Lichnanthe bruneri Paulsen

Paulsen, M. J., 2024, Two new species of bumblebee scarabs (Coleoptera: Glaphyridae: Lichnanthe Burmeister) from the central United States; a new discovery in Wyoming resolves a century-old puzzle from the Nebraska Sand Hills, Insecta Mundi 2024 (33), pp. 1-11 : 8-9

Lichnanthe bruneri Paulsen , new species

Bruner’s bee scarab; Fig. 8, 10, 12–13 .

Type material. Holotype male ( Fig. 10 ) labeled ( Fig. 11 ): a) “ Dismal River / Neb. July”; b) handwritten “ Amphicoma / vulpina / Hentz / ♂ Det. Dawson ”; c) on orange paper, “ Lichnanthe / bruneri ♂ / Paulsen / HOLOTYPE ”; c) “U of Nebraska / State Museum / entomology / UNSMe / 9455” . Holotype deposited at UNSM .

Description. Holotype male ( Fig. 10 ). Length: 15.0 mm. Width: 5.4 mm at elytral humeri. Color: Integument of head and thorax piceous, nearly black, body densely clothed with long, fine, pale yellowish white setae. Pronotum, clypeus and scutellum with bronze metallic reflection. Antennal clubs and 3 distal abdominal segments orange-brown, remainder of abdomen and legs brown to light reddish brown. Antennal funicle (antennomeres 2–7) light brown ventrally, gradually becoming dark brown dorsally; elytral surface testaceous, macroscopically appearing unicolorous, setose; setae mostly testaceous but with some dark brown setae at base and on disc; setae fine, sparse, never forming spots or clumps. Elytral humeri lacking dark humeral spot. Head: Mandibles square, strongly angulate externally and truncate apically from above ( Fig. 8 ). Labrum deeply emarginate anteriorly, punctate, setose; setae moderate to long. Maxilla with terminal palpomere subparallel, width less than 1/2 length, apical sensory area wider than base of same palpomere. Clypeus widest at middle, longer than wide, lateral margins elevated anteriorly; clypeal surface rugose, densely punctate and setose; setae long. Frontoclypeal suture indistinct but with raised bump medially. Frons with long, hair-like setae (>1/2 length of antennal club); setae recumbent. Ocular canthi punctate, setose; setae shorter than on frons. Antennal club elongate, distinctly 2× longer than scape (antennomere 1). Thorax: Pronotum convex but impressed in apical half along midline; marginal bead entire, including near scutellum; pronotal disc densely punctate, densely setose with long, fine setae; posterolateral angles with small, smooth impunctate areas. Scutellum densely setose, punctate. Elytra contiguous along median suture for about 1/2 distance from scutellum to elytral apices, elytra gradually but distinctly dehiscent apically, sutural angle not produced, simply rounded, elytral apices broad. Legs: Secondary tooth of protibia large, strongly developed. First protarsomere subequal in length to next 2 collectively. Tarsal claws on all legs lacking basal tooth. Terminal oblique carina on mesotibia almost obsolete, corbels indistinct. Apex of meso- and metatibiae as in preceding species; metatibial spurs more or less equal; dorsal channel for tarsi strongly developed. Abdomen: Genitalia not demonstrably distinct from those of other species studied, however the parameral suture is straight in this species and the parameres nearly contiguous ( Fig. 12 ), while in all males of L. brusti dissected the parameres are sinuous along the suture and distinctly separated near the apices ( Fig. 11 ).

Remarks. This species is similar to L. brusti in overall coloration and the presence of square mandibles, a character unique to these two taxa within Lichnanthe as the remaining taxa have oval, externally rounded mandibles as in L. rathvoni ( Fig. 9 ). However, I do not consider these two taxa to be conspecific due to the differences discussed in the descriptions. The most striking difference is the long, dense, hair-like setae of the head of L. bruneri ( Fig. 8 ), given that over 100 examples of L. brusti all had shorter, spikier, and much less dense setae ( Fig. 7 ). This species has uniformly testaceous elytra, whereas the elytra in L. brusti appear longitudinally striped and have dark humeral spots.

Etymology. Bruner’s bee scarab is named for Lawrence Bruner, University of Nebraska professor considered a pioneer of Nebraska entomology, and collector of the single known specimen in 1889. Although Lichnanthe have been called bumblebee scarabs, most appear to be mimicking halictids, anthophorines, and andrenids (D.C. Hawks, pers. comm.), so the common name ‘bee scarab’ is suggested.

Distribution. The species is known only from Thomas County, Nebraska near the Dismal River ( Fig. 1 , 19 ).

Discussion. Unfortunately, the species has eluded rediscovery for 134 years and may possibly be extinct, especially if it is in fact tied to the presence of open sand dunes. Nebraska has the largest dune field in North America ( Muhs and Budahn 2019), and although the sand is currently grass-stabilized, the dunes were largely active 700 years ago ( Mason et al. 2004; Miao et al. 2007;). Some were mobile during the last 250 years ( Stokes and Swinehart 1997) and possibly into the mid-nineteenth century based on historical accounts ( Muhs and Holliday 1995).

Yet, after more than a century of confusion prolonged at least partially by my reluctance to entertain that a member of this mainly coastal group could occur in the middle of the continent, Nebraska boasts a native glaphyrid, and only its second endemic scarabaeoid. Although the state is approaching 300 species of scarabaeoid beetles, only one other species, the aphodiine Flaviellus gordoni (Ratcliffe) , is endemic to Nebraska ( Ratcliffe and Paulsen 2008). Both species are restricted to the Sand Hills.

My previous attempts to locate the species in Thomas County were unsuccessful, but the distribution of L. bruneri should be studied further and its conservation needs assessed. The blowouts near Plummer Ford could be seen in aerial photographs from the 1960s from the Thomas County soil survey ( Sherfey et al. 1965), but they are now entirely vegetated. New sampling should focus on the extensive blowout systems in the Sand Hills near the Dismal River to the west. If the habits of the similar Wyoming species are any indication, adults may only be active during a short period in July, and then only during the morning.

Both of these Lichnanthe species are distributed in the same areas as the endangered plant Penstemon haydenii Wats. (blowout penstemon) in Wyoming ( Heidel 2005) and in Nebraska. Perhaps the best chance to find extant populations of L. bruneri is where blowout penstemon currently survives ( Fig. 19 ). Because some Lichnanthe larvae feed at least partially on roots there may be undiscovered links between these beetles and the blowout penstemon beyond sharing a small and very limited relictual habitat.

Figures

Figure 1. Location of Plummer Ford, Thomas County, Nebraska. Map modified from Rydberg (1895) to indicate the locality (arrow) and county (highlighting).

Figure 19. Map of Lichnanthe species in selected states. Red indicates Thomas County, Nebraska, with a black dot for L. bruneri. Crosshatching indicates Nebraska counties where blowout penstemon occurs that are possible sampling areas for L. bruneri. Yellow indicates Carbon County, Wyoming, with white dots representing the two localities for L. brusti. Blue indicates counties of Colorado, Idaho, and Utah where members of the L. rathvoni complex are present.

Figures 7–13. Comparative images of Lichnanthe spp. 7–9) Heads of Lichnanthe spp. 7) Lichnanthe brustiPaulsen, new species. 8) L. bruneri Paulsen, new species. 9) L. rathvoni (LeConte), showing oval mandibles. 10) L. bruneri Paulsen, new species, holotype male, habitus. 11–12) Paramera of male genitalia, distal view. 11) L. brusti. 12) L. bruneri. 13) L. bruneri Paulsen, new species, holotype male, labels.