Agathidium columbianum Fall

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 : 49

Agathidium columbianum Fall Figures 8 , 64, 65 , 89

Agathidium columbianum Fall, 1934b: 121 ; Hatch, 1957.

TYPE MATERIAL: Holotype, Ƌ in MCZC labeled ‘‘Terrace, B.C. Mrs. M. E. Hippisley 1932 [number handwritten]/Ƌ/ TYPE columbianum [name handwritten, red line under ‘‘TYPE’’]/M.C.Z. Type 24032 [number handwritten, red label]/H.C. FALL COL­ LECTION / Agathidium columbianum Fall. [handwritten, red line around border]’’. Only the single holotype specimen of this species is known.

TYPE LOCALITY: Canada, British Columbia, Terrace.

DIAGNOSIS: This species differs from other members of this group by the concolorous, light brown dorsal surfaces, the anterior clypeal margin convex and extending distinctly, but not greatly, beyond the anterolateral margins of the frons (fig. 8), the mesosternum without a ventrally extending, flattened lobe between the mesocoxae, males without a left mandibular horn, the median lobe of the aedeagus in lateral aspect with the apex pointed and straight (fig. 65), and the operculum rounded without apical emargination (fig. 64). Agathidium columbianum is most similar to A. athabascanum , but that species has the apex of the median lobe of the aedeagus sharply pointed and strongly curved dorsad (fig. 65) and the operculum is apically distinctly emarginate (fig. 64).

DESCRIPTION: Body large (TBL = 2.74 mm), robust (PNW/TBL = 0.49), broadly rounded, moderately contractile.

Head, pronotum, and elytra yellow­brown to yellow­red; venter yellow to yellowbrown; antennae and palpi yellow; legs yellow to yellow brown.

Head broad (fig. 8) (MDL/OHW = 0.61), somewhat convex, without transverse, medial crease; temporum short, often forming distinct rim at posterior margin of eye (fig. 8); head finely punctate, punctures sparse, only one size present; eyes large, rounded, finely faceted; frontoclypeal suture moderately well defined medially; clypeal margin curved, extending distinctly beyond anterolateral margins of frons (fig. 8); anterior margin of labrum entire; antennomere ratio: length I:II:III = 1.8:1.0:1.6. Pronotum broad (PNL/PNW = 0.56), laterally not strongly produced, anterior margin not strongly concave, anterolateral angle subquadrate, posterolateral angle distinctive, but rounded; punctation and surface microsculpture similar to those of head. Elytra robust, broad (SEL/ELW = 1.13); coarsely punctate, more dense apically, not in series, with fine irregular microreticulation on surfaces between punctures; sutural stria about one­half length of elytron on most specimens. Mesosternum strongly concave posteriorly, without prominent lobe extending ventrally between mesocoxae, anterior portion less than one­half length of posterior portion; medial longitudinal carina absent on anterior portion. Metasternum relatively broad medially (MTL/ MTW = 0.34), slightly convex, setose; oblique carinae absent.

Male tarsi 5­5­4; pro­ and mesobasotarsomeres slightly expanded and with small ventral field of spatulate setae; left mandible unmodified in all specimens examined; metafemur very slender, otherwise unmodified; metasternal fovea small, slightly anterad of middle, slightly transverse with small brush of fine, dense setae. Median lobe in lateral aspect robust, with large basal region and subbasal constriction, broad and slightly curved distad of constriction, apical portion long, slender, directed dorsad and nearly straight (fig. 65); in ventral aspect broad, lateral margins subparallel, apical portion broad, slightly acuminate to sharp apex, orifice large (fig. 64); operculum fused to proximal margin of orifice, long, flat, slightly expanded, apex broadly truncate, not emarginate (fig. 64); lateral lobes long, slender, curved basally, apex narrowly rounded with 2 long setae (figs. 64, 65).

Female unknown.

DISTRIBUTION: This species is known only from the type locality in British Columbia (fig. 89).

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. 52–69. Agathidium pulchrum­group species, aedeagus: 52, 53, A. difforme: 52, ventral; 53, lateral. 54, 55, A. maculosum: 54, ventral; 55, lateral. 56, 57, A. pulchrum: 56, ventral; 57, lateral. 58, 59, A. amae: 58, ventral; 59, lateral. 60, 61, A. laetum: 60, ventral; 61, lateral. 62, 63, A. athabascanum: 62, ventral; 63, lateral. 64, 65, A. columbianum: 64, ventral; 65, lateral. 66, 67, A. rusticum: 66, ventral; 67, lateral. 68, 69, A. repentinum: 68, ventral; 69, lateral.

Fig. 89. Geographic distribution of Agathidium pulchrum­group species: A. athabascanum = -; columbianum = *; A. laetum = •; A. rusticum = ^.