Odontomachus latidens

Odontomachus latidens inhabits secondary and primary forests in the highlands (ca. 800–1300 m alt.), and nests in the soil near the base of living trees. The colony GK-38-12, from Leuser Ecosystem, Aceh Province, was collected nesting together with Pheidole tandjongensis Forel, 1913 (colony GK-39-12). Details concerning the nature of their relationship are unknown. (Satria et al. 2015)

Identification
A member of the Odontomachus rixosus group. The identities of O. latidens and Odontomachus procerus are discussed under Odontomachus procerus.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia. Oriental Region: Thailand.

Nomenclature

 *  latidens. Odontomachus latidens Mayr, 1867a: 80 (q.) INDONESIA (Java). Emery, 1892d: 560 (w.); Imai, et al. 1984: 67 (k.); Satria, et al. 2015: 14 (m.). Status as species: Emery, 1887b: 428; Dalla Torre, 1893: 51; Karavaiev, 1925c: 292; Brown, 1976a: 104; Satria, et al. 2015: 11 (redescription).

Taxonomic Notes
Satria et al. (2015) - In 1893, Emery described O. latidens r. procerus from the Malay Peninsula based on the queen, and then, in 1900, he described ''O. latidens subsp. sumatranus'' from Sumatra based on the worker and queen. Both of the two forms were regarded as varieties of O. latidens, and were synonymized by Brown (1976) with the nominotypical subspecies of O. latidens (type locality: Java).

During our survey on Sumatran species of Odontomachus, we discovered colonies (containing workers, queens and males) which seemed to be relevant to O. latidens sensu lato. We compared these non-type queens with the holotype (queen) of “''O. latidens subsp. procerus”; syntype queens of O. latidens subsp. sumatranus; and nontype queens from Java (colony JV02/03-SKY-39) which were identified by us as O. latidens'' based on Brown (1976). As a result of these comparisons we were able to separate two forms. The form “A” is characterized by the masticatory margin of the mandible with 6–9 distinct denticles that are reduced in size toward the base of the mandible, and the 1st gastral tergum without erect setae, and it is morphologically equivalent to the type material of “''O. latidens subsp. procerus” and “O. latidens subsp. sumatranus''”. On the other hand, the form “B” is characterized by the masticatory margin of mandible with very small denticles or sometimes without denticles (only preapical angle recognized), and the 1st gastral tergum with short erect setae that are shorter than those on vertex near ocelli. The form B is clearly different from the type material of “''O. latidens subsp. procerus” and “O. latidens subsp. sumatranus” but agrees well with the non-type queens of “O. latidens''” from Java. The forms A and B are also distinguishable from each other by the male morphology. The male of the form A is characterized by the following characters: body relatively dark; subpetiolar process in lateral view anteroposteriorly shorter than dorsoventrally high, triangular; posterior spine of 8th abdominal tergum long and slender, very weakly curved; disc of 9th abdominal sternum almost circular, much longer than apical lobe, of which almost parallel lateral margins and weakly convex apex; telomeral apex in lateral view longer than high. On the other hand, the male of the form B is characterized by the body relatively light in color; subpetiolar process in lateral view anteroposteriorly as long as dorsoventrally high, lobate; posterior spine of 8th abdominal tergum short and thick, very weakly curved; disc of 9th abdominal sternite not clearly differentiated from apical lobe, gradually merging into apical lobe, with basal margin almost straight; apical lobe gently tapering apicad, with apical margin truncated; telomeral apex in lateral view longer than high.

These differences between the two forms indicate a species-level delimitation between the two. Because we have not yet found the type material of O. latidens in any possible type depositories in Western countries, we are unable to confirm with certainty the identity of O. latidens. Thus, we provide here a tentative solution of this taxonomic problem: (1) the form A is identified as ''O. latidens subsp. procerus Emery, 1893, and the taxon is revived and raised to species; (2) O. latidens subsp. sumatranus is synonymized with O. procerus; and (3) the form B is, at present, treated as O. latidens''.

Worker
Satria et al. (2015) - (n=10): HW 2.43–3.13 mm, HL 3.23–4.05 mm, SL 2.83–3.65 mm, IFLW 0.60–0.76 mm, EL 0.31–0.40 mm, MDL 1.67–2.09 mm, WL 3.50–4.30 mm, PTL 0.50–0.69 mm, PTH 1.26–1.58 mm, CI 73–77, SI 109–123, MDI 51–55, PTHI 226–280.

Relatively large (HL 3.23–4.05 mm, WL 3.50–4.30 mm). Head in full-face view slightly longer than broad, with posterior margin weakly concave (sometimes almost straight); median furrow on vertex present as dark line; each side of line hardly humped; frontal lobes followed by strong frontal carinae which are slightly divergent posteriad and then become nearly parallel; minimum distance between margin of ocular ridge and margin of compound eye half as long as major axis of compound eye; mandible relatively slender; masticatory margin with very small denticles along its length, or only with preapical angle (without denticles); subapical tooth shorter than broad, with truncate apex; palp formula 4, 4. Mesosoma in lateral view stout; pronotum including its anteromedian lobe short, in lateral view with anterodorsal slope relatively steep; mesopleuron without anteroventral ridge, with anterodorsal margin weakly carinate, clearly separated by distinct dorsal carina from mesonotum and metapleuron; propodeum in lateral view with dorsum slightly convex, and gradually sloping posteriad, with posterior face steeply sloping; propodeal dorsum anteriorly with very weak median longitudinal depression. Petiolar node conical, with sharply pointed apical spine; node in lateral view, excluding apical spine with anterior face weakly convex or weakly and bluntly angulate, and posterior face weakly convex; apical spine short and relatively slender, less than 1/4 as long as petiolar height, sometimes weakly curved posteriad (but shape variable within species); subpetiolar process anteroposteriorly shorter than dorsoventrally high, lobate, directed ventrally. First gastral tergum in lateral view relatively short, with anterior face moderately long and vertical.

Head in full-face view largely smooth and shiny, but with striate area bordered by frontal carinae and ocular ridges; frontal lobe smooth and shiny; extraocular furrow smooth and shiny; median part of vertex along median furrow smooth and shiny; lateral face and venter of head smooth and shiny; median disc of clypeus almost smooth and shiny. Pronotal disc and mesonotum in dorsal view densely and transversely striate; posterolateral face of pronotum partly smooth and shiny; mesopleuron largely smooth and shiny, with anterior 1/4 finely striate; metapleuron moderately striate in its anterior 2/3, and smooth and shiny or faintly striate in its posterior 1/3; propodeum with transverse striation which is a little sparser and stronger than pronotum and mesonotum. Petiolar node largely smooth and shiny, but sometimes with its basal area faintly striate.

Vertex with a pair of long erect setae; frontal lobe without seta; pronotal disc without long erect setae; 1st gastral tergum with erect setae (but often missing artificially) which are 2/3 as long as setae on vertex. Head, mesosoma, petiole and gaster with fine appressed pubescence which is sparse and very short on head and gaster.

Body reddish brown to brown; gaster a little darker than head and mesosoma; all legs yellowish brown.

Queen
Satria et al. (2015) - (n=7): HW 2.89–2.99 mm, HL 3.60–3.95 mm, SL 3.35–3.55 mm, IFLW 0.70–0.76 mm, EL 0.50–0.52 mm, OL 0.13–0.20 mm, MDL 1.97–2.05 mm, WL 4.55–4.75 mm, FWL 10.48–11.17 mm, PTL 0.69–0.71 mm, PTH 0.94–1.85 mm, CI 76–80, SI 116–118, MDI 50–58, PTHI 131–277.

In general appearance queen is similar to worker. Vertex near ocelli not swollen; ocular ridge clearly developed; distance between lateral ocelli as long as distance between lateral and median ocelli, and as long as major axis of median ocellus; ocelli in lateral view protruded dorsad. Mesosoma with main sclerites associated with wing function, in dorsal view short and stout; anterodorsal slope of pronotum in lateral view steep; anterodorsal outline of mesoscutum in lateral view relatively steep; mesoscutum with very weak posteromedian depression; parapsidal furrow very weak and slightly curved; mesopleuron without oblique furrow; propodeum in lateral view relatively short, with dorsum very weakly convex and gradually sloping posteriad. Wing venation as in Figs. 6E and 6F. Petiolar node in lateral view, excluding apical spine with anterior face almost straight to weakly convex, and its posterior face weakly convex; apical spine short and relatively slender, and sometimes weakly curved posteriad (but variable in shape within species); subpetiolar process anteroposteriorly longer than dorsoventrally high. First gastral tergum in lateral view relatively short, with anterior face moderately long and vertical.

Head in full-face view largely smooth and shiny, but with striate area bordered by frontal carinae and ocular ridges; frontal lobe smooth and shiny; extraocular furrow faintly striate; median part of vertex along median furrow smooth and shiny; lateral face and venter of head smooth and shiny; median disc of clypeus almost smooth and shiny. Pronotum densely and weakly striate transversely; mesoscutum largely smooth and shiny, with faint striae on posteromedian depression and along posterior margin; mesopleuron largely smooth and shiny, with anteriormost part faintly striate; mesoscutellum smooth and shiny; propodeum strongly and sparsely striate transversely. Petiolar node excluding spine largely striate faintly.

Pair of long erect setae present on vertex near lateral ocelli; frontal lobe and pronotal disc without erect setae; 1st gastral tergum with erect setae (but often missing artificially) which are shorter than setae on vertex near ocelli. Head, mesosoma, petiole and gaster with sparse subdecumbent to decumbent pubescence which is extremely short on gaster; mesopleuron very sparsely pubescent.

Body reddish brown to brown; gaster a little darker than head and mesosoma; all legs yellowish brown.

Male
Satria et al. (2015) - (n=7): HW 1.60–1.65 mm, HL 1.26–1.31 mm, SL 0.26–0.28 mm, EL 0.88–0.91 mm, EW 0.50–0.51 mm, OL 0.20–0.22 mm, OES 0.26–0.28 mm, WL 3.55–3.70 mm, FWL 7.05–7.25 mm, PTL 0.63–0.64 mm, PTH 0.97–1.03 mm, CI 123–128, SI 16–18, PTHI 151–164.

Size large (HL 1.26–1.31 mm, WL 3.55–3.70 mm). Major axis of median ocellus smaller than minimum distance between lateral ocelli; antenna 13-merous; scape very short, 1/3 as long as 3rd antennomere; 2nd antennomere 1/2 as long as scape; 3nd to 13th antennomeres each extremely long; palp formula 6, 4; dorsal outline of clypeus in lateral view weakly convex. Mesosoma in lateral view relatively slender and long; dorsal outline of pronotum in lateral view weakly convex; anterodorsal outline of mesoscutum in lateral view relatively steeply sloping; mesoscutum with short weak median longitudinal depression; parapsidal furrow weak and slightly curved; oblique mesopleural furrow relatively shallow and narrow; ventrolateral part of katepisternum with a very weak longitudinal furrow; propodeum in lateral view with its dorsal outline roundly convex; metapleuron separated from propodeum indistinctly by a suture; wing venation similar to queen. Petiolar node in lateral view tapering gently to rounded apex with its anterior slope straight, and its posterior slope much steeper and shallowly concave; subpetiolar process in lateral view anteroposteriorly shorter than dorsoventrally high, lobate and slender; petiolar sternum without posteroventral process. First gastral tergum in lateral view long; posterior spine of 8th abdominal tergum short and thick, very weakly curved; pygostyle digitiform, with long setae in apical 2/3; disc of 9th abdominal sternite not clearly differentiated from apical lobe, gradually merging into apical lobe, with basal margin almost straight; apical lobe gently tapering apicad, with apical margin truncated; telomeral apex in lateral view longer than high; distiventral apex of valviceps weakly produced; basiventral corner of valviceps not produced; ventral margin of valviceps with 27−30 denticles.

Head largely smooth and shiny, with area between lateral ocelli faintly striate. Pronotum in dorsal view smooth and shiny; mesoscutum faintly and longitudinally striate or sometimes smooth and shiny; scuto-scutellar suture with sparse, strong, longitudinal rugae; mesopleural anepisternum and katepisternum smooth and shiny; propodeum with sparse, strong, longitudinal striate. Petiole smooth and shiny.

Head, mesosoma, legs, petiole, and gaster with fine dense subdecumbent to decumbent pubescence; mandible, vertex near ocelli and gaster except 1st gastral tergum with several long erect setae.

Head including scape, mesosoma, legs yellowish brown; funiculus dark brown; petiole and gaster darker than head and mesosoma.

References based on Global Ant Biodiversity Informatics

 * Brown W. L., Jr. 1976. Contributions toward a reclassification of the Formicidae. Part VI. Ponerinae, tribe Ponerini, subtribe Odontomachiti. Section A. Introduction, subtribal characters. Genus Odontomachus. Stud. Entomol. 19: 67-171.
 * Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
 * Emery C. 1887. Catalogo delle formiche esistenti nelle collezioni del Museo Civico di Genova. Parte terza. Formiche della regione Indo-Malese e dell'Australia (continuazione e fine). [concl.]. Ann. Mus. Civ. Stor. Nat. 25(5): 427-473.
 * Emery C. 1911. Hymenoptera. Fam. Formicidae. Subfam. Ponerinae. Genera Insectorum 118: 1-125.
 * Emery, C. "Catalogo delle formiche esistenti nelle collezioni del Museo Civico di Genova. Parte terza. Formiche della regione Indo-Malese e dell'Australia (continuazione e fine)." Annali del Museo Civico di Storia Naturale Giacomo Doria (Genova) (2) 5, no. 25 (1887): 427-473.
 * Forel A. 1905. Ameisen aus Java. Gesammelt von Prof. Karl Kraepelin 1904. Mitt. Naturhist. Mus. Hambg. 22: 1-26.
 * Forel A. 1912. Ameisen aus Java beobachtet und gesammelt von Edward Jacobson. III. Theil. Notes Leyden Mus. 34: 97-112
 * Imai H. T., M. Kubota, W. L. Brown, Jr., M. Ihara, M. Tohari, and R. I. Pranata. 1985. Chromosome observations on tropical ants from Indonesia. Annu. Rep. Natl. Inst. Genet. Jpn. 35: 46-48.
 * Jaitrong W.; Nabhitabhata, J. 2005. A list of known ant species of Thailand. The Thailand Natural History Museum Journal 1(1): 9-54.
 * Karavaiev V. 1925. Ponerinen (Fam. Formicidae) aus dem Indo-Australischen Gebiet. (Schluss). Konowia 4: 276-296.
 * Karavaiev V. 1926. Ameisen aus dem Indo-Australischen Gebiet. Treubia 8: 413-445.
 * Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58
 * Satria R., H. Kurushima, H. Herwina, S. Yamane, and K. Eguchi. 2015. The trap-jaw ant genus Odontomachus Latreille (Hymenoptera: Formicidae) from Sumatra, with a new species description. Zootaxa 4048(1): 001-036.
 * Yamane S.; Nona, A. R. 1994. Ants from Lambir Hills National Park, Sarawak. Pp. 222-226 in: Inoue, T.; Hamid, A. A. (eds.) 1994. Plant reproductive systems and animal seasonal dynamics. Long-term study of dipterocarp forests in Sarawak. Kyoto: Center for Ecological Research, Kyoto University, vii + 255 pp.