Stigmatomma roahady

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Stigmatomma roahady
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Amblyoponinae
Tribe: Amblyoponini
Genus: Stigmatomma
Species group: tsyhady
Species complex: tsyhady
Species: S. roahady
Binomial name
Stigmatomma roahady
Esteves & Fisher, 2016

Stigmatomma roahady casent0002104 p 1 high.jpg

Stigmatomma roahady casent0002104 d 1 high.jpg

Specimen Labels

Specimens were recorded from sifted leaf mold and rotten wood (34 collection records), pitfall traps (3 records), Malaise traps (4 records), ground foraging (1 record), and nesting or foraging in the the root mat on the ground (8 records), under moss on the ground or on rotten logs (2 records), in or under rotten logs (30 and 3 records, respectively), in a rotten tree stump (1 record), and in the soil (8 records). (Esteves and Fisher 2016)


Esteves and Fisher (2016) - A member of the tsyhady complex in the tsyhady species group. Worker. With characters of the species-group and complex, plus the following characters (asterisks flag unique characters within the genus in the Malagasy bioregion):

1. Integument orange-brown to black; large-sized ant (HL: 1.32-1.60, WL: 1.68-2.03).

2. Pairs of teeth on baso-masticatory margin of mandible are the same length along the basoapical axis.

3. Spatular setae ventrally skirting baso-masticatory margin of mandible.

4. Dorsal face of the head costulate-punctate/foveolate anteriorly, grading to punctate/foveolate posteriorly.

5. Palpal formula 4:3.

6. Pronotum and the dorsal face of remainder mesosoma punctate/foveolate; lateral face of remainder mesosoma mostly slightly punctate or smooth; propodeal declivitous face punctate.

7. Mesepisternum divided into anepisternum and katepisternum.

8. Basoventral half of calcar of strigil lamellar.

9. Anterior face of calcar of strigil with strap-like microtrichia.

10. Two mesotibial spurs.

11. Groove-like longitudinal sulcus present on the anterodorsal face of mesobasitarsus.

12. Two metatibial spurs.

13. Anterior face of posterior metatibial spur with sparsed lanceolate microtrichia.

14. Few stout paddle-like setae present on the baso-inner face of metabasitarsus.

15. * Groove-like longitudinal sulcus present on the anterior face of metabasitarsus.

16. Ventral margin of petiolar poststernite runs continuously posteriorly, not forming a fin.

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: -12.53444° to -24.76389°.

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.


Esteves and Fisher (2016) - This species occurs in sympatry with S. irayhady in two localities (nearby Andranomay, and at the Binara Forest), with S. tsyhady in twelve localities (Ambatovy Forest, Analamay Forest, Vevembe Forest, Mantadia National Park, Marojejy National Park, Ranomafana National Park, Zahamena National Park, Andohahela National Park, Andringitra Reserve, Ivohibe special reserve, Anosyenne Mountains, and at the Binara Forest), and with S. liebe in four localities (Andohahela National Park, Andringitra Reserve, Ivohibe Special Reserve, and at the Anosyenne Mountains).


Stigmatomma roahady was collected primarily in rainforest and montane rainforest habitats (just one collection occurred in montane shrubland habitat). All records fall within the limits of the humid forests ecoregions, in the eastern biome of Madagascar (sensu Burgess et al. 2004). Specimens were distributed at elevations ranging from 400 to 1400 m; however, of a total of 99 collection events, just nine were recorded at elevations lower than 800 m.







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

  • roahady. Stigmatomma roahady Esteves & Fisher, 2016: 103, figs. 73-87 (w.q.m.) MADAGASCAR.
    • Type-material: holotype worker, 8 paratype workers.
    • Type-locality: holotype Madagascar: Toamasina, Forêt Ambatovy, 14.3 km. 57° Moramanga, 1075 m., -18.85083, 48.32, 12.iv.2005, BLF11961, CASENT0318421, montane rainforest, ex rotten log (B.L. Fisher); paratypes with same data but CASENT0318422 to -424, 0318916 to -918, and 0227519.
    • Type-depositories: CASC (holotype); CASC, MCZC, MHNG, NHMB, NHMW, MZSP, USNM (paratypes).
    • Distribution: Madagascar.

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



(holotype values within parentheses): HL: 1.32-1.60 (1.57); HW: 1.23-1.46 (1.46); HW2: 1.05-1.24 (1.24); SL: 0.72-0.88 (0.85); ML: 0.98-1.12 (1.07); WL: 1.68-2.03 (1.95); PPW: 0.73-0.89 (0.87); PtL: 0.73-0.87 (0.87); PtW: 0.76-0.92 (0.92); CI: 87-93 (93); SI: 48-60 (54); MI: 68-74 (68); PtI: 92-100 (95).

Head: Five Mandibular baso-masticatory margin skirted dorsally by row of filiform setae; ventrally, by spatular setae. Mandibular dentition arrangement, from base to apex: single larger tooth; much smaller single tooth (absent or much reduced in some specimens); five to six pairs of teeth (each teeth pair with same dimensions, fused basally; pairs of teeth similar in length along mandible's basoapical axis); single preapical tooth; apical tooth. Anterior clypeal margin with seven to ten tubercle-like cuticular processes, arranged in a single row, anteriorly armed with asymmetrical, mucronate, dentiform seta. Lateral-most clypeal cuticular process with row of smaller conical setae anterolaterally, continuing laterally along clypeal anterior margin, arising from flat cuticle. Median clypeal cuticular processes with almost same length of associated dentiform setae. Pair of long, filiform setae on clypeal anterior margin bordering the central-most cuticular processes. Median area of clypeus extending posteriorly between antennal sockets; frontoclypeal sulcus round. Supraclypeal area as oval concavity. Twelve antennomeres. Genal teeth present. Widest diameter of compound eyes: four to five ommatidia. Palpal formula: 4:3 (four maxillary, three labial).

Mesosoma: In dorsal view, lateral margins of mesonotum continuous with posterior remainder of mesosoma, or expanded laterally. Metanotal suture well developed or absent. Sulcus dividing mesepisternum into anepisternum and katepisternum. Metathoracic spiracle slit-like, anterior margin somewhat swollen. Propodeal spiracle round, with swollen margin. Propodeal declivitous face slightly concave.

Legs: Basoventral half of calcar of strigil lamellar. Anterior face of calcar of strigil with strap-like microtrichia; posterior face with lanceolate microtrichia. Multiple paddle-like setae on anteroventral face of protibial apex, next to strigil's calcarcalcar of strigil. Multiple paddle-like setae on anterior face of probasitarsus; stout setae on posterior face, parallel to comb of strigil. Two mesotibial spurs: simple anterior spur, with lanceolate microtrichia; posterior spur somewhat falcate (with rounded baso-ventral projection), and with lanceolate microtrichia. Ventral margin of posterior mesotibial spur with digitiform cuticular projections, restricted to the most basal region or along entire ventral margin. Groove-like longitudinal sulcus on anterodorsal face of mesobasitarsus. Stout filiform setae along inner face of mesobasitarsus. Two metatibial spurs: simple anterior spur, with lanceolate microtrichia; posterior spur pectinate. Anterior face of posterior metatibial spur with sparse lanceolate microtrichia; posterior face mostly glabrous.

Groove-like longitudinal sulcus on anterior face of metabasitarsus. Few stout paddle-like setae on baso-inner face of metabasitarsus; stout filiform setae along remainder of inner face. Arolium on pro-, meso-, and metapretarsus.

Metasoma: Petiole sessile. Ventroanterior margin of petiolar tergite anterior dorso-lateroventral carina (Ward 1990) much shorter than anterior margin of subpetiolar process, in lateral view. Ventral margin of subpetiolar process running posteriorly in a continuous line. Presence of fenestra on lateral face of subpetiolar process. Petiolar proprioceptor zone a large, round concavity with numerous sensilla. Prora present. Scrobiculate sulcus between pretergite and postergite of abdominal segment III and presclerites and postsclerites of abdominal segment IV. Absence of stout setae on hypopygium.

Sculpture: Mandibular dorsal face mostly costate, except for smooth apical portion. Median clypeal area costate. Supraclypeal area mostly smooth. First third of the head, in dorsal view, costulate-punctate/foveolate, grading to punctate/foveolate posteriorly. Area posterior to tentorial pit carinate concentrically. Labrum mostly imbricate. Pronotum and dorsal face of remainder mesosoma scarcely punctate/foveolate. Anepisternum mostly smooth; katepisternum costulate dorsally, grading into rugulose to strigate ventrally. Metapleuron costate dorsoposteriorly and posteriorly. Lateral face propodeum slightly punctate or smooth; declivitous face punctate. Petiolar tergite mostly punctate/foveolate; laterotergite mostly smooth; poststernite imbricate/alveolate. Gaster mostly smooth; tergites of abdominal segments III and IV slightly punctate/foveolate; tergites of abdominal segments VI and VII slightly imbricate.

Pilosity and color: Suberect to decumbent pilosity on head. Erect to suberect pilosity on dorsal face of mesosoma, petiolar tergite, anterior half of petiolar poststernite, and abdominal segments III, IV, and V. Longer pilosity on abdominal segment VII. Body color orange-brown to black; gaster orange to black with slightly lighter apex; appendages yellow-brown to orange.

Character variation: A north-south geographical pattern is apparent considering: (1) number of tooth pairs on the mandible; (2) degree of mesonotum expansion and metanotal suture development; (3) amount of cuticular projections on the ventral margin of posterior mesotibial spur; and (4) head sculpture and body color.


Alate when virgin: Very similar to the worker caste but for the greater body length, larger compound eyes, presence of ocelli, and differences on the mesosoma due to the presence of wings. Parapsidal lines on the mesoscutum; scuto-scutellar suture narrow, without apparent sculpture on its midsection, but scrobiculate on its apexes. Mesepisternum divided into anepisternum and katepisternum; mesepimeral lobe distinct, but not well developed; metapleuron divided into upper and lower sections; upper metapleuron separated from propodeum by narrow scrobiculate sulcus; lower metapleuron separated from the propodeum by a carina, followed dorsally by a strigate sulcus. Forewing: pterostigma well developed; Rs.f2-3 present; Rs.f5 present and reaching R.f3; adventitious vein leaving Rs.f5 apically; 1r-rs absent; 2r-rs, M.f4, 2rs-m, Cu.f2, 1m-cu, and A.f2 present; cu-a intercepting M+Cu anteriorly to the separation point between Cu.f1and M.f1. Hindwing: C indistinct; R, Rs.f2, 1rs-m, and M.f2; adventitious crossvein at M+Cu, running towards Sc+R+Rs; Cu, cu-a, and A.f2 present. Intercaste between gynes and workers; wingless: Very similar to the worker caste but for the presence of of compound eyes and occelli, much larger mesonotum, and more developed metanotal suture.


Alate: Mandibles falcate, with sharp, single apical tooth. Anterior clypeal margin armed with dentiform setae. Compound eyes with sparse longer setae present among each ommatidium. Palpal formula 4:3. Notauli distinct and scrobiculate; parapsidal lines present; scuto-scutellar suture scrobiculate. Mesepisternum partially divided or not divided into anepisternum and katepisternum; posterior oblique sulcus short, not well developed; mesepimeral lobe well developed; metapleuron divided into upper and lower sections by a pit; scrobiculate sulcus separating upper metapleuron from propodeum; slightly strigate sulcus separating lower metapleuron from propodeum. Forewing: pterostigma well developed; Rs.f2-3 present; Rs.f5 present and reaching R.f3; 1r-rs absent; 2r-rs, M.f4, 2rs-m, Cu.f2, 1m-cu, and A.f2 present; cu-a intercepting M+Cu anteriorly to the separation point between M.f1 and Cu.f1. Hindwing: C slightly distinct; R, Rs.f2, 1rs-m, M.f2, Cu, cu-a, and A.f2 present. Pygostyles present. Posterior margin of abdominal segment IX convex. Paramere not visibly divided into telomere and basimere. Digitus tongue-plier-shaped: presence of a comparatively enlarged, but thin basal projection on the digitus; cuspis almost as long as digitus. Entire ventral margin of the penisvalva serrate; dorsal portion of the penisvalva not sclerotized.

Type Material

Holotype: Madagascar; Toamasina; Forêt Ambatovy, 14.3 km 57° Moramanga; 1075; -18.85083; 48.32; coordinates obtained from GPS; General collecting; 04/12/2005; montane rainforest; BLF11961; ex rotten log; 1w; pin; casent0318421; California Academy of Sciences. Paratypes: Same data as holotype. 1w, Naturhistorisches Museum Wien, Vienna, 1 w National Museum of Natural History, 1w, Musee d'Histoire Naturelle Genève, 1w, Naturhistorisches Museum, Basel, 1w, 1w, CASC, 1w, Museum of Comparative Zoology, 1w Museu de Zoologia da Universidade de Sao Paulo.


The name is formed by the junction of the Malagasy cardinal number roa, meaning two, and the Malagasy name hady, meaning sulcus, ditch, and trench. The name roahady is a reference to the presence of a longitudinal sulcus on the anterior face of the mesobasitarsus and the anterior face of the metabasitarsus. The presence of a groove-like sulcus on the anterior face of the metabasitarsus is unique among Stigmatomma species in the Malagasy bioregion.

Determination Clarifications

Amblyopone sp. Ma-01 (specimen CASENT0500015) and Amblyopone sp. (CASENT0500385) in Ouellette et al. (2006), as Stigmatomma MG01 (CASENT0135098) and as Stigmatomma MG05 ( CASENT0042894) in Ward and Fisher (2016), and as Stigmatomma MG01 (CASENT0227519) in Yoshimura and Fisher (2012b).


References based on Global Ant Biodiversity Informatics

  • Esteves F. A., and B. L. Fisher. 2016. Taxonomic revision of Stigmatomma Roger (Hymenoptera: Formicidae) in the Malagasy region. Biodiversity Data Journal 4: e8032.