Dixa repanda Peters

Moulton, John K., 2018, Rediscovery of Dixa repanda Peters and description of its putative sister species, Dixa falcata sp. nov., from the south-central United States (Diptera: Dixidae), Zootaxa 4459 (1), pp. 171-178: 175-177

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Dixa repanda Peters


Dixa repanda Peters  

( Figs 4 View FIGURES 3–4 , 6, 8, 10 View FIGURES 5–11 )

Dixa repanda Peters in Peters & Cook, 1966: 249   .

Type material examined. HOLOTYPE ♂ (card pointed) labeled: “ Goodhue Co. [unty], Minn.[esota]/ May 21 1937 ”; “ D.G. Denning / Collector”. “ HOLOTYPE / Dixa   / repanda   / Peters/ USNM No. 67271 [red-trimmed label]” (USNM). Terminalia: Not examined, presumed lost.  

Additional material examined. USA: Arkansas: STONE COUNTY, Ozark NF, Blanchard Sprs Crk below source [N35°57′31.4″ W92°10′43.1″, 166 m], 21.v.1991, B.J. Sinclair (1♂, CNC) GoogleMaps   . Iowa: JEFFERSON COUNTY, Black Bridge Spr, S of Waupeton , N42°39′44.2″ W90°52′55.7″, 195 m, 17.ix.2009, J.K. Moulton (13♂, 8♀) GoogleMaps   . Illinois: MONROE COUNTY, Bicklein Cave Spr, 8 km W of Waterloo, T2S R10W SE1/4SE1/4 Sec 19, Waterloo 7.5’ Quadrangle [N42°29′22.5″ W92°29′51.8″, 308 m], 14.xii.1996, J. Krejca et al (1♂, UWS) GoogleMaps   . Indiana: CRAWFORD COUNTY, Hoosier NF, Trickling str @ Hemlock Cliffs [N38°16′30.2″ W86°32′17.5″, 214 m], 19.v.1991, B.J. Sinclair (5♂, CNC) GoogleMaps   . PERRY COUNTY, Hoosier NF, Trib Middle Deer Crk @ CR10, N37°59′11.0″ W86°37′23.9″, 140 m, 4.x.2009, J.K. Moulton (2L*) GoogleMaps   . Kansas: RILEY COUNTY, Manhattan, “ Hibernating ” under rock [N39°10′13.1″ W96°39′01.7″], 13.xii.1930, H.L. Culer (1♂, USNM) GoogleMaps   . Missouri: PHELPS COUNTY, Meramac Spr, 12.9 km S St James [N37°57′12.8″ W91°31′57.8″, 261 m], 28.iv.1956, P.J. Spangler (1♂, USNM) GoogleMaps   . ST FRANCOIS COUNTY, St Francois SP, stream beside old schoolhouse, N37°59′21.6″ W90°30′49.7″, 238 m, 30.iv.2009, J.K. Moulton (2♂) GoogleMaps   . STONE COUNTY, Crane Crk @ Crane City Park , N36°54′08.2″ W93°34′25.0″, 339 m, 30.iv.2009, J.K. Moulton (1♀) GoogleMaps   . Oklahoma: JOHNSTON COUNTY, Viola Sprs @ McIntosh Rd , ex emergent vegetation, N34°22′46.5″ W96°31′36.5″, 241 m, 25.iii.2010, E.A. Bergey (1♂ & 3♀) GoogleMaps   . PONTOTOC COUNTY, unnamed spr ex D169 Rd, 4 km S of Fittstown , N34°34′22.7″ W96°38′51.0″, 313 m, 25.iii.2010, E.A. Bergey (1♂, 1♀) GoogleMaps   .

Diagnosis. The less strongly setose, curved, non-tapered, banana-like gonostylus coupled with obliterated cercus and larger, more protruding basal gonocoxal lobe distinguishes this species from all other Nearctic species, including D. falcata   sp. nov.

Redescription. Differing from D. falcata   sp. nov. as follows. Male. Wing length (n =10) 2.5–3.4 mm (avg=3.1). Terminalia ( Figs 4 View FIGURES 3–4 , 6, 8, 10 View FIGURES 5–11 ): Gonostylus slightly shorter, ca. 2.5X longer than greatest height, considerably less tapered apically and with shorter and sparser setae on medial surface. Basal gonocoxal lobe appearing more protrusive from dorsal gonocoxal margin in lateral view.

Female. Wing length (n =8) 2.7–3.7 mm (avg=3.3). Indistinguishable from those of D. falcata   sp. nov. and several other similarly colored, related species.

Distribution and bionomics. Attempts by the author to collect material from near the type locality in Illinois (Havana) and paratype locality (environs of Rochester, MN) were unfruitful. Streams in and around Havana, IL, are heavily degraded and inaccessible due to co-opting for agricultural production. New collections of this species broadened its known range to the east to include southern portions of Indiana and Illinois and southwesterly into Arkansas, Missouri and Oklahoma ( Fig. 14). It likely also occurs in the Arkansas Ozarks as well as northern Kentucky. Dixa repanda   appears to be multivoltine and likely typically overwinters as eggs, although one female examined taken near Manhattan, Kansas, was observed under a rock in mid-December. Larvae mature as early as March in the southern portion of the range. This species occurs in spring-fed streams ( Fig. 13 View FIGURES 12–13 ) very similar to those preferred by D. falcata   sp. nov., and they likely co-inhabit streams somewhere in the Ozark/Quachita region.

Remarks. Several issues hampered the author’s elucidation of the identity of this species. Firstly, the illustration of the male terminalia in Peters & Cook (1966, fig. 47) in lateral view does not accurately reflect the shape of the gonostylus. Secondly, the slide-mounted terminalia of the male holotype could not be located in the USNM and are presumed lost. Thirdly, the two paratype males could not be located and may also be lost. Lastly, attempts to collect streams in the environs of Havana, Illinois, the type locality, were fruitless as the streams were largely inaccessible and ones that were observed look extremely degraded. It was not until examining a male specimen taken near Manhattan, Kansas, that was identified as D. repanda   by T.M. Peters, that the association between my material and the holotype was synched. The absence of any other Dixa   species, besides the easily discernable D. fluvica Peters   , taken in the study area also reinforces this decision.


Canadian National Collection of Insects, Arachnids, and Nematodes


Smithsonian Institution, National Museum of Natural History














Dixa repanda Peters

Moulton, John K. 2018

Dixa repanda Peters in Peters & Cook, 1966 : 249

Peters & Cook, 1966 : 249