Lichnanthe brusti Paulsen, new species

Lichnanthe brusti Paulsen, new species

Brust’s bee scarab; Fig. 2–7, 11, 14–18.

Type material. Holotype male (Fig. 2), labeled (Fig. 3): a) “ USA: WYOMING: / Carbon Co.: 25 mi NNE / Sinclair, Seminoe Dunes/42.1039 °,−106.9379 ° / 11.vii.2023; M.L.Brust ”;b)on orange paper,“ Lichnanthe / brusti ♂ /Paulsen / HOLOTYPE ”; c) “U of Nebraska / State Museum / entomology / UNSMe / 9453”. Holotype deposited at UNSM. Allotype female (Fig. 5) labeled (Fig. 6): a) as holotype; b) on orange paper, “ Lichnanthe / brusti ♀ / Paulsen / ALLOTYPE ”; c) “U of Nebraska / State Museum / entomology / UNSMe / 9454”. Allotype deposited at UNSM.

Two paratype females (CSCI, UNSM), 107 paratype males (5 CSCA, 20 CSCI, 5 CMNC, 10 DCCC, 7 FSCA, 10 NMNH, 25 UNSM, 5 UWIM, and 20 to be distributed in the future as needed) labeled: a) as holotype; b) on yellow paper, “ Lichnanthe / brusti [♂ or ♀] / Paulsen / PARATYPE ”.

Five paratype males (3 CSCI, 2 UNSM) labeled: a) “ USA: WYOMING / Carbon Co.: 14.2 mi. E / of Lamont; Ferris Dunes / 42.19474 °, −107.19905 ° / 16.vii.2022; M.L. Brust ”; b) on yellow paper, “ Lichnanthe / brusti ♂ / Paulsen / PARATYPE ”.

Description. Holotype male (Fig. 2). Length: 14.5 mm. Width: 5.8 mm at elytral humeri. Color: Integument piceous, nearly black, 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. Antennal funicle (antennomeres 2–7) light brown ventrally, and dark brown dorsally; tarsi bicolored with the antennal coloration inverted; elytral surface testaceous, macroscopically appearing striped from alternating longitudinal areas of testaceous or dark brown setae; setae fine, sparse, never forming spots or clumps. Elytral humeri with variably sized dark brown humeral spot. Head: Mandibles square, moderately angulate externally and truncate apically from above (Fig. 7). Labrum deeply emarginate anteriorly, punctate, sparsely and finely setose. Maxilla with terminal palpomere subparallel, width less than 1/2 length, apical sensory area wider than base of same palpomere. Clypeus subparallel, sides converging weakly at anterior 1/3, longer than wide, lateral margins elevated anteriorly; clypeal surface rugose, densely punctate, weakly setose; setae sparse and short. Frontoclypeal suture indistinct but with raised bump medially. Frons with moderately short setae (<1/3 length of antennal club); setae erect. Ocular canthi punctate, setose; setae longer than on frons. Antennal club elongate, distinctly longer than scape (antennomere 1). Thorax: Pronotum convex but impressed in apical half along midline; marginal bead almost entire but obsolete 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 with rounded protuberance (see Fig. 2), elytral apices otherwise gradually rounded, 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 hind tibia as in figure 31 of Carlson (1980); metatibial spurs more or less equal; dorsal channel for tarsi strongly developed. Abdomen: Genitalia (Fig. 4) not demonstrably distinct from those of other species studied, internal sac with a median spine and bird-skull shaped sclerite immediately preceding the terminal flagellum, as shown in figure 41 of Carlson (1980). The parameres of all L. brusti specimens dissected are not contiguous along the suture (Fig. 11).

Description. Allotype female (Fig. 5). Length: 16.8 mm. Width: 6.8 mm at elytral humeri.

Coloration and setation as holotype male except setation on head and pronotum relatively shorter; and abdomen distally with reddish-brown coloration reduced. The body overall appears to be more robust, especially the shorter and rounder metafemora. The antennal club is much shorter than in the male, just slightly longer than scape. On the pronotum the impunctate areas near posterior-lateral corners are markedly larger, and the marginal bead is apparently entire near the scutellum. The elytra of the allotype female display discoloration from being stored in isopropyl alcohol.

Variation in males. Paratype males (n = 111) differ from the holotype as follows. Length: 12.0– 16.5 mm. Width: 5.1–6.3 mm. Coloration and setation as holotype male except 31% of males have a large humeral spot on the elytron, while 67% have small spots, and spot size was not consistently symmetrical. Two specimens had 4 spots due to the presence of an additional spot on each elytron nearer to the scutellum. The development of the sutural apex also exhibited interesting variation. In 58% of males the apex was produced into a bulbous rounded process as in the holotype, but the remaining 42% lacked the process and the apices were simply rounded.

Variation in females. Paratype females (n = 2) differ from the allotype as follows. Length: 12.8–15.8. mm. Width: 5.7–7.0 mm. With only two examples, the only significant difference from the allotype appears to be adult size.

Remarks. This species is light-colored and densely setose, adaptations to living in sand as seen in the coastal California species L. albipilosa Carlson and L. ursina (LeConte). However, its distribution and square mandibles make confusion with these species impossible. Specimens of L. brusti have faint but distinct longitudinal striping on the elytra formed from variation in the color of the elytral setae (see Fig. 17), and a humeral spot on the elytra.

Etymology. Brust’s bee scarab is named for Dr. Mathew Brust, professor at Chadron State College who collected the entire type series and recognized the uniqueness of the material. He is one of the most keen and dedicated collectors I know, and without his entomological knowledge and collecting expertise the species would have remained unknown and undescribed.

Distribution. The species is known from two locations in Carbon County, Wyoming, Seminoe Dune and the Ferris Dunes (Fig. 14, 18, 19).

Discussion. Brust first discovered the species in 2022, flying amid sparse vegetation in the morning at the Ferris Dunes (Fig. 14–15), although none were found there in a late afternoon visit to the same spot a year later. However, additional specimens were found flying at the nearby Seminoe Dune (Fig. 16– 18) the following morning between 8:30 and 10 a.m. (Cook 2023). Some specimens were also seen on the sand, but a focus on netting flying specimens may account for the skewed sex ratio and support a previous study that found that females fly only infrequently. A three-year study of Lichnanthe rathvoni sex ratios by Carlson (1977) found that a large sample (n = 2660) of flying adults was skewed to 93% males, while the sex ratio of pupa excavated from the sandy substrate did not differ from 50:50. Although the mouthparts (especially the brushy maxillae) appear functional, dissection of the abdomen showed an atrophied digestive tract and no evidence of pollen or other food (David Hawks, pers. comm.)

With respect to the key to Lichnanthe species in Carlson (1980), males of this new species progress through couplet six due to the impunctate areas near the posterolateral corners of the pronotum, which may be minute but are always present. The unicolorous hind femora lead to couplet 8, there reaching a dead end as neither the characters of L. rathvoni or L. brachyselis Carlson pertain to this species. Females would skip to couplet 11 due to their strong pronotal anterolateral bead, to couplet 12 with abruptly dehiscent elytra. Couplet 13 cannot be passed, as the combination of a wide terminal maxillary palpomere and deeply emarginate labrum is not presented.

The key could be modified with a couplet at any point distinguishing square, apically truncate mandibles (L. brusti and the new species below) from oval mandibles with rounded apices (all other species), regardless of sex. The two new species could be distinguished from each other therein by the density and length of setae on the head (Fig. 7–8) and the presence of a dark humeral spot on the elytra in L. brusti.