Pseudocanthon Bates, 1887

Nazaré-Silva, Everton E. & Silva, Fernando A. B., 2021, A taxonomic revision of the South American species of Pseudocanthon Bates, 1887 (Coleoptera: Scarabaeidae: Scarabaeinae: Deltochilini), Zootaxa 5027 (1), pp. 61-86 : 64-65

Pseudocanthon Bates, 1887

Pseudocanthon Bates, 1887: 35 (original description); Bates 1889: 386 (redescription); Gillet 1911: 27 (as junior synonym of Canthon ); Lucas 1920: 548 (catalogue); Islas 1942: 333 (cited as a synonym of Canthon ); Blackwelder 1944: 198 (as junior synonym of Canthon ; checklist); Martínez 1947: 263–264 (taxonomic remarks); Pereira & Martínez 1956: 95, 109, 184 (catalogue, distribution, and identification key); Martínez 1959: 57–58 (catalogue, distribution, and taxonomic remarks); Halffter 1961: 231–233 (identification key and taxonomic remarks); Vulcano & Pereira 1964: 591 (catalogue); Halffter & Matthews 1966: 261 (checklist and distribution); Matthews 1966: 83–85 (catalogue, description, distribution, and taxonomic remarks); Vulcano & Pereira 1967: 551 (identification key); Halffter & Martínez 1977: 35, 45, 60, 62 (checklist, identification key, and taxonomic remarks); Howden & Young 1981: 35 (diagnosis); Halffter & Edmonds 1982: 139 (checklist and distribution); Medina & Lopera-Toro 2000: 301, 311 (checklist and identification key); Vazde-Mello 2000: 194 (checklist); Ratcliffe 2002: 13 (checklist); Medina et al. 2003: 41 (remarks about the diagnosis of Pseudocanthon ); Medina & Pulido 2009: 56, 59 (checklist); Smith 2009: 40 (checklist); Vaz-de-Mello et al. 2011: 6, 11, 18, 26, 33, 41, 45, fig. 149 (identification key); Carvajal et al. 2011: 99, 119, 314 (checklist, description, and distribution); Solís & Kohlmann 2012: 2, 4 (checklist); Boilly & Vaz-de-Mello 2013: 107 (identification key); Tarasov & Dimitrov 2016: 15 (new concept for Deltochilini); Tissiani et al. 2017: 414 (identification key); Cupello & Vaz-de-Mello 2018: 12, 13, 17, 18, 20, 32, 35, 36, 37, 39, 173 (taxonomic remarks); Chamorro et al. 2018: 76 (identification key); Schoolmeesters 2020 (catalogue); Vaz-de-Mello 2020 (checklist).

Canthon (Pseudocanthon) : Krajcik 2006: 25 (checklist); Krajcik 2012: 63 (checklist).

Opiocanthon Paulian, 1947: 29–30 (distribution, identification key, original description, and taxonomic remarks); Matthews 1966: 85 (subjective synonymy of Opiocanthon with Pseudocanthon ); Ratcliffe 2002: 13 (cited as a synonym of Pseudocanthon ); Smith 2009: 40 (cited as a synonym of Pseudocanthon ); Solís & Kohlmann 2012: 4 (cited as a synonym of Pseudocanthon ); Peck et al. 2014: 43 (cited as a synonym of Pseudocanthon ); Cupello & Vaz-de-Mello 2018: 18 (cited as a synonym of Pseudocanthon ).

Type species. Pseudocanthon : Canthon perplexus LeConte, 1847 by monotypy. Opiocanthon : Canthon vitraci Fleutiaux & Sallé, 1889 , by original designation.

Diagnosis. Within Deltochilini (sensu Tarasov & Dimitrov 2016), Pseudocanthon is diagnosed by the following combination of characters. Small body (3–6 mm), elongate and flat dorsoventrally. Clypeus quadridentate, with medial teeth larger than lateral teeth. Base of clypeal teeth covered by a single row of short setae extending almost to paraocular area (gena). Lateral edges of pronotum nearly straight and subparalell ( Fig. 1B ). Elytra surface with minute setae ( Fig. 1D ). Anterior portion of hypomera strongly excavate, posteriorly delimited by a transversal carina ( Fig. 1E ). Tarsal claws angulate at base.

Taxonomic remarks. Pseudocanthon can be easily confused with Sylvicanthon in Deltochilini (sensu Tarasov & Dimitrov 2016). These taxa share the hypomera anteriorly excavated and divided by a transversal carina ( Fig. 1E ), and tarsal claws angulated basally. However, Pseudocanthon can be easily distinguished from Sylvicanthon by the elongate general shape of the body; clypeus with four acute teeth, covered basally by a single row of short setae almost reaching the gena; lateral edges of pronotum nearly straight and subparallel ( Fig. 1B ); and elytra surface coated with minute setae ( Fig. 1D ). On the other hand, specimens of Sylvicanthon have an oval body; two or four clypeal teeth, with a row of setae limited to the base of the teeth; lateral edges of pronotum angulate at medial portion ( Fig. 1A ); and smooth elytral surface ( Fig. 1C ).

Redescription. Body black or brown with metallic reflections. Orange or red spots on different parts of the body, varying between species. Orange or black legs. Length. 3–6 mm. Head. Surface with well-impressed and dense granulation. Foveolate punctures spaced by approximately once to twice their diameter. Clypeus with four acute teeth. Medial teeth larger than lateral teeth. Base of clypeal teeth covered by a single row of short setae extending almost to paraocular area. Edge between clypeogenal suture and clypeal teeth substraight. Edge of paraocular area curved outward, with rudimentary tooth after junction with the clypeus. Interocular width approximately five times width of eye in dorsal view. Thorax. Surface of pronotum granulate ( Fig. 2A ), or with inconspicuous granulation ( Fig. 2B ). Lateral edges and anterior angle of pronotum with imbricate microsculpture. Foveolate punctures of pronotum spaced by approximately two to three times their diameter. Anterior angles acute, directed forward. Posterior edge of pronotum without margin. Hypomera divided into two parts by a transversal carina ( Fig. 1E ). Anterior portion of hypomera excavate ( Fig. 1E ), with imbricate microsculpture, and setae near to transversal carina. Integument punctation of prosternum inconspicuous, only visible at high magnification. Posterior edge with row of setae. Mesoventrite with dense and well-impressed granulation. Mesoventrite approximately five to eight times wider than long. Meso-metaventral suture straight or lightly arched. Metaventrite with granulate microsculpture conspicuous at anterior and posterior portions; visible only in some species at central portion. Imbricate microsculpture at anterior portion and lateral edges. Foveolate punctures of metaventrite spaced by approximately once or twice their diameter at anterior and posterior portions; lateral edges with eliptical foveolate punctures almost confluent. Mesepimeron and metanepisternum with imbricate microsculpture. Elytra. Surface with dense and well-impressed granulation. Interstriae with setigerous foveolate punctures spaced by approximately two to three times their diameter. Lateral edge arched. Striae well impressed ( Fig. 1D ). Fifth stria closer to sixth than to fourth stria. Seventh stria discontinuous at base. Eighth stria absent ( Fig. 2C ) or reduced to basal fourth of elytra, or extending to approximately the anterior half of elytra ( Fig. 2D ). Epipleuron with imbricate microsculpture. Abdomen. Pygidium rounded apically ( Fig. 2G–H ). Base with small tubercle at central portion. Pygidium and propygidium not separated by carina. Surface of pygidium densely granulate and well impressed; foveolate punctures spaced by approximately five times their diameter. Surface of ventrites with dense and well-impressed granulation; foveolate punctures shallow. Legs. Tibiae and femora with granulate microsculpture and foveolate punctures. Protibia with three lateral teeth, and two longitudinal carinae with row of setae in dorsal and ventral views. Margin of metafemur discontinuous at anterior edge. Mesotibiae and metatibiae smoothly arched. Mesotarsomeres and metatarsomeres 1–4 subtriangular, the apical subrectangular. Tarsal claws angulate basally. Secondary sexual characters. Males with protibial spur bifid at apex; females with spiniform spur. Furthermore, females have the sixth abdominal ventrite evenly wide while in males this ventrite is narrower at the middle. Tegmen. Parameres symmetrical, curved at apex, with spiniform projection, or truncate ( Fig. 5A–F ). Endophallus. Lacking lamella copulatrix (LC). Superior right peripheral (SRP) endophallite circular shaped, with expanded handle at distal part ( Fig. 6E–F ). Frontolateral peripheral (FLP) endophallite elongate and sinuous ( Fig. 6E–F ). Complex of axial and subaxial (A+SA) endophallites elongate and irregular ( Fig. 6E–F ). Some species have a small and I-shaped accessory endophallite (AE) near the anterior portion of A+SA ( Fig. 6A, D–F ).

Figures

FIGURE 1. Details of the external morphology in species of Deltochilini. A, Sylvicanthon candezei (Harold, 1869) pronotum (arrows indicate angle at lateral edge); B, Pseudocanthon chaquensis new species pronotum (arrows indicate angle at lateral edge); C, S. candezei (Harold, 1869) left elytron; D, P. chaquensis new species left elytron; E, P. xanthurus (Blanchard, 1847) hypomera (transversal carina pointed). Scale bar: 1 mm (1A, C); 0.5 mm (1B, D–E).

FIGURE 2. Details of the external morphology in species of Pseudocanthon Bates, 1887. A, P. vazdemelloi new species pronotal disc; B, P. xanthurus (Blanchard, 1847) pronotal disc; C, P. vazdemelloi new species detail of left lateral of elytron; D, P. pantanensis new species detail of left lateral of elytron (arrow indicates eighth elytral stria present); E, P. perplexus (LeConte, 1847) protibia in dorsal view (arrow indicates median emargination); F, P. xanthurus (Blanchard, 1847) protibia in dorsal view; G. P. pantanensis new species pygidium; H, P. chaquensis new species pygidium. Scale bar: 0.5 mm (2A–D); 0.2 mm (2E–H).

FIGURE 5. Aedeagus in South American species of Pseudocanthon Bates, 1887, lateral and ventral views, respectively. A, Pseudocanthon perplexus (LeConte, 1847); B–C, P. xanthurus (Blanchard, 1847) (arrows indicate variation at apex of parameres); D. P. vazdemelloi new species; E, P. pantanensis new species; F, P. chaquensis new species. Scale bar: 0.5 mm.

FIGURE 6. Endophallites in South American species of Pseudocanthon Bates, 1887. A, Pseudocanthon perplexus (LeConte, 1847); B–C, P. xanthurus (Blanchard, 1847); D, P. vazdemelloi new species; E, P. pantanensis new species; F, P. chaquensis new species. Accessory endophallite (AE). Complex of axial and subaxial (A+SA) endophallite. Frontolateral peripheral (FLP) endophallite. Superior right peripheral (SRP) endophallite. Scale bar: 0.2 mm.