Griburius bicoloratus, Sassi, 2024

Sassi, Davide, 2024, Revision of the Griburius posticatus (Suffrian, 1866) species group (Coleoptera: Chrysomelidae: Cryptocephalinae), Zootaxa 5406 (2), pp. 201-237 : 226-229

Griburius bicoloratus sp. nov.

urn:lsid:zoobank.org:act:C7CDA6F1-F09D-42CB-B076-E60E2D67A624

(Figs 9; 11f; 13c)

Types. HOLOTYPE: ( NMPC) ♂, body, aedeagus and detached abdomen glued on the same card // “ Mineiro Goyaz Brésil ” [white label, printed] // “ex coll. J. Achard National Museum Prague, Czech Republic ” [white label, printed] // “ Griburius bicoloratus sp. nov . HOLOTYPUS D. Sassi des.” [red label, printed] // PARATYPES (31): ( NMPC, DSPC) 1♂ 2♀, same data of the holotype; ( USNMNH) 1♂ // “ Mineiro Goyaz Brésil ” [white label, printed] // “ F. Monros Collection 1959” [white label, printed] //; ( NHMB) 1♂ // “ Mineiro Goyaz Brésil ” [white label, printed] // “ Scolochrus rufomarginatus Suffr. [unreadable ciphers]” [white label, printed] //; ( USNMNH) 5♂ 2♀ // “ Jatahy GOYAZ” [white label, printed] // “gift of F. C. Bowditch ” [white label, printed]; ( USNMNH) 1♂ // “ Jatahy (GOYAZ)” [white label, printed] // “gift of Thomas Barbour ” [white label, printed]; ( MNHN) 1♂ 1♀ // “ Jatahy (GOYAZ)” [white label, printed] // “ Muséum Paris 1937 Coll. Ch Demaisons ” [white label, printed] //; ( MNHN) 1♀ // “ Jatahy Etat de Goyaz Ch. Pujol 1895-96” [white label, printed] //; ( MNHUB) 1♀ // “ Brasilien Jatahy ” [white label, printed] //; ( USNMNH) 1♂ 2♀ // “ Jatahy Prov. Goyas. Brésil ” [green label, printed] // “gift of F. C. Bowditch ” [white label, printed]; ( ERPC) 1♀ // “BRASIL, Goiás Jatai XI-1972 M. Alvarenga Malaise Trap ” [white label, printed] //; ( MNHN) 1♂ 3♀ // “ Trindade (Goyaz) Ch. Pujol ” [white label, printed] //; ( MNHN) 1♀ // “ Goyaz ” [white label, printed] // “ Museum Paris 1930 Coll. Sicard ” [white label, printed] //; ( SMNS) 1♂ 1♀ // “Corumba Matt. [sic] Grosso ” [white label, printed] // “ Metallactus det. L. Medvedev ” [white label, printed] //; ( BMNH) 1♀ // “ BRAZIL: Mato Grosso, 12°50’S., 51°47’ W. 18.X.1968 O.W.Richards R.S. & R.G.S. Exped. B. M. 1968-260” [white label, printed] // “ Campo ” [white label, printed] //; ( MNHN) 1♀ // “ Museum Paris Et. De Santa Catharina Salto do Pirahy, prés de Jaragua Coll. E. Gounelle, 1919” [green label, printed] //; ( MNHN) 1♀ // “ Brésil ” [white label, printed] // “ Museum Paris 1930 Coll. Sicard ” [green label, printed] //. All paratypes are also labelled: // “ Griburius bicoloratus sp. nov. PARATYPUS D. Sassi des.” [red label, printed] //.

Type locality. Mineiro (Goiás, Brazil).

Etymology. The specific name is the Latin adjective bicoloratus (- a, - um), meaning “having two colours”, given in reference to the most common dorsal colour pattern in male specimens.

Distribution. Brazil (Goiás, Mato Grosso, Mato Grosso do Sul).

Diagnosis. The predominantly black dorsal coloration, with the exception of the reddish pronotum in males and some possible reddish spots on the pronotum and elytra in females, makes this species quite easily recognizable; however, submelanic specimens of G. posticatus or G. consanguineus could pose some difficulties in accurate identification. The finer elytral punctation, typically fading in the posterior half, should allow the separation of G. bicoloratus from these two species. In this case, however, an examination of the morphology of the aedeagal apex and the spermathecal duct ensures a more secure determination. Basically, the duct is short and coiled in G. consanguineus , long and coiled only towards the bursa copulatrix in G posticatus , long and not coiled – or coiled only close to the vasculum – in G. bicoloratus . However, see the discussion about possible “convergences” in the “remarks” paragraph of the following species.Additionally, in G. bicoloratus the sclerotized part of the sperm gland insertion is usually longer than in the other species, and the postscutellar area is more impressed, above all in the males. Moreover, the interocular distance tends to be narrower in G. bicoloratus compared to G. posticatus and G. consanguineus , this is more evident in male specimens. The dorsal coloration is also similar to G. hyacinthinus , which is, however, characterized by apparent metallic hues.

Description of male. Habitus in figs 9a–b (HT). BL = 4.8–5.5 mm, BW = 3.1–3.5 mm, PL = 1.5–1.7 mm, PW = 2.9–3.2 mm. Interocular distance 8.3–9.1 % of BL.

Head totally black. Labrum dark brownish. Vertex and frontoclypeal surface with sparse, short whitish setae and well impressed punctation, denser along ocular margins and along a transverse band between ocular canthi just above frontoclypeal suture. Mid-cranial suture detectable from vertex to mid of frons. Fontoclypeal suture shallow but easily perceptible. Upper lobes of eyes strongly separated along median line. Ocular lines narrow, strictly adhering to ocular rim, marked with line of punctures. Ocular canthus rounded, with surface almost hidden by dense, appressed setosity. Antennae normal in shape, first five antennomeres yellowish, bright, 3–5 subcylindrical, the subsequent ones gradually darker, dull, moderately flattened and more diffusedly setose.

Pronotum totally chestnut. Pronotal shape elliptical, rather short. Lateral margins moderately narrow, barely visible from above along anterior half, slightly angulate behind midline with maximum width behind half length. Posterolateral impressions shallow, short, barely perceptible. Surface slightly flattened, above all in front of scutellum, with rather close, two-sized punctation (namely moderate punctation mixed up with finer punctures).

Scutellum brownish bordered with black, distinctly raised, almost square with apex truncated in straight line, finely setose and minutely punctured.

Elytron surface black with chestnut patch along anterior fourth of lateral margin, extended to part of humeral callus and epipleuron. Elytral outline short, slightly flattened with sides mildly convergent toward apex. Lateral margins rather narrow, barely visible simultaneously from above. Scutellar area slightly raised. Humeral callus prominent, impunctate. Surface with very fine punctation arranged in irregular rows. Sometimes punctation almost obliterated and surface covered with tiny transverse wrinkles. Epipleuron surface slightly convex, smooth, impunctate.

Pygidium black, covered by dense, appressed, whitish setae.

Hypomera mostly chestnut, shiny, almost bare, with scattered well impressed punctures, remainder of inferior parts of thorax and abdomen black but surface almost totally hidden by dense, short, appressed silvery setae. Prosternal process wide, almost flat with parallel sides and large rounded apex slightly but perceptibly angulate in respect of remainder of surface. Surface coarsely punctured with sparse, semi-erect setae. Legs totally black. Anterior tarsi short and squat.

Median depression on fifth abdominal ventrite shallow and hardly distinguishable from remainder of ventrite surface. Posterior margin of fifth abdominal ventrite weakly notched at middle. Median lobe of aedeagus (Figs 9k– n) moderately flattened dorso-ventrally along apical half, terminated with short, triangular apex. Sides of triangular apex obliquely convergent, slightly arcuate. Setose depressions narrow, shifted on sides, setose only along margins, separated from glabrous depressions by evident partition septum. Aedeagal ventral surface with long, sharp, median carina.

Female. BL = 5.8–6.2 mm, BW = 3.9–4.1 mm, PL = 1.7–1.8 mm, PW = 3.4–3.7 mm. Interocular distance 12.1–12.9 % of BL.

Female differs in the larger size and in the larger interocular distance.Additionally, the pronotal light colouration is more variable, being reduced to a large reddish band along anterior half, or to a single patch at the middle of the disc. At times the pronotal surface is totally black. Pronotum entirely chestnut, as typical in males, has not been observed in any of the available specimens.

Fifth abdominal ventrite in females with a large, almost circular, moderately deep pit. Bottom of pit bald, matt, impunctate but covered by tiny wrinkles. Vasculum of spermatheca (Fig. 11f) scarcely pigmented, slender, the proximal lobe is not swollen, and the base is gently turned backward. The distal lobe is slender as well, long, regularly tapered, with a rather blunt apex. The ampulla is short, not pigmented. The duct insertion and sperm gland insertion are barely separate. The duct is long, more or less coiled and turned at around its mid length, with a long, not coiled section in proximity of the bursa copulatrix. Sometimes coils are reduced to almost missing. The insertion on bursa copulatrix is simple and unpigmented.

Variability. In a single male from Jataí and in two females, from Jataí and from Mato Grosso do Sul, there is an oval chestnut spot just on elytral apex.