Psilothrix (Psilothrix) foveicollis ( Kirby, 1837 ) Gimmel & Mayor, 2019

Gimmel, Matthew L. & Mayor, Adriean J., 2019, On the North American Species of Dolichosoma Stephens and Psilothrix Küster (Coleoptera: Melyridae: Dasytinae: Dasytini), The Coleopterists Bulletin 73 (2), pp. 395-407 : 396-404

Psilothrix (Psilothrix) foveicollis ( Kirby, 1837) , new combination

( Figs. 1–5 , 7 )

Dasytes foveicollis Kirby 1837: 243 . Type locality: “on journey from New York to Cumberlandhouse [Saskatchewan]”.

Dolichosoma foveicollis: LeConte 1866: 358 . Reported from “ Nebraska, near the Rocky Mountains, and northwards” but “ Nebraska ” here probably refers to Colorado, Wyoming, or Montana, and not present-day Nebraska, since Nebraska Territory in the 1850s and 1860s encompassed parts of presentday Nebraska, Colorado, Wyoming, Montana, South Dakota, and North Dakota.

Type Material. Holotype ( BMNH), female ( Fig. 1 ), labeled “Type [round label with red border] // N. Amer. [round label, handwritten] 5978 \ a [handwritten on underside] // Dasytes foveicollis Kirby \ N. Amer. 5978. Rev. W. Kirby. [handwritten]”. Mounted on minuten; left antennomeres 4–11, right antennomeres 9–11, left protarsus, and right foreleg missing.

Taxonomic Notes. This species was the first member of the North American fauna of Dasytinae to be described. Kirby (1837) placed it in the genus Dasytes Paykull , but LeConte (1866) later transferred it to Dolichosoma , along with Pristoscelis nigricornis Bland, 1864 [now Dasytellus nigricornis (Bland) ], based on the asymmetry of the tarsal claw appendages. However, based on the roughly quadrate (not elongate-narrow) pronotum ( Fig. 3 ), absence of scale-like pubescence and presence of erect setae on the elytra ( Fig. 2 ), and relatively short and thick median lobe ( Fig. 7E ), this species is clearly referable to Psilothrix (s. str.). From the remainder of the North American dasytine fauna, it may be distinguished by the combination of a lack of spines along the protibia, pronotum with distinct marginal bead ( Figs. 2 , 3 ), the absence of a developed elytral epipleuron ( Fig. 2 ), and asymmetrical tarsal claw appendages ( Fig. 4 ). At 4.2–6.3 mm (middorsal length of pronotum plus elytra, and excluding head), they are also the longest dasytines in North America. We directly compared this species to the common Palearctic species Psilothrix viridicoerulea (Geoffroy, 1785) ( Fig. 6 ; specimens deposited in NMPC), with which it is quite similar in habitus. Majer (1994) referred to Psilothrix as having “species that extend into the Nearctic and Afrotropical regions”, the Nearctic reference presumably represented by P. foveicollis , but he never explicitly stated the genus-species combination.

Recent molecular phylogenetic evidence suggests that Dolichosoma and Psilothrix are quite closely related genera within Dasytini ( Bocakova et al. 2012; Gimmel et al. 2019). However, given their considerable divergence in general habitus, we thought it pertinent to formalize the generic transfer to more properly reflect the affinities of the North American species.

Psilothrix foveicollis can be distinguished from the Palearctic species by the following combination of characters: bluish (not greenish or black) metallic luster ( Fig. 5 ); densely punctate but not rugosely sculptured pronotum (distinctly flat, smooth regions present among punctures; Fig. 3 ); mixture of erect and suberect black setae on the elytra ( Fig. 2 ); smooth (non-denticulate) margins of the elytral apices ( Fig. 5 ); lack of a distinct emargination on the male pygidium ( Fig. 7A ); shape of the last male abdominal ventrite ( Fig. 7B ); and by characters of the male genitalic sclerites ( Fig. 7C–F ), including the median lobe with a slightly upturned apex (in lateral view) and a lack of conspicuous sclerites within the internal sac. Illustrations of the male pygidia of Psilothrix aureola (Kiesenwetter, 1859) and P. viridicoerulea are in Liberti (2009), while illustrations of the median lobe of P. aureola and Psilothrix protensa (Gené, 1836) are in Constantin and Liberti (2011). Comparative illustrations of the male abdominal sternites and pygidia of P. aureola , Psilothrix constantini Bahillo de la Puebla and López-Colón, 2014 , Psilothrix illustris (Wollaston, 1854) , Psilothrix severa (Kiesenwetter, 1859) , and P. viridicoerulea are in Bahillo de la Puebla and López-Colón (2014). Similar modifications of ventrite 5 (sternite VII) in males, variously excavated in species illustrated in Bahillo de la Puebla and López-Colón (2014), suggest that this character may be important in defining the genus Psilothrix , and in differentiating its species.

Both sexes have a fairly distinct U-shaped frontal impression ( Fig. 5 ), but males have slightly longer and more serrate antennae. The elytra are narrower and the sutural angles slightly more projecting in males. Females have a small but distinct apical emargination on the pygidium.

Psilothrix foveicollis is the only known native Nearctic species of Dasytinae that is clearly referable to a genus also present in the Palearctic, making Psilothrix the only truly Holarctic genus of Dasytinae . There are a number of native North American species nominally included in Dasytes , but these are clearly misplaced ( Mayor 2002; MLG and AJM, personal observation); some are actually more closely related to Dasytellus Casey or Hoppingiana Blaisdell , and at least some may represent one or more new genera. However, at least one valid species of Dasytes , D. (Mesodasytes) plumbeus (Müller, 1776) , is introduced in North America (British Columbia) from the Palearctic region ( Hoebeke and Wheeler 2013).

Nomenclatural Note. The genus name Psilothrix is based on a feminine Greek noun, whereas Dolichosoma is neuter. Therefore, with the generic transfer, the epithet in D. foveicolle must change to

1.0 mm.

P. foveicollis to match grammatical gender ( International Commission on Zoological Nomenclature 1999: Article 31.2.1).

Biology. Psilothrix foveicollis apparently occurs in cool, grassy marshland, where adults may be found on inflorescences of grasses, sedges, and other flowering plants. During June 2017, the first author collected about 20 specimens by sweeping grasses and sedges in a marshy area below Jordanelle Reservoir in Wasatch County, Utah ( Fig. 8 ). One specimen was also observed visiting a flower of Thermopsis montana Nutt. (Fabaceae) , but further inspection and sweeping of dozens of additional plants of that species produced no additional dasytines. Based on the material we examined, seasonal adult activity extends from at least 27 April until 25 August, with an apparent peak in June ( Fig. 9 ). Webster et al. (2012) reported this species as occurring in salt marshes in New Brunswick. More investigation is needed to determine the precise habits and habitat of the adults.

Larvae of this species remain undiscovered, but those of the European P. viridicoerulea were first described in detail by Fiori (1971) and compared with other known larvae of Dasytinae by Constantin (1990), Constantin and Klausnitzer (1996), and Constantin and Liberti (2011). Larvae of P. viridicoerulea are aphagous in the first instar, scavengers on dead insects in the second and third instars, and bore into stems of living herbaceous plants in later instars ( Fiori 1971; Constantin 1990).

Material Examined. n = 380. CANADA: ALBERTA: McMurray , 14 July 1953, G.E. Ball (1♀, CNC) ; Grande Prairie , 11 June 1961, A. R. Brooks (466, 3♀♀, CNC) ; Calgary , 13 June 1943, E. J. Kiteley (16, 1♀, CNC) ; same except 15 July 1945 (16, CNC) ; Calgary , 16 April 1956, Carr (2♀♀, CNC) ; same except 6 June 1957 (16, CNC) ; same except 2 June 1957 (16, CNC) ; same except 2 June 1963 (16, 2♀♀, CNC) ; Township 33, Range 20, W. 4 Mer. , 10 June 1963, B. & J. Carr (16, CNC) ; Waterton , 13 July 1923, H. L. Seamans (1♀, CNC) ; Waterton Lakes National Park, km 9, Chief Mountain Highway, 4 July 1980, H. J. Teskey, 4500’ (1♀, CNC) ; same except 7 July 1980 (16, 2♀♀, CNC) ; same except 17 July 1980 (1♀, CNC) ; same except 22 July 1980, D. E. Bright (16, 1♀, CNC) ; same except mile 3, 6 June 1980, J. M. Campbell (16, 2♀♀, CNC) ; Waterton Lakes National Park , 7-12 July 1980, H.J. Teskey (1♀, CNC) ; Waterton Lakes National Park , lake at park entrance, 11 June 1980, 4200’, J. M. Campbell (266, CNC) ; same except 16 June 1980, 4400’ (266, CNC) ; same except Maskinonge Lake , 14-19 June 1980, 4200’, ex dung trap (1♀, CNC) ; Waterton Lakes National Park, meadow near picnic area on Waterton River , 12-19 June 1980, I. M. Smith, pitfall trap at edge prairie-meadow (16, CNC) ; Lethbridge , 13 June 1929, Robert Glen (1♀, CNC) ; Elkwater Lake , 12 June 1956, E.E. Sterns (2♀♀, CNC) ; Elkwater , 12 June 1956, O. Peck (16, 5♀♀, CNC) ; BRITISH COLUMBIA: Cranbrook , 15 June 1926, A. A. Dannys (266, 2♀♀, CNC) ; same except 20 June 1926 (16, CNC) ; Duncan , 20 June 1955, W. J. Brown (1566, 19♀♀, CNC) ; Duncan , 9 June 1955, R. Coyles (16, CNC) ; Jordan Meadows [Vancouver Island], 12 July 1928, W. Downes (2♀♀, CNC) ; MANITOBA: Aweme , 30 May 1911, E. Criddle (266, 1♀, CNC) ; Aweme , 27 June 1924, R.M. White (1♀, CNC) ; Onah , 9 July 1916, J.B. Wallis (1♀, CNC) ; Onah , 12 July 1918, N. Criddle (266, CNC) ; Virden , 8 July 1953, Brooks & Kelton (16, CNC) ; 5 miles SW of Shilo , 16 June 1958, R. B. Madge, floodplain community in tamarack bog (1♀, CNC) ; Carberry , 15 June 1953, Brooks & Kelton (16, 3♀♀, CNC) ; NEW BRUNSWICK: Kouchibouguac National Park , 11 July 1978, H. Goulet, 7787M (16, CNC) ; same except 14 June 1977, S.J. Miller, 5275W (1♀, CNC) ; same except 27 June 1977, 5435A (16, CNC) ; same except 31 July 1978, D. B. Lyons, 7372N (16, CNC) ; same except 16 June 1978, 70714 (1♀, CNC) ; Fredericton , 7 June 1981, L. LeSage, sweep (266, 1♀, CNC) ; ONTARIO: Ottawa, G. Horn (1♀, CNC) ; Sudbury (16, CNC) ; Sault Ste. Marie , 5-6 July 1961, G. Brumpton (1♀, CNC) ; 12 miles NE Moosonee , 1 July 1973, R. Parry & J. M. Campbell (16, CNC) ; Kirkland Lake , 17 July 1961 ,

G. Brumpton (16, CNC); North Bay , 14-15 July 1961, G. Brumpton (1♀, CNC) ; SASKATCH- EWAN: Redberry , 5 June 1959, A. R. Brooks (16, 4♀♀, CNC) ; Roche Percee , 4 July 1927, S. Criddle (266, 2♀♀, CNC) .

USA: CALIFORNIA: Siskiyou Co.: Bartle, McIntosh Ranch, near Ponderosa , 1210 m, 24 June 1976, Fisher & Orth (16, UCRC) ; COLORADO: Grand Co.: 13 mi. E of Toponas , 4 June 1969, W. E. Clark (1♀, BYU) ; Grand / Jackson Cos.: Highway 40, Rabbit Ears Pass , 15 July 1962, G. H. Nelson (16, UCRC) ; Jackson Co.: Grizzly Creek, Petersen Wildlife Preserve , 10 mi. SW of Walden, 19 May 1991, L. J. Liu (16, BYU) ; Lake Co.: Independence Pass , 12,100’, 7 July 1961, B. H. Poole, tundra (3♀♀, CNC) ; Routt Co.: Toponas , 19 June 1960, W. F. Rapp (1♀, UNSM) ; Summit Co.: Dillon , 39 38’N 106 03’W, 9000 ft., 17 June 2012, S. M. Clark (266, 1♀, BYU) ; IDAHO: Caribou Co.: Portneut River , N of Pebble, 27 April 1992, R.W. Baumann & Zenger (16, 1♀, BYU) ; Cassia Co. : Steer Basin Campground, Sawtooth National Forest , 1 August 1990, R. W. Baumann (16, BYU) ; Franklin Co.: Beaver Creek, below Beaver Creek Campground, 42 01’N 111 32’W, 8 August 2005, R. W. Baumann (16, 1♀, BYU) ; Fremont Co.: Blue Creek Reservoir, 23 July 2002, S. M. & B. D. Clark (16, BYU) ; Oneida Co.: Curlew National Grassland, Twin Springs Campground , 14 June 2004, S. M. Clark & M. H. Goodman (866, 6♀♀, BYU) ; same except 42.2632° -112.7652°, 13 May 2015, S. M. Clark (366, 3♀♀); MONTANA: Gallatin Co.: Three Forks , 18 June 1959, A. R. Gittins (1♀, UCRC) ; Jefferson Co.: Delmoe Lake , 45 59.1’N 112 21.2’W, 6120 ft., 16 July 2005, S. M. Clark & D. J. Cavan (16, 2♀♀, BYU) ; Ravalli Co.: Skalkaho Creek, Black Bear Campground , 46 09.9’N 113 55.4’W, 3400 ft., 17 August 2005, S. M. Clark (1♀, BYU) ; Silver Bow Co.: Big Hole River at Dickie Bridge , 30 May 1993, R. W. Baumann & L. J. Liu (266, 5♀♀, BYU) ; OREGON: Klamath Co.: 3 mi. SE of Odell Lake , 8 June 1941, Schuh & Gray (366, UCRC) ; Crescent, Highway 97, 4400 ft., 19 June 1972, AS-928, T. W. Fisher & R. E. Orth (1♀, UCRC) ; Wallowa Co.: Mottet Meadows, Blue Mountains , 11 June 1940, K. M. Fender & G. P. MacKenzie (266, 266, UCRC) ; SOUTH DA- KOTA: Lawrence Co.: 2 mi. SE of Cheyenne Crossing , 19 June 1968, W. E. Clark (2♀♀, BYU) ; UTAH: Box Elder Co.: Lynn , 22 June 1983, C. Riley Nelson (16, BYU) ; Raft River Mountains, Clear Creek Canyon at mouth, 15 July 1980, S. M. Clark (1♀, BYU) ; West Corinne , 12 May 1979, C. R. Nelson (1♀, BYU) ; Cache Co.: Logan Canyon , 30 June 1949, G. F. Knowlton & S. L. Wood (1♀, BYU) ; Logan , 6 July 1955, S. L. Wood, on sedge (1♀, CNC) ; same except 16 July 1955 (1♀, CNC) ; Emery Co.: Huntington Creek , 2 mi. N Engineer Canyon, 26 June 1990, S. M. Clark (266, BYU) ; Rich Co.: Logan Canyon summit, 7800 ft., 6 August 1981, G. F. Knowlton (1♀, BYU) ; Summit Co.: Smith Morehouse Creek, Ledge Fork Forest Camp, Wasatch National Forest , 16 mi. NE (mostly E) of Oakley , in Hudsonian life zone, 7800 ft., 6 July 1971, Ross Hardy (266, 1♀, UCRC) ; Echo Canyon, near Emory , 41 03.9’N 111 17.0’W, 6030 ft., 21 June 2013, S. M. Clark (666, 3♀♀, BYU) ; Soapstone Campground, Hwy. 150, 40.5782°N 111.0283°W, 2400 m, 19 July 2014, S. M. Clark (266, 4♀♀, BYU) ; Stillwater Fork Bear River, Christmas Meadow Campground , 14 July 1986, Baumann & Sargent (1♀, BYU) ; West Fork Blacks Fork River , 25 August 1983, R. W. Baumann (266, BYU) ; East Fork Black Fork River, East Fork Black Fork Campground, Uinta Mountains , 8 July 2005, R. W. Baumann (1♀, BYU) ; Utah Co.: Spanish Fork , 19 June 1960, R. Hatfield (1♀, BYU) ; Spanish Fork environs, 7 June 1977, R.C. Mower (1♀, BYU) ; Cedar Valley , Vasco M. Tanner (266, BYU) ; Provo, May 192[], Vasco M. Tanner (1♀, BYU) ; Provo environs, 5 June 1973, D. Gutierrez (16, BYU) ; Powell Slough , 4 May 1979, S. M. Clark (466, 4♀♀, BYU) ; same except 17 May 1982, A. R. Myrup (16, 1♀, BYU) ; East Utah Lake , 19 May 1979, R. C. Mower (16, 2♀♀, BYU) ; Utah Lake, Orem Marina , 4 June 1981, S. M. Clark (16, BYU) ; Utah Lake , east side, 9 June 2001, I. S. Winkler (16, BYU) ; Goshen Ponds, W. Santequin , 8 June 1991, L. J. Liu (16, BYU) ; American Fork Springs , 8 May 2001, Baumann & Winkler (966, 5♀♀, BYU) ; Jordan River near Saratoga Resort , 30 June 1998, S. M. Clark & R. W. Baumann (16, 1♀, BYU) ; Utah Lake, Provo Bay , 40 12’N 111 39’W, 9 May 2012, S. M. Clark (266, 3♀♀, BYU) ; Wasatch Co.: Strawberry Reservoir , 16 June 1989, Wells-Whiting (666, 1♀, BYU) ; same except 1 June 2002, R. C. Mower (16, BYU) ; Strawberry Reservoir, Bryants Fork , 14 June 1990, L. J. Liu (16, 1♀, BYU) ; same except 21 June 1990, S. M. Clark (366, 2♀♀, BYU) ; same except 21 June 1991, Liu & Liu (2♀♀, BYU) ; Daniels Canyon, Lodgepole Campground , 26 July 1999, I. S. Winkler (16, 1♀, BYU) ; same except K. T. Huntzinger (16, BYU) ; same except M. D. Terry (2♀♀, BYU) ; Provo River near Charleston , 40 28.9’N 111 28.3’W, 12 June 2006, S. M. Clark (566, 2♀♀, BYU) ; same except 30 June 2011 (566, 3♀♀, BYU) ; same except J. W. Quist (1♀, BYU) ; Jordanelle Wetland, below Jordanelle Reservoir , 40 34.7’N 111 25.8’W, elev. 5770 ft, 11 June 2010, S. M. Clark (266, 7♀♀, BYU) ; same except A. R. Myrup (1♀, BYU) ; Jordanelle State Park, Rock Cliff , 40 36’N 111 21’W, elev. 6170 ft, 11 June 2010, S. M. Clark (16, 1♀, BYU) ; Jordanelle Wetlands , 40 34.7’N 111 25.8’W, 30 June 2011, S. M. Clark (16, 11♀♀, BYU) ; same except elev. 5830 ft, 21 June 2013 (16, BYU) ; Jordanelle Wetlands , 40.5785 N 111.4295 W, 1770 m, 19 July 2014, S. M. Clark & L. Sekerka (16, BYU) ; same except 40.5798°N 111.4296°W, 21 May 2015, S. M. Clark & E. G. Riley (366, 6♀♀); Cottonwood Bridge, Provo River , 40.58000° -111.42946°, 1770m, 6 June 2017, sweeping marsh, M. & L. Gimmel, ML183 (766, 12♀♀, SBMNH) ; White River, 1 mile east of Soldier Summit , 9 June 1988, R.W. Baumann (1566, 9♀♀, BYU) ; WASHINGTON: Benton Co.: Richland , 11 June 1949, Francis Ritz (16, UCRC) ; WYOMING: Park Co.: Valley (A-Z Ranch ) [near Cody], 1 August 1971, Suzy Frommer (16, UCRC) ; Teton Co.: Lower Geyser Basin, Yellowstone National Park , Vasco M. Tanner (1♀, BYU) ; Hoback CG, 7.5 mi. E Hoback Jct., hwy 191, 43.27959°, -110.59935°, 25 June 2008, Pollocks (16, 1♀, ENMU) ; Uinta Co.: Fort Bridger , June 1926, Clarence Cotton (266, 2♀♀, BYU) ; same except Vasco M. Tanner (16, 1♀, BYU) .

Literature Records. CANADA: NEW BRUNSWICK: Albert Co.: Shepody N.W.A., Mary’ s Point Section , 45.7320°N, 64.6765°W, 16.VI.2004, R. P. Webster, margin of salt marsh near forest, sweeping (1 specimen) ; Gloucester Co.: near Acadian Historical Village , 47.7873°N, 65.0756°W, 29.VI.2006, R. P. Webster, inland margin of salt marsh, sweeping vegetation (6 specimens) ; Sunbury Co.: Burton, near Sunpoke Lake , 45.7662°N, 66.5526°W, 20.VI.2007, R. P. Webster, seasonally flooded marsh, sweeping vegetation (1 specimen) ; York Co.: Mazerolle Settlement , 45.8765°N, 66.8260°W, 8.VI.2008, R. P. Webster, beaver meadow, sweeping vegetation along brook margin (2 specimens) [all records in this section from Webster et al. (2012)].

Distribution. This species is reported in the literature from across Canada (Alberta, British Columbia, Manitoba, New Brunswick, Ontario, Québec) ( Bright 1991; Webster et al. 2012) and the western USA (Colorado, Idaho, Montana, Nebraska, Oregon, Washington) ( Hatch 1962; Mank 1934; Mawdsley 1999) ( Fig. 10 ), although the Nebraska record should be called into question (see above). To this we add the US states of California, South Dakota, Utah, and Wyoming and the Canadian province of Saskatchewan. Psilothrix foveicollis and H. hudsonica are the only dasytines known from east of about 95° W in America north of Mexico.

Figures

Fig. 1. Holotype (BMNH) of Dasytes foveicolle, dorsal, right lateral, and frontal views, and labels. Scale bars = 1.0 mm.

Fig. 2. Psilothrix foveicollis, male (top) and female (bottom), lateral view. Scale bars = 1.0 mm.

Fig. 3. Psilothrix foveicollis, male (left) and female (right), head and pronotum in dorsal view.

Fig. 4. Psilothrix foveicollis, right metatarsal claws, apical view. Scale bar = 0.10 mm.

Fig. 5. Psilothrix foveicollis, male (left) and female (right), dorsal (top) and frontal (bottom) views. Scale bars =

Fig. 7. Psilothrix foveicollis, male. A) Pygidium, dorsal view, B) Abdomen, apicoventral view showing emarginate ventrite 5, C) Sternite VIII (ventrite 6), D) Spiculum gastrale, E) Median lobe, right lateral view; F) Tegmen and apex of tegmen in distal view. Scale bars = 0.5 mm.

Fig. 6. Psilothrix viridicoerulea, dorsal view, specimen from Agay, France. Scale bar = 1.0 mm.

Fig. 8. Macrohabitat of Psilothrix foveicollis in Jordanelle Wetlands, Wasatch Co., Utah, June 2017. Arrow points to microhabitat among heads of grasses and sedges.

Fig. 9. Phenology of examined adults of Psilothrix foveicollis with temporal data, based on 375 total specimens across the range of the species.

Fig. 10. Map of localities for examined specimens and precise literature records of Psilothrix foveicollis. The species has also been recorded in the literature from Québec (province record only).