Zethus ( Zethoides ) acromion Lopes, 2025

Lopes, Rogério Botion & Hermes, Marcel Gustavo, 2025, The Neotropical Zethus biglumis species-group (Hymenoptera, Vespidae, Zethinae): description of three new species, with notes on the evolution of the group, Zootaxa 5701 (2), pp. 122-130 : 124-126

Zethus ( Zethoides) acromion Lopes , sp. nov.

Type material. Holotype female: “[ Brazil] AM [ Amazonas]— Manaus \ i–ii.2017 ” [ DZSJRP-Hymenoptera].

Diagnosis. The species can be distinguished by the combination of presenting the mandible without subapical deflected tooth, a practically straight clypeal apex, strongly projected humeral angles and slender petiole.

Description of female. Coloration. Black with the following creamy yellow markings: ventral surfaces of antennal scape; spot on ocular sinus; narrow band along base of pronotal carina; anterior and posterior spots on tegula; subapical bands on T1 to T3 and S2 (medially interrupted on T1 and S2). Outer surface of fore and mid tibiae yellow. Testaceous-colored regions: apex of mandible; ventral surface of pedicel; fore tibia except for posterior surface; fore tarsus entirely; mid tarsomeres III to V; hind tarsomeres IV and V. Tegula dark brown. Fore wings hyaline, light brown, with costa darker and dark brown venation.

Structure. Clypeus strongly convex in profile; without subapical ridge nor teeth, apex nearly straight with faint indication of biconcavity in end-on view. Mandible 4-toothed and without inflexed tooth. Genal margin sinuous. Pronotal carina high as a translucent lamella on dorsum and short and sinuous laterally. Humerus rounded with angles as strong spine-like projections. Outer margin of tegula evenly curved nearly transversal to body axis and raised along its entirety. Scutellum convex. Metanotum strongly bent in profile, with a flat posterior face that is longer than the dorsal surface. Mid tibia with two apical spurs. Socket of hind coxa with reflexed inner margin. Spines on outer surface of mid tibia scattered and in a line in the hind tibia. Posterior surface of propodeum weakly concave. Dorsal propodeal aperture present, slit and without dorsal margin. Apical propodeal lamella triangular, dark in color. T1 regularly convex in profile view, with greatest width near closely after the start of expansion. S1 flat. T2 lamella longer laterally than medially. S2 regularly convex. T3 lamella tripartite. S3 lamella reduced with large median lobe.

Sculpture. Clypeus with dense macropuncatation and obsolete micropunctation. Interantennal carinas sharp, forming a “T”. Macropunctures of head, dorsum of pronotum, mesoscutum and scutellum large, dense and shallow with cariniform interspaces. Coalescent macropunctures on pronotum and only a few observed on anterior portion of mesoscutum. Micropunctures discernable on posterior margin of pronotum and on scutellum only. Notauli absent. Welts evident and smooth. Discoid puncture present on top of a very small, smooth tubercle. Mesopleura without dorsal suture. Metanotum with a mediam thin tooth. Lateral carina of metanotum lamellar with posterior portion curving inwards. Propodeum with complete lateral carina and submedian carinas reaching only 2/3 of propodeum. Propodeal concavity with weak transverse striae. Some strong oblique striae branch laterally from submedian and lateral propodeal carinas. T1 with sub-basal carina well-developed. T1 with moderate to dense coarse macropunctation interspaced by smooth areas. T2 and T3 with very dense micropunctation that obscures any macropuncture and is interrupted subapically, where a smooth band is formed. S2 mostly smooth with sparse small macropunctures, laterally taken over by very dense micropunctation. S3 with very dense micropunctation basally, gradually transforming into moderate macropunctarion apically. T4 densely micropunctate. T5 and T6 and S4 to S6 shagreened with apical very shallow and small punctation.

Pilosity. Overall covered by long erect golden setae. Clypeus also with golden and appressed pilosity on lateral and dorsal portions. Erect setae longer on propodeum. T2 with dense golden tomentum than becomes gradually sparser on following terga. Erect setae on T4 to T6 and S4 to S6 limited to apical portion.

Fore wing length 7.4 mm.

Male. Unknown,

Distribution. Brazil ( Amazonas).

Etymology. Acromion can be translated from Greek as “top of the shoulder” and is a reference to a process in the human scapula. Interpreted as a noun in apposition.