Ceratoxenus tricornis Mann, 1923

(Figs. 1A–D, 2A–C, 6A, D)

Ceratoxenus tricornis Mann 1923: 360 (original description);

Xenopelta tricornis; Emerson 1935: 369 Seevers 1957: 107 (redescription as X. tricornis); Jacobson et al. 1986: 64 (redescription as X. tricornis).

Diagnosis: The species is easily recognized by the presence of long bristles on vertex, head lateral projections composed of two long and broad frontal processes in front of each antennal insertion, transpassing the antennal insertions anteriorly; medial process between lateral projection weak and obtuse, gena straight, not carinate; pronotum with anterior impression longer and slightly narrower than posterior, and anterior margin straight.

Head with gena straight; long bristles present on vertex; surface roughly scamose; head lateral projections at frons composed of two long and broad frontal processes in front of each antennal insertion, transpassing the antennal insertions anteriorly; medial process acutely projected, not overtaking the level of frontal elevations; frontoclypeal suture with weak and obtuse medial process, between frontal projections (Figs. 1A–B, 2A, C, 6A). Head surface somewhat scamose. Antenna with antennomere 1 cylindrical, with almost same length of antennomeres 2–4 combined; 2–4 longer than wide, subequal in length; 5–7 shorter than previous, longer than wide, about same length; 8 slightly shorter than previous segments and longer than segments 9–10, subquadrate; 9–10 transverse, subequal. Secondary maxilar palpomere slightly rounded and inflated at apex. Postmentum occupying more than half of total head length, longer than wide, slightly longer than gula, entirely covered by bristles.

Thorax. Pronotal disc light brown with lateral margins darker; anterior impression longer and slightly narrower than posterior, and with anterior margin straight; bearing long bristles marginally; posterior half of pronotal disc with circular impression occupying almost entire pronotal width, with slight circular elevation medially; anterior region slightly elevated behind head, with one row of three bristles; lateral margins parallel with longitudinal row of three long bristles symmetrically distributed (Fig. 1C, 2C). Elytra elongate, wider on posterior region; light-brown, outer margin darker. Legs with pro- and mesocoxa transverse; metacoxa triangular. Tibia slightly longer than femur, covered with long and thick bristles along entire length; outer margins of tibia slightly convex, and inner margin straight; pro-, meso-, and metatarsi increasing in length.

Abdomen. As described to genus.

Material examined. HOLOTYPE. “Kartabo P., Br. Guiana, Aemerson [col.]”; “ Kartabo, Bartica District, British Guiana, 22.VIII.1920 ”; “WMMann [W. M. Mann], cooln, 1940”; “Type No., 64133, U.S.N.M.”; “USNMENT 01374929”. PARATYPE. “Kartabo, British Guiana, 15:X:1920”; “ Coll. By A. Emerson #424”; “FMNHINS 4431876”.

Remarks. Ceratoxenus tricornis is characterized especially by the presence of the two long and narrow frontal horns anterior to and transpassing antennal insertions, presence of vertexal bristles, and a straight and uncarinated gena; pronotal impressions are also distinct, with the anterior half longer and just slightly narrower than posterior, and with anterior margin straight.

Distribution. Guyana —Kartabo.

Biology. The host of C. tricornis recorded in Mann (1923) was Nasutitermes guayanae (Holmgren, 1910), but data in Emerson (1935) leaves little doubt if the host is actually the newly described species, N. similis Emerson, 1935.