Scybalocanthon sexspilotus ( Guérin-Méneville, 1855 )

Silva, Fernando A. B. & Valois, Marcely, 2019, A taxonomic revision of the genus Scybalocanthon Martínez, 1948 (Coleoptera Scarabaeidae: Scarabaeinae: Deltochilini), Zootaxa 4629 (3), pp. 301-341 : 333-335

Scybalocanthon sexspilotus ( Guérin-Méneville, 1855)

( Figs. 1 C-G, 4U, 5T, 6B)

Canthon sexspilotum Guérin-Méneville, 1855: 587 (original description and taxonomic remarks); Blackwelder 1944: 201 (checklist).

Canthon sexspilotus: Harold 1868: 140 (catalog); Bates 1887: 28 (taxonomic remarks); Harold 1869: 992 (catalog); Gillet 1911: 33 (catalog); Schmidt 1922: 65, 80 (diagnosis); Balthasar 1939: 193 (description); Vulcano & Pereira 1964: 630 (catalog); Vulcano & Pereira 1967: 552 (distribution, identification key); Krajcik, 2006: 31 (catalog); Krajcik 2012: 64 (catalog).

Canthon rufulus Harold, 1868: 13 , 54 (identification key and description); Harold 1869: 994 (catalog; synonymized Canthon rufulus with Canthon sexspilotus ).

Scybalocanthon sexpilotus: Halffter & Martínez 1977: 67 (species list); Vaz-de-Mello 2000: 194 (checklist); Ratcliffe et al. 2015: 196 (cited for Peru).

Canthon imitans Harold, 1868: 13 , 56 (identification key and description); Harold 1869: 991 (catalog); Gillet 1911: 30 (catalog); Schmidt 1922: 65, 75 (diagnosis); Balthasar 1939: 193 (redescription); Blackwelder 1944: 199 (checklist); Roze 1955: 41 (checklist); Krajcik 2006: 27 (catalog); Krajcik 2012: 63 (catalog). New subjective synonymy

Scybalocanthon imitans: Pereira & Martínez 1956: 114 , 115 (catalog and identification key); Vulcano & Pereira 1964: 638 (catalog); Halffter & Martínez 1977: 67 (species list); Vaz-de-Mello 2000: 194 (checklist); Ratcliffe et al. 2015: 196 (cited for Peru).

Diagnosis. Specimens of S. sexspilotus are readily distinguishable from all other species by the head, pronotum, femora, and pygidium bicolored, with yellow and black areas ( Figs. 2 C–G). The pronotum may have different spot patterns ( Figs. 2 C–G). In addition, males have an aedeagus with the parameres elongate, subrectangular, not excavated ventrally ( Fig. 4U ); and endophallus lacking bristles or microbristles close to the FLP sclerite ( Fig. 5U ).

Description. Body. Oval-elongate. Color. Body opaque, completely microgranulate. Central portion of head, most of pronotum, lateral portion of hypomera, central portion of metaventrite, abdominal ventrites, margin of pygidium, and middle of femora yellow or light brown. Margin of head, elytra, prosternum, mesoventrite, mesoepisternae, metaepisternae, lateral portion of metaventrite, coxae, trochanters, proximal and distal portions of femora, tibiae, and central portion of pygidium dark brown or black. Length. 8.0–9.0 mm. Thorax. Pronotum with six black spots (five spots at the anterocentral portion and one spot at the posterior portion) ( Fig. 2F ). In some specimens, spots fused in a different way, with irregular shapes ( Figs. 2 C–E). Anterior angles of pronotum with approximately 80°. Lateral margin regularly curved outward, not forming an angle at the middle portion. Elytra. Striae thin, almost inconspicuous. Eighth stria effaced at the basal third, lacking carina at the anterior portion. Aedeagus. Parameres symmetrical, with subrectangular shape ( Fig. 4U ). Dorsal margin of parameres curved inward from the basal to medial portions, apical portion substraight. Ventral margin of parameres substraight. SRP circular, with curved handle-shaped extension ( Fig. 5U ). FLP I-shaped ( Fig. 5U ). A+SA with two superposed and elongate sclerites ( Fig. 5U ). AS I-shaped ( Fig. 5U ).

Type material. Canthon sexspilotum Guérin-Méneville , neotype ♂ (here designated; CEMT): “ BRAZIL / AM- ( Rio Solimões ) / Ilha de Marchantaria / 59°58’W, 3°15’S Várzea/ J. Adis leg. 6.I.1982 ” .

Taxonomic notes for neotype designation. According to the information provided on Methods section, specimens belonging to the type series of Canthon sexspilotum Guérin-Méneville are considered by us to be irretrievably lost ( International Commission on Zoological Nomenclature 1999; Article 75.3.4). Hence, there is an exceptional need to clarify its identity in the context of this taxonomic revision ( International Commission on Zoological Nomenclature 1999; Article 75.3.1). Because no name-bearing type specimen is believed to be extant, and a namebearing type is necessary to fix the name of the species objectively, we herein designate neotype. So, in order to maintain the stability of nomenclature, a specimen from a locality described as the original type locality ( International Commission on Zoological Nomenclature 1999; articles 75.3.3 and 75.3.6) and corresponding to its original description (pronotum with six black spots ( Fig. 1N ); see Guérin-Méneville 1855) was chosen to be the neotype ( International Commission on Zoological Nomenclature 1999; articles 75.3.2 and 75.3.5), and deposited in a recognized scientific institution that maintains a research collection with proper facilities for preserving name-bearing types ( International Commission on Zoological Nomenclature 1999; Article 75.3.7).

Non-type material [ 34 males, 43 females]: BOLIVIA: BENI: San Ramón, Estacíon San Lorenzo , disturbed gallery forest (64°26’6”W, 13°25’36”S), 13.x.2003, pitfall, human feces, 140m, A.C. Hamel & K. Walker— 2♀ ( CEMT) ; PANDO, Riberalta (11°1’S, 66°3’W), xi.1956, Fritz— 1♂ ( CMNC) ; SANTA CRUZ, CIMCA [= Centro Integral de Manejo del Comportamiento Animal?], Gral Agustín Saavedra (17°13’30’’S, 63°12’30’’W), 5.x.1984, L. Valaz— 1♂ ( CMNC); Hotel Flora y Fauna , 5 km SSE Buena Vista, 440 m (17°29.925’S, 63°39.128’W), 15- 24.xii.2003, S. & J. Peck, forest, flight interception trap (2003-131)— 1♀ ( CMNC); Provincia Ñuflo de Chaves , As- censión, xii.1953, Andrae— 1♀ ( CMNC); Provincia Ñuflo de Chaves , Ascensión, xii.1963, Andrae— 1♀ ( CMNC); Jardín Botanico Andrés Ibañez, 17–30.ix.2006, T. Vidaurre, M. Amaya, & G. Mollos— 3♂ 4♀ ( CEMT) . BRAZIL: AMAZONAS: Ilha de Marchantaria, Rio Solimões, Várzea (59°58’W, 3°15’S), 20.x.1981, J. Adis— 1♂ ( CEMT); Ega [=Tefé] (3°22’S, 64°42’W), [no date], [anonymous]— 1♂ ( CMNC); PARÁ: Colônia Rio Branco , Obidos , 2– 12.xi.1952, P.A. Telles— 1♂ ( CMNC); Mocajuba , Mangabeira (2°36’30’’S, 49°37’0’’W), xii.1952, O. Rego— 1♀ ( CMNC); Abaetetuba , 4–25.vii.1994, N. Degallier— 3♂ 7♀ ( CEMT) ; RONDÔNIA: São Francisco do Guaporé, Rebio Guaporé (63°26’W, 12°31’S), 2.x.2013, S.E. Silva— 2♀ ( CEMT) . RORAIMA: Amajari, Ilha de Maracá (61°36’424”W, 3°31’829”N), Amazon rainforest, pitfall, human feces, 10.v.2009, R. Andrade— 2♂ 1♀ ( CEMT) . COLOMBIA: META: Mozambique, Franja de bosque de galeria, iv.1996, pitfall, human feces, 190 m, J.A. Noriega— 2♂ ( CEMT); AMAZONAS, Isla Santa Sofia , Leticia (4°2’41’’S, 70°6’5’’W), 23.ii–2.iii.1974, J. Peck— 13♂ 16♀ ( CMNC, MZUFPA); Leticia , 215 m (4°11’20’’S, 69°56’9’’W), 23.ii–2.iii.1974, [anonymous]— 1♂ 2♀ ( CMNC) . VENEZUELA: APURE: San Fernando (67°28’23’’W, 7°53’38’’N), 26.viii.2006, curso NM 2006— 1♂ 1♀ ( CEMT) . BARINAS, Santa Bárbara (7°48’30’’N, 71°10’30’’W), x.1972, Solano— 2♀ ( CMNC) . TACHIRA: Isla de Betancurt, 29.v.1986, D. Havranek— 1♀ ( CEMT) . PERU: near Ramón Castilla, 24.ii.1972, H. & A. How-den— 3♂ 1♀ ( CMNC); near Ramón Castilla , 26.ii.1974, H. & A. Howden— 1♂ 1♀ ( CMNC) .

Distribution. Known from Bolivia, Brazil (Amazonas, Pará, Roraima, Rondônia), Colombia, Venezuela, and Peru ( Fig. 6B ). Endemism areas: Brazilian sub-region: Pacific dominion: Sabana province; Boreal Brazilian dominion: Imerí, Pantepui, and Pará provinces; South Brazilian dominion: Rondônia province (see Morrone 2014; fig. 12). As far as we know, S. sexspilotus is the most widely distributed species of the genus. From available data, this species inhabits lowlands, gallery forests, and floodplains.

Remarks. Specimens of S. sexspilotus from the same locality may have different spot patterns on the pronotum. The spot patterns may vary gradually from a broadly distributed black spot to only a small and restricted spot at the central portion of the anterior and posterior margins ( Figs. 2 C–G).

The holotypes of Canthon imitans Harold, 1868 and Canthon rufulus Harold, 1868 were not found by us (see Methods section). However, the possible collections in which these specimens could be found have not yet been exhaustively examined. Thus, we have decided not to designate neotypes for these nominal species at this time. According to the original description, Canthon imitans can be characterized by the type locality ( Venezuela) and its yellow pygidium with a black central spot ( Fig. 3C ) ( Harold 1868). As specimens of S. sexspilotus are diagnosed by having a black spot on the pygidium, we are confident to establish this new synonymy. The original description is not sufficient to establish the identity of Canthon rufulus . Thus, this situation is a typical example of a “species inquirenda”. However, because the nominal species was synonymized with Canthon sexspilotum Guérin-Méneville, 1855 by its own author ( Harold 1869), we prefer to maintain here the synonymy previously proposed in order to maintain the stability of the nomenclature.

Figures

FIGURE 1. Species of Scybalocanthon, dorsal habitus. A, Scybalocanthon acrianus new species; B, S. adisi new species; C, S. aereus; D, S. arnaudi new species; E, S. batesi; F, S. chamorroi new species; G, S. cyanocephalus; H, S. darlingtoni; I, S. federicoescobari new species; J, S. haroldi new species; K, S. kaestneri; L, S. kelleri; M, S. korasakiae; N–O, S. maculatus; P, S. martinezi new species; Q–R; S. moniliatus; S. S. nigriceps; T. S. papaxibe new species. Scale bar: 2 mm.

FIGURE 2. Species of Scybalocanthon, dorsal habitus. A, Scybalocanthon pinopterus; B, S. pygidialis; C–G, S. sexpilotus; H–J, S. trimaculatus; K, S. uniplagiatus. Scale bar: 2 mm.

FIGURE 3. Details of the external morphology in Scybalocanthon. A, Elytral surface in S. chamorroi new species; B, elytral surface in S. acrianus new species; C, pygidium in S. sexpilotus; D, detail of the eighth elytral stria in S. pygidialis (carina point- ed); E, mesofemur in S. kaestneri; F, mesofemur in S. nigriceps; G, mesotarsus in S. moniliatus; H, metatarsus in S. moniliatus; I, mesotibia in S. aereus; J, mesotibia of Canthon arcabuquensis.

FIGURE 4. Aedeagus, detail of parameres in left and right view. A, Scybalocanthon acrianus new species; B, S. adisi new species; C, S. aereus; D, S. aereus (lectotype); E, S. arnaudi new species; F, S. chamorroi new species; G, S. cyanocephalus; H, S. darlingtoni; I, S. federicoescobari new species; J, S. haroldi new species; K, S. kaestneri; L, S. kelleri; M, S. korasakiae; N, S. maculatus; O, S. martinezi new species; P, S. moniliatus; Q, S. nigriceps; R, S. papaxibe new species; S, S. pinopterus; T, S. pygidialis; U, S. sexspilotus; V, S. trimaculatus; W, S. uniplagiatus. Scale bar: 0.5 mm.

FIGURE 5. Sclerites of endophallus. Superior right peripheral (SRP) sclerite. Fronto-lateral peripheral (FLP) sclerite. Complex of axial and subaxial (A+SA) sclerites.Additional sclerite (AS). Set of microbristles (Smb). Set of bristles (Sb). A, Scybalocanthon acrianus new species; B, S. adisi new species; C, S. aereus; D, S. arnaudi new species; E, S. chamorroi new species; F, S. cyanocephalus; G, S. darlingtoni; H, S. federicoescobari new species; I, S. haroldi new species; J. S. kaestneri; K, S. kelleri; L, S. korasakiae; M, S. maculatus; N, S. martinezi new species; O, S. moniliatus; P, S. nigriceps; Q, S. papaxibe new species; R, S. pinopterus; S, S. pygidialis (specimen from Amazonas, Brazil); T, S. pygidialis (specimen from Cayenne, French Guiana); U, S. sexspilotus; V, S. trimaculatus; W, S. uniplagiatus. Scale bar: 0.5 mm.

FIGURE 6. Known distribution of species of Scybalocanthon.