Thaumatomyrmex mutilatus

Identification
Kempf (1975): The present species and Thaumatomyrmex contumax, differ from all other known species by the microscopically shagreened and subopaque integument of body which has a silky sheen; the presence of two close-set setae on center of clypeal disc spreading V-shaped fashion (Figs. 12, 13); the pale, thick, apically truncate hairs; the presence of three hairs on lateral border of propodeal declivity (Figs. 21, 22), the lowermost hair arising from the bottom end of the inferior ridge or carina (among all other species, only Thaumatomyrmex cochlearis has three setae in this region, but the lowermost seta arises from the top of the ridge); the deep and broad excision between the basal tooth and the proximal spine of mandibles (Figs. 31, 33, 35); the relatively shorter proximal and intermediate mandibular spines, the latter distinctly shorter than one half the chord length of the apical spine; the marked and almost sharp transverse margin between the anterior and posterior surface of petiolar node, a condition approximated only in paludis, in which, however, it does not attain the same degree of sharpness; the antero-posteriorly more compressed and scale-like node of petiole, a character which was not explored statistically but may eventually be significant when more material is at hand.

The differences between mutilatus and contumax consist mainly in proportional measurements and are given under the latter species.

Key to Thaumatomyrmex

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil, Paraguay.

Kempf (1975) stated "Known from southeastern and central Brazil, this species inhabits the humid and more xerophilous latifoliate forests of these regions." We now also know it occurs in Paraguay.

Biology
This species, i.e., the Agudos morph, has twice been found associated with termites, suggesting that the latter might be the favorite if not exclusive food of these ants, whose three-tined mandibles are ideally adapted for piercing soft-bodied insects. However, as already stated above in the introduction, an actual feeding on termites has not been observed so far (Kempf 1975).

Nomenclature

 *  mutilatus. Thaumatomyrmex mutilatus Mayr, 1887: 531 (w.) BRAZIL. Kempf, 1954: 48 (m.); Wheeler, G.C. & Wheeler, J. 1964b: 450 (l.). See also: Kempf, 1975b: 103.

Worker
Kempf (1975): TL 3.6-4.2 mm; HL 0.76-0.91 mm; HW 0.77-0.91 mm; CI 95-105; ML 0.72-0.89 mm; MI 86-102; IfW 0.56-0.69 mm; IfI 72-78; SL 0.63-0.76 mm; SI 81-89; WL 1.12-1.27 mm; PnW 0.55-0.64 mm; HfL 0.80-0.92 mm; HfI 99-110; PW 0.64-0.76 mm. Black, mandibles, frontal lobes, antennae and legs (except fore coxae) ferruginous. Integument of body minutely shagreened, i. e. densely and microscopically striolate-punctulate, subopaque, with a silky sheen. Mandibles finely striate on basal third, remainder smooth and shining. Frontal lobes striato-rugose. Exposed portions of terga III and IV of gaster superficially reticulate to reticulate-punctate, quite shining. Antennal scapes and legs rugulose-punctate, the latter somewhat shining. Hairs on body stiff, curved, with blunt tips, pale yellowish, their distribution shown in Figs. 12 and 21; note the pair of close-set standing hairs on center of clypeal disc, spreading out in the fashion of an inverted V, and the three hairs bordering the propodeal declivity, two of which arise from the top and the bottom of the inferior carina. Long (sensory?) hairs on mandibles shown in Figs. 31 and 35. Antennae and legs with short, appressed hairs. Fine pubescence confined to funiculi and tarsomeres.

Head (Fig. 12) about as long as broad, its greatest width between the eyes (the latter included) and its greatest length between anterior tip of frontal lobes and posterior most part of occiput in full-face view, not broadened in front of eyes, the mandibular acetabula not projecting in a stalk-like fashion, the sides of head not strikingly receding behind eyes, but posteriorly curved forming a semicircle with the occiput. Mandibles (Figs. 31, 35) with a well-developed tooth on dilated base of proximal spine, their chord length subequal to head width, their apex not noticeably protruding beyond genae when closed (Fig. 12), the apical spine distinctly shorter than twice the distance between its origin and the mandibular base, length of intermediate spine shorter than half the length of apical spine. Frontal lobes narrowly rounded in front but not pointed. Frontal area and frontal suture at least vestigial. Eyes with about 14 facets in a row across the greatest diameter which is subequal to one third of head length. Maximum width between frontal lobes about three-fourth of head width. Antennal funicular segments II-VI distinctly broader than long. Carinulate border of occipital foramen not visible from above in full-face view. Thorax (Fig. 21) lacking a metanotal groove, suture or ridge. Propodeum in profile more or less evenly rounded, inferior half of lateral border of declivous face strongly carinate. Petiole seen from above much broader than long, seen from the side with more strongly convex (in both directions) and inclined anterior surface, and steeper and less convex posterior surface, both forming a point at apex, and meeting at a transverse, very distinct, subacute carina.

Male
Kempf (1975): I give in translation the original description of this sex: Total length 4.2. mm. Median head length, excluding mandibles, 0.61 mm; Weber's length of thorax 1.41 mm. Black; funiculi, trochanters, femora and tibiae chestnut brown; mandibles, tarsomeres and genitalia testaceous.

Head subopaque, broader than long (30:25); interocular width less than median head length (20: 25). Mandibles small, finely punctate, with very short chewing border lacking teeth, scarcely distinct from basal border, forming an acute angle with lateral border. Maxillary palps with three, labial palps with two segments. Clypeus discally rather convex, with the anterior border gently arcuate and the postero-lateral borders vestigial to nearly obsolete. Frontal carinae absent. Eyes large, elliptical, their diameter surpassing one half of median head length. Ocelli conspicuous and salient. Occipital border, between posterior ocelli, slightly concave. Antennae filiform. Scape short, as long as broad. first funicular segment subequal to scape. Second funicular segment thrice as long as broad. Apical segment longer than first and second funicular segments combined. Integument of head uniformly and finely reticulate-punctate.

Thorax subopaque and moderately shining, its general outline shown, in Fig. 1. Pronotum vertical on disc, on sides uniformly curved downward and backward without forming an angle at shoulders; finely reticulate-punctate. Scutum greatly convex, elevated above level of pronotum, without Mayrian furrows (notaulices) but with distinct parapsidal sutures and a weak sagittal furrow, distinct in front and behind but obsolete on disc. Integument of scutum finely reticulate-punctate with delicate and dense striae which are more or less longitudinal but form concentric arcs on the posterior portion between the parapsidal sutures. A deep transverse sulcus between the scutum and the body of the scutellum, the latter strongly convex in both directions and covered with dense, longitudinal rugae. Metanotum with a sagittal keel. Basal face of propodeum finely reticulate, with an abrupt depression in front, posteriorly separated from the plane and distinctly reticulate declivous face by a fine, transverse, somewhat undulate carinule. Sides of thorax finely reticulate-punctate and somewhat rugose on upper half, smoother on lower half.

Legs subopaque. Claws simple. Apex of anterior and posterior tibiae with a big pectinate spur, of mid tibiae with a simple and delicate spur on internal face.

Petiole with a high scale, conical in profile, rounded at apex, smooth and shining. Anterior surface gently convex, posterior surface slightly concave. Subpetiolar process in the form of a longitudinal keel which is subdentate in front and behind.

Gaster smooth and shining, with the sculpture nearly obsolete. Pygidium with a robust apical spine, curved downwards. Cerci visible. Hypopygium with the apical border convex and entire. When the genitalia are retracted, only the apices of the parameres are visible at each side of pygidial spine. Anatomical details of genitalia shown in Figs.

Wings hyaline). Fore wing with the radial cell closed and appendiculate, with one closed cubital cell and a discoidal cell which is open. The basal vein is removed from the transverse median vein by a distance which exceeds the length of the latter. Veins of both wings as well as the stigma faintly infuscated.

Mandibles, head, dorsum of thorax, sides of declivous face, petiole and gaster with sparse hairs, somewhat bristly and curved, suberect on thorax, more inclined on head and on gaster. Hairs of legs denser, smaller and rather decumbent».

Type Material
Type. One (?) worker, Mayr collection, Naturhistorisches Museum, Vienna, Austria. Not seen.