Griburius gracilis, Sassi, 2023

Sassi, Davide, 2023, Five new species of the genus Griburius Haldeman from Central America (Coleoptera: Chrysomelidae, Cryptocephalinae), Fragmenta entomologica (Deerfield Beach, Fla.) 55 (1), pp. 117-138 : 123-124

Griburius gracilis sp. nov.

( Figs 2 , 8b )

Types. HOLOTYPE: m#, body, aedeagus and detached abdomen glued on the same card, // “ MEXICO Quintana Roo ” [white label, printed] // “Celarain Point Cozumel Island 21-IV-1960 J.F.C.Clarke” [white label, printed, partly handwritten] // “ Griburius gracilis sp. nov. HOLOTYPUS D. Sassi des.” [red label, printed] // (USNMNH). PARATYPES (26 specimens): MEXICO, QUINTANA ROO: same data of the HT (14m #12f#, USNMNH, DSPC, MSNM). All paratypes are labelled: // “ Griburius gracilis sp. nov. PARATYPUS D. Sassi des.” [red label, printed] //.

Type locality. Celarain Point on Cozumel Island (Quintana Roo, Mexico) .

Etymology. Latin adjective meaning “frail”, stressing the relatively small size and the poor contrast of the dorsal colouring.

Distribution. Mexico. This taxon is likely to be endemic to Cozumel Island (Quintana Roo), which is well known for hosting several endemic animal species (see for instance Cuarón et al. 2004).

Diagnosis. The dorsal colouration, with a weak contrast between the whitish-yellow light areas and reddish-brown dark ones, characterizes the species quite well, even if, quite rarely, a darker pattern is shown on the central part of the elytra ( Fig. 2e ). The most similar species is G. textus , which however differs in the wider and more angular outline of the aedeagal median lobe, in the larger size and the more robust dorsal punctation.

Description of male. Habitus in Fig. 2 a-c (PT). BL = 2.8–3.0 mm, BW = 1, 8 mm, PL = 1.1–1.6 mm, PW = 1.6–1.7 mm. Interocular distance = 0.0–3.6 % of BL.

Head yellow with vertex, ocular perimeter, lower clypeal margin and antennal insertions brownish. Labrum yellow. Head surface basically devoid of setosity. Vertex shallowly but closely punctured. Surface of frontoclypeal area with scattered, well-impressed punctation above all on ocular canthi and between antennal insertions. Mid-cranial suture shallow, barely detectable between upper lobes of eyes. Upper lobes of eyes close to each other along midline but not really in contact. More rarely, upper ocular lobes touching each other for short distance. Ocular lines usually distinct above all along lower part of upper lobes, marked by row of punctures, strictly adhering to ocular rim. Ocular canthus large, angular. Antennae ( Fig. 2h ) with first two antennomeres yellow, reminders brownish. Antennomeres 3-5 bright, subcylindrical; antennomeres 6-11, dull, more flattened and more diffusedly setose.

Pronotum light brown with lateral and anterior margins yellow. Two trapezoidal spots in posterior part of disc, close to midline, touching posterior margin and median line raising from anterior margin and reaching middle of disc yellow as well. Pronotal shape elliptical, scarcely transverse, regularly convex. Lateral margins narrow, visible from above only along posterior third, regularly curved, with maximum width at about middle. Surface moderately shiny with strongly impressed punctation evenly distributed across whole pronotal surface. Posterolateral impressions weakly impressed but still detectable.

Scutellum brownish, triangular with apex truncated in straight line. Surface sparsely micropunctured.

Elytron light brownish with large yellow patch at center of disc, broadened at middle and reduced to simple stripe along apical clivus. Apical margin yellow as well. Bottom of punctures brown also in lighter areas. Epipleuron yellow. Elytral outline with sides almost straight and 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 distinct up to posterior clivus, arranged in almost regular rows along inner half of elytron, more confused elsewhere. Intervals flat. Postscutellar area slightly raised. Humeral callus prominent, impunctate. Epipleuron smooth, impunctate, with slightly convex surface.

Pygidium totally yellow Surface bright, covered with shallow punctures and short, semi-erect pale setae.

Ventral parts of thorax light brown, only metasternum almost completely yellow. Abdominal ventrites yellow with central part of ventrites 1-4 light brown. Medial projection of ventrite 1 yellow. Hypomera, almost bare, shiny, covered with dense, strong punctures; mesoepimera and mesoepisterna shiny, almost devoid of punctation. 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, terminated with a round apex; surface almost flat, shallowly punctured, covered with long, semi-erect setae. Legs totally yellow.

Median depression on fifth abdominal ventrite indistinct, hardly detectable. Ventrite posterior margin shallowly notched. Median lobe of aedeagus ( Fig. 2 m-o) dorsoventrally flattened, terminated by triangular apex. In lateral view apex perfectly straight. Ventral surface almost smooth. Setose depressions very shallowly impressed, with surface covered by small punctures and few short setae

Female. Habitus in Fig. 2 d-f (PT). BL = 3.6–3.8 mm, BW = 2.4–2.6 mm, PL = 1.3–1.4 mm, PW = 2.1–2.3 mm. Interocular distance = 8.3–10.5 % of BL.

In females the head surface is brownish with a transverse yellow band between the ocular canthi. Two further yellow spots just below the antennal insertions. The eyes are smaller and more separated along midline, and the head surface is evenly covered with coarse punctation and sparse short setae. Sometimes, the yellow patch on elytron tends to change into dark brown shades ( Fig. 2e ).

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 by tiny wrinkles. The vasculum of the spermatheca ( Fig. 2i ) is scarcely pigmented, sickle shaped with straight, slightly swollen proximal lobe. The distal lobe is slender, regularly curved, distally tapered, and terminated with a slender apex. The ampulla is not pigmented, almost square. The duct insertion is ahort and slightly thickened. The sperm gland insertion is rather long, slender and curved. The duct is uniform in size, short, slender, quite rigid, straight, devoid of coils and turns. The insertion on the bursa copulatrix is simple, neither swollen nor pigmented.

Figures

Fig. 2 – Griburius gracilis sp. nov. a–b, habitus, dorsal and lateral view (PT, male); c, frontal view, male; d, frontal view, female; e–f, colour variation, females; m–o, median lobe of aedeagus in ventral (m), dorsal (n) and lateral (o) view [0.6 mm]; h, antenna [1.2 mm]; i, spermatheca [0.3 mm]. sd, setose depressions. Square brackets: length of scale segment.

Fig. 8 – Distribution maps. a, Griburius febriculosus; b, G. gracilis; c, G. mokaya; d, G. puncturatus; e, G. textus.