Ashea megacephala Kim & Ahn (Coleoptera, Staphylinidae, Aleocharinae), a new gyrophaenine genus and species from Peru

Abstract Ashea megacephala, a new Peruvian genus and species is described. The specimens were collected on mushrooms and mushroom-associated trees. This genus can be readily distinguished from the other genera of the subtribe Gyrophaenina by the large head and the three indistinctly articulated labial palpomeres. A key to the known genera of Gyrophaenina is provided. A habitus photograph and illustrations of diagnostic characters are also presented.


Introduction
The subtribe Gyrophaenina Kraatz contains 833 species in 21 genera worldwide Thayer 2005, Ashe 2007) and most are obligate inhabitants of fresh mushrooms in the larval and adult stages (Ashe 1984). Members of Gyrophaenina are characterized by the following characters: lacinia truncate at apex with well-developed spinose area, spines and setae reduced on inner margin of lacinia; labial palpus with two palpomeres, non-styliform, one medial seta on prementum; mesocoxal cavities broadly separated, broad meso-and metaventral processes not joined by isthmus but meeting along broad suture (Ashe 2001).
During an ongoing worldwide revisionary study of the Homalotini, a series of small specimens were found in the Snow Entomological Museum Collection, Lawrence, USA, each with very large head. After detailed study of the specimens, we conclude that this is a new genus and species belonging to Gyrophaenina.
In this paper, Ashea megacephala gen. n. and sp. n. is described and a key to the known genera of Gyrophaenina is provided, as well as a habitus photograph with illustrations of diagnostic characters.

Methods
Specimens were dissected in water and mounted on sticky carbon tape. They were dried at 60 °C on a slide warmer for 24 h, sputter-coated with Pt/Pd nanoparticles using a sputter coater (208 HR, Cressington Scientific Instruments, Watford, Hertfordshire, UK), and examined with SEM (S-4800, Hitachi High-Technologies, Tokyo, Japan). Descriptive terms used here follow Ashe (1984). Holotype and six paratypes are deposited in Snow Entomological Museum Collection (SEMC), University of Kansas, Lawrence, USA. Six paratypes are deposited in the Chungnam National University Insect Collection (CNUIC), Daejeon, Korea.
Etymology. Named after the late James S. Ashe in honor of his research on the subtribe Gyrophaenina. He was the first collector of these beetles.
Distribution. Peru. Remarks. Ashea gen. n. can be distinguished from other gyrophaenine genera by the diagnostic characters presented above. Especially, the combination of the large head and indistinctly articulated three labial palpomeres clearly makes this new genus unique among all other Gyrophaenina.
Ashea gen. n. belongs to the "Gyrophaena" lineage (sensu Ashe 1984) based on the following characters: body slightly pubescent; ligula entire apically, prementum with a single medial seta. Among the lineage, this genus is probably the most closely related to Eumicrota Casey. These two genera share a small body size, entire and protruded ligula, markedly transverse pronotum, mesoventrite without medial longitudinal carina, tergite X with medial setose area arranged in distinct V-shape, and median lobe with apical process slender and elongate.
Tergite X provides useful characters in the study of the subtribe Gyrophaenina classification (Ashe 1984). Loss of setae antero-medially and postero-laterally results in one or a few rows of setae arranged in a distinct "V" shape. This distribution of microsetae is found only in Eumicrota and Ashea gen. n.
On the other hand, the genus Ashea gen. n. differs from Eumicrota by the following diagnostic characters: head very large, as wide as and distinctly longer than pronotum; right mandible with very large median tooth; labial palpus with three indistinctly separated palpomeres.
We have not had the opportunity to study any specimens of the following three gyrophaenine genera (Brachycantharus Bierig, Microbrachida Bierig, Neobrachychara Bierig) described from Central America by Bierig (1939). Original descriptions of these genera did not include sufficient diagnostic characters and they have not been redescribed since their original description. However, Bierig (1939) provided very clear scientific habitus illustrations and they can be easily distinguished from Ashea gen. n. by the following diagnostic characters: body subparallel-sided in Ashea (body elongated-oval, sides of abdomen convergent to apex in Microbrachida); pronotum strongly transverse in Ashea (pronotum moderately transverse in Brachycantharus); tergite X with medial setose area arranged in distinct V-shape in Ashea (tergite X with medial setose area arranged in chevron-shape in Neobrachychara). Description. Body length 1.0-1.4 mm. Head. Very large, slightly transverse and flattened, as wide as and distinctly longer than pronotum; eye large, longer than temple, length ratio of eye to temple 1.56; antennomere 1 longest, about 2.8 times as long as wide, 2 about 1.5 times as long as wide and 1.5 times as long as 3, 3 about 1.4 times as long as wide, 4 about 1.4 times as wide as long, 5 about 1.1 times as wide as long, 6-7 about 1.2 times as wide as long, 8-9 about 1.3 times as wide as long, 10 about 1.36 times as wide as long, 11 about 1.4 times as long as wide (Fig.  3). Mouthparts. Labrum (Fig. 4) markedly transverse, about 2.3 times as wide as Figures 8-13. Ashea megacephala, SEM photographs: 8 pronotum, dorsal aspect 9 tergite X, dorsal aspect 10 median lobe, lateral aspect 11 paramere, lateral aspect 12 male elytron, dorsal aspect 13 male tergite VII, dorsal aspect. long; mandible (Figs 5-6) about 1.5 times as long as basal width, ventral condylar molar patch moderate in size, about 0.3 times of basal width; maxillary palpomere 2 (Fig. 7) about 2.3 times as long as wide, 3 about 2.25 times as long as wide and about 1.4 times as long as 2; prementum ( Fig. 14) with medial seta distinctly longer than ligula. Thorax. Pronotum (Fig. 8) markedly transverse, more than 2.0 times as wide as long, widest at middle; mesoventral process ( Fig. 15) extended to about half of mesocoxal cavities. Genitalia. Spermatheca (Fig. 16) simple and round at base; median lobe ( Fig. 10) bulbous at base, apical process long, slender and recurved subapically, flagellum long, slender and more or less whip-like; paramere ( Fig. 11) with apical lobe of paramerite short and subcylindrical with four setae, basal two distinctly longer than others, paramerite enlarged, slightly longer than apex of condylite. Secondary sexual characteristics. Male: elytron ( Fig. 12) with tubercle at near suture about 0.2 length of elytron from posterior margin; subapical margin of tergite VII (Fig. 13) with two tooth-like tubercles; posterior-medial margin of tergite VIII (Fig. 17) with triangular projection.

Ashea megacephala
Distribution. Tambopata, Peru. Etymology. Named from the Greek mega meaning "large" and cephalus meaning "head", which refers to large head.
Remarks. Specimens were collected on mushrooms and/or mushroom associated trees in Peru.