Amiota nigrescens Wheeler, 1952

Jones, Lance E. & Grimaldi, David A., 2022, Revision Of The Nearctic Species Of The Genus Amiota Loew (Diptera: Drosophilidae), Bulletin of the American Museum of Natural History 2022 (458), pp. 1-181 : 120-122

Amiota nigrescens Wheeler, 1952

Figures 61E–F , 62C , 65 , 93C

Amiota nigrescens Wheeler, 1952: 170 (original description); Wheeler, 1965: 761 (Nearctic catalog); Brake and Bächli, 2008: 254 (world catalog).

DIAGNOSIS: Small to medium-sized fly (ThL 0.99–1.27 mm), dark brown nearly black; legs yellow (femora light brown in some individuals); surstylus slender, armlike, 4 prensisetae, 2 most lateral larger and 2× length of the others; subepandrial sclerite process behind surstylus, like a fifth prensiseta; paraphyses fully sclerotized; outer paraphysis on right side slightly sinuous; apex tapered, base swollen; left outer paraphysis shorter, apex also tapered, base swollen; inner paraphysis lost.

DESCRIPTION: Small to medium-sized fly (ThL 0.99–1.27 mm), dark brown nearly black. Legs dark yellow (femora dark brown in in some individuals). Frons dark brown (nearly black in Ontario populations. Cheek dirty yellow to brown. Facial marking small, width 0.5× length (depth smaller in Ontario populations). Palp brown. Arista: Short, plumose; longest branch D3; A.R. 0.31; 4 long dorsal, 1 long ventral branches; D4 pointed laterad; arista trunk with medium microtrichia for most of its length. Male genitalia: Epandrium fused at midline, indistinct; ventral lobes with dense cluster of setae, lower third of epandrium devoid of long setae. Cercus long, pendulous, distinct from surrounding membrane, ventral portion overlapping bases of surstyli. Surstylus armlike, bent at midpoint, entirely glabrous; 4 prensisetae, apices blunt, closely spaced, lateral 2 prensisetae 2× length of the 2 medial; heavily sclerotized subepandrial sclerite process anterior to surstylus, resembling a fifth prensiseta. Subepandrial sclerite consisting of 3 lobes in posterior view, 2 lateral lobes and central lobe; lateral lobe large, rounded, faintly sclerotized, central flange running to margin, thick, flange apex flared distally; central lobe heavily sclerotized, bulbous, apex tapering, incomplete flange reaching outer margin; central lobe with squarelike extension anterior to surstylus, the central portion with process. Outer paraphyses slightly asymmetrical, both heavily sclerotized; left one slightly longer and slightly sinuous, distal end tapered to a point; base bulbous, flaring outward; right outer paraphysis parallel to left one with apex tapered, base bulbous with a small notch. Inner paraphysis lost. Aedeagal apodeme bent 90° at midpoint, of equal length and width; widely flared distally, with deep concave emargination; 2 strong lateral flanges at base. Hypandrium simple, thickness consistent across length; apex simple, V-shaped; lateral arm with small posteriorly pointing gonopod. Ejaculatory apodeme slightly bent at base, 0.7× length of epandrium. Head and thorax measurements: (n = 5; Am 129, 138, 146, 583, 585) FL/FW 0.70 (0.63–0.86), EL/EW 1.41 (1.34– 1.52), EL/CW 11.32 (10.2–12.6), FML/FMW 0.33 (0.28–0.48), PR /RR 0.39 (0.33–0.44), ThL 1.16 (0.99–1.27 mm).

TYPE MATERIAL: Holotype: As reported by Wheeler (1952): “ ♂, 2164.7, from Slide Rock Campground, Oak Creek Canyon, Coconino National Forest , south of Flagstaff, Arizona, collected June, 1951 by the writer” [not examined]. Deposited in National Museum of Natural History, Washington D.C. ( USNM) . Paratypes: Localities and numbers of paratype specimens in AMNH differ slightly from Wheeler (1952) in some cases: “4, same data as holotype” [ ARI-ZONA: Oak Creek Canyon, Coconino Nat. For., 15 mi. S. Flagstaff, VI/21 - VI/22 /51, 2164.7, W.B. Heed and M. R. Wheeler , paratype], [34.907104, -111.727342], 1♂ and 3♀ (Am 138–141*, AMNH) ; “Tonto Creek near Payson (11, one on slide),” [Tonto Creek Camp, Arizona, June 1951, MR Wheeler and WB Heed , 2168.3, paratype], [34.320806, -111.084756], 5♂ and 4♀ (Am 129– 135*, 142*, AMNH) ; “Long Valley near Pine (2),” [ARIZONA: Clover Springs, Coconino Nat’l. Forest , 50 mi S Flagstaff, VI/22 - VI/23 /51, W.B. Heed and M. R. Wheeler , 2165.12, paratype], [34.506258, -111.362842], 1♂ (Am 144, AMNH) ; “NEW MEXICO: Cherry Creek Camp, near Silver City (5)” [New Mexico: “ Cherry Creek ” Campground, Gila Nat. For., N. Silver City, VI/7 - VI/8 /51, W.B. Heed and M. R. Wheeler , 2151.4, paratype], [32.914274, -108.225999], 1♂ and 3♀ (Am 145–148*, AMNH) .

OTHER MATERIAL EXAMINED: Canada: Ontario: Algonquin Park, Swan Lake Station, Scott Lake Station , 1993-05-19 through 1993-05-31, leg. Larson / Marshall / Barr, malaise A1 lakeshore, 1♂ (Am 536*[dissection missing], DEBU) ; 1993-06-03 through 1993-06-14, leg. Larson / Marshall / Barr, malaise A1 lakeshore, 2♂ (Am 542*, 543*, DEBU) ; 1993-06-03 through 1993-06-17, leg. Larson / Marshall / Barr, Pan A3, clubmoss/hemlock, 1♂ (Am 539*, DEBU) ; 1993-06-17 through 1993-06-19, leg. Larson / Marshall / Barr, 1♂ (Am 545*, DEBU) ; 1993- 07-16 through 1993-07-28, leg. Larson / Marshall / Barr, malaise A1 lakeshore, 1♂ (Am 544*, DEBU) ; Algonquin Park, Swan Lake Station, Scott Lake Survey , 1994-06-07 through 1994-06-14, [collector unknown], C1 shore malaise trap, 2♂ (Am 583*, 591*, DEBU) ; 1994-06-23 through 1994-06-30, [collector unknown], C1 shore malaise trap, 1♂ (Am 594*, DEBU) ; 1994-07-10 through 1994-07-17, [collector unknown], C1 Shore malaise trap, 1♂ (Am 597, DEBU) ; 1994-07-18 through 1994-07-31, [collector unknown], C1 shore malaise trap, 1♂ (Am 557*, DEBU) ; 1995-05-29 through 1995-06-16, leg. S.A. Marshall, fresh stump emergence, 2♂ (Am 582*, 584*, DEBU) ; 1995-05-29 through 1995-06-17, leg. S.A. Marshall, D2 Hemlock pans, 1♂ (Am 585*, DEBU) ; Algonquin Provincial Park, W. R.S. G (B2), 1995-06-11, leg. R. Bonduriansky, moose antler, 1♂ (Am 611*, DEBU) ; Fathom Five National Park, Bear Rumpis , 1996-06-23 through 1996-07-26, leg. T. Woodcock and S. Marshall, Dry Alvar Pan Trap #4, debu00078364, 1♂ (Am 527, DEBU) ; Nipissing Distr., Algonquin Park., Swan Lake Station , Scott Lake . Shore site A1., 1995-07-04, [no collector], debu00104926, pan traps, 1♂ (Am 634*, DEBU) ; Ottawa , 1991-08-01, leg. J. R. Vockeroth, damp growth Acer-Betula wood, 1♂ (Am 1253*, CNC) ; 1993-06-22, leg. J. R. Vockeroth, damp growth AcerBetula wood, 1♂ (Am 1228*, CNC) ; Ottawa, Chapel Hill , NW Wood, 2002-07-01, leg. J. R. Vockeroth, CNC Diptera #193451, 1♂ (Am 1197*, CNC) . Quebec: Knowlton Lodge , 1968-07-18, leg. J. R. Vockeroth, 1♂ (Am 1580*, CNC) . USA: Arizona: Oak Creek Canyon, 1951-06-21, [collector unknown], [possible paratypes?] 2♂ (Am 136*, 137*, AMNH) .

DISTRIBUTION: Amiota nigrescens has disjunct populations from central Arizona and southwestern New Mexico as well as Ontario, Canada. No intervening populations between these extremes are known.

COMMENTS: It is unknown whether this species is attracted to the eyes and face like other Amiota . Populations of Amiota nigrescens in Ontario are commonly caught in Malaise and pan traps. This species is a documented saproxylic, one specimen (DEBU) having been reared from a tree stump emergence trap. The species is variable for the brown femora and cheek seen in the other species of the group. Four of 19 specimens in the Southwest had the light brown femora, 12 of 21 Great Lakes specimens had light brown femora, while 2 had dark brown femora. The facial marking in Ontario populations is also much smaller in depth. No discernable differences are found in the male genitalia of both populations. It would be very useful to compare DNA barcodes of specimens in the two localities.

Figures

FIG. 61. Heads and lateral views, A. nigrescens species group. A–B. A. fulvitibia, sp. nov. (Am 577). C–D. A. nanonigrescens, sp. nov. (Am 540, holotype). E–F. A. nigrescens Wheeler (Am 146, paratype, lateral image flipped).

FIG. 62. Aristae, A. nigrescens species group. A. fulvitibia. B. A. nanonigrescens. C. A. nigrescens Wheeler. Not to the same scale.

FIG. 65. Male terminalia, A. nigrescens Wheeler. A. Epandrium and cerci. Surstyli and subepandrial sclerite shaded. B. Lateral view, with ejaculatory apodeme. C. Ventral view. D. Dorsal view. (Am 137).

FIG. 93. Distribution maps, A. nigrescens species group. A. A. fulvitibia. B. A. nanonigrescens. C. A. nigrescens Wheeler.