Holotype Male: Brazil: Mate Grosso, 12°49′S51°45′W, 19 Nov 1968, W. J. Knight (Royal Soc. / Royal Geog. Soc.) (Xavantinal Cachimbo Expedition 1967–1968) (on Grassland) (BMNH). Paratypes: 1 female: Brazil, Para, Santa Isabel, 29 Oct 1968, J. and B. Bechyne (UNAM). 1 female: Brazil, Porto Santana (AP), 3 Jul 1961, J. and B. Bechyne (UMRM). 1 male: Brazil, Goias, Dianopolis, 25 Jan 1962, J. and B. Bechyne (UMRM). 1 male: Brazil, Mato Grosso, Faz. Rec. Franco, 6 Mar 1961, J. and B. Bechyne (UNAM).

Description: Male. Dorsal coloration: Head orange, with apex of juga, and outer face of ocelli black; antennal segments I and IV dark orange, and II and III dark orange with apical joint brown; pronotum orange hazel with humeral spines black; scutellum orange hazel, basally with 2 black spots lateral to midline; clavus orange hazel; corium orange hazel with 3 black spots near middle third of endocorium; hemelytral membrane dark brown; connexival segments III to VI glossy orange, VII glossy orange with posterior margin brown; abdominal segments III to VI glossy orange, VII glossy orange with wide brown spot at middle third. Ventral coloration: Orange hazel; rostral segment I reddish brown with apex yellow, II to IV reddish brown; pro-, meso-, and metasternum black; metathoracic peritreme dark yellow; evaporative area black; fore and middle legs with coxae, trochanter, and femora orange hazel, and tibiae orange hazel with 1 or 2 diffuse yellow rings; hind leg with coxa, trochanter, and femur dark brownish orange, and femoral spines brownish black; hind tibia dark orange with 3 diffuse yellow rings; tarsi of each leg with basal half of each tarsus dark yellow and apical half brownish black.

Structure: Body oblong-ovoid, small size, less than 7.00 mm. Head. Wider than long, triangular, porrect, much shorter than pronotal length, non declivent, and clearly projected anteriorly, between bases of antennae; interocular space near the middle third of each eye smooth, without spine or tubercle; tylus unarmed, apically globose, raised, extending anteriorly to and laterally higher than juga and antenniferous tubercles; juga unarmed; antenniferous tubercles unarmed, never contiguous, and the space between them wider than 1 tubercle; antennal segment I uniformly stout, subcylindrical, basally constricted, slightly curved outward, shorter than head; segments II and III robust, cylindrical, and IV thickest, fusiform; antennal segment IV the longest, I the shortest, and II slightly shorter than III, or II subequal to III; eyes prominent, hemispheric; ocelli set on tubercles; buccula rectangular, short, raised, entire, not projected beyond antenniferous tubercles, open posteriorly; rostrum reaching anterior or middle third of metasternum; rostral segment I not extending beyond posterior third of eye. Thorax.-Pronotum, Wider than long, trapeziform, strongly declivent; collar wide; frontal angles obtuse, not exposed; humeral angles projected on large, slender and acute spine, directed outward, and slightly backward; anterior border smooth, weakly curved; anterolateral borders obliquely straight, smooth, not emarginated; posterolateral borders straight, with upper third stout, tuberculate; triangular process broad, laminate; posterior border straight, smooth; calli flat, entire, separated at midline by two deep pits, each lateral to midpoint (Fig. 1.1). Prosternum sunken, with posterior third in front of the area between fore legs produced into narrowed acute, tubercle; mesosternum and metasternum at midline with wide longitudinal furrow; metathoracic peritreme auriculiform; evaporating area poorly developed. Legs. Fore and middle femora slender, unarmed or with tiny tubercles; hind femur extending beyond apex of abdomen, curved, strongly clavate, the basal half very slender, the apical half abruptly incrassate, thickened, dorsally smooth, and ventrally armed with 2 rows of spines and tubercles; fore and middle tibiae unarmed; hind tibia shorter than femur, curved, compressed, with outer margin sulcate, inner margin not expanded, and apically armed with broad medium size spine. Scutellum. Longer than wide, triangular, shorter than clavus, acutely angulate; scutellar disk with high conical tubercle, directed upward, and weakly backward. Hemelytra. Macropterous, extending beyond apex of last abdominal segment; costal margin emarginated, shallowly concave near midpoint; apical margin long, oblique, almost straight; apical angle subacute to truncate. Abdomen. Connexivum scarcely raised above tergum, with posterior angle of each segment entire, not expanded into spine; abdominal spiracle circular, tiny, closer to anterior third of each sterna; abdominal sterna without median furrow. Genital capsule. Posteroventral edge weakly concave at midpoint, with lateral angles rounded. Paramere. Bilobate; outer and inner lobe rounded, and almost same size (Fig. 1.2–3). Integument. Finely and thickly pubescent; clothed with a mat of woolly pubescent hairs; scutellar disk basally with large black glabrous spots; central area of corium with large black glabrous spots, forming an irregular black patch; antennal segments I to IV and legs finely pubescent; pronotal disk smooth, without transversal ridges.

Female: Color and habitus similar to male holotype. Base of clavus and corium black; upper margin of propleura and metapleura with black marks; connexival segments VIII and IX yellow; dorsal abdominal segments III to IX black with odoriferous scars III-IV and IV-V dark orange; genital plates yellowish orange.

Structure: Scutellar disk with high subconical tubercle directed upward. Genitalia. Abdominal sternite VII with plica and fissure; plica rectangular, narrowed; fissure with inner margin overlapping; gonocoxae I subtriangular, enlarged antero-posteriorly; paratergite VIII triangular, small, with spiracle visible; paratergite DC squarish, conspicuously larger than paratergite VIII.

Variation: (1) Ocellar tubercle, apex of tylus, and calli black. (2) Fore and middle tibiae orange hazel with 2 to 4 yellow rings. (3) Corium tinged with yellow. (4) Connexival segments III to V reddish orange, and VI-VII glossy orange with posterior margin brown. (5) Dorsal abdominal segment VII black with posterior margin yellow.

Measurements in mm (n = 1): Male (female). Head length 0.99 (0.80); width across eyes 1.17 (1.10); interocular space 0.60 (0.55): interocellar space 0.31 (0.30); preocular distance 0.55 (0.40). Length of antennal segments: I, 0.62 (0.71); II, 0.63 (0.72); III, 0.65 (0.74); IV, 1.48 (1.58). Pronotum: Total length 1.36 (1.24); width across humeral angles 2.54 (2.23). Scutellar length 0.99 (0.86); width 0.77 (0.68). Total body length 6.83 (5.70).

Etymology: The specific name refers to the conspicuous conical tubercle at scutellar disk.

Discussion: This new species is related to M. (M.) tristis Perty in having the hind femur strongly clavate, swollen distally, with proximal half slender, the interocular space unarmed, the pronotal disk smooth, and the anterolateral borders of pronotum entire. In M. (M.) tumulus the humeral angles are expanded into large and acute spines, directed outward and slightly backward, the upper margin of metapleura without large tubercular expansion and the body size shorter than 7.00 mm, and conspicuously slender. In M. (M.) tristis the humeral angles are almost obtuse with short spines, the upper margin of metapleura with large tubercular expansion, and the body length longer than 8.50 and robust.