Odontomachus mormo

Biological information about this species is sparse. The holotype was reported as (Brown 1976): a unique taken in wet forest in a ravine leading up into the first (westernmost) foothills of the Andes just east of the highway, about 3 km SW of Bucay, Provo Guayas, Ecuador, by W. L. Brown, July 1973. The worker was found walking slowly on the ground in shade near midday; seen alive, it was at first thought to be a large specimen of Odontomachus chelifer.

Identification
Brown (1976) - This species is the largest Odontomachus in the New World, equaling and slightly exceeding the largest workers of Odontomachus chelifer available for study. The records are all from Ecuador west of the Andes. It will be interesting to see how far north and south the range of this species extends.

Distribution based on Regional Taxon Lists
Neotropical Region: Colombia, Ecuador.

Nomenclature

 *  mormo. Odontomachus mormo Brown, 1976a: 161, figs. 10, 15 (w.) ECUADOR.

Worker
Holotype: TL 18.8, HL 4.34, HW ( across vertex) 2.30, HW (across ocular prominences) 2.80, ML 2.58, scape L 4.66, eye L 0.6 1, WL 5.78 m m ; CI 53, MI 59, SI 203.

A very large species related to Odontomachus hastatus, but differing in the following characters:

(1) Head broader and with sides of vertex nearly parallel, only feebly converging posteriad behind temporal ridges ; posterior angles broadly rounded, but more sharply so than in hastaius. Posterior border biconvex, with a median concavity bounded by the V of the nuchal carina. Carina distinct, but not raised into a narrow collar as it is in hastatus. Extraocular furrows and temporal ridges more distinct than in hastatus; antennal fossae deep and confluent at the deep median furrow, which runs forward nearly to the midlength of the head. Striation of frontal region coarse, spreading fanwise only to the posterior limits of the antennal fossae.

( 2) Mandibles more robust than in hastatus (maximum W, without teeth, about 0.6 mm in the mormo holotype, 0.5 mm in the largest hastatus workers available), outer borders gently but distinctly convex in outline seen full-face. Large dorsal subapical tooth broad, hardly more than twice as long as broad, with bluntly rounded (subtruncate) apex; in unworn hastatus, this tooth is much more slender and has an acute, or at least conical apex. Teeth on inner margin of blade low, blunt, decreasing in size basad, 10-11 in  number, followed at base by 3-6 minute serrations.

(3) Striation of pronotum and mesonotum fine and distinct, transverse on the discs, not effaced in holotype (center of posterior pronotal disc usually smooth and shining in hastatus).

(4) Entire trunk relatively more robust (less attenuated) in mormo than in hastatus; as seen from the side, mesonotal and metanotal outlines both feebly convex, meeting at the deep suture to form a distinct, broadly open V (in hastatus, mesonotum concave, forming a shallow saddle with metanotum; suture between them scarcely interrupting the concave outline of the saddle).

(5) Petiole of a special shape, not distinctly subpedunculate in front as in hastatus, but the anterior face gently concave in about its upper 2/3, below root of apical spine. Node smooth and shining.

(6) Most of body entirely without erect hairs. One pair of long inclined hairs near the middle of the cephalic dorsum, close to the posterior edge of the frontal striated area. A few other short, fine, inconspicuous hairs here and there on anterior part of head, especially on free clypeal margin, under-mouthparts, and a few on anterior half of ventral surface of head, on anterior and ventral surfaces of coxae, on flexor edges of femora, on distal flexor surfaces of tibiae, undersides of petiole and gaster, and dorsal surface of first gastric tergum near its posterior margin. Longer fine hairs (0.4-0.6 mm long) on the 4 segments of gastric apex, and some longer oblique hairs ranged along the undersides of the inner mandibular borders. O. hastatus has abundant fine erect pilosity over most of the body.

Pubescence distinct only on scapes, tibiae and tarsi, where it is short, fine, and appressed to obliquely erect. Dilute appressed pubescence on mandibular shafts. On trunk, petiole, and especially on the smooth and shining gastric dorsum, pubescence is extremely fine and dilute, so that the gaster, at least, seems free of it except at high magnifications in certain lights, when widely separated, very fine, appressed hairs are sometimes visible.

(7) Mesepisternal margin distinct its whole length above (often obliterated in front of metathoracic spiracle in hastatus); metasternal surface vertically striate over about anterior quarter, otherwise smooth, with satiny blue lustre.

(8) Head, mandibles, trunk, petiole, and tibiae dark reddish brown; gaster, mandibular apices and tarsi piceous; coxae and femora dull yellow, the femora infuscated apicad. The smooth parts of the body, especially sides of head, mesepisterna, and node, with bluish iridescence.

Additional metric data : petiole L 1.21, petiole height above spiracle 1.30, without ventral process 1.70, including ventral process 2.01, left hind femur L 4.62, left hind tibia L (without basal condyle) 3.70 mm.

Type Material
Holotype a unique taken in wet forest in a ravine leading up into the first (westernmost) foothills of the Andes just east of the highway, about 3 km SW of Bucay, Provo Guayas, Ecuador, by W. L. Brown, July 1973. The worker was found walking slowly on the ground in shade near midday; seen alive, it was at first thought to be a large specimen of Odontomachus chelifer. Paratype workers: Two specimens were received belatedly, when this manuscript was nearly finished. They were both collected in 1975 in Provo Pichincha, Ecuador, by Stewart and Jarmila Peck. The first worker, slightly larger than the holotype, comes from 3 km east of Tandapi, 1300 m, in wet ravine (B-303). The second is a partial specimen, consisting only of head and pronotum with appendages, from Tinalandia, 16 km southeast of Santo Domingo de los Colorados, 680 m, in litter berlesate. This last specimen is a little smaller than the holotype, and has the palpi extended and segments countable at 4,4.

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.
 * Fernández F., and E. E. Palacio. 1995. Hormigas de Colombia IV: nuevos registros de géneros y especies. Caldasia 17: 587-596.
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.