Griburius posticatus
Creators: name: Sassi, Davide
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Griburius
Griburius posticatus

description: Griburius posticatus (Suffrian, 1866)
(Figs 1a; 4; 5; 11d; 12c)
Scolochrus posticatus Suffrian, 1866: 101; Clavareau, 1913: 91 [Griburius] (catalogue); Blackwelder, 1946: 640 [Griburius] (catalogue).
= Scolochrus distigma Suffrian, 1866: 104; Clavareau, 1913: 89 [Griburius] (catalogue); Blackwelder, 1946: 639 [Griburius] (catalogue). Syn. nov.
= Scolochrus rufomarginatus Suffrian, 1866: 150; Clavareau, 1913: 91 [Griburius] (catalogue); Blackwelder, 1946: 640 [Griburius] (catalogue). Syn. nov.
Types. Suffrian (1866) did not mention the number of the specimens available for the description of Griburius posticatus, but he reported he was able to examine both male and female specimens of the species. Fifteen syntypes were traced down in NMV (2), in SDEI (1), in BMNH (5), in MNHUB (6). The typification was made as follows, in order to stabilize the epithet. LECTOTYPE (by present designation): (SDEI) ♂, glued, median lobe of aedeagus and abdomen glued on a separate card // “ Scolochrus rufulus Heydn posticatus Mus. Petr. Suffr. Vid Paraguay. Vogt.” [white label, handwritten] // “Coll. v. Heyden” [white label, printed] // “ Griburius posticatus (Suffrian, 1866) (Scolochrus posticatus) LECTOTYPUS D. Sassi des.” [red label, printed]. PARALECTOTYPES (14) were designated as follows. (NMV) 1♂, 1♀, pinned // “Ypanema Brasilien Natterer” [White label, printed] //; (MNHUB) 5♂, 1♀, pinned // “24023” [white label, printed] // “ Scolochrus posticatus Suffr. * Brasil. v. Olf.” [blue label, handwritten] // [only one of them actually labelled, but they all certainly belong to the type series]; (BMNH) 1♂, pinned // “Minas Geraes” [White label, handwritten] // “a D. Suffrian determinat” [White label, printed] // “67-56” [White label, printed] // “TYPE” [White label, printed] // “49” [Blue label, handwritten] // “posticatus ” [Blue label, handwritten] // “ SYNTYPE ” [White-blue label, printed] //; (BMNH) 1♂, pinned // “ Bolivia v. d’Orbigny” [White label, handwritten] // “E. Coll. Chev. t ” [White label, printed] // “67-56” [White label, printed] // “type” [White label, printed] // “203” [Blue label, handwritten] // “posticatus ” [Blue label, handwritten] // “ SYNTYPE ” [White-blue label, printed] //; (BMNH) 1♂, pinned // “ Scolochrus posticatus Suffr Brazil ” [White label, handwritten] // “Type Suffr. Coll. Baly” [White label, handwritten] // “Baly Coll.” [White label, printed] // “ SYNTYPE ” [White-blue label, printed] //; (BMNH) 1♂, pinned // “ Scolochrus posticatus Suff Bresil ” [Green label, handwritten] // “Type Suffr. Coll. Baly” [White label, handwritten] // “Baly Coll.” [White label, printed] // “ SYNTYPE ” [White-blue label, printed] //; (BMNH) 1♂, pinned // “54 2” [White label, handwritten] // “95” [White label, handwritten] // “Type Suffr. Coll. Baly” [White label, handwritten] // “Baly Coll.” [White label, printed] // “ SYNTYPE ” [White-blue label, printed] //.
The label information and the number of syntypes for the MNHUB paralectotypes matches the registration data from the old catalogue of the MNHUB (“24023. posticatus Suffr. *. 6. – [Brasil], Sèllo”. All paralectotypes were labelled: // “ Griburius posticatus (Suffrian, 1866) (Scolochrus posticatus) PARALECTOTYPUS D. Sassi des.” [red label, printed] //.
As regard Griburius distigma, Suffrian (1866) did not mention the number of the specimens available for the description, but he writes that only males were available. Besides, he suggests that the species he was about to describe might be a simple form of the highly variable G. posticatus, stressing that he was using the new name only provisionally, awaiting further available data. One syntype was traced down in BMNH, three in MNHUB, three in NMV. The typification was made as follows, in order to stabilize the epithet. The lectotype was chosen in BMNH because the locality is more precise and matches what reported in the original description. LECTOTYPE (by present designation): (BMNH) ♂, pinned // “Pern[ambuco]” [white label, handwritten] // “ Scol. distigma Suffr. ” [white label, handwritten] // “67-56” [white label, printed] // “type [white label, printed] // “ Griburius distigma (Suffrian, 1866) (Scolochrus distigma) LECTOTYPUS D. Sassi des.” [red label, printed] // “ Griburius posticatus Suffr. D. Sassi det. 2023” [white label, printed] //. PARALECTOTYPES: (NMV) 3♂, pinned // “Helm 953” [White label, handwritten] // “Alte Sammlg. Brasilien.” [White label, printed] //; (MNHUB) 3♂, pinned // “24025 distigma Suffr. * Brasil. V. Olf.” [white label, printed] // [only one of them actually labelled, but they all certainly belong to the type series] //. The label information and the number of syntypes for the MNHUB paralectotypes matches the registration data from the old catalogue of the MNHUB (“24025. distigma Suffr. *. 3. Brasil, v. Olf.”. All paralectotypes were labelled: // “ Griburius distigma (Suffrian, 1866) (Scolochrus distigma) PARALECTOTYPUS D. Sassi des.” [red label, printed] // “ Griburius posticatus Suffr. D. Sassi det. 2023” [white label, printed] //.
Regarding Griburius rufomarginatus, again, Suffrian (1866) did not mention the number of the specimens available for the description, but he reported that several specimens were examined from Amazon River to Rio de la Plata, coming from almost every collection he had examined during his research. Besides, he gave a long description of several chromatic variations, claiming that the species “must be regarded as the most variable of the whole genus, and you often will hardly believe that you are seeing specimens of the same species”. All the specimen depositories listed by the author were searched for the type series, and 42 syntypes were traced down. The typification was made as follows, in order to stabilize the epithet. LECTOTYPE (by present designation): (SNMF) 1♂, glued, median lobe of aedeagus and abdomen glued on a different card // “ Paraguay Vogt.” [White label, printed] // “v. Heyden. Museum” [White label, printed] // “Senckenberg-Museum Frankfurt/Main” [White label, printed] // “ Griburius rufomarginatus (Suffrian, 1866) (Scolochrus rufomarginatus) LECTOTYPUS D. Sassi des.” [red label, printed] // “ Griburius posticatus Suffr. D. Sassi det. 2023” [white label, printed] //. PARALECTOTYPES (41) were designated as follows. (SNMF) 3 specimens, pinned, same data of the lectotype; (SDEI) 1♂, pinned // “ Scolochrus Vogtii Heydn rufomarginatus Suffr. Suff. vid Paraguay Vogt” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “DEI Müncheberg Col - 14411” [Green label, printed] //; (SDEI) 1♀, pinned // “ Scolochrus Vogtii Heyden v. flavomaculatus Hdyn Suff. vid. Paraguay Vogt” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “DEI Müncheberg Col - 14408” [Green label, printed] //; (SDEI) 1♀, pinned // “ Scolochrus Vogtii Heydn. v. 4 pustulatus Hydn. Suff. vid. Paraguay Vogt” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “65-” [White label, handwritten] // “DEI Müncheberg Col - 14404” [Green label, printed] //; (SDEI) 1♀, pinned // “ Scolochrus Vogtii Hydn. v. 4 maculatus Hydn. Suff. vid. Paraguay Vogt” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “DEI Müncheberg Col - 14410” [Green label, printed] //; (SDEI) 1♀, pinned // “ Scolochrus Vogtii Heydn. v. collaris Hyd. Suff. vid Paraguay Vogt” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “DEI Müncheberg Col - 14406” [Green label, printed] //; (SDEI) 1♀, pinned // “ Scolochrus Vogtii Heyden. v. semimarginatus Hydn Suff. vid Paraguay Vogt” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “DEI Müncheberg Col - 14405” [Green label, printed] //; (SDEI) 1♀, pinned // “ Scolochrus Vogtii Heyden. v. marginatus Heydn Suff. vid Paraguay Vogt” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “DEI Müncheberg Col - 14409” [Green label, printed] //; (SDEI) 1♀, pinned // “ Scolochrus Vogtii Heyden. v. interruptus Hydn Suff. vid Paraguay Vogt” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “DEI Müncheberg Col - 14412” [Green label, printed] //; (SDEI) 1♀, pinned // “ Scolochrus Vogtii Heyden v. maculicollis Hydn. Suff. vid Paraguay Vogt” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “DEI Müncheberg Col - 14414” [Green label, printed] //; (SDEI) 1♂, pinned // “ Scolochrus Vogtii Heyden. v. nigricollis Hydn Suff. vid Paraguay Vogt” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “DEI Müncheberg Col - 14413” [Green label, printed] //; (SDEI) 1♀, pinned // “Suffr. Vid.” [White label, handwritten] // “coll. v. Heyden” [White label, printed] // “DEI Müncheberg Col - 14407” [Green label, printed] //; (SDEI) 4♀, pinned // “ Paraguay v. Heyd.” [White label, handwritten, one of the specimens lacks this label, but it certainly belongs to the same series] // “coll. Haag” [White label, printed] // “DEI Müncheberg Col - [numeration follows from 14415 to 14418]” [Green label, printed] //; (BMNH) 1♂, pinned // “ Bolivia ” [White label, handwritten] // “ S. rufomarginatus ” [White label, handwritten] // “67-56” [White label, printed] // “E. Coll. Laferté” [White label, printed] // “ SYNTYPE ” [White-blue label, printed] //; (BMNH) 1♀, pinned // “ Scolochrus rufomarginatus Suffr. Amazonas” [White label, handwritten] // “Type Suffr Coll Baly” [White label, handwritten] // “Baly Coll.” [White label, printed] //; (BMNH) 1♀, pinned // “Minas Geraes” [White label, handwritten] // “67- 56” [White label, printed] // “E. Coll. Laferté” [White label, printed] // “ SYNTYPE ” [White-blue label, printed] //; (BMNH) 1♀, pinned // “Minas Geraes” [White label, handwritten] // “67-56” [White label, printed] // “E. Coll. Chev. t ” [White label, printed] // “ SYNTYPE ” [White-blue label, printed] //; (MNHUB) 9♀, pinned, only one of them actually labelled, but they all certainly belong to the type series // “24022” [white label, printed] // “rufomarginatus Suffr.* Brasil. v. Olf.” [blue label, handwritten] //; (MNHUB) 1♀, pinned // “ Brasil Sello” [blue label, handwritten]; (MNHUB) 1♀, pinned // “ Brasil Cornaz” [white label, handwritten] //; (MNHUB) 1♀, pinned // “ Brasil Virm.” [blue label, handwritten] //; (NMV) 1♂ ♀, pinned // “Alte Sammlg. Brasilien.” [White label, printed] // “Helm. 853” [White label, handwritten] //; (NMV) 1♂ 2♀, pinned // “Asuncion” [White label, printed] // “Helm. 853” [White label, handwritten] //; (NMV) 1♂, pinned // “Ypanema Brasilien Natterer” [White label, printed] //; (SMNH) 2♀, pinned // “ Brasil ” [White label, printed] // “M. Wien” [White label, handwritten]; (MLUH) 1♂ 1♀, pinned // “rufomarginatus m. Brasil.” [Green label, handwritten] // “27777” [and] “28009” [White label, handwritten, first one the male, second one the female]. All paralectotypes were labelled: // “ Griburius rufomarginatus (Suffrian, 1866) (Scolochrus rufomarginatus) PARALECTOTYPUS D. Sassi des.” [red label, printed] // “ Griburius posticatus Suffr. D. Sassi det. 2023” [white label, printed] //. The careful comparison between the type specimens and the review of the abundant material available from a wide area of South America, despite the surprising chromatic variability does not reveal differences at a specific level. For this reason, the following synonymies are proposed here: Griburius posticatus (Suffrian, 1866) = Griburius distigma (Suffrian, 1866) syn. nov., = Griburius rufomarginatus (Suffrian, 1866) syn. nov.
Type locality. G. posticatus: “ Paraguay ”. G. distigma: Pernambuco, Brazil. G. rufomarginatus: “ Paraguay ”.
Additional material examined. ARGENTINA: Chaco: Charata I.1995 (2, MSNM); Resistencia (1, MSNG); Resistencia XI.1945 (1, USNMNH); Rio Tapenaga Colonia Florencia 1903(2, MNHN). Córdoba: Cosquin I.1988 (12, DSPC); N of San Roque 5–25.I.1985 (DSPC); Los Cocos 1180m 11.XII.2015 (1, DSPC). Corrientes: “ Corrientes ” coll. Haag (SDEI). Entre Rios: Liebig XI.1987 & XII.1989 & XI.1990 & X.1993 (12, DSPC); P. Nacional El Palmar 12.I.1981 (2, MDPC); Colonia Peña XII.1993 (4, MSNM); 4km NW Jcn. 127 on Hwy 6 15.I.1989 (1, BYU). Formosa: 22 Km W Clorinda 26.I.1989 (2, BYU); Clorinda XI.1947 (1, USNMNH); 22km SW Formosa 28.I.1989 (1, BYU). Jujuy: “Jujuy” I.1949 (2, USNMNH). Misiones: San Ignacio Missions (1, NMPC); Corrientes prov. nr Posadas Isla Apipé Grande XI.1945 (1, USNMNH); S of Corrientes River Parana 16.I.2009 (1, MSNG); “ Territ. Des Misions ” Wagner coll. (1, NMPC); Alto Parana 1–18.XII.1933 (1, BMNH). Salta: Rosario de la Frontera El Naranjo II.1944 (13, USNMNH); Rosario de la Frontera II.1944 (4, USNMNH); Rosario de la Frontera S of Salta 1.II.2009 (1, MSNG); Rosario de la Frontera Alto El Muño XII.1947 (3, USNMNH); San Lorenzo 6.I.1945 (2, USNMNH); Cerro San Bernardo 5.I.1945 (2, USNMNH); 50 KM S of Salta E of Coronel Moldes 23.I.2009 (2, MSNG); Rosario de Lerma 1200m 14.XII.1990 (2, SMNS); Gran Chaco Rio Salado S of Macapillo SE Salta 20.I.2009 (24, MSNG); S of Corrientes River Parana 16.I.2009 (9, MSNG); Salta [Higlesia de?] Sumalao XI.1983 (2, DSPC); Salta Chicoana I.1964 (1, DSPC); Salta Dique Cabra Corral 1060m 5.III.2015 (1, DSPC); El Carmen (1, NMV); Salta Cabeza de Buey 20.I.1951 (3, USNMNH); Salta Zuviria (1, NMV); Salta (6, NMV); Salta (1, USNMNH); Ivian Prov. General Ball (1, USNMNH). Santa Fe: Santa Fe 31°39’55.7”S 60°42’48.7”W 4.I.2023 (1, GBIF). Santiago del Estero: Rio Salado (5, NMPC); Rio Salado (2, USNMNH); Icaño 1904 & 1909 & 1910 & 1914 leg Wagner (6, MNHN); Rio Hondo 14.I.1948 (1, USNMNH). Tucumán: La Criolla 1500m I.1903 (1, MNHUB); San Pedro de Colalao I.1957 (1, USNMNH). “Argentinien” Reimoser (10, NMV). BOLIVIA: Beni: José Ballivián Prov. Rurrenabaque env. 18– 20.XI.1998 (1, MSNG); Guayaramerín Fundo Nuevo Cuba 26.XI.1966 (1, HNHMB). Cochabamba: Villa Tunari 5.XII.2001 (1, MSNG). La Paz: Nor Yungas, Huarinilla 3750 ft 11.XI.2009 & 28.XI.2011 (6, BYU); Nor Yungas Coroico 27.XII.1948 (1, USNMNH); Nor Yungas Vagante 3650ft 12.XI.2009 (1, BYU); Sud Yungas Ocobaya Finca Colaya 1.I.1949 (2, USNMNH). Santa Cruz: Andrés Ibáñez, Potrerillo del Guenda on Mimosa simplex 26.XI.2014 & 27–28.XI.2014 & 29–30.XI.2014 & 1–3.XII.2014 (66, LSPC); Potrerillo del Guenda 436m 23.XI.2013 (5, USNMNH); “Halco” nr Potrerillo 1270m 1.XII.2012 (1, JEWPC); Santa Cruz 10.XI.1956 (1, USNMNH); Santa Cruz 3, 7 km SSE Buena Vista Hotel Flora & Fauna 430m 2–13.II.2000 (2, FSCA); Andrés Ibáñez Prov. Santa Cruz de la Sierra 500m I–IV.1904 (4, MNHUB); Chiquitos prov. Lapango XI.1926 (1, ZSM); Ñuflo de Chávez prov. Hacienda San Sebastian 530m on Mimosa sp. 530m 1–4.XII.2013 (1, LSPC); Florida prov. Refugio Los Volcanes on Mimosa simplex 16.XII.2014 (3, LSPC); Refugio Los Volcanes 1050–1150m 10–14.XII.2011 on Mimosa sp. (2, LSPC); Refugio Los Volcanes Amboro National Park 1000m 20.XI–12.XII.2004 (2, BMNH); Refugio Los Volcanes 1350m 6.XII.2013 (2, USNMNH); Santa Cruz (5, USNMNH); Santa Cruz 500m 10.II.1955 (2, ZSM); “ Santa Cruz ” II.1956 (1, USNMNH); “ Santa Cruz ” (5, USNMNH); “ Santa Cruz ” 500m 25.XI.1955 (2, ZSM); (5, USNMNH); San Juan 17°20’38”S 63°50’10”W 3.XII.2021 (2, GBIF); “Halco” nr Potrerillo 1270m 1.XII.2012 (1, JEWPC); Ichilo Prov. Buena Vista (1, ZSM); Sara prov. (2, MNHUB). Tarjia Dept. G. Chaco 2 km SW Villamontes 12–16.XII.2011 (1, JEWPC). BRAZIL: Amazonas: São Paulo de Olivença VI.1946 (1, USNMNH). Goiás: Trindade (6, MNHN); Mineiros (2, NMPC & USNMNH); Jataí XII.1897 – I.1898 (5, USNMNH); Jataí (7, NMPC & USNMNH). Mato Grosso: Corumbá (2, MNHUB); Campo & Cerrado 12°50’S., 51°47’ W. (4, BMNH); Lavras 7.XII.1978 (1 FSCA). Mato Grosso do Sul: 70 km SW Nova Andradina 18–25.XI.2000 (2, DSPC); Bonito 27–28.XI.2000 (1, DSPC). Minas Gerais: Minas Uberaba coll. Le Moult (2, FSCA); Lagoa Santa Reinhard coll. (5, ZMUC); Belo Horizonte 1–2.XII.1937 (1, NHMB); UFMG Campus Pampulla 19°52’ S 43°58’ W 830 m Malaise 28.XI.1996 (1, TAMU); Lambari XI.1924 & XI.1926 (4, USNMNH). Pará: Santarém (1, MNHN). Paraná: Ponta Grossa II.1947 (4, USNMNH). São Paulo: “São Paulo” (2, MNHUB & ZSM); “Trisanga” [Irisanga (= Orissanga)] (1, NMV). “Brésil” (9, MNHN & NMPC). “Brazil” (1, USNMNH); “Brasilien” Alte Sammlung (2, NHMB). PARAGUAY: Amambay: Estancia Kai Rague 23–27.XI.2013 (1, UDPC). Asunción: Asunción Jardín Botánico XI.1990 (1, DSPC); Asunción XI.1990 (1, DSPC); Asunción Vezényi coll. (2, HNHMB); Asunción (1, ZSM). Boquerón: Chaco Boreal 90 km Filadelfia 27.I.2008 (1, DSPC). Caaguazú: Morombi 12–15.XII.2013 (1, UDPC). Central: Arroyo Mburicao 30.XI.1989 & 4.I.1991 & 21.I.1991 (3, DSPC); Capiatá II.1995 3, MSNM); Nemby 11.I.1983 (1, ERPC). Concepción: 120 km NEE Concepción 2.II.2008 (1, NMPC); Garay-Cué 28.XI– 2.XII.2012 (2, UDPC). Cordillera: San Bernardino (1, MNHUB); San Bernardino Fiebrig coll. 1905 (1, BMNH); San Bernardino (5, USNMNH); San Berbardino XI.1898 Boggiani coll. (2, MSNG). Guairá: Cerro Acati I.1994 (7, MSNM); Tacuarita I.1994 (1, MSNM); Colonia Independencia 11.III.1950 (1, ZSM); “Guairá” 8.XII.1950 (3, NHMB). Itapúa: Hoenhau IX.1933 (1, ZSM). Paraguarí: Sapucay I.1992 (1, DSPC); Naranjo II.1995 (1, MSNM). Presidente Hayes: Buffalo Bill 108 m 4.XII.2010 (1, JBPC); Villa Hayes Monte Lindo XI.1993 (1, MSNM); Monte Lindo Chaco 13.I.1972 (1, FSCA). San Pedro: W Vacajhù [Vaca Jhu], Est. Triangulo 180m 7–11.XI.1995 (1, SMNS). “Paraguay” Fiebrig (15, MNHUB). “Paraguay” (8, MNHUB). “ Paraguay ” coll. Fry 1905 (1, BMNH). VENEZUELA: Anzoátegui: 2 KM e La Ceiba 1360ft 2.VIII.1988 (1, BYU).
Distribution. Argentina, Bolivia, Brazil (Amazonas, Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Pará, Paraná, São Paulo), Paraguay, Venezuela.
Diagnosis. This species is characterized by a strong chromatic variability that can still be traced back to two chromatic limit forms, formerly described as independent species: G. posticatus and G. rufomarginatus. It is rather curious that the first form is largely prevalent but not exclusive in males, while the second is much more frequent but also not exclusive in females. To simplify the discussion of this chromatic variability, in the following description and in general in the text, informal names will be used: “ posticatus form” and “ rufomarginatus form”. However, the species is practically indistinguishable from G. consanguineus unless examining the shape of the apex of the ventral lobe of the aedeagus and the ductus of the spermatheca. In its ‘rufomarginatus form,’ the dorsal coloration may resemble that of G. ephippiatus. Nevertheless, it can be differentiated by its greater dorsal convexity and the finer elytral punctation. G. bicoloratus is very similar as well, but it can be distinguished by the darker elytral coloration, the pronotum in males totally reddish, and the finer elytral punctation.
Description of male (“ posticatus form”). Habitus in figs 4a–b (LT). BL = 4.7–5.3 mm, BW = 2.9–3.4 mm, PL = 1.6–2.0 mm, PW = 2.7–3.3 mm. Interocular distance 10.6–11.3 % of BL.
Head totally black. Labrum dark brownish. Vertex and frontoclypeal surface with sparse setae and fine, sparse punctation. Punctures denser and stronger along ocular margins and on lower part of frontoclypeal surface. Between ocular canthi setosity generally dense, silvery, appressed, basically hiding surface along frontoclypeal boundary.Mid-cranial suture slender but usually detectable from vertex to upper part of frons. Upper lobes of eyes well separated from each other. Ocular lines narrow, strictly adhering to ocular rim. Ocular canthus rounded, with surface almost hidden by short, dense, appressed, silvery setosity. Antennae normal in shape, first five antennomeres yellowish, bright, 3–5 subcylindrical, subsequent ones gradually darker, dull, moderately flattened and more diffusedly setose.
Pronotum yellow or chestnut. At times with two or four rounded black spots (inner two larger) in transverse line at middle of disc. Such spots often reduced or even totally obliterated. Pronotal shape elliptical, scarcely transverse. Lateral margins narrow, barely visible from above, not or slightly angulate at about middle with maximum width just behind half length. Posterolateral impressions short and shallow, but usually perceptible. Surface moderately convex, flattened above all behind midline, with scattered, medium-sized punctation, sparser at middle of disc but usually well visible.
Scutellum black, dull, distinctly raised, very minutely punctured, surface covered with rather dense, whitish setae. Apex truncated in straight line.
Elytron yellow or chestnut with rounded black spot just behind middle. Such black spot often reduced or missing. Elytral outline squat, slightly flattened with sides mildly convergent toward apex, Lateral margins rather narrow, barely visible simultaneously from above. Scutellar area perceptibly raised. Humeral callus prominent, impunctate. Surface with rather fine, dense, rather confusedly arranged punctures above all on anterior half. Sometimes punctation sparser, distributed in almost regular rows. Epipleuron surface plane, shiny, smooth.
Pygidium yellow, covered by fine punctures and rather dense whitish setae.
Ventral surface totally black except hypomera, reddish on outer half. Hypomera scarcely setose, bright. Remainder of ventral surface matt, minutely punctate, covered with dense, short silvery setae. Prosternal process wide, almost flat to slightly depressed along midline, with parallel sides and wide subtriangular apex. Surface coarsely punctured with sparse, semi-erect setae. Legs totally black. Anterior tarsi short and squat.
Median depression on fifth abdominal ventrite shallow, diffusedly setose, barely distinguishable from remainder of ventrite surface. Posterior margin of fifth abdominal ventrite straight.
Median lobe of aedeagus (Figs 4k–n) dorso-ventrally flattened, in ventral view terminated with robust, triangular apex laterally delimited by horizontally arranged anterior margin of shaft. Apex slightly bent ventrally in lateral view. Setose depressions narrow, shifted on sides, setose only along external margins, separated from glabrous depressions by evident partition septum (Figs 4k–m). Aedeagal ventral surface with two deep rounded glabrous depressions just below apex and long sharp median carina, usually depressed at middle in lateral view.
Chromatic variation (“rufomarginatus form ”). Only the chromatically differing parts are described here. Habitus in fig. 4f (LT of G. rufomarginatus). Light dorsal colouration generally reddish rather than yellow or chestnut as observed in “ posticatus ” form. Pronotum usually totally black, but at times anterior margin narrowly and lateral margins more widely reddish. Sometimes pronotum black on posterior half, reddish on whole anterior one. Again, elytron reddish or chestnut with large black patch on disc. The black patch can extend from the anterior quarter of the elytra backwards along the entire surface, usually leaving a reddish circular area free at the apex. The black design generally extends to the suture but often leaves the margin or a good part of it free. The shape of the black spot can vary, sometimes square, other times assuming an elliptical outline with a narrow apex obliquely extended forward to affect the humeral calli. Still, the black design can cover the entire elytra, excluding the apex, the lateral margin, and at times a narrow area around the scutellum. On the other hand, the opposite tendency has never been observed, i.e., the humeral area remains free, but the black design extends along the suture to the scutellum. This last chromatic pattern is common to other rather similar species, not treated in this study, such as G. erythrospilus (Suffrian, 1866), G. rotundatus (Suffrian, 1866), G. scintillans (Suffrian, 1866), G. corpulentus (Suffrian, 1866). If confirmed, this tendency could be useful in the process of species identification.
Female. BL = 4.9–6.0 mm, BW = 3.5–3.8 mm, PL = 1.5–1.9 mm, PW = 2.9–3.5 mm. Interocular distance 12.2–15.0 % of BL.
Female differs in the larger size, in the larger interocular distance, in shorter antennae, in slenderer anterior tarsi. Regarding the chromatic pattern, the “rufomarginatus form ”, as mentioned earlier, is clearly predominant in females, so much so that the “posticatus form ” can be defined as decidedly rare in this sex. In any case, the black elytral colour tends to be more extensive, and a certain number of females with entirely black dorsal coloration have been observed.
The fifth abdominal ventrite in females has a large, almost circular, deep pit. The bottom of the pit is bald, matt, impunctate but covered by tiny wrinkles. The vasculum of spermatheca (Fig. 11d) is scarcely pigmented, slender, with the proximal lobe slightly bent at base, scarcely swollen. The distal lobe is slender as well, long, regularly curved, with a sharp apex bent downward. The ampulla is short, not pigmented. The duct insertion and the sperm gland insertion are barely separate. The duct is long, slender, forming a tangle outside or close to the vasculum, basically straight or at times very loosely coiled, above all near the insertion on the bursa copulatrix. Such insertion copulatrix is simple, not pigmented.
description: Published as part of Sassi, Davide, 2024, Revision of the Griburius posticatus (Suffrian, 1866) species group (Coleoptera: Chrysomelidae: Cryptocephalinae), pp. 201-237 in Zootaxa 5406 (2) on pages 213-220, DOI: 10.11646/zootaxa.5406.2.1, http://zenodo.org/record/10618162