Agathidium conjunctum Brown

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 : 79-81

Agathidium conjunctum Brown Figures 102 , 157–165

Agathidium conjunctum Brown, 1933: 46 ; Fall, 1934.

Agathidium obtusum Hatch, 1957: 36 . NEW SYN­ ONYM.

TYPE MATERIAL: Agathidium conjunctum : holotype, Ƌ in CNCI, labeled ‘‘Langley B.C. 7.III 1931 / K.Graham [handwritten]/ HO­ LOTYPE Agathidium conjunctum Brown, 1933 [red label with black line border]’’.

Agathidium obtusum : holotype not examined.

TYPE LOCALITY: Agathidium conjunctum : Canada, British Columbia, Langley.

Agathidium obtusum : Canada, British Columbia, Creston.

DIAGNOSIS: This species is distinguished from others in the group by the elongate oval body, the elytra dorsoventrally compressed (figs. 161, 162), the punctures of the head similar in density to those of pronotum (figs. 157, 158), the elytron without serial series of punctures, punctation dense, confused (fig. 159), the male metasternal fovea small, circular (fig. 160), and the aedeagus with the apex of the median lobe arrowhead­shaped with a median ventral ridge (figs. 164, 165).

DESCRIPTION: Body broadly oval, contractile, moderately convex (figs. 161, 162); TBL = 2.0– 2.5 mm. Color dark reddish­brown, nearly black; clypeal region, perimeter of pronotum, mouthparts, and appendages slightly paler.

Head broad, subquadrate, dorsoventrally flattened (figs. 161, 162); OHW/MDL = 1.6; OHW/PHW = 1.1; dorsal surface with moderately dense, shallow punctures (fig. 157), surface between shiny but with microscopic, sparse punctules and slightly alutaceous; clypeal suture absent; eyes large, slightly protruding; postocular temporum distinct, short; antennomere III long, about as long as IV + V + VI; length II:III = 1:3; VII slightly broader than VIII; width VII:VIII:IX = 1: 1:2.1. Pronotum broad, convex; PNW/PNL = 1.6; PNL/PNH = 1.4; PNW/PNH = 2.2; without defined posterior angles, slightly emarginate posteromedially; surface with punctation similar to head (fig. 158). Elytra broad, but longer than wide, moderately dorsoventrally flattened; dorsal surface with dense, irregular punctures only slightly larger than those of head and pronotum (fig. 159), surface between as on head and pronotum, including subalutaceous microscopic pattern; sutural stria present, strongly impressed, complete. Mesosternum horizontal, with median carina; surface densely alutaceous. Metasternum surface alutaceous, pattern dense laterally. MSL/MTL = 0.7; MTL/MTW = 0.4.

Male tarsi 5–5–4; with pro­ and mesobasotarsomeres moderately expanded; left mandible unmodified; metasternal fovea small, round, with fine setae, in smooth impunctate area anteromedially (fig. 160); metafemur gradually widened into blunt, subapical, posterior tooth defined on apical side only. Aedeagus long, narrow, curved, apical one­fifth abruptly narrowed, ventrally curved but arched slightly dorsally (fig. 163); median lobe narrowed, distinctly spatulate near apex, apex pointed, with ducts obliquely fanning to each side of midline (figs. 164, 165); ventral operculum deeply emarginate, each branch long, parallel­sided, and truncate, pores sparse and irregular except moderately dense in apical transverse line (fig. 165); lateral lobes nearly as long as median lobe, enlarged in apical fifth in ventral aspect, with two large subapical setae (figs. 163, 164).

Female not observed.

DISTRIBUTION: This species was recorded by Fall (1934) from British Columbia, Washington, ‘‘W.T.’’ (Washington Territory?), and Nevada. In this study, numerous specimens were examined from southern British Columbia south to extreme southwestern California and east to southwestern Montana (fig. 102).

SPECIMENS EXAMINED: ‘‘W.T.’’ [probably Washington Territory] (2, MCZC).

CANADA: British Columbia: Trinity Valley , 14 May 1929, JR Howell (1, CASC) ; Midday Valley, Merritt , 14 May 1925, J Stanley (1, CASC) ; Lorna , 10 Jul 1925, Pinus contorta, H Richmond (1, MCZC) ; Trinity Valley , 1 Jun 1928 (1, CASC) .

UNITED STATES: California: Calistoga , 12 Jul 1934, Bryant (1, CASC) ; Poway , FC Bowdin (1, MCZC) ; Butte Co.: Feather Falls , 16 May 1971, DS Chandler (1, CASC) ; Feather Falls , 16 Feb 1971 , RF Lagler (1, WSUC) ; Feather Falls , 16 May 1971, DS Chandler (1, QDWC) ; El Dorado Co.: 3 mi W Grizzly flat, 24 Mar 1982, on polypore slimemold under oak bark, F Andrews (5, FGAC) ; 2 mi NE Riverton , 30 Nov 1976, un­ der bark of Pinus, F Andrews (1, FGAC) ; 0.5 mi N Stumpy Meadows Lake , 20 Apr 1989, 4200′, litter from Quercus kellogi, F Andrews, T Eichlin (6, FGAC) ; 1 mi W Grizzly Flat , 24 Mar 1982, under oak bark, F Andrews (10, FGAC) ; Lake Co.: Adams Springs , 24 Apr 1976, under bark, JF Lawrence (3, MCZC) ; Marin Co.: 2 mi N Taverness , 23 Mar 1965, WJ Turner (1, WSUC) ; Pt Reyes Natl Seashore, Mt Vinson overlook, 29 Nov 1977, F Andrews (2, FGAC) ; Mendocino Co.: UC Hopland Field Station nr HQ, 13 Apr 1968, malaise, WJ Turner (2, WSUC) ; Nevada Co.: Sagehen Crk , 15 Jul 1970, DS Chandler (1, CASC) ; Sagehen Crk , 24 Jun 1970, DS Chandler (1, CASC) ; Sierra Co.: 9 mi W Alleghany , 4 Apr 1985, under logs, Pinus sabiniana, F Andrews , A Hardy (2, FGAC) ; Trinity Co.: 5 mi W Coffee Crk Ranch , 19 Jun 1972, pine duff, DS Chandler, DP Levin (1, CUIC) ; Yuba Co.: Sierra Foothill Field Station 3 mi N Smartville, 3 May 1980, Quercus litter, JT Doyen (9, CASC). Idaho: Latah Co. : Moscow Mt, 28 Apr 1973, WJ Turner (2, WSUC). Montana: Gallatin Co. : Bozeman Crk (1, MTEC). Nevada: state only (1, MCZC). Oregon: state only (1, MCZC) ; Jackson Co.: Soda Mt Rd , 7 mi S 13 mi E Ashland, 15 Oct 1972, under willow bark, E Benedict (1, PECK) ; Umatilla Co.: 25 km E Ukiah, Frazier Camp , 25 Aug 1982, M Sorenson (1, LUND) ; Wallowa Co.: Wallow Pk St Prk , 8 Jun 1921, under bark, D Ferro (1, WSUC). Washington: Seattle, OB Johnson (1, WSUC) ; Seattle , 4 May 1912 (2, MCZC) ; Chelan Co.: Squillchuck St Pk , 8 mi SSW Wenachee, 14 May 1983, 2900′, WJ Turner (7, WSUC) ; Columbia Co.: Tucannon Riv. 22 mi S Mareugo Umatilla NF, 18 May 1974, under bark of Pinus ponderosa, WJ Turner (2, WSUC) ; Whitman Co.: 8 mi SW Pullman, Lyle Grove , 14 Apr 1974, JA Logan (1, WSUC) .

DISCUSSION: Agathidium obtusum Hatch is synonymized here with this species based on Hatch’s (1957) description and illustration of the ventral view of the aedeagus. His specimens appear to fit well within the range of variation observed for A. conjunctum . Hatch’s (1957: pl. IV, fig. 20) concept of A. conjunctum appears to actually refer to A. omissum based on the key and his illustration of the male genitalia.

Agathidium conjunctum has been collected frequently under bark of various trees, including pine and oak. It has also been collected from various litter types, including oak leaf litter and pine duff. Elevation records are from 2900 to 4200 ft.

Agathidium angustoperculum Wheeler and

Figures

Figs. 101–103. Geographic distribution of Agathidium revolvens group species: 101, A. virile Fall;

Figs. 157–162. Agathidium conjunctum Brown: Figs. 157–159, punctation detail: 157, head; 158, pronotum; 159, elytron. 160. M male metasternal fovea. Figs. 161, 162, habitus: 161, dorsal; 162, lateral. Bars = 0.5 mm.

Figs. 163–165. Agathidium conjunctum Brown, aedeagus: 163, lateral; 164, ventral; 165, apex of median lobe, ventral.