Royidris clarinodis

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Royidris clarinodis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Royidris
Species group: robertsoni
Species: R. clarinodis
Binomial name
Royidris clarinodis
(Heterick, 2006)

Royidris clarinodis casent0019565 p 1 high.jpg

Royidris clarinodis casent0019565 d 1 high.jpg

Specimen Labels

Royidris clarinodis is found in spiny forest, shrubland and uapaca woodland, where it nests under stones, but it has also been collected from litter samples, as ground foragers, and from pitfall traps.


A member of the robertsoni species group. Bolton and Fisher (2014) - Within the robertsoni group, Royidris clarinodis is immediately isolated as it is the only species to combine an unsculptured head capsule with a sharply impressed, V-shaped, metanotal groove.

Keys including this Species


Endemic to Madagascar.

Latitudinal Distribution Pattern

Latitudinal Range: -18.0213° to -25.58333333°.

Tropical South

Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.



Known only from the worker caste.

Images from AntWeb

Royidris clarinodis casent0102685 h 1 high.jpgRoyidris clarinodis casent0102685 p 1 high.jpgRoyidris clarinodis casent0102685 d 1 high.jpgRoyidris clarinodis casent0102685 l 1 high.jpg
Worker. Specimen code casent0102685. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by CAS, San Francisco, CA, USA.
Royidris clarinodis casent0453836 h 1 high.jpgRoyidris clarinodis casent0453836 p 1 high.jpgRoyidris clarinodis casent0453836 d 1 high.jpgRoyidris clarinodis casent0453836 l 1 high.jpg
Holotype of Royidris clarinodisWorker. Specimen code casent0453836. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by CAS, San Francisco, CA, USA.
Royidris clarinodis casent0453839 h 1 high.jpgRoyidris clarinodis casent0453839 p 1 high.jpgRoyidris clarinodis casent0453839 d 1 high.jpgRoyidris clarinodis casent0453839 l 1 high.jpg
Paratype of Royidris clarinodisWorker. Specimen code casent0453839. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by CAS, San Francisco, CA, USA.


The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • clarinodis. Monomorium clarinodis Heterick, 2006: 89, figs. 14, 35, 36 (w.q.) MADAGASCAR.
    • Type-material: holotype worker, 74 paratype workers.
    • Type-locality: Madagascar: Prov. Toliara, 6.1 km. 182° S Marovato, 20 m., 25°35’S, 45°18’E, 14.ii.2002, BLF 5528, CASENT0453836 (holotype), under stone, spiny forest thicket (B.L. Fisher et al); paratypes with same data.
    • Type-depositories: CASC (holotype); ANIC, BMNH, CASC, MCZC (paratypes).
    • Combination in Royidris: Bolton & Fisher, 2014: 47.
    • Status as species: Bolton & Fisher, 2014: 47 (redescription).
    • Distribution: Madagascar.

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

Bolton and Fisher (2014) - In Heterick’s (2006) treatment of what was then the shuckardi group of Monomorium, clarinodis was regarded as a single species that from its description was extremely variable. In the present analysis we conclude that his taxon is certainly compound, and actually contains six separate species from two species groups (admixta and depilosa of the admixta group; anxietas, clarinodis, pallida and pulchra of the robertsoni group); the original description of clarinodis includes morphological elements of almost all of them. This confusion is inexplicable as members of the admixta group have a strikingly different mesosomal configuration from the rest of the genus, and within the robertsoni group only clarinodis has a sharply incised metanotal groove.



Bolton and Fisher (2014) - TL 2.0–2.5, HL 0.48–0.60, HW 0.40–0.48, CI 79–83, SL 0.37–0.47, SI 90–100, PW 0.28–0.34, WL 0.56–0.72 (14 measured).

Antennal club 3-segmented. Mandible smooth, unsculptured except for scattered small pits; in a few workers minute striolae may occur near the extreme base, but if present these do not extend onto the apical half of the mandible. Scapes relatively short (SI 100 or less); when laid straight back in full-face view the apex of the scape just reaches the posterior margin of the head. With head in full-face view the eyes in front of the midlength of the side of the head capsule. EL 0.09–0.12 (EL/HW 0.22–0.26). Dorsum of head from level of eyes to posterior margin smooth, with scattered minute pits; in some individuals there are also very weak vestiges (often almost entirely effaced) of superficial microreticulation. Promesonotum in profile convex and swollen, the mesonotum posteriorly descending to the distinctly impressed metanotal groove, which is V-shaped to narrowly U-shaped. Propodeal dorsum slopes posteriorly and is strongly depressed, the entire dorsum on a considerably lower level than the highest point of the promesonotum. Dorsa of pronotum and mesonotum usually each with 2 pairs of setae (sometimes with only one pair on one or the other, but this may be due to abrasion); dorsum of propodeum lacks setae. Pronotal dorsum smooth and shining, with widely scattered minute punctulae. Mesonotum as pronotum but some extremely weak vestiges of superficial microreticulation may be present. Propodeal dorsum microreticulate to reticulate-punctulate, the sculpture weak and superficial but usually stronger than on the promesonotum. Mesopleuron and metapleuron weakly reticulate-punctulate, the sculpture extending anteriorly onto the side of the pronotum as microreticulation. Metafemur relatively short, MfL 0.38–0.48 (MfL/HW 0.93–1.04, MfL/MfH 3.67–4.00). Petiole with a pair of setae on the posterior face of the node; postpetiole with 1–2 pairs of setae posteriorly; first gastral tergite with scattered short setae. Postpetiole relatively narrow in dorsal view, maximum width 0.14–0.19 (0.35–0.38 × HW). Dorsum of postpetiole and first gastral tergite unsculptured. Colour varies from mid-brown with a dark gaster, to entirely dark brown.

Type Material

HOLOTYPE: worker, Prov. Toliara, 6.1 km 182 S Marovato 25°35′S, 45°18′E, 20 m. 14.ii.2002, Fisher et al. BLF#5528 /under stone spiny forest/thicket/ CASENT 0453886 California Academy of Sciences). PARATYPES: Prov. Toliara (all specimens with same collection data as holotype): 1 worker (Australian National Insect Collection); 21 workers (The Natural History Museum); 21 workers (CAS); 31 workers (Museum of Comparative Zoology).

Bolton and Fisher (2014) - Heterick (2006: 89) specifically restricted the clarinodis type-series to those specimens with the same data as the holotype, i.e. the series numbered BLF 5528 and with the locality data given above. However, in California Academy of Sciences there is at least one specimen, name-tagged and labelled as a paratype by Heterick, which has been partially mislabelled and wrongly included in the type-series. The upper data label on the pin of this specimen gives BLF 5528, but the lower (main) data label has BLF 5504 (Prov. Toliara, Rés. Cap Sainte Marie, 12.3 km. 262° W Marovato, 25°34.90’S, 45°10.10’E, 200 m., 11–15.ii.2002). This specimen, and any others from that locality, from series BLF 5504, are excluded from the type-series.


Latin ‘clarus’ (‘shiny’) + pl. of ‘nodus’ (masc. ‘knot’)


References based on Global Ant Biodiversity Informatics

  • Bolton B., and B. L. Fisher. 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): 1-99.
  • Heterick B. 2006. A Revision of the Malagasy Ants Belonging to Genus Monomorium Mayr, 1855 (Hymenoptera: Formicidae). Proceeding of the California Academy of Sciences (PCAS) 57: 69-202