The Dixa inextricata Dyar & Shannon (Diptera: Dixidae) species group, with two new cryptic species from the eastern Nearctic Region Moulton, John K. Zootaxa 2016 4121 4 458 472 9HRKB [151,396,726,752] Insecta Dixidae Dixa Animalia Diptera 2 460 Arthropoda species appalachiensis sp. nov.    Typematerial.   HOLOTYPE ♂, labeled: “  USA:  NC/ Haywood County/ Woodfin Cascades @ Blue Ridge Parkway NP/ N35°27′05.53″ W83°05′39.04″,  1256 m/  16.vii.2006/ J.K. Moulton”; “HOLOTYPE/ Dixa/ appalachiensis/ J.K. Moulton[red label]” ( CNC).   PARATYPES: Same data as holotype, 8♂and 2♀each to CNCand USNM.  Additional material examined.   USA. KENTUCKY: BELL COUNTY, Cumberland Gap NHP, Tunnel Crk,  28.xi.2005, JKM— 6♂, 2♀.   NORTHCAROLINA: BUNCOMBE COUNTY, Shope Frk, UV light trap, 25.v.2007, J. Robinson— 12♂, 3♀. Ox Crk, UV light trap, 25–26.v.2007, J. Robinson— 71♂, 12♀.  HAYWOOD COUNTY, Great Smoky Mtns NP, small stream atop Hemphill Bald, 15.vi.2007, JKM— 4♂, 2♀. GSMNP-Cataloochee Section, Rough Frk, 862 m, N35°36′58.47″ W83°07′11.71″, 26.vii.2005, JKM— 4♂. Blue Ridge Parkway NP, Woodfin Cascades, 1256 m, N35°27′05.53″ W83°05′39.04″, 16.vii.2006, JKM— 82♂, 5♀. Pisgah National Forest, W Frk Pigeon R @ NC215, UV light trap, 12.vi.2008, J. Robinson— 1♂.  MACON COUNTY, Upper Reynolds Branch, Coweeta Hydrological Laboratory/ LTER, Malaise trap, 980 m, N35°02.00′ W83°27.00′, 5–11.iv.2008, G.W. Courtney ( 3♂, ISU).  GRAHAM COUNTY, Robbinsville, 9.vi.1976, G.E. Bohart ( 1♂, CSU).  MACON COUNTY, Coweeta Hydrological Stn, Upper Shope Frk, 928 m, N35°03′37.00″ W83°27′35.10″, 28.iii.2012, JKM— 10♂, 3♀, 1L#.  TRANSYLVANIA COUNTY, Bee Branch @ NC215, UV light trap, 12.vi.2008, J. Robinson— 2♂. Trib S Mills R @ jct. US276 & FSR1203, UV light trap, 12.vi.2008, J. Robinson— 2♂.  12 mi. NW of Brevard, UV light trap, 7.vi.1971, Anonymous— 2♂. WATAUGA COUNTY, Blue Ridge Parkway NP, Goshen Crk @ BRPMP286, UV light trap, N36°11′07″ W81°36′21″, 9–10.vi.2007, C. Parker & J. Robinson ( 8♂, 2♀, USGS).  SOUTH CAROLINA: OCONEE COUNTY, Issaqueenah Falls @ US 28, 7.iii.1987, D. Pinson— 2L.  TENNESSEE: CLAIBORNE COUNTY, Cumberland Gap NP, Gap Crk, 405 m, N36°36′02.19″ W83°40′05.50″, UV light trap, 19–20.vii.2006, C. Parker & J. Robinson ( 93♂, 5♀, USGS).  COCKE COUNTY, Great Smoky Mtns NP, Cosby Crk, N35°46′31.06″ W83°12′45.03″, 16.vi.2006, JKM— 1♂, 6♀.  SEVIER COUNTY, Trib. Webb Crk., Pittman Center, 408 m, UV light trap, N35°45′18.84″ W83°23′20.98″, 27.v.2005. JKM— 9♂.  VIRGINIA: BEDFORD COUNTY, Blue Ridge Parkway NP, Falling Rock Crk @ MP67.1, UV light trap, 17–18.vii.2007, C. Parker & J. Robinson ( 6♂, 3♀, USGS).  PAGE COUNTY, Shenandoah NP, Lewis Falls, A.L. Melander ( 1♂, TX A& M).   Diagnosis. Males of this species can be distinguished from those of all other Nearctic dixids by the following assemblage of characters: Morphological. (from  Dixellaspp.) katepisternum haired; flagellomere II slightly fusiform; gonocoxite with well-developed basal lobe. (from other  Dixaspp.) scutum brown; wings lacking infuscation at junction of Rs, R2+3, R4+5, and crossvein r-m; epiproct reduced; gonostylus triangular. (from  D. calciphila  sp. nov.and  D. inextricata) basal gonocoxal lobe oval-round, directed dorsally, its width ca. 1/ 3Xlength of gonocoxite, not extended beyond proximal 2/3 of gonocoxite; gonostylus with ventral margin slightly convex; cercus blunt, directed posteriorly, its length 1/ 2Xlateral width of proctiger. Proctiger square or nearly so in lateral view. Molecular. Among the most notable differences that serve to distinguish this species from the other two within the 66 nucleotides (22 codons) of BZF provided ( Fig. 38) is an amino acid substitution at codon position 15 (leucine vs. methionine).   Description.  Male( Fig. 1). Wing length ( n=11) 3.0–3.3 (avg=3.1) mm. Headand its structures brown. Antenna (Fig. 5) ca. 2/ 3Xlength of wing, clothed with whorls of short setae. Scape small, collar-like. Pedicel globose, 4Xwidth of flagellomere I. Flagellum with 14 articles. Flagellomere I 1.6X length of flagellomere II. Flagellomeres II & III most noticeably subcylindrical, with remaining flagellomeres gradually shortening and increasingly cylindrical. Apical flagellomere shortest with pair of divergent apical setae. Maxillary palpus 4- segmented; segments 1–4 as follows: 1:3:5:6. Thoraxwith scutum (Figs 7, 8) brown, lacking discernible stripes, with 4 rows of dark brown setae per side with a few additional setae interspersed, particularly anteriorly; midline raised, with adjacent lateral areas concave. Scutellum brown, with 10–13 posteriorly directed transverse setae along posterior margin. Pronotal lobe brown, with 2 short and 1–2 long apical setae. Anepisternum and anepimeron brown, concolorous with head and scutum, bare. Katepisternum (Fig. 8) brown, with 2–3 setae medially. Katepimeron light brown, bare. Metaepisternum and metaepimeron light brown, bare. Laterotergite brown, bare. Legsbrown, ca. 5 mmin length (4.8–5.3). Pro- and mesothoracic legs symmetrical, with following segment length ratios [coxa, trochanter, femur, tibia, t1, t2, t3, t4, t5 (including claw)]: 2.2, 12, 14.4, 14.4, 10, 4, 2, 1, 1.2. Metathoracic legs differing in that t1 ca. 25–30% longer, i.e., ratio of 12.0–13.0, rather than 10. Coxae light brown, with setae anterolaterally, those of metacoxa positioned more laterally. Foretibia not expanded apically. Fore- and mesotarsal claws pectinate, with 4–5 prominent subapical tines, sometimes with additional, much smaller tines interspersed, especially basally. Metathoracic claw with 1 mesal and 1 basal much reduced secondary tines, sometimes with third one between them. Pro- and mesotibia not expanded apically. Metafemur expanded apically, with transverse row of ca. 12–14 uniformly sized setae on bulge. Tarsomeres 3 and 4, most noticeably of meso- and metathoracic legs, with variably thickened, sometimes hooked, proximal seta on ventral surface. Wing(Fig. 6) smoky grayish brown, lacking infuscation at junction of Rs, R2+3, R4+5, and crossvein r-m. Wing veins brown, setose. Rs arising near terminus of Sc. R2+3 arising proximal to crossvein r-m. Crossvein m-m weakened medially. False vein (FV) prominent, clearly distinct from and running parallel to CuA for most of its length. Halter brown, stem mostly brown, lighter on basal 1/5. Abdomenmostly dark brown, with sparse blue-green iridescence visible under some lighting conditions. Basal fringe brown; segments 2–6 with dark brown terga and grayish brown pleura. Segments 7–9 dark brown. Terminalia( Figs 9, 12–14, 21): Tergite 9 (9T; epandrium) subtrapezoidal, with anterior margin convex. Sternite 9 (9S; hypandrium) subrectangular. Epiproct reduced, weakly sclerotized ( Fig. 21). Cercus blunt, weakly sclerotized, directed posteriorly, one-half length of lateral width of proctiger ( Fig. 21). Proctiger square in lateral view, with distal portion very weakly sclerotized ( Fig. 12). Subepandrial sclerite (SES) bilobed, somewhat kidney-shaped in lateral view ( Figs 9, 12), with proximal lobe adjoining posterodorsal margin of 9T and distal lobe articulating with ventral portion of proctiger by narrow strap-like connection. SES bearing medial projection articulated with aedeagal/parameral complex. Distal lobes of SES appearing as adjoined triangular processes beneath proctiger in dorsal view ( Fig. 21). Gonocoxite subcylindrical, tapered apically, ca. 2Xas long as broad, with prominent basal and apical lobes ( Figs 9, 12). Basal gonocoxal lobe directed dorsally, with prominent setae medially and spinules apically, its oval-rounded apex extended slightly beyond anterior coxal margin in lateral view, greatest width ca. 1/ 3Xlength of gonocoxite, not extended beyond basal 2/3 of gonocoxite, with horizontal margin not distended dorsally resulting in proximal bulge when viewed laterally ( Fig. 9, 12). Apical gonocoxal lobe digitiform, ca. 1/ 3Xlength of gonostylus in lateral view, with prominent setae along posteroventral margin ( Figs 9, 12). Anterior margin of basal gonocoxal lobe intimately associated with gonocoxal apodeme and origin of parameres and ventral wall of aedeagus. Gonostylus triangular, ca. 1.3–1.5X longer than greatest depth, clothed with posterodorsally directed moderately developed setae, those on inner surface longer, slightly thickened; ventral margin slightly convex; posterior margin strongly and irregularly serrated; in ventral view apices expanded laterally ( Fig. 13). Aedeagus membranous, wrinkled ( Fig. 14) positioned between complex strap-like parameres, claspettes, and penis valves. Ventral plate deeply divided medially into roughly diamondshaped halves. Ejaculatory duct short.  Female. ( Fig. 2). Similar to male except as follows: Wing length ( n=8) 2.9–3.6 (avg=3.3) mm. Body coloration generally lighter. Antenna slightly more robust. Tarsal claws simple. Thoracic pleurae light brown. Abdominal terga light brown, with pinkish-purple sheen. Terminalia( Figs 25–28): 9S thin, strap-like. Cercus in dorsal view ( Fig. 25) roughly triangular, with apices slightly divergent; in lateral view ( Fig. 25) cercus rounded. 10S lobes ( Fig. 26) thin, oblong, comma-shaped, with apices expanded gradually. Spermatheca ( Fig. 27) golden brown, round, smooth, with short sclerotized neck. Spermathecal duct with whorls of cuticular outgrowths yielding bottlebrush appearance. Bursa copulatrix with two groups of ca. 8–10 setae positioned laterally of central group of variably numbered thorn-like spicules, much like depicted for  D. inextricatain Figure 29.   Etymology. Named for the geographic region in which this species is distributed.   Distribution.  Dixa appalachiensis  sp. nov.is known to occur in the southern Appalachian Highlands from Shenandoah National Park (NP) south to Great Smoky Mountains NP of western North Carolina and eastern Tennessee ( Fig. 37).   Remarks.  Dixa appalachiensis  sp. nov.is most often found in and around second order, high gradient streams between 3–5 meters in width characterized by having falls and cascades among large boulders ( Figs 31, 32). To date it has not been found in the same streams as  D. inextricata,with which it is sympatric. It is frequently found in association with  D. modestaJohannsen sensu Peters, another species complex in this genus (JK Moulton, unpublished). Adults emerge by mid-March in Great Smoky Mountains NP. There is little doubt that it will eventually be taken in adjacent northeastern Georgia. The northern limit of the distribution is less certain and requires further field studies to elucidate.  FIGURES 5–8. Antennae, wing, head and thorax,  Dixa appalachiensis  sp. nov.5, antennae (male). Scale bar = 1 mm; 6,left wing (male). Scale bar = 1 mm. 7, head and scutum, anterodorsal view. Scale bar = 0.1 mm; 8, thorax, lateral view. Blue circle denotes katepisternal setae. Scale bar = 0.1 mm. Abbreviations: A1 =first anal vein; C= costal vein; CuA= anterior branch of cubital vein; CuP= posterior branch of cubital vein; FV= false vein; h= humeral crossvein; M1= first branch of media; M2= second branch of media; M3+4= third branch of media; m–cu= medial-cubital crossvein; m–m= medial crossvein; Rs= radial sector; R1= anterior branch of radius; R2= first branch of R2+3; R2+3= second branch of radius; R3= second branch of R2+3; R4+5= fourth branch of radius; r–m= radial –medial crossvein; Sc—subcostal vein. 1270709717 2006-07-16 CNC J. K. Moulton United States of America Haywood County 1256 35.451538 Woodfin Cascades @ Blue Ridge Parkway NP 1 -83.09418 2 460 1 1 NC holotype 1270709723 2006-07-16 CNC, USNM J. K. Moulton United States of America Haywood County 1256 35.451538 Woodfin Cascades @ Blue Ridge Parkway NP 1 -83.09418 2 460 10 2 8 NC paratype 1270709728 2 460 1270709733 2 460 1270709719 2 460 1270709727 2 460 1270709732 2 460 1270709720 2 460 1270709729 2 460 1270709735 [482,1323,1265,1290] 2 460 1270709721 2 460 1270709731 2 460 1270709734 2 460 1270709722 [151,1437,1481,1506] 2 460 1270709726 2 460 1270709718 2 460 1270709725 2 460 1270709724 2 460 1270709730 2 460