Leptomorphus nebulosus (Walker)

Borkent, Christopher J. & Wheeler, Terry A., 2012, Systematics and Phylogeny of Leptomorphus Curtis (Diptera: Mycetophilidae) 3549, Zootaxa 3549, pp. 1-117: 46-48

publication ID


publication LSID


persistent identifier


treatment provided by


scientific name

Leptomorphus nebulosus (Walker)


22. Leptomorphus nebulosus (Walker)  

( Figures 24–27, 63–64, 83, 111, 125,128,129, 131, 144, 150, 154)

Diomonus nebulosus Walker, 1848: 87   .

Leptomorphus nebulosus: Edwards, 1925: 556  

Leptomorphus subcaeruleus gurneyi Shaw, 1947: 155   new synonym.

Leptomorphus (Diomonus) nebulosus: Matile, 1977: 146   .

Leptomorphus nebulescens: Papavero, 1978   (lapsus).

References: Osten Sacken 1878: 9 (catalogue); Kertész 1902: 49 (catalogue); Aldrich 1905: 141 (catalogue); Johannsen 1909: 45 (catalogue), 1910: 155 (description, key reference, MA), 1926: 51 (notes on type); Coquillett 1910: 533 (type designations); Alexander 1924: 55 (compared to L. panorpiformis   ); Procter 1946: 359 (ME); Shaw 1947: 156–7 (compared to L. s. gurneyi); Shaw & Fisher 1952: 192 (key to species, NH); Laffoon 1965: 223 (catalogue); Matile 1977: 141, 146 (subgeneric placement); Vockeroth 1981: 231 (wing figure in generic key), 2009: 270 (wing figure in generic key); Poole and Gentili, 1996: 194 (catalogue, synonymy); Søli et al. 2000: 66 (wing figure in generic key).

DIAGNOSIS: The only extant species of Leptomorphus   with the following combination of characters: apical half of the antennae white (base dark brown); scutum with setae on entire surface; males with a midfemoral spinelike process; R 4 present; male genitalia with two long sickle-like structures (aedeagus) curving dorsally ( Fig. 111).

This species is most easily confused, in its light form, with L. magnificus   or L. perplexus   . It can be distinguished from the former by the presence of dark markings on the scutum and the bicoloured antennae ( Fig. 27). It differs from the latter species by the slightly concave R 5 wing vein ( Figs 63, 64, rather than sinusoidal Fig. 69) and the placement of the ocelli in a cluster more than their own diameter away from the eye margin. The dark form ( Figs 24, 25, 26) is most similar to L. panorpiformis   , L. bifasciatus   and L. subcaeruleus   and differs from the first in having a Nearctic distribution, by the presence of the midfemoral spine in the male, and the shape male genitalia. The dark form differs from the latter two species in having bicoloured antennae and from L. subcaeruleus   in having the coxae and at least one set of femurs dark brown or black. The shape of the male genitalia of L. nebulosus   ( Fig. 111) and L. bifasciatus   ( Fig. 94) is very different, particularly the shape of the aedeagus.

DESCRIPTION: Male. ( Figs. 25, 27) Head: yellow with dark brown band posterodorsally to completely dark brown/black, somewhat dorsoventrally compressed in anterior view. Antenna with basal 5 flagellomeres dark brown/black, white apically; scape yellow to dark brown, with brown to black setae in short row on apicodorsal margin and thick patch covering apicoventral process, remainder bare, anterobasal patch of setulae present; pedicel brown, with 2–3 large bristles, several setae on apicodorsal margin, none ventrally; flagellomere 1 with tapered base brown remainder brown; flagellomere 6 1.6X as long as broad. Clypeus brown, circular, strongly protruding; bristles on clypeus light brown, both strong, smaller bristles on entire surface, all directed ventrally, clypeus 2X as long as face. Face brown; shape a slightly wider than tall triangle, covered with many fine bristles. Frons light to dark brown; bare, frontal furrow running 1/2–3/4 distance from dorsal margin towards ventral margin, frontal cleft initially running to lateral ocellus then barely in front of median ocellus. Palpus ranging from yellow to brown; segment 1 small but visible below eye, segments increasing in length, segment 5 subequal in length to segment 4 with even width from base to apex, segment 3 without distinct lateral patch of fine setae. Labellum brown. Eye with a number (in ~1/4 of the ommatidial junctions) of long inter-ommatidial setulae scattered on posterior half. Occiput dark brown with appressed, anteriorly directed setae. Ocelli in a straight line, space between ocelli 1.0–1.5X diameter of laterals, lateral ocelli 1.5X their own diameter from eye margin, ocellar triangle dark brown/ black with electric blue green specks. Thorax: Length 2.34 ± 0.47 mm (2.01–2.71 mm, n = 10). Dark brown, sometimes with dorsal yellow spots. Scutum ranging from completely dark brown/black, to dark brown with pair of mediolateral yellow spots and anteriorly placed V of yellow, rarely brown with yellow anteromedial triangle and lateral margins yellow; surface of scutum covered with small setae; acrostichal setae absent; dorsocentral setae present as multiple lines of very short, thin setae for anterior half and longer setae on posterior; multiple rows of lateral setae present; patch of setae on scutum at wing base present. Scutellum dark brown; with 6–8 large bristles and many small bristles. Prescutum yellow. Mediotergite dark brown with 10–20 bristles on posterolateral corners, absent. Laterotergite brown; anterior margin of laterotergite not reaching katepisternum. Anepimeron brown. Anepisternum dark brown. Katepisternum dark brown. Antepronotum and proepisternum dark brown. Margin of anterior and posterior spiracles yellow with yellow trichia. Metepisternum dark brown (a few specimens from Kansas and Iowa yellow with central dark spot). Anapleural suture straight and clear. Halter dark brown in northwest of range, to light brown and yellow in southeast. Legs: principally dark brown; trochanters white or yellow; fore- and midfemora typically yellow, though sometimes brown, hind femur with base and apex yellow; extreme anteroapical corner dark brown on all femora. Midfemur with apical spine-like process ( Fig. 83). Tibia with covering of brown macrotrichia, foretibia without comb of short setae along length of anteroventral surface, tibial spurs yellow, foretibial spur length 1.7X apical thickness of foretibia, midtibia with strong, dorsal, bare patch of even thickness for 5/7 of its length, placed basally, shortest midtibial spur 0.75X length of longest, longest midtibial spur 3.5X apical thickness of midtibia, shortest hind tibial spur subequal to length of longest, longest hind tibial spur 3X apical thickness of hind tibia. Foreleg first tarsomere 1.2X length of foretibia. Wing ( Figs. 63–64): Length 8.2 ± 1.5 mm (7.5–9.6 mm, n = 10). Hyaline; apical macula dark brown but fading towards apex and posterior margin, running from anterior to posterior wing margin, beginning halfway along R 5; medial macula extending from Sc to near fork of M 1 and M 2. Macrotrichia in all cells. Setae on basal posterior margin of wing (along base of cell a) alternating long and short for margin of alula, remainder short. Calypter bare. Vein sc-r present, apical end joining R within its own length before or after origin of Rs. R 4 present. R 5 slightly concave for entire length. M 1 reaching apex before R 5, apices of M veins clearly reaching wing margin. M 4 -CuA fork arising well before origin of r-m. A 2 faintly present as crease. Abdomen: Tergite 1 always dark brown/black, remainder ranging from completely reddish brown to completely dark brown/black, when dark often with T3–4 dark reddish brown. Tergite 8 smaller than all other abdominal sclerites and covered with many bristles. Genitalia ( Fig. 111): orangish yellow to dark brown. Sternite 9 light-darkly sclerotized, rounded rectangle, 2/3 the length of T9 but wider than genitalia. Tergite 9 as wide as long, with basal half of lateral margins parallel, remainder tapering to rounded medial apex. Gonocoxite placed apically on T9, tapering to a point on apicolateral margin, medial margin not reaching medial line, bearing gonostylus basally. Gonostylus a single lobe tapering towards apex and bearing several setae, gonocoxite III associated with dorsal margin of gonostylus but not fused to it. Aedeagus ~1.2X length of T9, tapering to middle and then becoming a lateral sclerotized sickle-like hook with serrated tip (smaller than in L. subcaeruleus   or L. magnificus   ), apodemes sclerotized and 1/7 total length. Parameres a swollen lobe with apex covered in small spines, apodemes 1/4 length of parameres and strongly united with gonocoxal apodemes.

Female adult. ( Figs. 24, 26) As for male, except as follows. Thorax: Length 2.34 ± 0.70 mm (1.85–2.95 mm, n = 10). Wing: Length 8.0 ± 2.1 mm (6.5–9.8 mm, n = 10). Legs: Midfemur without apical spine-like process. Abdomen: Cercus yellow to black.

Immatures. Similar in general appearance to L. subcaeruleus   ( Figs. 128, 129, 131, 133).

BIOLOGY: Immatures of L. nebulosus   were found feeding under the sporophores of Fomitopsis pinicola   , a woody bracket fungus ( Figs. 125, 128, 129). The behaviour of the larvae agreed closely with that found by Eberhard (1970). Larvae spun pupation lines under or near the fungus, moved to the middle of the line, and pupated there ( Figs. 131, 133).

DISTRIBUTION: Nearctic, particularly Canada and the eastern USA ( Fig. 144), 20–1800 masl.

DISCUSSION: Leptomorphus   s. gurneyi was originally described as a subspecies of L. subcaeruleus ( Shaw 1947)   based on similar genitalia (shared by L. magnificus   , L. nebulosus   and L. subcaeruleus   ), and then synonymized with L. subcaeruleus   by Poole & Gentili (1996). However it is actually a lighter form of L. nebulosus   (differs from L. subcaeruleus   in having bicoloured antennae and distinct body colouration). Leptomorphus nebulosus   ’ colour ranges from lighter (yellowish with some dark spots) in the southwest part of the range to completely black in the north. Since no discrete boundaries are seen between the lighter and darker forms, we do not recognize a distinct subspecies.

As discussed below in the phylogeny section, the placement of Leptomorphus species   in subgenera ( Matile 1977) is not supported by our phylogenetic results. This species is therefore removed from the subgenus Diomonus   and placed solely in the genus Leptomorphus   .

MATERIAL EXAMINED: Holotype: adult male, glued to card on pin. Wing glued to separate card, labelled “[Circular label with red edge] HOLO-/ TYPE; [Circular label with green edge] Type; Diomonus   / nebulosus/ Walker/ (type); 686/ Sciophila   / nebulosa; One of Walkers/ series so named/ EAW; a. St. Martin’s Falls,/ [underside] lines; [label upside down] BMNH (E) #/ 257830; [circular label] 44/ 17/ [underside] Hudson’s/ Bay; HOLOTYPE ♂ / Leptomorphus nebulosus   /(Walker) / Det. C.J. Borkent 2012” [ BMNH]. This specimen was apparently collected by G. Barnston along the Albany River , Ontario, Canada ( Walker 1848), probably at the Martin Falls Fort of the Hudson’s Bay Co. (51.53°N, 86.5°W). GoogleMaps  

Other material: CANADA, BC, 14km E Coal River , 14.vi–3.ix.1984, S. & J. Peck. (1♂, CNC)   ; 23km NE Nelson , 10.vii.2008, A. Borkent. (1♂, LEM)   ; 2km W Little Slocan Lk. Cmpgnd. , 1.vii.2008, A. Borkent. (3♂, 1♀, LEM)   ; 3.8mi. S Steamboat , 22.vi.1989, P.H. Arnaud, Jr. (1♂, CAS)   ; 6km E Salmon Arm , 13.vi.2009, A. Borkent. (1♂, LEM)   ; Kaslo , 18.vii, A.N. Caudell. (1♀, USNM)   ; Likely , 6.vii.1938, G.S. Walley. (1♂, CNC)   ; Robson , 14.vi.1948, H. R. Foxlee. (1♂, CNC)   ; Rosebery , 11.vii.2008, A. Borkent. (1♂, 1♀, LEM)   ; Quesnel , 26.vi.1948, G.J. Spencer, (1♂, UBCZ)   ; Salmon Arm , 1.vi.2006, A. Borkent. (1♀, LEM)   ; 10.vi.2006. (1♀, LEM)   ; 12.vi.2006. (1♀, LEM)   ; 26.vi.2006. (1♀, LEM)   ; 7.vii.2007. (1♀, LEM)   ; 9.vii.2007. (1♂, LEM)   ; 14.ix.2008. (1♂, LEM)   ; 12.vi.2008, C.J. Borkent. (1♂, 2♀, LEM)   ; Trinity Valley , 13.vii.1937, K. Graham. (1♂, CNC)   ; ON, Algonquin Park ( South of Shirley Lake ), 21–28.vii.1984, K. Pendreigh. (1♂, CNC, 1♂, DEBU); 16–24.vi.1984. (1♂, DEBU)   ; 18–26.v.1984. (2♂, CNC)   ; 18–26.v.1984. (3♂, DEBU)   ; Fathom 5 N. P., N Cove Isl., 25.vi.1995, S.A. Marshall. (1♂, DEBU)   ; Finland , 8.vii.1960, S.M. Clark. (1♂, CNC)   ; Macdiarmid , 6.vii.1922, Bigelow. (1♂, CNC)   ; Orwell , 14.vi.1978, W.A. Attwater. (1♀, DEBU)   ; Kent Co., Rondeau Prov. Pk., Spicebush Trail , Carolinian Forest , 15.viii–7.ix.2003, Marshall et al. (1♀, DEBU)   ; Rondeau Park , 14.viii–7.ix.2003, Buck & Marshall. (1♀, DEBU)   ; 15.viii–7.ix.2003, Marshall et al. (1♀, DEBU)   ; QC, 2.3km SSW Rapide-Danseur , 27.v–29.vi.2007, A. Hibbert. (1♂, LEM)   ; Laniel , 12.vi.1944, A. R. Brooks. (1♂, CNC)   ; Masham Twp., Duncan Lake , 13.ix.1975, D.M. Wood. (2♂, 1♀, CNC)   ; 17.ix.1975. (1♀, CNC)   ; 1.ix.1985. (1♂, 3♀, CNC)   ; 8.ix.1985. (1♂, CNC)   ; 11.ix.1985. (1♂, 2♀, CNC)   ; 16.ix.1985. (1♀, CNC)   ; 16.ix.1985. (1♂, 1♀, CNC)   ; 10–12.ix.1986. (1♂, CNC)   ; 12.ix.1986. (1♂, CNC)   ; 7.x.1985. (4♂, CNC)   ; 10.x.1985. (3♂, 1♀, CNC)   ; USA, IA, Boone Co., Ledges State Park , 13.x.1950, J.L. Laffoon. (1♂, ISUI)   ; 18.ix.1951. (1♀, ISUI)   ; Winneshiek Co., Kendallville , 14.vii–4.viii.2008, M.J. Hatfield. (1♂, LEM)   ; KS, Douglas Co., U. Kansas Nat. Hist. Res. , 13.vi.1974, C.W. Young. (1♂, CMNH)   ; 10–20.vi.2005, Z.H. Falin. (1♀, SEMC)   ; 20.vi.2005. (1♂, SEMC)   ; 19–24.vii.2005. (1♂, SEMC)   ; 7–16.ix.2005. (1♀, SEMC)   ; 16.ix–1.x.2005. (2♂, SEMC)   ; MD, Cabin John , R. M. Fouts. (1♂, USNM)   ; Patuxent Refuge, Bowie , 4.vii.1945. (1♀, USNM)   ; Plummer’s Island , 1906, D.H. Clemons, H.S. Barber. (1♀, USNM)   ; 27.vi.1909, W.L. McAtee. (1♀, USNM)   ; 8.viii.1917, Schwarz & Barber. (1♂, USNM)   ; Calvert Co., Port Republic , 12–15.x.1996, D.M. Wood. (1♀, CNC)   ; Prince George Co., Camp Springs , 20.ix.1979, G.F. Hevel. (1♀, USNM)   ; Wash. Co., 5km NE Boonsboro, Greenbrier St. Pk. , 12–14.viii.1989, M.E. Steiner et al. (1♂, USNM)   ; ME, Houlton , 5.vii. (1♀, USNM)   ; MI, Isle Royale , 3–7.viii.1936, C.W. Sabrosky. (1♂, USNM)   ; MO, Camp Crowder, 7.x.1942, A.B. Gurney. (2♂, 1♀, USNM, Type specimens of L. s. gurneyi); MS, Oxford , 20.vi.1966, F.M. Hull. (1♀, CNC)   ; NH, Carriage Road, Mt. Washington, G. Dimmock. (1♀, USNM)   ; Carr. Co., 1mi. N Wonalancet, E Fk., Spring Brk. , 18–23.vii.1985, D.S. Chandler. (1♂, UNHC)   ; The Bowl (2.5mi. NW Wonalancet), 8–14.vi.1984, D.S. Chandler. (2♂, UNHC)   ; The Bowl (2.5mi. NW Wonalancet), 15–20.vi.1984. (3♂, UNHC)   ; The Bowl (2.5mi. NW Wonalancet), 28.vi–4.vii.1984. (1♂, UNHC)   ; The Bowl (2.5mi. NW Wonalancet), 20–26.vii.1984. (2♂, UNHC)   ; The Bowl (2.5mi. NW Wonalancet), 2–10.viii.1984. (1♂, UNHC)   ; The Bowl (2.5mi. NW Wonalancet), 11–16.viii.1984. (3♂, 2♀, UNHC)   ; The Bowl (2.5mi. NW Wonalancet), 18.ix–3.x.1984. (2♂, UNHC)   ; The Bowl (2.5mi. NW Wonalancet), 20.x–7.xi.1984. (1♂, UNHC)   ; NJ, Stockton , 1–15.vii.1906. (1♀, USNM)   ; NY, 7mi. south town of Long Lake , 26.viii.1956, J.L. Laffoon. (1♂, 1♀, ISUI)   ; Essex Co., foot Cliff Mtn , 26.vii.1920, J. Bequaert. (1♂, MCZ)   ; PA, North Mt. , 1.ix.1917. (1♀, USNM)   ; Warren Co., 2.2km NW Truemans , 4.viii.1994, M.J. Ricke. (1♂, CMNH)   ; SC, Anderson Co., Pendleton, Tanglewood Sprg. , x.1987, J. Morse. (1♀, CNC)   ; 22.vii.1987. (1♂, CUAC)   ; 30.ix.1987. (1♀, CUAC)   ; VA, Fairfax Co., Dead Run , 22.vi.1915, R. C. Shannon. (1♀, USNM)   ; Turkey Run , mouth, 24.vi.2006, W.N. Mathis, T. Zatwarnicki. (1♀, USNM)   ; WA, Pierce Co., 6.5km W Ashford , 8.vii.2008, C.J. Borkent. (1♂, LEM)   ; 9.vii.2008. (1♂, LEM)   ; 10.vii.2008. (3♀, LEM)   ; WV, Hampshire Co., 8km NW Capon Bridge ( Buffalo Gap Camp ), 12–14.ix.1986, W.E. Steiner; J.M. Swearingen. (1♀, USNM)   .


Canadian National Collection of Insects, Arachnids, and Nematodes


California Academy of Sciences


Smithsonian Institution, National Museum of Natural History


Departamento de Geologia, Universidad de Chile


University of British Columbia, Spencer Museum


Ontario Insect Collection, University of Guelph


National Museum of Natural History, Bulawayo


Iowa State University


The Cleveland Museum of Natural History


University of Kansas - Biodiversity Institute


Museum Donaueschingen


Museum of Comparative Zoology


Clemson University Arthropod Collection


Tavera, Department of Geology and Geophysics














Leptomorphus nebulosus (Walker)

Borkent, Christopher J. & Wheeler, Terry A. 2012

Leptomorphus (Diomonus) nebulosus: Matile, 1977: 146

Matile, L. 1977: 146

Leptomorphus subcaeruleus gurneyi

Shaw, F. R. 1947: 155

Leptomorphus nebulosus:

Edwards, F. W. 1925: 556

Diomonus nebulosus

Walker, F. 1848: 87