Agathidium cavisternum Fall

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 : 72-74

Agathidium cavisternum Fall Figures 100 , 141–148

Agathidium cavisternum Fall, 1934: 111 ; Hatch, 1957.

TYPE MATERIAL: Holotype, Ƌ in MCZC labeled ‘‘Sifting moss [‘moss’ handwritten]/ Terrace BC Mrs WW Hip pisley IV­8–1924 [date handwritten]/ Ƌ/ TYPE cavisternum [‘TYPE’ underlined in red, ‘cavisternum’ handwritten]/ M.C.Z. Type 24031 [red label]/ H.C. FALL COLLECTION / HOLOTYPE, Agathidium cavisternum Fall, 1934 [red label with black line border]’’.

TYPE LOCALITY: Canada, British Columbia, Terrace.

DIAGNOSIS: This species is distinguishable from others in the group by the following character combination: body relatively large and elongate (fig. 145); punctation of head finer and less dense than on pronotum (figs. 141, 142); elytral punctation confused, without serially arranged punctures (fig. 143); with large metasternal fovea placed in a depressed area anteromedially on the metasternum (fig. 144); and aedeagus with median lobe apically slender and elongate, apex blunt (fig. 148).

DESCRIPTION: Body broadly oval, moderately dorsoventrally compressed, partially contractile (figs. 145, 146); TBL = 4.0 mm. Color reddish­brown; elytra darker reddishbrown at base approaching black, paler apically; appendages paler, slightly orange.

Head large, subquadrate, dorsoventrally flattened (figs. 145, 146); surface with moderately dense, small, irregularly distributed punctures (fig. 141); areas between punctures smooth, shiny, with irregularly distributed micropunctules; OHW/MDL = 1.3; OHW/ PHW = nearly 1.0; postocular temporum short, distinct; eye large, oval, anterolateral, conspicuous, finely faceted; supraocular ca­ rina present from lateral edge clypeal region to approximately one eye­length posterior to eye; antennomere III long, about as long as next three antennomeres combined; II:III = 1:2; antennomere VII larger than VIII, much smaller than IX; VII:VIII:IX = 0.9:1:1.7; with abrupt 3­segmented club. Pronotum large, broad, convex; posterior edge with shallow median emargination; corners broadly rounded; surface with punctation similar to that of head; punctures slightly more dense, area between as on head except with sparse, irregularly distributed, short pairs or sets of parallel microscopic impressions (fig. 142); PNW/PNL = 1.5; PNL/PNH = 1.5; PNW/PNH = 2.2. Elytra broadly oval, not sharply attenuate posteriorly; ELW/SEL = about 1.0; humeral angles obtuse, broadly rounded; punctures larger than those of head or pronotum, dense, irregularly distributed, area between smooth, shiny, with sparse mi­ cropunctules, without serial punctures (fig. 143); sutural stria present, extending from slightly forward of half elytral length to apex, apically convergent. Mesosternum carinate, with lateral oblique lines; MSL/MTL = about 1.0. Metasternum large, densely minutely alutaceous, with weak transverse rugulose lines, including in male arced line forming posterior edge of median depressed, smooth area; MTL/MTW = 0.3.

Male tarsi 5–5–4; pro­ and mesobasotarsomeres strongly expanded, with dense spatulate setae; left mandible not modified; metafemur with large tooth located about onefourth length femur before apex, with oblique line between apex of tooth and apex of femur; metasternal fovea large, located near middle in large, smooth depression, bearing long setae (fig. 144). Aedeagus with median lobe elongate, ventrally curved, apical portion relatively slender, constricted, moss’’. Other specimens have been collected from spruce and hemlock forests.

Two female specimens reported from the type locality were reported by Fall (1934), but these appear to have been returned to C.A. Frost, are not at the MCZC, and were not examined by us.

Figures

Fig. 100. Geographic distribution of Agathidium revolvens group species: A. cavisternum Fall = ·; A. falcatoperculum, n.sp. = •; A. revolvens LeConte = *; A. omissum Fall = ^.

Figs. 141–146. Agathidium cavisternum Fall: Figs. 141–143, punctation detail: 141, head; 142, pronotum; 143, elytron. 144. Male metasternal fovea. Figs. 145, 146, habitus: 145, dorsal; 146, lateral. Bars = 0.5 mm.

Figs. 147–148. Agathidium cavisternum Fall, aedeagus: 147, lateral; 148, ventral.