Trichaptus mutillarius (Perty 1832)

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 : 51-53

Trichaptus mutillarius (Perty 1832)

( Figs. 1–15)

Rhigus mutillarius Perty 1832: 70 ; Dalla Torre et al. 1936: 10 ( Trichaptus ) (catalog); Blackwelder 1947: 792 (checklist); Wibmer and O’Brien 1986: 47 (checklist).

Rhigus myrmosarius Perty 1832: 71 ; Pascoe 1880: 420 ( Trichaptus ); Dalla Torre et al. 1936: 10 (as syn. of R. mutillarius and C. linnei ).

Cyphus linnei Boheman 1833: 629 ; Pascoe 1880: 422 (as syn. of R. myrmosarius ).

Cyphus linnaei (error); Schoenherr 1840: 153 (as syn. of R. myrmosarius ).

Diagnosis. Species large, robust (female 17–20 mm long, male 15–17 mm long). Color ( Fig. 1): Dorsum of head, pronotum, elytra and antennae black, except narrow areas near the base of pronotum and around scutellum and sixteen yellowish and reddish elytral maculae. One pair of round, large, reddish maculae on sides of anterior half, from intervals 4 to 8; 4 pairs of yellowish maculae distributed along midline from base to apex, close to suture, from intervals 1 to 3 or 1 to 4; 3 pairs of yellowish maculae on sides of elytra, the former on humeri and the other two behind the reddish maculae, from intervals 5 to 9 or 6 to 9. Vestiture: Black areas covered with long, fine, erect, setae; reddish maculae covered with lanceolate imbricate scales and lacking setae; yellowish maculae with vestiture of elongate, partially overlapped scales and long, erect setae; vestiture of venter similar to that of yellowish maculae, but with more sparse scales; legs covered with long, erect, yellowish setae. Other morphological features of females and males as those described for the genus ( Figs. 2–15).

Note on Synonymy. Perty (1832) gave a short description of Rhigus myrmosarius and R. mutillarius , based on different specimens from Minas Gerais, Brazil. In those descriptions the former is larger than the latter and has slight differences in color pattern. We suspect that they would correspond to the female and male of the species.

Boheman (1833) described Cyphus linnei indicating that it was a synonym of Trichaptus mutillarius Germar in litteris, but ignoring that this species had been already described by Perty (1832). Schoenherr (1840) also referred to these species but using the name C. linnaei (error).

Pascoe (1880) described Trichaptus , designating R. myrmosarius as type species (pag. 420) and indicating that it is a synonym of C. linnei (pag. 422). The synonymy of the three species mentioned above was established in the catalog by Dalla Torre et al. (1936), and has been reiterated in subsequent checklists.

Type Material Studied. Two females and one male from Brazil, with type labels Rhigus mutillarius , of the type collection of the Naturhistoriska Riksmuseet (Box 176). The colors of the vestiture are better preserved in the male than in the females. We interpret that all these specimens are syntypes of the series studied by Boheman (1833) and Schoenherr (1840). On the other hand, in the Schoenherr collection of the Naturhistoriska Riksmuseet (Box 14), there is one female from Brazil, with label of paratype. We are not sure if this is a true type, since in the original descriptions by Perty (1832) and Boheman (1833) there is not information on the designation of the holotype and paratypes. The type material studied by Perty (1832) should be at the Museum of Munich ( Kuschel 1955) but we have not examined it.

Other Material Examined. BRAZIL. No loc. (15 $$ 5 ## BMNH, 1 $ CWOB, 2 $$ MCZH, 2 $$ MZSP, 4 $$ 1 # USNM, 1 $ 1 # NHRS). Espǐritu Santo: Río Bonito , 600 m (1 $ DZUP) . Minas Gerais: Aimorés , 4-XII-1970, C. Elías leg. (1 $ DZUP) ; Río Matipoó , II- 1910 (1 $ MZSP) .

Note on Potential Mimicry. Even though there is not any previous reference on the potential mimicry of Trichaptus mutillarius and the wasps of the family Mutillidae , it is obvious that the author of the species had realized the resemblance between both taxa, since the etymology of the weevil species refers to the Aculeate Hymenoptera . Mutillidae is a cosmopolitan family of wasps with about 8,000 species distributed in dry savannas, semi-deserts and lowlands rainforests, mainly in tropical areas ( Brothers 1975, 1995). They behave as ectoparasitoids of resting terrestrial immatures of other insects, especially bees and wasps (e.g. sphecids and eumenine vespids), being distasteful or poisonous organisms that produce very painful stings.

The similarity between the suggestive protected model and the mimic is evident in the body size, general morphology, and vestiture, composed of dense pilosity of various colors, especially black, red, yellowish and white, forming a distinct pattern of maculae. The Mutillidae are wasps with short petiole, and Trichaptus is one of the few Naupactini with humped, constricted near base prothorax, which gives the appearance of a petiole. The best candidate models of T. mutillarius belong to the Sphaeropthalminae , a subfamily characterized by the round, convex eyes, which is a feature also present in the weevil. Within the Sphaeropthalminae the species that best resemble Trichaptus belong to Traumatomutilla André (parasites of Sphecidae ) and Hoplomutilla Ashmead (parasites of bees), two genera highly diversified in South America and occurring throughout the range of the weevil.

We also suspect a potential resemblance in the pre-ovipositional behavior of weevil and wasps, since the apterous females of Mutillidae used to search the soil or rotting logs for host nests or cocoons, to oviposit directly into the cell or cocoon of the host ( Brothers 1995), whereas most females of Naupactini oviposit in hide niches in the soil, near the base of trunks and stems of its host plants, or between dead or fallen leaves ( Lanteri et al. 2002). During this period, potential predators such as birds, would avoid the mimic species when it is mistaken for the inedible model. Their aposematic coloration would warn these predators.

Batesian mimicry in beetles is probably much more common than the scattered literature might suggest, especially in tropical areas ( Hespenheide 1995). Field work and a phylogenetic approach will be necessary to understand the biological association between weevils, wasps and predators in the rainforests of the Neotropics, and to explain the evolution of these complex adaptive systems.