Agathidium

WHEELER, QUENTIN D. & MILLER, KELLY B., 2005, Slime-Mold Beetles Of The Genus Agathidium Panzer In North And Central America, Part I. Coleoptera: Leiodidae, Bulletin of the American Museum of Natural History 2005 (290), pp. 1-95 : 37-39

AGATHIDIUM

1. Mesosternum subhorizontal, in approximately same plane as metasternum (fig. 43)... 2

— Mesosternum concave posteriorly, anterior portion clearly in different plane from metasternum (fig. 46)................. 4

2(1). Size extremely small (TBL = 1.15–1.51 mm); tarsal formula 4–4– 3 in both male and female; without oblique femoral carinae on metasternum; male without me­ tasternal fovea; southern Mexico (this group based on an undescribed species to be treated in part 2 of this revision)......................... A. iota group

— Size larger (TBL = 1.76–5 mm); tarsal formula Ƌ 5–5–4, ♀ 5–4–4; with or without oblique femoral carinae on metasternum; male generally with metasternal fovea though it may be small; widespread.. 3

3(2). Body highly contractile (fig. 51); metasternum with paired oblique femoral carinae which often meet medially along posterior margin (fig. 48), though these carinae may be indistinct; usually dorsally impunctate or nearly so; humeral angle of elytron broadly rounded............................ A. oniscoides group

— Body moderately contractile (fig. 50); me­ tasternum without paired oblique femoral lines or with faint traces; frequently with conspicuous, confused dorsal punctation; humeral angle of elytron angulate.................... A. revolvens group

4(1). Clypeus distinctly protruding beyond anterolateral margins of frons, with onethird to one­half of clypeus occuring beyond sides of front of cranium (fig. 44); body not strongly convex dorsally nor contractile...... A. sexstriatum group

— Clypeus not or only slightly protruding beyond anterolateral margins of frons, at most with less than one­third of clypeus protruding beyond sides of front of cranium; body generally dorsally convex and moderately to strongly contractile... 5

5(4). Metasternum extremely short, meso­ and metacoxae nearly touching; male often with prominent mandibular horn (figs. 80, 81); anterior portion of mesosternum moderately broad along center line compared to posterior portion, but without longitudinal carina medially, posterior portion of mesosternum moderately concave; western United States...................... A. brevisternum group

— Metasternum not extremely shortened, meso­ and metacoxae at least moderately separated by metasternum; male mandibular horn present or absent; anterior portion of mesosternum generally much shorter than posterior portion, if broad then with prominent longitudinal carina medially; widespread............. 6

6(5). Postocular temporum long and prominent, when viewed in dorsal aspect extending lateral margin of head posterad of eye about 0.5 to 1.0 times eye length at which point head is narrowed (fig. 47), in some species protruding very prominently laterally beyond eye in rounded bulge when head viewed in dorsal aspect (fig. 47).................. A. concinnum group

— Postocular temporum short, extending lateral margin of head posterad of eye less than 0.5 times eye length in dorsal aspect (fig. 44), head narrowed immediately posterad of eye..................... 7

7(6). Mesosternum moderately concave posteriorly, anterior portion as broad as or broader along center line than posterior portion and with prominent longitudinal carina medially; metasternum relatively short (MTL/MTW = 0.12–0.16); without horn on male left mandible; male metasternal fovea generally very large and sit­ uated slightly posterad of middle................. A. compressidens group

— Mesosternum generally strongly concave posteriorly, rising nearly vertically between mesocoxae, anterior portion narrower along center line than posterior portion and usually without prominent longitudinal carina medially; metasternum relatively broader (MTL/MTW = 0.19–0.40); with or without horn on male left mandible; male metasternal fovea generally smaller and situated medially or slightly anterad of middle........................... A. pulchrum group