Agathidium rotundulum Mannerheim, 1852

MILLER, KELLY B. & WHEELER, QUENTIN D., 2005, Slime-Mold Beetles Of The Genus Agathidium Panzer In North And Central America, Part Ii. Coleoptera: Leiodidae, Bulletin of the American Museum of Natural History 2005 (291), pp. 1-167 : 53-54

Agathidium rotundulum Mannerheim Figures 11 , 72, 73 , 91

Agathidium rotundulum Mannerheim, 1852: 370 ; Horn, 1880; Leng, 1920; Fall, 1934b.

Agathidium kincaidi Hatch, 1936: 39 ; 1957 (synonymized with A. rotundulum ).

TYPE MATERIAL: Agathidium rotundulum : Lectotype (designated here to fix this name with the species), Ƌ in MCZC labeled ‘‘95/ Type 7945 [red label]/ A rotundulum Sitkha Mannh. [handwritten]’’.

Agathidium kincaidi : holotype, ♀ in USNM labeled ‘‘Loveland, Wash. April 8, 1913 / TYPE Ƌ Agathidium (Neoceble) kincaidi 1935 —M.H. Hatch [handwritten, red label]’’.

TYPE LOCALITY: Agathidium rotundulum : United States, Alaska. Agathidium kincaidi : United States, Washington, Loveland.

DIAGNOSIS: This species differs from other members of the group by its small size (TBL <2.2 mm), concolorous elytra, the anterior clypeal margin extending approximately to level of anterolateral margins of frons, antennomere II subequal in length to III, the male metasternal fovea absent, the male left mandibular horn absent, the median lobe of the aedeagus in lateral aspect with a very large basal portion and the apical portion moderately long, straight, and apically slightly expanded and rounded (fig. 73). The female tarsi are 4­4­4.

DESCRIPTION: Body small (TBL = 1.78– 2.12 mm), rotund (PNW/TBL = 0.50–0.52), laterally broadly rounded, moderately strongly contractile.

Head piceous, clypeus red; pronotum redbrown, yellow along margins; elytra redbrown; venter dark red­brown to yellow­red; antennae and palpi yellow­brown; legs yellow­red.

Head broad (MDL/OHW = 0.65), dorsally flattened, with prominent medial crease; temporum very short, inconspicuous; head finely and sparsely punctate, surfaces shiny and smooth between punctures; eyes large, rounded, finely faceted; frontoclypeal suture obsolete medially; clypeal margin very slightly excavate, extending about to level of anterolateral margins of frons (fig. 11); labrum entire; antennomere ratios: length I:II: III = 1.3:1.0:0.8, width VII:VIII:IX = 1.0: 1.0:1.6. Pronotum broad (PNL/PNW = 0.57–0.62), laterally not strongly produced, anterolateral angle subquadrate, posterolateral angle distinctive, somewhat rounded; punctation similar to that of head, very fine and sparse. Elytra broad and robust, lateral margins rounded (SEL/ELW = 0.88–0.98); punctation slightly more coarse than on pronotum, but sparse, surface between punctures shiny and smooth; sutural stria absent. Mesosternum moderately concave posteriorly, without prominent lobe extending ventrally between mesocoxae, anterior portion shorter than posterior portion; medial longitudinal carina absent on anterior portion. Metasternum moderately narrow medially (MTL/ MTW = 0.22), slightly convex, setose; oblique carinae absent.

Male tarsi 5­5­4; pro­ and mesobasotarsomeres slightly expanded and with moderately large ventral field of spatulate setae; left mandible not modified; metafemur moderately slender, unmodified; metasternal fovea absent. Median lobe in lateral aspect with large, robust basal portion and submedial constriction, relatively straight distal to constriction, apical portion moderately long, straight, apically slightly expanded and rounded (fig. 73); in ventral aspect slender lateral margins subparallel, apical portion elongate­triangular, apex narrowly rounded (fig. 72); operculum broad, short, flat, apically broadly rounded (fig. 72); lateral lobes moderately broad basally, slightly curved, apically narrowly rounded and with 2 long, stout setae (figs. 72, 73).

Female tarsi 4­4­4.

DISTRIBUTION: This species occurs along the west coast of North America from Alaska south to northern California (fig. 91).

SPECIMENS EXAMINED: CANADA: Alberta: 11 mi NE Robb, 4 Aug 1985, lodgepole pine forest, FIT, RS Anderson (1, CNCI). British Columbia: Queen Charlotte Island (1, CASC) ; Monashee Mtn nr Cherryville, 10 Aug 1982, 1400–1600 m, M Sorensson (1, LUND) ; Toco , 28 Apr 1984, R and J Camenisch (2, CNCI) ; Charlotte Islands, Grahm Island , 1 mi NW Tiell, 27 Jun 1984, Sitka spruce, hemlock forest, RS Anderson (15, CNCI) ; Vancouver (5, MCZC) ; Queen Charlotte Island (1, MCZC) ; Massett, Graham Island, moss, Clark (1, MCZC) ; Vancouver Island (2, MCZC) .

UNITED STATES: Alaska: Seward, 26 Jun 1984, mature poplar­spruce, malaise­FIT, S and J Peck (1, PECK). California: Santa Cruz Mts (1, MCZC) ; Amador Co.: 1 mi W Pine Grove , 24 Jun 1975, leaf litter, mixed hardwood conifer forest, A Newton, M Thayer (1, MCZC) ; Del Norte Co.: Crescent City , 1 Mar 1978, pine duff, Berlese, TR Haig (12, FGAC) ; Humboldt Co.: Kneeland , 9 Jan 1980, redwood duff, Berlese, TR Haig (3, FGAC) ; Blue Lake , 21 Oct 1977, redwood duff, Berlese, TR Haig (16, FGAC) ; Orick, 29 Oct 1976, redwood duff, Berlese, TR Haig (25, FGAC). Oregon: Linn Co.: 32.5 mi S Sweet Home, 20 Oct 1967, Abies , spruce, pine, hemlock duff, Malcolm (1, CUIC). Washington: Jefferson Co. : 20 km NE Kalaloch, 1 Sep 1982, M Sorensson (4, LUND) .

DISCUSSION: Agathidium rotundulum and A. kincaidi are synonyms based on our examination of the type specimens and following Hatch (1957).

This species has been collected from various forest habitats including redwood, lodgepole pine, poplar­spruce, Sitka sprucehemlock, etc. Altitude records are from 1400 to 1600 m.

Figures

Figs. 3–16. Agathidium concinnum­ and A. pulchrum­group species. 3–15. Heads, dorsal aspect: 3, A. akallebregma. 4, A. hatchi. 5, A. concinnum. 6, A. laetum. 7, A. athabascanum. 8, A. columbianum. 9, A. rusticum. 10, A. repentinum. 11, A. rotundulum. 12, A. atronitens. 13, A. oregonense. 14, A. hamulum. 15, A. politum. 16, A. rusticum, left antenna, dorsal aspect. Bars = 0.5 mm, except fig. 16 bar = 0.25 mm.

Figs. 70–85. Agathidium pulchrum­group species, aedeagus: 70, 71, A. marae: 70, ventral; 71, lateral. 72, 73, A. rotundulum: 72, ventral; 73, lateral. 74, 75, A. aristerium: 74, ventral; 75, lateral. 76, 77, A. atronitens: 76, ventral; 77, lateral. 78, 79, A. oregonense: 78, ventral; 79, lateral. 80, 81, A. picipes: 80, ventral; 81, lateral. 82, 83, A. hamulum: 82, ventral; 83, lateral. 84, 85, A. politum: 84, ventral; 85, lateral.

Fig. 91. Geographic distribution of Agathidium pulchrum­group species: A. aristerium = ^; A. marae = *; A. rotundulum = •.