Trichaptus Pascoe 1880

Lanteri, Analia A. & Del Río, M. Guadalupe, 2005, Taxonomy of the Monotypic Genus Trichaptus Pascoe (Coleoptera: Curculionidae: Entiminae), a Potential Weevil Mimic of Mutillidae, The Coleopterists Bulletin 59 (1), pp. 47-54 : 48-51

Trichaptus Pascoe 1880

Trichaptus Pascoe 1880: 422 . Type species: Rhigus myrmosarius Perty 1832: 71 (by indication, monotypy).

Diagnosis. Species large (about 20 mm long). Integument mostly covered by very long, erect, dark setae, interrupted by elytral maculae of pale yellowish and reddish scales, imitating the color pattern of Mutillidae (Hymenoptera) . Rostrum robust, separated from epistome by a transversal callosity. Antennal scrobe bent downward at almost right angle. Antennae black, short, robust. Prementum subhexagonal, with few fine setae on external surface. Eyes strongly convex, with triangular preocular depression. Pronotum subcylindrical, humped. Humeri strongly prominent. Corbel plate enclosed, setose; tarsomere 2 transverse. Spermatheca globose, with short nodulus and slightly prominent ramus. Aedeagus with acute apex, and piriform sclerotized endophallic structure.

Redescription. Species large (female 17–20 mm long, 10–11 mm wide; male 15–17 mm long, 8 mm wide). Integument black. Vestiture ( Fig. 1): Dorsal surface mostly covered by very long, fine, erect, black setae, interrupted by elytral pale yellowish and reddish maculae, imitating the color pattern of Mutillidae (Hymenoptera) ; venter and legs covered by long, pale yellowish setae. Rostrum ( Figs. 2–3): Stout, about as long as wide at apex, sides slightly convergent towards apex, thickened; dorsum depressed; median groove wide, exceeding hind margin of eyes; scrobes curved downward at almost right angle, apical end slightly visible from above; epistome depressed, covered with small sparse scales, separated from rostrum by a transverse callosity. Frons depressed, vertex flat. Eyes strongly convex; preocular triangular depression present, postocular constriction distinct. Mouthparts ( Figs. 4–6): Prementum subhexagonal, external surface ( Fig. 4) slightly concave on posterior half, slightly convex on center, depressed and having about five fine setae on lateral sides of anterior half; internal surface ( Fig. 5) with strong central keel flanked by lateral depressions; palpi almost perpendicular regarding prementum. Maxillae ( Fig. 6) with suboval mala, parallel to longitudinal axis of palpus; palpifer and all articles of palpus subcylindrical. Antennae ( Fig. 7): Robust, short, black, covered by fine, dark setae; scape not reaching hind margin of eye; funicular article 2 about 1.5 3 as long as article 1, articles 3 to 6 subglobose, article 7 truncate conical, wider than long; club ovoid, about 2–3 3 as long as wide. Pronotum: Subcylindrical, slightly wider than long, strongly convex on dorsum, especially towards anterior third (humped) and constricted near base; disc rugose; apical margin slightly curved anteriorly, basal margin slightly bisinuate. Scutellum: Small, covered with yellowish setae. Elytra: Broad, widest at humeri, about 1.4 3 as long as wide on middle; base bisinuate, humeri strongly prominent, slightly constricted behind; disc convex; subapical callus distinct; apex slightly bifid; 10 punctuate striae present, punctures broad, intervals rugose, slightly convex. Metathoracic wings present. Legs: Fore coxae contiguous, slightly closer to anterior margin of pronotum than to posterior margin; fore tibiae strongly curved inwards near apex, with row of 10 small denticles on inner face, lacking mucro; middle and hind tibiae lacking denticles and mucro; corbel plate of hind tibiae enclosed, broad, setose; apical comb about twice as long as dorsal comb; tarsomere 1 about as long as wide, tarsomere 2 transverse. Mesepimera large and triangular. Abdomen ( Fig. 8): Intercoxal portion of abdomen slightly narrower than hind coxae; suture between ventrites 1 and 2 acute on middle; ventrite 5 with pair of lateral depressions, about as long as 3 þ 4 along middle. Female genitalia: Sternite VIII ( Fig. 9) subrhomboidal, with strong Vshaped sclerotization near base, covered with moderately long setae on apical half; apodeme about 3 3 as long as plate. Ovipositor ( Fig. 10) about 0.85 3 as long as abdomen; baculi subparallel; hemisternites slightly sclerotized; styli directed dorsally, slightly visible from ventral view. Spermatheca ( Fig. 11) usually globose, occasionally small and slender ( Fig. 12), with conical, short nodulus, slightly prominent ramus and short cornu; spermathecal duct membranous, thin, about as long as spermathecal gland. Male genitalia: Tergite VIII, sternites VIII–IX and spiculum gastrale as in Fig. 13. Aedeagus ( Figs. 14–15) about 1.3 3 as long as apodemes, with acute apex and large ostium, strongly curved laterally; endophallus folded and with surface studded with short, pointed tubercles near middle; endophallic structure consisting of a central piriform piece with portion of spermoduct close to it, strongly sclerotized ( Fig. 15).

Sexual Dimorphism. Males more slender and smaller than females, with elytra more acute towards apex, and tarsi bigger and strongly transverse.

Distribution. Trichaptus is endemic to Brazil, where it was found in tropical and subtropical forests of Espíritu Santo and Minas Gerais states. This area corresponds to the Neotropical Region, Amazonian domain, Atlantic and Cerrado provinces, according to the biogeograpic scheme of Cabrera and Willink (1980). Nothing is known about host plant associations.

Remarks. Pascoe (1880) provided a short diagnosis of Trichaptus designating R. myrmosarius as type species. Since then the genus has been included in various keys ( Marshall 1922; Emden 1936, 1944; Hustache 1947), but it has never been described in detail. In those keys, Trichaptus keys close to Lamprocyphus Marshall (junior synonym of Briarius [Fischer de Waldheim], according to Alonso-Zarazaga and Lyal (1999), recently revised by Lanteri and del Río (2003). In fact, characters of the antennae, eyes, mouthparts (prementum and maxillae), legs (denticles of tibiae, corbel plates, proportion of tarsites) and female and male genitalia show that these genera are probably closely related. For example, the subcylindrical article 3 of the maxillary palpus and the mala parallel to this palpus, are probably apomorphic features only present in Trichaptus , Briarius and Thoracocyphus Emden. In most Naupactini the mala is almost transverse in relation to the palpus, and the article 3 of this palpus is subconical instead of subcylindrical ( Díaz et al. 1990; Lanteri and del Río 2003). Characters of the male and female genitalia are also similar in Trichaptus and Briarius , the main differences relating to the shape of the endophallic piece of the aedeagus.

The most remarkable differences between Briarius and Trichaptus are manifested in the body vestiture, the shape of the rostrum (including epistome and scrobes), and the pronotum. In Briarius the vestiture is mostly composed of oval to lanceolate scales, usually iridescent, and very short, recumbent setae; the rostrum lacks the transverse callosity separating the epistome; the antennal scrobes are not strongly curved downward; and the pronotum is usually truncate conical and depressed on the disc instead of humped.