Dixa vockerothi, Moulton, John K., 2017

Moulton, John K., 2017, 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, Zootaxa 4216 (3), pp. 247-260 : 256-258

publication ID

https://doi.org/ 10.5281/zenodo.231794

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scientific name

Dixa vockerothi

sp. nov.

Dixa vockerothi sp. nov.

( Figs 18–20 View FIGURES 12 – 20 , 23 View FIGURES 21 – 23 )

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) GoogleMaps ; King Mtn , sm str, 16.xi.2011, B.J. Sinclair (1♂, CNC) ; Lac Philippe [Gatineau Park], 45° 37′N 76°W, 22.viii.1959, J.R. Vockeroth (1♂, CNC) ; Old Chelsea , Mulvihill Brook at 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) GoogleMaps ; same locality, 24.vii.2011, JKM (1♀, ANSP) GoogleMaps . 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) GoogleMaps .

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. 18 View FIGURES 12 – 20 vs. 12, 15), creating more conspicuously concave horizontal margin, most noticeable in terminal view ( Fig. 20 View FIGURES 12 – 20 vs. 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 View FIGURES 12 – 20 ). Apex of gonostylus not strongly twisted ca. 90° medially, most obvious in ventral view ( Fig. 19 View FIGURES 12 – 20 ). Molecular. Within the 66 nucleotides (22 codons) shown ( Fig. 35 View FIGURE 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: Wing length (n =10) 3.8–4.1 (avg=4.0) mm. Terminalia ( Figs 18–20 View FIGURES 12 – 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 View FIGURES 12 – 20 ). Gonostylus with apex straight, not twisted ca. 90° medially, most obvious in ventral view ( Fig. 19 View FIGURES 12 – 20 ). 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 View FIGURES 12 – 20 ).

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 type series, 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 View FIGURE 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 vockerothi is found in high gradient, rapidly flowing streams 3–5 m in width with waterfalls, often stair-cased ones ( Figs 32, 33 View FIGURES 29 – 33 ). It occurs with D. ubiquita sp. nov. in Woodfin Cascades in western NC, and no other dixid associations are known.


Canadian National Collection of Insects, Arachnids, and Nematodes


Academy of Natural Sciences of Philadelphia


Southeastern Shanxi Teachers School


Forest Research and Development Center and Nature Conservation














Dixa vockerothi

Moulton, John K. 2017

Dixa brevis

Peters 1966: 241
Garrett 1924: 6