Andersonoplatus, Linzmeier, Adelita M. & Konstantinov, Alexander S., 2018

Linzmeier, Adelita M. & Konstantinov, Alexander S., 2018, Andersonoplatus, a new, remarkable leaf litter inhabiting genus of Monoplatina (Coleoptera, Chrysomelidae, Galerucinae, Alticini), ZooKeys 744, pp. 79-138 : 80-81

Andersonoplatus gen. n. Figs 1-35

Description.

Body length 1.62-4.00 mm, width 0.81-1.78 mm, sparsely pilose to pilose, elliptical, moderately flat to convex in lateral view. Color yellow to pale brown to dark. Apterous.

Head: hypognathous, flat to slightly convex in lateral view, generally smooth or reticulated, sparsely pubescent. Frons and vertex flat or forming a 135° angle in lateral view. Supraorbital pore small, almost indistinguishable to large, generally among other pores, bearing a seta. Antennal callus generally longer than wide, rounded to quadrate separated by long midfrontal sulcus, delineated from vertex by a shallow or deep, straight or inclined sulcus, entering interantennal space. Suprantennal sulcus well developed. Orbit narrow. Antennal socket elongatew or rounded. Frontal ridge short, wider at middle or V-shaped, usually poorly defined laterally. Anterofrontal ridge generally long, relatively tall, oblique, poorly defined. Eyes large to very small generally rounded. Clypeus long. Labrum slightly notched in middle, with six setiferous pores, four with log setae and two with short setae. First maxillary palpomere as wide as long, as wide as the second. Second maxillary palpomere twice as long as first, globose in some species. Third maxillary palpomere thinner, conical, and as long as the first. First labial palpomeres quadrate, second longer than first and, third smaller, thinner and conical. Antenna with eleven antennomeres, filiform to moniliform.

Thorax: pronotum trapezoidal, narrower than elytra, anterior margin straight, wider than posterior; posterior margin nearly straight to slightly convex; lateral margin sinuated. Anterior and posterior angle generally bearing seta, anterior angles in some species pointed outward. Surface shiny to dull, generally reticulated and with punctuation shallow and disperse to deep and well defined; pilosity short and sparse to dense. Post basal impression present, generally absent in middle, but represented by two generally shallow, rounded impressions laterally. Some species have lateral margin notched near middle. Pronotal disc flat to weakly raised. Scutellum rounded to triangular, wider than long, setose. Prosternal surface reticulated to punctuated. Prosternal intercoxal process narrow or thin, generally margined, extended posteriorly beyond coxa ending in a triangular form. Posterior end nearly twice as wide as middle. Procoxae globose. Procoxal cavities closed to narrowly open posteriorly. Mesosternum as long as prosternal process, T-shaped, straight posteriorly. Metasternum smooth, with sparse pilosity, convex in lateral view, shorter than pro- and mesosternum together; posterior margin with deep furrow medially that runs longitudinally along 1/3 of metasternum. Elytra elliptical, generally fused, truncate at apex. Elytral surface shiny, with sparse to dense semi-erect hairs. Punctures forming seven or nine striae (excluding short scutellar and marginal striae). Interspaces flat to convex. Humeral and basal calli generally absent. Epipleura wide, sinuous, nearly vertical or nearly horizontal, narrowing at elytral apex, reaching it.

Fore- and midlegs with femora slightly dilated and thickened toward apex; tibiae subcylindrical, somewhat enlarged toward apex; apex of tibiae with row of denticles; pubescence sparsely distributed. First and second pro- and mesotarsomeres similar in size, as wide as long; third tarsomere varies in length; fourth visible tarsomere as long as the first and second together. In males the first pro- and mesotarsomeres more globose. Metafemur greatly enlarged, longer than wide and longer than metatibia. Metatibia nearly straight in lateral view, curved or nearly straight in dorsal view. Outer lateral dorsal ridge ending in an apical tooth followed by numerous denticles. Inner lateral dorsal with some denticles at end, in some species ending in an apical tooth. Metatibial spur generally short. Metatarsomeres one to three variable in length, generally similar in size; third metatarsomere not bilobed; visible globose, swollen with its base elongate. Claws simple or appendiculate and long.

Abdomen: sparsely pubescent, reticulated, sparsely punctured, with five visible ventrites. Fifth ventrite variable in length, with distinct sexual dimorphism: males with small salient lobe located centrally on posterior margin and perpendicular line; females with last ventrite evenly conical at apex. Posterior margin of fourth ventrite straight to concave. Abdominal pleurites as sclerotized as ventrites.

Male genitalia: median lobe simple, convex in lateral view; in ventral view, with lateral margins almost parallel, apex subtriangular, slightly protruding into more or less differentiated denticle, in some species round on top. Basal part long and bent ventrally in lateral view.

Female genitalia: eighth tergite with rounded anterior margin, more sclerotized laterally, bearing many moderately long setae. Tignum long, narrow, with central canal; posterior and anterior sclerotization variable in shape. Vaginal palpi elongate, posteriorly and anteriorly strongly sclerotized, each with approximately eight setae at apex. Palpi narrowly rounded at apex, enlarged at last third but thinned at apex, situated close together and merged anteriorly for more than half of their length. Spermatheca curved, with receptacle and pump not differentiated from each other. Apex of pump with spoon-like projection. Spermathecal duct long, not forming coils.

Type species.

Andersonoplatus microoculus Linzmeier & Konstantinov, sp. n.

Etymology.

We dedicate this new genus to R. Anderson for his remarkable discoveries of leaf litter flea beetles in the New World. The name is masculine.

Differential diagnosis.

Andersonoplatus differs from all other known genera of Monoplatina in having the dorsoventrally flat, elliptical elytra and the pronotum being trapezoidal, usually anteriorly wider than posteriorly, much narrower than elytra with sinuate lateral margin. All the Andersonoplatus species are apterous with mostly fused elytra, lacking wings. Flightlessness is a common feature of leaf litter or other substrate living leaf beetles. Other apterous Monoplatina species are placed in Andersonaltica Linzmeier & Konstantinov, 2012, Apleuraltica Bechyne, 1986, Distigmoptera Blake, 1943 and Ulrica Scherer, 1962. Andersonoplatus can be easily differentiated from Andersonaltica in having mostly filiform antennae. Antennae in Andersonaltica are clubbed. Andersonoplatus can be differentiated from Apleuraltica and Distigmoptera based on having pronotum laterally margined with distinct border and mostly flat disc. In Apleuraltica and Distigmoptera the lateral margin of pronotum is lacking distinct border (or with very faint one in Distigmoptera ) and the disc is with two noticeable bumps separated by a longitudinal impression. Andersonoplatus can be differentiated from Ulrica by a body thinner in lateral view and the pronotum being anteriorly wider than posteriorly. In Ulrica the body is thicker in lateral view and the pronotum being anteriorly narrower than posteriorly.