A new species of Scelidopetalon Delkeskamp (Coleoptera, Erotylidae) from China with a key to world species of the genus

Abstract A new species Scelidopetalon biwenxuani sp. n. is described from China, representing the first occurrence of the genus in Hainan province. A key to the world species of this genus is provided.


Introduction
The subfamily Erotylinae includes colorful fungus-feeding beetles commonly called "pleasing fungus beetles". They are worldwide in distribution with over 2500 described species. In general, species of the tribe Tritomini are characterized by an antennal club of 3 to 5 antennomeres, dilated maxillary palpi, closed procoxal cavities (with prosternal-proepimeral suture located at the midpoint posterior to the procoxae), mesometasternal suture having a broadened dicondylic connection, and pseudotetramerous tarsi (tarsomere IV small and hidden by an expanded tarsomere III). Larvae and adults feed on larger basidiomycete fungi (e.g. mushrooms, polypore or bracket fungi, etc.).
The name "pleasing fungus beetle" is likely derived from the large size and colorful patterns of many species.
While examining Burmese specimens of Amblyopus Lacordaire, Gorham (1896) established Petaloscelis based on its small and finely facetted eyes (Fig. 1), which are large and coarsely facetted in Amblyopus (Fig. 2). Arrow (1925Arrow ( , 1926 described four additional species in Petaloscelis. While examining the African species, Arrow (1945) noted that Gorham confused African species with an Indian species and considered Petaloscelis a synonym of Amblyscelis Gorham. Delkeskamp (1957) thought Petaloscelis and Amblyscelis were distinct based on eye characters as mentioned above and on differences in tibial dilation. Because the name Petaloscelis Gorham was a junior homonym of Petaloscelis Bergoth (see Chûjô and Chûjô 1990), Delkeskamp (1957) proposed the name Scelidopetalon for the species of Petaloscelis Gorham with Petaloscelis instabilis Gorham, 1896, as the type. Araki (1941) described Pseudamblyopus for the Japanese species Amblyopus palmipes Lewis. Araki noted Pseudamblyopus is easily distinguished from Amblyopus by the small and finely facetted eyes and mentioned this genus differs from Petaloscelis in the antennal club structure. But neither Arrow nor Delkeskamp were aware of Araki's work. Thus, Scelidopetalon and Pseudamblyopus were both separated from Amblyopus based on the same characters.
Because no specimens of Pseudamblyopus are available for study, we are not treating Scelidopetalon as a synonym to Pseudamblyopus. This should be considered in future revisionary work.
Previously, a total of six species have been reported for Scelidopetalon and two species for Pseudamblyopus worldwide.

Material and methods
To examine the genitalia, the abdominal segments were detached from the body after softening in hot water. The genitalia, together with other dissected parts, were mounted in Euparal (Chroma Gesellschaft Schmidt, Koengen, Germany) on plastic slides. Photos of sexual characters were taken with a FUJIFILM X10 camera attached to an Olympus SZX 16 stereoscope; habitus photos were taken with a Canon macro photo lens MP-E 65 mm attached to a Canon EOS7D camera.
The specimen treated in this study is deposited in the following public collection: SNUC Department of Biology, Shanghai Normal University, P. R. China taxonomy

Scelidopetalon Delkeskamp and Pseudamblyopus Araki
Diagnosis. These two genera can be distinguished from other Tritomini genera by eyes small and finely facetted (Fig. 1). Tibiae (Fig. 8) triangular, with the extremities very broad and hollowed for the tarsi. Prosternal lines of prosternum (Fig. 7) short, not extending in front of procoxal cavities. These three characters have not existed together in other genera of Tritomini. The distinct difference between species of these two genera is antennal club structure. Most species of Scelidopetalon with antennomere XI much broader than long, one species of Scelidopetalon and all the species of Psudodamblyopus with antennomere XI almost as long as broad.

Key to world species of genus Scelidopetalon and Pseudamblyopus
Parts of the following key were taken from Arrow (1925).  Description. Body (Fig. 3, 4) oval, convex, shining; length: 6.50 mm; width: 3.79 mm. Body black; legs, palpi and antennae reddish-brown. Elytron black, with red at basal third.
Pronotum transverse, convex above, widest at base (pl/pw = 0.70); anterior angles weakly projecting; lateral margins gently curved toward eyes. Pronotum distinctly punctured medially, finely and closely punctured laterally. Prosternum (Fig. 7) strongly punctured, the front margin is produced to a short point in the middle, prosternal lines short, not extending in front of procoxal cavities; Mesosternum coarsely punctured. Metasternum coarsely punctured at the sides and almost smooth in the middle, with distinct coxal lines. Abdomen fairly strongly and closely, its sides coarsely, punctured, with distinct coxal lines on first ventrite nearly attaining posterior margin.
Scutellum pentagonal, finely and sparely punctured. Legs short, tibiae triangular, with the extremities very broad and hollowed for the tarsi. Elytra widest at middle, then gradually narrowing to apex; each with 9 punctate lines. Female genitalia ( Fig. 9) with gonostyli fringed apically with some elongate setae; female spermatheca ( Fig. 6) with capsule almost egg-shaped.
Distribution. China (Hainan Province). Diagnosis. The new species can be distinguished from other species in this genus by the black pronotum and red markings of the elytra.