Royidris diminuta

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Royidris diminuta
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Royidris
Species group: notorthotenes
Species: R. diminuta
Binomial name
Royidris diminuta
Bolton & Fisher, 2014

Royidris diminuta casent0002420 p 1 high.jpg

Royidris diminuta casent0002420 d 1 high.jpg

Specimen Labels

Both series of diminuta, which nests under stones in spiny forest, were included under notorthotenes by Heterick (2006).


A member of the notorthotenes species group. Bolton and Fisher (2014) - This small form is separated from Royidris notorthotenes with some reservations. In terms of general morphology and critical indices, workers of the two are similar, but in terms of absolute dimensions there is a distinct and persistent gap between them in the ranges of all measurements, with no trace of intermediates. No species of Royidris show any signs of worker dimorphism, but the possibility that the diminuta workers represent the undersized first brood of new foundress queens of notorthotenes cannot be entirely ruled out. An alternative hypothesis, that diminuta, Royidris etiolata and notorthotenes constitute a single species, results in a monomorphic species with SI 115–158, an exceptionally broad range. All three species are found in sympatry in the Mahafaly Plateau.

Keys including this Species


Endemic to Madagascar.

Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb



Males have yet to be collected.



The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • diminuta. Royidris diminuta Bolton & Fisher, 2014: 50, figs. 48-50, Map 138 (w.q.) MADAGASCAR.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.



(holotype in parentheses). TL 2.8–3.0 (3.0), HL 0.66–0.73 (0.72), HW 0.50–0.58 (0.58), CI 76–81 (81), SL 0.66–0.73 (0.70), SI 121–130 (121), PW 0.34–0.38 (0.37), WL 0.88–0.96 (0.96) (7 measured). EL 0.16–0.18 (EL/HW 0.30–0.32). MfL 0.66–0.76 (MfL/HW 1.25–1.33, MfL/MfH 3.36–3.80).

Matching the description of Royidris notorthotenes, and with critical indices falling within the same ranges, but diminuta much smaller in absolute measurements. For comparison of measurements see Table 2, Bolton and Fisher 2014.


(gyne). Alate when virgin. Very much larger than the worker. TL 6.8, HL 1.25, HW 1.21, CI 97, SL 1.04, SI 86, PW 0.90, WL 2.08, EL 0.36 (EL/HW 0.30), MfL 1.22 (MfL/HW 1.01, MfL/MfH 4.36) (1 measured).

Type Material

Holotype worker (top specimen of three on pin), Madagascar: Prov. Toliara, Mahafaly Plateau, 6.2 km. 74° ENE Itampolo, 24°39.2’S, 43°59.8’E, 80 m., 21–25.ii.2002, BLF 5814, CASENT0002420, under stone, spiny forest/thicket (Fisher et al.) (California Academy of Sciences). Paratypes. 2 workers on same pin as holotype, 2 workers with same data but CASENT0002421, 1 worker with same data but CASENT0009802 (CASC).


  • Bolton, B. & Fisher, B.L. 2014. The Madagascan endemic myrmicine ants related to Eutetramorium (Hymenoptera: Formicidae): taxonomy of the genera Eutetramorium Emery, Malagidris nom. n., Myrmisaraka gen. n., Royidris gen. n., and Vitsika gen. n. Zootaxa 3791:1–99. doi:10.11646/zootaxa.3791.1.1