Griburius biverrucatus ( Suffrian, 1852 )

Sassi, Davide, 2023, Revision of the Griburius scutellaris (Fabricius, 1801) species group (Coleoptera: Chrysomelidae: Cryptocephalinae), Zootaxa 5315 (6), pp. 501-548 : 514-516

Griburius biverrucatus ( Suffrian, 1852) stat. restored

( Figs 3 ; 12b )

Scolochrus biverrucatus Suffrian, 1852: 115 (original description); Suffrian 1858: 389 (taxonomic notes); Jacoby, 1880: 59 (as syn. of G. albilabris , taxonomic notes).

Griburius biverrucatus: Clavareau, 1913: 88 (as syn. of G. albilabris , catalogue).

Griburius albilabris biverrucatus: Blackwelder, 1946: 639 (as subsp. of G. albilabris , catalogue).

Types. Suffrian did not mention the number of specimens available for the description of Griburius biverrucatus , but he reported that he examined Mexican material sent for study by Thorey. I was able to track down four specimens (three males and one female) in Suffrian’s collection ( MLUH) that must have been part of the type series. For this reason, one male specimen is here designated as lectotype. LECTOTYPE (by present designation): ♁, body, aedeagus and detached abdomen glued on the same card, // “biverrucatus m. Mexico ” [green label, handwritten] // “27089” [white label, handwritten] // “ Griburius biverrucatus ( Suffrian, 1852) ( Scolochrus biverrucatus ) LECTOTYPUS D. Sassi des.” [red label, printed] // (( MLUH). Paralectotypes: 1♁, pinned, // “25285” [white label, handwritten]; 1♁, pinned, // “25286” [white label, handwritten]; 1♀, pinned, // “30481” [white label, handwritten]. All paralectotypes housed in MLUH and provided with additional label: // “ Griburius biverrucatus ( Suffrian, 1852) ( Scolochrus biverrucatus ) PARALECTOTYPUS D. Sassi des.” [red label, printed] //.

Additional material examined. MEXICO: “ Mexico ” Deyrolle coll. Haag (1, SDEI). OAXACA: 37 mi NW Oaxaca, 74 at night VI-I-1974 O’Briens & Marshall (2, BYU); 8 miles NE El Punto 18-VII-1985 (1, TAMU). In BMNH a single female from Baly collection, labelled // “ Scolochrus biverrucatus Suffr Mexico ” [white label, handwritten] // bears a further handwritten label (by Baly himself) stating that the specimen was seen and determined by Suffrian (// “named by Suffr.” [white label, handwritten] //). However, in the original description Suffrian (1852, p. 116) reported a single female being available for the study (“Das einzige mir vorliegende female….). For this reason, the specimen from London cannot be considered as belonging to the type series.

Type locality. “ Mexico ”.

Distribution. The currently ascertained distribution is Oaxaca State ( Mexico).

Diagnosis. Griburius biverrucatus is very similar to G. albilabris and it is no surprise that the systematic status of the taxon had been controversial. The most evident diagnostic trait is the pronotal punctation, which is much stronger in G. biverrucatus . However, the size and the distribution of pronotal punctures are greatly variable in G. albilabris , and I myself had long been inclined to confirm the synonymy when I came across some specimens from Oaxaca State whose punctation pattern looked really very distinctive. The inspection of the aedeagus, more slender and terminated with a more pronounced median denticle, supports the present conclusion of species status. The comparison with the types in Suffrian’s collection supported the decision of removing it from synonymy with G. albilabris .

Description of male. Habitus in Fig. 3a–b (LT). BL = 4.5 mm, BW = 2.8 mm, PL = 1.7 mm, PW = 2.4 mm. Interocular distance 2.2 % of BL.

Head ( Fig. 3c ) yellow with vertex, area between upper lobes of eyes, lower clypeal margin and antennal insertion black. Labrum yellow. Vertex closely punctured with very few, short, sparse setae. Surface of frontoclypeal area with scattered, well-impressed punctation and sparse setae. Mid-cranial suture shallow, barely detectable between upper lobes of eyes. Upper lobes of eyes close to each other along midline, but always separated by distinct strip of frons space. Ocular lines narrow, marked by row of coarse punctures, strictly adhering to ocular rim. Ocular canthus large not differentiated in punctation and setosity from the remainder of frontoclypeal surface. Antennae ( Fig. 3m ) with antennomeres 3–5 yellowish, bright, subcylindrical; antennomeres 6–11 brownish, dull, more flattened and more diffusedly setose.

Pronotum black with lateral margins and sides of anterior margin yellow. Pronotal shape roughly elliptical, scarcely transverse, regularly convex. Lateral margins narrow, visible from above only along posterior third, regularly curved so that maximum width about at middle. Surface moderately shiny with coarse, strongly impressed punctation evenly distributed across whole pronotal surface, irregularly mixed with much finer punctures. Posterolateral impressions weakly impressed. Pronotal posterior margin thickened on sides.

Scutellum yellow bordered with black to totally black, almost square with apex truncated in straight line. Surface sparsely micropunctured.

Elytron black with large chestnut spot from basal margin to almost middle of elytron and from lateral margin to second row of punctures, not covering humeral callus. Elytral outline rather lengthened with sides almost straight and fairly convergent posteriorly. Lateral margins narrow, simultaneously visible from above only along posterior half. Elytral surface slightly flattened on disc, moderately shiny with strong, well-impressed punctation arranged in almost regular rows, well visible up to posterior clivus. Intervals flat. Postscutellar area fairly raised. Humeral callus prominent, impunctate. Epipleuron smooth, impunctate, with convex surface.

Pygidium black, sometimes with two irregularly shaped yellow spots close to lateral margins; in one specimen such spots extended to cover almost whole surface. Surface rather shiny, covered with close shallow punctures and appressed, pale setae above all on basal half.

Ventral parts of thorax totally black, only apical margin of prosternal process bordered with yellow. Abdominal ventrites black with distal part of fifth ventrite largely bordered with yellow. Medial projection of first ventrite partly yellow as well. Hypomera, mesepimera and mesepisterna almost bare, shiny, with scattered punctures. Remainder of ventral surface of thorax matt, covered with thick, short, regularly distributed setae and fine, shallow punctures. Prosternal process large, with sides almost straight between anterior coxae, then weakly converging in large, round apex; surface anteriorly almost flat and closely punctured, covered with long, semi-erect setae. Legs black with femora partly yellow.

Median depression on fifth abdominal ventrite hardly detectable, only setosity sparser and shorter. Posterior margin of ventrite very shallowly notched. Median lobe of aedeagus ( Fig. 3g –k ) with apex terminated by well differentiated, long median denticle. In lateral view apex directed slightly backward. Ventral outline marked with low, quite sharp, median carina along apical half. Setose depressions large, shallow, with surface covered by small punctures and long arcuate setae.

Female. BL = 4.6–5.3 mm, BW = 2.9–3.3 mm, PL = 1.5–1.8 mm, PW = 2.5–2.8 mm. Interocular distance 8.7–9.4 % of BL.

In females, the eyes ( Fig. 3c ) are smaller and more separated along midline, and the head surface is evenly covered with coarse punctation. The head is almost completely black, with a discontinuous transverse yellow line extended between the ocular canthi.Additionally, the yellow pattern on pronotum is less extended and the scutellum is black. The light colour is reduced on ventrites and the pygidium as well.

The fifth abdominal ventrite in females has a quite large, rounded and deep pit. The bottom of the pit is glabrous, matt, impunctate but covered with tiny wrinkles. The vasculum of the spermatheca ( Fig. 3n ) is poorly pigmented, sickle-shaped with slightly swollen proximal lobe. The distal lobe is slender, scarcely tapered with a rather blunt apex slightly bent downwards. The ampulla is mildly pigmented. The duct is uniform in size, robust, quite rigid, not coiled with a series of 4–5 turns just beside the vasculum, then almost straight. The insertion on the bursa copulatrix is simple, neither swollen nor pigmented.

Figures

FIGURE 3. G. biverrucatus. a–b: habitus, dorsal and lateral view (LT); c: frontal view, female (PLT); d: frontal view, male (LT); e–f: colour variations (e: PLT female; f: male, Oaxaca, Mexico); g–k: median lobe of aedeagus in ventral (g), dorsal (h) and lateral (k) view [0.5 mm]; m: antenna [1.0 mm]; n: spermatheca [0.3 mm]. hd: setose depressions. Square brackets: length of scale segment.

FIGURE 12. Distribution maps for the Griburius scutellaris species-group. a: G. albilabris; b: G. biverrucatus; c: G. boucardi; d: G. decoratus; e: G. errans; f: G. larvatus. Black markings: data from specimens analyzed during the study. Red markings: data from the public database Global Biodiversity Information Facility (GBIF.com).