Odontomachus simillimus

Found in clearings and secondary growth throughout the Indo-Pacific.

Identification
Sorger & Zettel (2011) - Odontomachus simillimus can be easily recognised even in the field by small size, dark colour, proportionally large head and short scape. In the Philippines, there is no other species with a short, truncate subapical tooth of the mandible, and none with fine reticulation on visible part of gaster tergite 2 (but note that the anterior part of tergite 2 which is usually covered by tergite 1 is also reticulate in other species).

Odontomachus simillimus is surprisingly uniform over its large distribution area. It is distinguished from the second Old World species, Odontomachus troglodytes from Africa, Madagascar, and the Seychelles, by its smooth gaster tergite 1.

Distribution
Sorger & Zettel (2011) - Widely distributed from India to Polynesia (Wilson 1959, Brown, 1976), “undoubtedly many of the island records represent accidental introductions by man” (Brown 1976: 87). No distribution limit in the Philippines; records from 21 islands (19 in this study).

Distribution based on Regional Taxon Lists
Afrotropical Region: Mozambique. Australasian Region: Australia, New Caledonia. Indo-Australian Region: Borneo, Fiji, Guam, Indonesia , Kiribati, Krakatau Islands, Malaysia, Marshall Islands, Micronesia (Federated States of), New Guinea, Niue, Northern Mariana Islands, Palau, Philippines, Samoa, Solomon Islands, Tonga, Wallis and Futuna Islands. Oriental Region: Bangladesh, Cambodia, India, Nicobar Island, Sri Lanka, Thailand.

Habitat
Sorger & Zettel (2011) - Odontomachus simillimus is a common species which also can be found in open or moderately to strongly disturbed habitats, like coastal areas, coconut groves, villages, and even lawns on university campuses. It usually does not enter dense forests, but can be occasionally found on banks of stream running through forests. According to collections by Chapman in eastern Negros, the species can be found from sea level up to an elevation of 900 m (Wheeler and Chapman 1925).

Nomenclature

 *  simillimus. Odontomachus simillimus Smith, F. 1858b: 80, pl. 5, figs. 8, 9 (q.) FIJI IS. Mayr, 1867a: 79 (w.); Karavaiev, 1925c: 294 (m.); Wheeler, G.C. & Wheeler, J. 1980: 530 (l.); Imai, Brown, et al. 1984: 67 (k.); Tjan, Imai, et al. 1986: 57 (k.). Junior synonym of haematodus: Roger, 1861a: 24; Mayr, 1865: 64; Emery, 1911d: 114. Revived from synonymy: Wilson, 1959a: 499; Brown, 1976a: 106. Senior synonym of fuscipennis: Wilson, 1959a: 499; of breviceps, pallidicornis: Brown, 1976a: 106. See also: Brown, 1976a: 165; Fisher & Smith, 2008: 15; Sorger & Zettel, 2011: 158.
 * pallidicornis. Ponera pallidicornis Smith, F. 1860a: 73 (m.) INDONESIA (Sulawesi). Combination in Euponera (Brachyponera): Donisthorpe, 1932c: 458; in Odontomachus: Brown, 1976a: 106. Junior synonym of simillimus: Brown, 1976a: 106.
 * fuscipennis. Odontomachus haematodes var. fuscipennis Forel, 1913k: 19 (w.q.m.) SRI LANKA. Junior synonym of simillimus: Wilson, 1959a: 499.
 * breviceps. Odontomachus haematoda var. breviceps Crawley, 1915b: 239 (w.) CHRISTMAS I. Junior synonym of simillimus: Brown, 1976a: 106.

Type Material


Ponera pallidicornis

Holotype male in. Labelled “Mak” (= Makassar, Sulawesi) and with a Donisthorpe type-label.

Odontomachus simillimus

Type-localities are give as Fiji, and secondarily Ceylon (= Sri Lanka). As far as can be ascertained, all the types were queens. I can find no trace of any Smith material from these localities at, where the only specimen present in Smith’s collection is a dealate queen from Waigeo I., New Guinea.

In there is a single, damaged queen from Ceylon which may be one of the original type-series, labelled “Ceylon. 50/56,” and also with a “Farren White” label. Acc. Reg.: “1850 no. 56 (June 17) Ceylon. Presented by Dr Joseph Hooker FRS.” In addition, has a single, headless, alate queen from Fiji, without further data, that may be one of the original specimens.

Worker
Sorger & Zettel (2011) - Worker with smallest HW: CI 83, HL 1.97, HW 1.63, MdI 53, MdL 1.05, MsL 2.43, SI 108, SL 1.77, PnW 0.87, PtH 0.75, PtL 0.64, PtW 0.38, TL 7.63; worker with largest HW: CI 82, HL 2.52, HW 2.07, MdI 53, MdL 1.33, MsL 2.93, PnW 1.13, PtH 0.89, PtL 0.99, PtW 0.52, SI 106, SL 2.20, TL 11.06.

Structures: Mandibles short and stout, with very fine denticles, sometimes completely edentate but always with three apical teeth (intercalary tooth slightly shorter than apical and subapical teeth). Apex of mandibles with some setae. Mandibles mostly smooth, some fine ridges / striae may occur, with fine white pubescence, hair pits distinct. Head in dorsal view rectangular, longer than wide, broadest at level of eyes which do not surpass outline of head. Dorsum of head striate, striation almost reaching nuchal carina (at dorsal margin, area of about the width of the scape, smooth). Eyes located dorsolaterally in first third of head. Mesosoma elongate in dorsal view, broadest at level of pronotum. Pronotum with round striation, often slightly oval or longitudinal in centre, but some entire circles always visible in dorsal view. Mesonotum and propodeum with transverse striation (slightly coarser on propodeum). Mesopleuron smooth in centre, some striation at margins. Metanotal spiracle inconspicuous, situated dorsolaterally. Petiole short and straight, conspicuously “tear-shaped” in frontal view, broad with short petiolar spine, posteriorly flat with transverse striation. Gaster rounded to oval; anterior part of first tergite evenly convex in lateral aspect, without impression; first tergite smooth, second with some reticulation, at least anteriorly.

Pilosity: Fine white semi-appressed pubescence on entire body, very dense on appendages including petiole, on mesosoma, head and gaster distance between hairs approximately their length. Few standing setae on pronotum, several standing hairs on gaster increasing in length towards apex of abdomen. Some isolated hairs on head venter and one pair of standing setae on head dorsum.

Colour: Body, including all appendages, dark brown (almost black in some specimens).

Fisher and Smith (2008) - Measurements: maximum and minimum based on n = 10 from Madagascar: HL 2.33–2.63, HW (across vertex) 1.64–2.03, HW (across upper eye margin) 1.77–2.06, CI 75–81, EL 0.20–0.23, ML 1.14–1.28, MI 48–51, SL 2.16–2.43, SI 109–123, WL 2.62–3.06. FL 2.29–2.56, PW 1.02–1.24.

Workers and males are very similar in morphology and size to Odontomachus troglodytes. Bivariate plots of metric measurements did not distinguish the two species. Workers and queen have fine, glossy dorsal striation on head and mesosoma. Metasternal process low and rounded. Metasternal process can be viewed in mounted specimens by removing a hind leg and coxa. Brown (1976) provides a description and references.

Queen
Sorger & Zettel (2011) - Gyne with smallest HW: CI 87, HL 2.27, HW 1.97, MdI 57, MdL 1.30, MsL 2.93, PnW 1.60, PtH 1.00, PtL 0.78, PtW 0.49, SI 107, SL 2.10, TL 9.88; gyne with largest HW: CI 85, HL 2.47, HW 2.10, MdI 54, MdL 1.33, MsL 3.13, PnW 1.65, PtH 1.02, PtL 0.88, PtW 0.61, SI 104, SL 2.18, TL 10.31.

Structures: Differs only in the following characters: pronotum with transverse striation, mesonotum with longitudinal striation, scutellum shiny, sexual female morph-specific characters (wing insertions, mesosoma and gaster bigger).

Fisher and Smith (2008) - Measurements: maximum and minimum based on n = 5 from Madagascar: HL 2.37–2.55, HW (across vertex) 1.79–2.03, HW (across upper eye margin) 1.87–2.13, CI 79–84, EL 0.49–0.53, ML 1.17–1.30, MI 49–52, SL 2.15–2.38, SI 111–118, WL 3.13–3.19. FL 2.36–2.58.

Male
Fisher and Smith (2008) - Measurements: maximum and minimum based on n = 1 from Madagascar: HL 0.89, HW 1.19, CI 133, EL 0.59, SL 0.19, SI 16, WL 2.44. FL 1.73.

Determination Clarifications
Known though most of the literature as O. haematode (Linnaeus) 1758, which is a different species (Fisher and Smith 2008).