Myrmoteras williamsi

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Myrmoteras williamsi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Myrmoteratini
Genus: Myrmoteras
Species: M. williamsi
Binomial name
Myrmoteras williamsi
Wheeler, W.M., 1919

MCZ ENT Myrmoteras williamsi 001 hal(2.jpg

MCZ ENT Myrmoteras williamsi 001 had(2.jpg

Specimen Label

Little is known, but J. W. Chapman (in Creighton, 1930) indicated that the ants are "slow and clumsy in movement." F. X. Williams (in Wheeler, 1922) reported that the species nests in the soil. (Moffett 1985)



Zettel & Sorger (2011) - Myrmoteras mcarthuri is similar to Myrmoteras williamsi and has been initially mistaken for this species by the first author. However, close examination of material from Leyte yielded the discovery that in fact it represents a distinct new species. Myrmoteras williamsi was described based on sexuals (two gynes and one male) from Los Baños, Laguna, Luzon Island (Wheeler 1919). Moffett (1985) redescribed gynes (types and additional specimens) from Luzon and Negros and workers from Dumaguete, Negros Island. Although he noted important differences between the material from the two islands, he considered them as conspecific, following Creighton (1930).

Myrmoteras williamsi gynes collected at the type locality and deposited in the first author’s collection agree perfectly with the original description of this taxon. Myrmoteras mcarthuri differs in some important characteristics from M. williamsi: In M. mcarthuri the posterior face of the temples, behind a blunt ridge, is granulate, where it is smooth and shiny in M. williamsi. The Mandible Index is larger in M. mcarthuri (145–154) than in M. williamsi (124–130; measurements partly from Moffett 1985). In lateral aspect, the petiolar node is wide in M. mcarthuri, but narrow in M. williamsi. Another very obvious difference is found in the antenna: The funiculus of M. williamsi is stouter than that of M. mcarthuri, especially the basal joints (except antennomere 2) are not much longer than broad in M. williamsi, while their length is almost twice their width in M. mcarthuri. The length of antennomere 3 is approximately 0.7 times the length of antennomere 2 in M. williamsi, but almost 1.0 times in M. mcarthuri. In addition, the length of setae, especially on pronotum, is slightly longer in M. mcarthuri than in M. williamsi.

Although this compares a gyne with a worker, all characters mentioned do not seem to be morph-related, at least there are no differences in the differential diagnoses of worker and gynes of other species (see Moffett 1985).

Myrmoteras mcarthuri differs from Moffett’s (1985) description of “M. williamsi” workers from Negros, as the latter “have a feeble granulate sculpture on the legs, scapes, and mandibles” which is absent in M. mcarthuri. We suspect that this Negros material will turn out being another undescribed species.

Moffett (1985) - Shape of the trunk in workers distinctive: pronotum and propodeum high and strongly convex; mesothorax relatively depressed. M. williamsi has only been collected in the Philippines. Myrmoteras karnyi (tentatively placed in the donisthorpei group) has a somewhat similarly shaped trunk, but the head and trunk of this species are apparently not strongly granulate (Gregg, 1954).

Keys including this Species


Distribution based on Regional Taxon Lists

Indo-Australian Region: Philippines (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb






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

  • williamsi. Myrmoteras williamsi Wheeler, W.M. 1919e: 146 (q.m.) PHILIPPINES. Creighton, 1930a: 189 (w.). Combination in M. (Myagroteras): Moffett, 1985b: 50.

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



Moffett (1985) - Known only from Negros. Two measured (numbers in brackets indicate measurements that could only be taken on the smaller specimen): TL [5.0], HW 0.95 to 1.00, HL 0.95 to 1.00 (CI 100), ML 1.38 to 1.50 (MI 145 to 151), SL [1.10] (SI [113]), EL 0.55 to 0.58, HFL 1.05 to 1.18 (TWI [21]), WL 1.30 to 1.40 mm. Frontal sulcus very narrow but well defined. Frontal area present but poorly demarcated. Clypeus less strongly convex medially than in most other Myagroteras species, although not as flattened as in most Myrmoteras. Palpal segmentation 6,4 (two workers inspected). Mandibles with 11 to 13 teeth and two preapical denticles. Apical denticles small, the smallest tiny, but conspicuous, the largest closely applied to apical tooth for much of its length. Mandibles bent more strongly ventrad at penultimate tooth than in other Myagroteras, but not as strongly as in subgenus Myrmoteras.

Both pronotum and propodeum very high and rounded (except declivity of propodeum virtually straight), so that mesonotum appears relatively very depressed. In profile with a wide concavity between metathoracic tubercles and propodeum, but metanotal groove not visible as a conspicuously impressed notch in profile. Petiole with steep to nearly vertical anterior slope; posterior slope less steep, straight but curving gently up to summit.

Head (including frontal area and clypeus), pronotum and propodeum finely and evenly granulate, granules 0.01 to 0.02 mm across, present as well on back of head and laterally beneath eyes, and with traces of granular sculpture beneath head; declivity of propodeum smooth; mesothorax with feeble granulate sculpture, widely separated narrow longitudinal rugae on sides and virtually smooth above; funiculi, mandibles and legs feebly granulate, with the sculpture strongest on the tibiae; petiole and gaster smooth. Pilosity sparse to moderate, with 6 to 18 hairs breaking dorsal margin of trunk when viewed in profile (but specimens in very poor condition and conceivably have lost hairs). Hairs short, rising 0.06 mm on head, trunk and gaster; one to two hairs on or near each metathoracic tubercle and two to three on node of petiole. Head and trunk reddish orange (except clypeus and occiput orange red); petiole same but slightly lighter; gaster brownish or yellowish orange; legs yellowish orange; mandibles and antennae orange yellow.


Moffett (1985) - Syntypes (two measured): TL 4.4 to 5.0, HW 0.91 to 0.96, HL 0.88 to 0.93 (CI 103), ML 1.15 to 1.18 (MI 127 to 130), SL 0.91 to 0.94 (SI 99 to 100), EL 0.53 to 0.56, HFL 0.89 to 1.00 (TWI 19 to 22), WL 1.18 to 1.28 mm. Hairs moderately dense and longer than in Dumaguete worker specimens (0.08 to 0.10 mm). Trunk finely and evenly granulate, propodeum transversely granulo-rugose, including on declivity. Funiculi, mandibles and legs smooth.


Moffett (1985) - Single male from Mt. Makiling: HW 0.68, HL 0.75 (CI 91), SL 0.84 (SI 124), EL 0.38, WL 1.2 mm. Frontal sulcus a shallow groove beginning well above clypeus and ending before reaching median ocellus. Maxillary palpi with six segments. Head and trunk granulate; longitudinally granulo-rugose dorsad on mesonotum, more feebly granulate laterally; propodeum feebly granulate with a conspicuous network of raised ridges, except declivity virtually bare outside of medial ruga.

Type Material

Moffett (1985) - Philippine Islands: Luzon: Los Bafios, 2 alate queens, 1 male (F. X. Williams, Museum of Comparative Zoology, queens examined, male missing).

Determination Clarifications

Zettel & Sorger (2011) - Although Moffett (1985) describes workers from Negros, only sexuals (gynes and males) from Central Luzon belong to M. williamsi without doubt. At the Discover Life website, Alpert et al. (2010) present another record from Camarines Sur in southern Luzon; however, this record should be reconfirmed, since the first author studied males from the same province which did not fully agree with the M. williamsi-male from the type locality.


References based on Global Ant Biodiversity Informatics

  • Creighton W. S. 1930. A review of the genus Myrmoteras (Hymenoptera, Formicidae). Journal of the New York Entomological Society 38: 177-192.
  • Gregg R. E. 1954. Geographical distribution of the genus Myrmoteras, including the description of a new species (Hymenoptera: Formicidae). Psyche (Cambridge) 61: 20-30.
  • Moffett M.W. 1985. Revision of the genus Myrmoteras. Bulletin of the Museum of Comparative Zoology 151: 1-53.
  • Zettel, H. & D.M. Sorger. 2011. New Myrmoteras ants (Hymenoptera: Formicidae) from the Southeastern Philippines. Raffles Bulletin of Zoology 59(1):61-67