Description
Worker measurements (mm): HW 0.65; HL 0.73; SL 0.53; EL 0.16; WL 1.03; PL 0.36; PPL 0.24; GL 1.00; TL 3.50. Indices: CI 89; SI 82.
Head slightly longer than wide. Sides of head slightly convex, evenly rounded into the posterior border, latter more or less straight with a small medial concavity. Mandibles with four teeth: the apical larger than the others, the subapical separated by a space from the basal teeth. Maxillary palps 2 segmented. Clypeus convex with no trace of carinae, extended posteriorly as smooth and shiny frontal area. Clypeus anteriorly convex. Antenna 12 - segmented with club 3 - segmented. Frontal carinae short.
Eyes large, well developed, with about 11 ommatidia in the maximum diameter, situated in the middle of the head.
In lateral view mesosoma with promesonotum convex. Metanotal groove deep, well marked. Propodeum unarmed. Declivity of propodeum devoid of transverse carinae. Propodeal spiracle with a thin walled vestibule anteriorly. Metapleural lobes small, rounded. Petiole with short peduncle, node rounded above. Petiolar spiracle at beginning of node. Petiolar ventral process consisting of anterior median keel. In dorsal view postpetiole wider than petiole. In side view postpetiole subcampaniform, with a ventral strong median tubercle, pointed anteriorly. Sting developed.
Entire body smooth and shining. Moderate erect pilosity on head, promesonotum, petiole, postpetiole and gaster, very few on propodeum. Larger hairs about 0.15 mm, those of head shorter. Clypeus with two series of transverse setae, those of anterior margin increasing in size toward the somewhat larger median apical setae. Body brown, most of gaster dark brown.
Queen and male unknown.
Type data: Holotype worker, Brazil , Bahia , Fazenda Amarillina , Guaratinga , 28. vii. 1993(Pula / MichelliNo. 4675 - D ) ( CEPLAC ) .
Distribution: Eastern Brazil.
Etymology: This species is named for my friend and colleague Dr. Jacques Delabie, for his continuous supply of interesting ants.
Comments
In M. delabiei there are two transverse rows of hairs on the clypeus. In the row on the anterior border, the hairs increase in length from the lateral ones towards the midpoint, where they are longest (although not very much longer than the rest); in other words, there is no single medial hair that stands out, a characteristic typical of the tribe. This is also typical of some Megalomyrmex , and in at least some “ Antichthonidris ” workers, there is no apical medial seta. The clypeus forms a medial convexity with only a very weak trace of carinae. The tentorial pit is more than halfway between antennal receptacles and mandibular base (as in some “ Antichthonidris ”), rather than near the antennal alveolus (as in some Neotropical Monomorium ). The form of the propodeal spiracle is somewhat similar to that of Nothidris (Bolton, 1994: 104), with a visible vestibule preceding anteriorly the spiracle proper: in typical Monomorium and Megalomyrmex the spiracle is round and without anterior vestibules. The postpetiole has a robust, pointed ventral tubercle, a characteristic apparently not shared with other members of the genus or with Megalomyrmex . The absence of the transverse propodeal carina excludes, by definition, the inclusion of this species in the typical Megalomyrmex , although the character is not universal within the genus, and can be present in some Monomorium .
