Dixa modesta Johannsen, 1903 : 429

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 : 248-249

Dixa modesta Johannsen, 1903: 429 .

( Figs 3–5 )

Dixa similis Johannsen, 1923: 57 . syn. nov.

Type material. D. modesta : LECTOTYPE, ♂ labeled: “Ithaca, N.Y./ Apr.”; “OA Johannsen/ Lot 1304/ Sub slides, vial/ Cornell U.”; “HOLOTYPE/ Cornell U./ No. 2992” [red label]”; “HOLOTYPE/ Dixa / modesta Joh [red-trimmed label]”; “Lectotype/ Dixa modesta / Johannsen/ Fixation by T.M. Peters, 1968 / (labeled: J.K. Moulton, 2016)” (CUIC).

D. similis : HOLOTYPE, ♂ labeled: “Ithaca, N.Y. 28 Aug. [18]’94”; “OA Johannsen/ Lot 1293 Sub vial/ Cornell U.”; “HOLOTYPE/ Dixa / similis / Johannsen [red-trimmed label]”; “HOLOTYPE/ Cornell U./ No. 2993”. ALLOTYPE, ♂ labeled: “Ithaca, N.Y./ 28 Aug. [18]’94”; “OA Johannsen/ Lot 85/ Sub. 1147/ Cornell U.”; “ALLOTYPE/ Cornell U./ No. 2993”; “ALLOTYPE Dixa similis Johannsen ” (CUIC).

Remarks. In 1954, Alice Dietrich, Cornell University Insect Museum, accessioned holotype #2992 ( Figs 3–5 ), the pinned “ holotype ” male of Dixa modesta (J. Liebherr, pers. comm.). This male, clearly having a striped scutum ( Figs 3–4 ), corresponds to the adult successfully reared by Johannsen (1903) from a larva (and pupa, the exuviae of both included in the syntype series) partly serving as the basis for Johannsen ′s original description. Examination of the lectotype and additional material studied by Johannsen confirmed the presence of a mixed series. Examination of the primary types of D. modesta and D. similis , including the badly faded terminalia of the former, confirmed they are of the same nominal species. Therefore, D. similis falls as an objective junior synonym of D. modesta . This species will be re-described in a future study.

Examination of Johannsen’s material, in addition to the lectotype, revealed one male (actually only partial terminalia in glycerin) each of D. ubiquita sp. nov. from Ithaca, NY and Black Mtn, NC, one male of Dixa brevis (terminalia in glycerin), and one larva from Cascadilla Creek near Ithaca. Confirmation of D. ubiquita sp. nov. from the Ithaca area fits nicely with the hypothesized, but unidentified, collection locality, Fall Creek (Flat Rock), a karst stream now largely contained within a Cornell Plantations Natural Area (Jason Dombroskie, pers. comm.). The larva from Cascadilla Creek could be either D. ubiquita sp. nov. or D. vockerothi sp. nov. based upon photographs of the stream, which has numerous staircase falls within a gorge.

Figures

FIGURES 1 – 5. Dixa ubiquita sp. nov., 1, Male, lateral habitus; 2, Male, anterodorsal habitus; 3, D. modesta Johannsen holotype male, lateral habitus; 4, D. modesta holotype male, anterodorsal habitus; 5, D. modesta holotype male, locality and determination labels. Scale bar = 1 mm.