Peters & Cook, 1966 : 241 Garrett, 1924 : 6 The true identity of Dixa modesta Johannsen (Diptera: Dixidae) resolved: synonymy of Dixa similis Johannsen, designation of the Dixa ubiquita species group, and description of three new eastern Nearctic species Moulton, John K. Zootaxa 2017 4216 3 247 260 9HYNR [151,344,1481,1507] Insecta Dixidae Dixa Animalia Diptera 9 256 Arthropoda species vockerothi sp. nov.     Dixa brevis  Peters & Cook, 1966: 241, not  Garrett, 1924: 6(misidentification of northeastern North American specimens).   Type material. HOLOTYPE, ♂ labeled: “Old Chelsea/ Que. 5.xi.1958/ J.R. Vockeroth”; “ Dixa brevis/ Garrett/ Det. T.M. Peters 1964”; “HOLOTYPE/ Dixa/ vockerothi/ J.K. Moulton [red label]” (CNC). PARATYPES: Old Chelsea, 5.xi.1958, J.R. Vockeroth (10♂; CNC); Same data, except 15.x.1958, J.R. Vockeroth (10♂; CNC).   Additional material examined.  CANADA: NS: Grande Anse R, Cape Breton Highlands NP,  8–10.vii.1984, I.M. Smith( 1♂, CNC);  Kentville,  6.viii.1958, J.R. Vockeroth( 14♂; CNC);  Lone Shieling, swept along fast rocky stream,  11.vii.1983, J.R. Vockeroth( 2♂, 2♀; CNC).  ON: Normandale, 42°42′ 80°19′,  21.v.1956, J.R. Vockeroth( 1♂, CNC);  Sterling,  14.x.1956, J.R. Vockeroth( 2♂, CNC);  Ottawa,  30.ix.1956, J.R. Vockeroth( 1♂, CNC);  Ottawa, Hog′s Back,  16.x.1947, G.E. Shewell( 2♂, CNC).  QC: Eardley,  18.x.1956, J.R. Vockeroth( 2♂, CNC);  Gatineau Park, Mackenzie King Falls@ Waterfall Tr, N45°28′41.08″ W75°51′02.98″, ex. above falls,  24.vi.2009, B.J. Sinclair( 2♀, CNC);  King Mtn, sm str,  16.xi.2011, B.J. Sinclair( 1♂, CNC);  Lac Philippe[Gatineau Park], 45° 37′N76°W,  22.viii.1959, J.R. Vockeroth( 1♂, CNC);  Old Chelsea, Mulvihill Brookat Mountain Rd, in one moderately dense swarm 6–8′ over stream,  5.xi.1958, J.R. Vockeroth( 22♂, 1♀, CNC: ethanol); Old Chelsea,  5.xi.1958, J.R. Vockeroth( 21♂, CNC);  Old Chelsea,  15.x.1958, J.R. Vockeroth( 42♂, CNC);  Old Chelsea,  5.ix.1958, C.H. Mann( 1♂, CNC);  Old Chelsea,  22.vii.1956, J.R. Vockeroth( 1♂, CNC);  Mt. Orford,  29.viii., 9.ix.1937, G.E. Shewell( 2♂, CNC).   USA: NC:  HAYWOOD COUNTY, Woodfin Cascade, Blue Ridge Parkway NP, N35°27′08.30″ W83°06′10.6″,  16.vii.2006, J.K. Moulton& G.R. Curler( 2♂, 1L, ANSP); same locality,  24.vii.2011, JKM ( 1♀, ANSP).  NY:  CATTARAUGUS COUNTY, Stoddard Hollow,  1720–1880 ft, 42°4′N W78°45′,  10.viii.1961, D.L. Deonier/ J.L. Laffoon( 10♂, 2♀, ISIC).   Diagnosis. This species can be distinguished from  D. ubiquita  sp. nov.and  D. elkmontensis  sp. nov.by the following characters: Morphological. Basal gonocoxal lobe with apex more digitiform and dorsally directed ( Fig. 18vs. 12, 15), creating more conspicuously concave horizontal margin, most noticeable in terminal view ( Fig. 20vs. 14, 17). Anterior lobe of SES acute apically, with thin, strap-like, connection to ventral apodeme of proctiger acutely angled; distal lobe of SES narrow, lip-like in lateral view ( Fig. 18). Apex of gonostylus not strongly twisted ca. 90° medially, most obvious in ventral view ( Fig. 19). Molecular. Within the 66 nucleotides (22 codons) shown ( Fig. 35) a thymine at position 46 (vs cytosine), an adenine at position 51 (vs. guanine), and a guanine at position 54 (vs. cytosine) serve to distinguish this species from the other two. Within the encompassing amplified fragment of BZF,  D. vockerothi  sp. nov.is 6.1% divergent from  D. ubiquita  sp. nov.and 9.1% divergent from  D. elkmontensis  sp. nov.(JK Moulton, unpublished).   Description. Male. Same as  D. ubiquita  sp. nov., except as follows: Winglength ( n=10) 3.8–4.1 (avg=4.0) mm. Terminalia( Figs 18–20): Basal gonocoxal lobe narrowed, less than half as broad as gonocoxite depth, with apex more digitiform and dorsally directed, with ventral margin straight to slightly convex ( Fig. 18). Gonostylus with apex straight, not twisted ca. 90° medially, most obvious in ventral view ( Fig. 19). Anterior lobe of SES rounded apically, with connection to 9T and ventral apodeme of proctiger broader; distal lobe of SES narrow, liplike in lateral view ( Fig. 18).  Female. Wing length ( n=7) 4.4–4.9 (avg=4.6) mm. Not reliably distinguishable from  D. ubiquita  sp. nov.or  D. elkmontensis  sp. nov.   Etymology.Named in honor of Dr. Richard (Dick) Vockeroth, who collected numerous adults of this species, including the typeseries, from several localities in and around the Gatineau area and elsewhere in eastern Canada.   Distribution.  Dixa vockerothi  sp. nov.appears to be the most northerly distributed of the three members of this species group ( Fig. 34). It is confirmed from numerous localities in the Gatineau Hills region of Quebec, a few sites in Nova Scotia, one site in the Alleghany Mountains of Pennsylvania, and one site in the Southern Appalachian Highlands of western North Carolina.   Remarks.  Dixa vockerothiis found in high gradient, rapidly flowing streams 3–5 min width with waterfalls, often stair-cased ones ( Figs 32, 33). It occurs with  D. ubiquita  sp. nov.in Woodfin Cascades in western NC, and no other dixid associations are known. 1423743198 1984-07-08 1984-07-10 1984-07-08 CNC Grande Anse R & Cape Breton Highlands NP & I. M. Smith Canada CANADA 9 256 1 1 1423743214 [423,996,1799,1824] 1958-08-06 CNC J. R. Vockeroth Canada Kentville 9 256 14 14 1423743207 1983-07-11 CNC J. R. Vockeroth Canada Lone Shieling 9 256 4 2 2 1423743211 1956-05-21 CNC J. R. Vockeroth Canada Normandale 9 256 1 1 1423743200 [302,858,1871,1896] 1956-10-14 CNC J. R. Vockeroth Canada Sterling 9 256 2 2 1423743208 [875,1432,1871,1896] 1956-09-30 CNC J. R. Vockeroth Canada Ottawa 9 256 1 1 1423743217 [151,817,1907,1932] 1947-10-16 CNC G. E. Shewell Canada Back Ottawa Hog 9 256 2 2 1423743218 [830,1432,1907,1932] 1956-10-18 CNC J. R. Vockeroth Canada Eardley 9 256 2 2 1423743203 2009-06-24 CNC B. J. Sinclair Canada Waterfall Tr 45.478077 Gatineau Park 1 -75.85082 Mackenzie King Falls 9 256 2 2 1423743197 [435,1045,1979,2004] 2011-11-16 CNC B. J. Sinclair Canada King Mtn 9 256 1 1 1423743206 1959-08-22 CNC J. R. Vockeroth Canada 10 257 45.616665 Lac Philippe 9 256 1 1 1423743219 1958-11-05 CNC J. R. Vockeroth Canada Mountain Rd Old Chelsea Mulvihill Brook 10 257 44 1 43 1423743209 [632,1266,223,248] 1958-10-15 CNC J. R. Vockeroth Canada Old Chelsea 10 257 42 42 1423743199 1958-09-05 CNC C. H. Mann Canada Old Chelsea 10 257 1 1 1423743216 [566,1188,260,285] 1956-07-22 CNC J. R. Vockeroth Canada Old Chelsea 10 257 1 1 1423743215 29. viii., 9. ix. 1937 CNC G. E. Shewell Canada Mt. Orford 10 257 2 2 1423743210 2006-07-16 HAYWOOD, COUNTY, ANSP Blue Ridge Parkway NP & J. K. Moulton & G. R. Curler United States of America 35.452305 Woodfin Cascade 1 -83.10294 10 257 2 2 1423743201 2011-07-24 ANSP Blue Ridge Parkway NP & J. K. Moulton & G. R. Curler United States of America 35.452305 Woodfin Cascade 1 -83.10294 10 257 1 1 1423743220 1961-08-10 CATTARAUGUS, COUNTY, ISIC D. L. Deonier & J. L. Laffoon United States of America 549 42.066666 Stoddard Hollow 1152 -78.75 10 257 12 2 10