Aksakidion Flowers 2023, new genus
Creators: name: Flowers, R. Wills
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Aksakidion

description: Aksakidion Flowers, new genus   
Figures 1–9  
 Type species. Aksakidion odontokeras Flowers, new species, here designated.   
 Description. Male: Body oval, dorsally convex (Fig. 1). Head distinctly broader than long, width across eyes 2× length, slightly concave between eyes and mouthparts (Fig. 2), vertex with short longitudinal depression between eyes. Head with surface between punctures strongly microreticulate, frons with a narrow longitudinal depression in the middle. Clypeus shallowly concave with a narrow bead laterally, with lateral margins sulcate anteriorly; apex emarginate; antennal calli concave at antennal insertion. Eyes oval, shallowly and broadly emarginate at antennal insertion. Antenna with scape elongate oval, pedicel subglobose, shorter than scape, flagellum clavate, antennomeres 3–6 filiform with scattered appressed setae; antennomeres 7–11 robust, their segments widened apically, densely pubescent, with whorl of long erect setae at apex. Outer margin of each mandible with a long, tusk-like, erect projection, flattened on dorsal side with seta-bearing punctures (Fig. 3), apex blunt, angulate. Maxillary palpi with apical segment tapered. Prothorax distinctly wider than long, L/W = 0.44; pronotum convex, with posterior margin wider than anterior margin; anterior angles acute, directed anteriorly, posterior angles obtuse; all angles with a seta-bearing puncture; basal marginal bead present; lateral margins narrow, evenly rounded, pronotal width greatest at posterior angles; disc regularly, finely punctate, with punctures separated by a distance greater than their diameters; surface between punctures shining, weakly microreticulate medially, more densely microreticulate near antero-lateral angles. Prosternum with anterior margin concave, anterior edge of lateral arms weakly convex; finely punctate, expanded laterally behind coxae; intercoxal process with deep sulci laterally for reception of antennae (Fig. 4), posterior margin truncate. Hypomeron strongly excavated behind procoxae for reception of forelegs, sparsely punctate, with punctures separated by distance greater than diameter of a puncture, with surface alutaceous. Mesosternum between mesocoxae narrower than prosternum, flat, surface alutaceous. Metasternum smooth with numerous short yellow setae; metepisternum broad, slightly narrowed posteriorly with surface alutaceous. Legs robust, sparsely covered with short prostrate setae; all surfaces alutaceous. Femora strongly swollen in middle. All tibiae curved, expanded apically (Fig. 4), multicarinate, slightly to moderately sulcate between carinae, with setae increasing in length toward apex of tibiae. Tarsi densely and uniformly pilose beneath; basal tarsomere of fore- and middle legs triangular, not expanded, with length greater than width; second tarsomere broadly triangular, with acute apicolateral angles; third tarsomere longer than second, deeply bilobed; terminal tarsomere distinctly surpassing apex of third tarsomere; claws divergent, appendiculate. Elytra evenly punctate with punctures separated by distance slightly greater than the diameter of a puncture; surface between punctures weakly alutaceous, shining; humeri not prominent, broadly rounded, basal calli obsolete; postbasal depression lacking. Sides broadly rounded, convergent, a low lateral costa present in apical fourth; apices conjointly rounded. In lateral view (Fig. 5) elytral margin strongly sinuate with lobe in basal third. Epipleuron narrow, horizontal, tapering evenly from base to apex. Scutellum V-shaped, with base subequal to length; surface smooth, with few punctulae. Abdomen with segments decreasing in length, with appressed whitish setae laterally, surface of segments granulate. Sternum VII with lateral margins smooth, a pore-like depression in center (Fig. 6). Pygidium (Fig. 7) with longitudinal median groove narrow, extending to apical margin, median carina present on floor of median groove; pygidial surface microreticulate, lateral margins smooth. Genitalia. Basal hood lightly sclerotized; subbasal fenestra present; basal spurs small; tegmen triangular (Fig. 8–9). Female: unknown.   
 Etymology. Aksak, the beetle creator-god of the Paraguayan Enxet (Lengua) people, who lived in the vicinity of Asunción (Hawtrey 1901; Ratcliffe 2006; Smid 2016; Byrne and Lunn 2019); idion, Greek, a diminutive suffix. The gender is neuter.   
 Differential diagnosis. Aksakidion will key to Spintherophyta in Bechynĕ (1997), and closely resembles that genus in size, body shape, and sculpture of the head and prothorax. In addition to the obvious mandibular projections (Fig. 3), Aksakidion differs from Spintherophyta by having a pair of deep grooves on the prosternum for reception of the antennae (Fig. 2, 4), a transversely elongate head (in contrast to the head only slightly broader than long in Spintherophyta), all legs with tibiae broad and distinctly curved (Fig. 4) (tibiae narrower and weakly curved in Spintherophyta), and a small circular depression at the center of sternum VII (Fig. 6).   
 Remarks. Female specimens of the new genus are unknown. In the similar genera Metaparia Crotch, Dispardentium Sublett and Cook (Sublett and Cook 2021), and in Aristonoda Bechynĕ (Bechynĕ 1953), males display some degree of mandibular enlargement that is not found in the females; thus, is it probable that female mandibles of the new genus will differ from those of the male. In Metaparia and Dispardentium the mandibles in the male are asymmetrically enlarged, whereas in Aksakidion the mandibles and their projections are symmetrical.   
 Reid and Beatson (2013) described two species in two other non-eumolpine genera in which the males have dorsal projections on the mandible: one species in Chaloenus Westwood (Galerucinae: Alticini), and two in Scaphodius Chapuis (Cryptocephalinae: Cryptocephalini). These authors also reviewed the occurrence of enlarged male mandibles in Chrysomelidae and listed 191 species, of which 165 are in the subfamily Cryptocephalinae.   
 Mandibular projections aside, Aksakidion specimens somewhat resemble species of Oomorphus Curtis (Lamprosomatinae), in having antennal grooves in the prosternum and depressions on the venter for folding the legs. However, in Akaskidion the depressions are less well defined than those in Lamprosomatinae, and a pygidial groove is present in Aksakidion but lacking in all lamprosomatines.
description: Published as part of Flowers, R. Wills, 2023, Aksakidion odontokeras (Coleoptera: Chrysomelidae: Eumolpinae: Eumolpini), a new genus and species in an old collection from Paraguay, pp. 1-5 in Insecta Mundi 2023 (17) on pages 2-4, DOI: 10.5281/zenodo.10622059