), while others are concolourous. Rhytidoponera carinata is therefore treated as a junior synonym in this work.