Dixa appalachiensis , Moulton, John K., 2016

Moulton, John K., 2016, The Dixa inextricata Dyar & Shannon (Diptera: Dixidae) species group, with two new cryptic species from the eastern Nearctic Region, Zootaxa 4121 (4), pp. 458-472: 460-463

publication ID

http://doi.org/10.11646/zootaxa.4121.4.6

publication LSID

lsid:zoobank.org:pub:F15F9CC4-A5CE-45D9-94F7-7C112AE71544

persistent identifier

http://treatment.plazi.org/id/03F37E07-6F4C-4101-FF40-34BDFAA6F95B

treatment provided by

Plazi

scientific name

Dixa appalachiensis
status

sp. nov.

Dixa appalachiensis  sp. nov.

( Figs 1 –2View FIGURES 1 – 4, 5–8, 9, 12 –14, 21, 25–28)

Type material. HOLOTYPE ♂, labeled: “ USA: NC / Haywood County / Woodfin Cascades @ Blue Ridge Parkway NP / N 35 ° 27 ′05.53″ W 83 °05′ 39.04 ″, 1256 m / 16.vii. 2006 / J.K. Moulton ”; “HOLOTYPE/ Dixa  / appalachiensis  / J.K. Moulton [red label]” ( CNCAbout CNC).GoogleMaps  PARATYPES: Same data as holotype, 8 ♂ and 2 ♀ each to CNCAbout CNC and USNMAbout USNMGoogleMaps  .

Additional material examined. USA. KENTUCKY: BELL COUNTY, Cumberland Gap NHP, Tunnel Crk , 28.xi. 2005, JKM— 6 ♂, 2 ♀.  NORTH CAROLINA: 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, N 35 ° 36 ′ 58.47 ″ W 83 °07′ 11.71 ″, 26.vii. 2005, JKM— 4 ♂.  Blue Ridge Parkway NP, Woodfin Cascades, 1256 m, N 35 ° 27 ′05.53″ W 83 °05′ 39.04 ″, 16.vii. 2006, JKM— 82 ♂, 5 ♀.  Pisgah National Forest, W Frk Pigeon R @ NC 215, UV light trap, 12.vi. 2008, J. Robinson— 1 ♂.  MACON COUNTY, Upper Reynolds Branch, Coweeta Hydrological Laboratory/ LTER, Malaise trap, 980 m, N 35 °02.00′ W 83 °27.00′, 5–11.iv. 2008, G.W. Courtney (3 ♂, ISUAbout ISU).  GRAHAM COUNTY, Robbinsville, 9.vi. 1976, G.E. Bohart (1 ♂, CSUAbout CSU).  MACON COUNTY, Coweeta Hydrological Stn, Upper Shope Frk, 928 m, N 35 °03′37.00″ W 83 ° 27 ′ 35.10 ″, 28.iii. 2012, JKM— 10 ♂, 3 ♀, 1 L#.  TRANSYLVANIA COUNTY, Bee Branch @ NC 215, UV light trap, 12.vi. 2008, J. Robinson— 2 ♂. Trib S Mills R @ jct. US 276 & FSR 1203, 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 @ BRP MP 286, UV light trap, N 36 ° 11 ′07″ W 81 ° 36 ′ 21 ″, 9–10.vi. 2007, C. Parker & J. Robinson (8 ♂, 2 ♀, USGSAbout USGS).  SOUTH CAROLINA: OCONEE COUNTY, Issaqueenah Falls @ US 28, 7.iii. 1987, D. Pinson— 2 L.  TENNESSEE: CLAIBORNE COUNTY, Cumberland Gap NP, Gap Crk, 405 m, N 36 ° 36 ′02.19″ W 83 ° 40 ′05.50″, UV light trap, 19–20.vii. 2006, C. Parker & J. Robinson (93 ♂, 5 ♀, USGSAbout USGS).  COCKE COUNTY, Great Smoky Mtns NP, Cosby Crk, N 35 ° 46 ′ 31.06 ″ W 83 ° 12 ′ 45.03 ″, 16.vi. 2006, JKM— 1 ♂, 6 ♀.  SEVIER COUNTY, Trib. Webb Crk., Pittman Center, 408 m, UV light trap, N 35 ° 45 ′ 18.84 ″ W 83 ° 23 ′ 20.98 ″, 27.v. 2005. JKM— 9 ♂.  VIRGINIA: BEDFORD COUNTY, Blue Ridge Parkway NP, Falling Rock Crk @ MP 67.1, UV light trap, 17–18.vii. 2007, C. Parker & J. Robinson (6 ♂, 3 ♀, USGSAbout 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 Dixella  spp.) katepisternum haired; flagellomere II slightly fusiform; gonocoxite with well-developed basal lobe. (from other Dixa  spp.) scutum brown; wings lacking infuscation at junction of Rs, R 2 + 3, R 4 + 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 / 3 X length of gonocoxite, not extended beyond proximal 2 / 3 of gonocoxite; gonostylus with ventral margin slightly convex; cercus blunt, directed posteriorly, its length 1 / 2 X lateral 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 BZFAbout BZF provided ( Fig. 38View FIGURE 38) is an amino acid substitution at codon position 15 (leucine vs. methionine).

Description. Male ( Fig. 1View FIGURES 1 – 4). Wing length (n = 11) 3.0– 3.3 (avg= 3.1) mm. Head and its structures brown. Antenna (Fig. 5) ca. 2 / 3 X length of wing, clothed with whorls of short setae. Scape small, collar-like. Pedicel globose, 4 X width of flagellomere I. Flagellum with 14 articles. Flagellomere I 1.6 X 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. Thorax with 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. Legs brown, ca. 5 mm in length (4.8–5.3). Pro- and mesothoracic legs symmetrical, with following segment length ratios [coxa, trochanter, femur, tibia, t 1, t 2, t 3, t 4, t 5 (including claw)]: 2.2, 12, 14.4, 14.4, 10, 4, 2, 1, 1.2. Metathoracic legs differing in that t 1 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, R 2 + 3, R 4 + 5, and crossvein r-m. Wing veins brown, setose. Rs arising near terminus of Sc. R 2 + 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. Abdomen mostly 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 9View FIGURES 9 – 11, 12–14View FIGURES 12 – 20, 21View FIGURES 21 – 24): Tergite 9 (9 T; epandrium) subtrapezoidal, with anterior margin convex. Sternite 9 (9 S; hypandrium) subrectangular. Epiproct reduced, weakly sclerotized ( Fig. 21View FIGURES 21 – 24). Cercus blunt, weakly sclerotized, directed posteriorly, one-half length of lateral width of proctiger ( Fig. 21View FIGURES 21 – 24). Proctiger square in lateral view, with distal portion very weakly sclerotized ( Fig. 12View FIGURES 12 – 20). Subepandrial sclerite (SES) bilobed, somewhat kidney-shaped in lateral view ( Figs 9View FIGURES 9 – 11, 12View FIGURES 12 – 20), with proximal lobe adjoining posterodorsal margin of 9 T 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. 21View FIGURES 21 – 24). Gonocoxite subcylindrical, tapered apically, ca. 2 X as long as broad, with prominent basal and apical lobes ( Figs 9View FIGURES 9 – 11, 12View FIGURES 12 – 20). 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 / 3 X length of gonocoxite, not extended beyond basal 2 / 3 of gonocoxite, with horizontal margin not distended dorsally resulting in proximal bulge when viewed laterally ( Fig. 9View FIGURES 9 – 11, 12View FIGURES 12 – 20). Apical gonocoxal lobe digitiform, ca. 1 / 3 X length of gonostylus in lateral view, with prominent setae along posteroventral margin ( Figs 9View FIGURES 9 – 11, 12View FIGURES 12 – 20). Anterior margin of basal gonocoxal lobe intimately associated with gonocoxal apodeme and origin of parameres and ventral wall of aedeagus. Gonostylus triangular, ca. 1.3–1.5 X 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. 13View FIGURES 12 – 20). Aedeagus membranous, wrinkled ( Fig. 14View FIGURES 12 – 20) positioned between complex strap-like parameres, claspettes, and penis valves. Ventral plate deeply divided medially into roughly diamondshaped halves. Ejaculatory duct short.

Female. ( Fig. 2View FIGURES 1 – 4). 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 25–28View FIGURES 25 – 30): 9 S thin, strap-like. Cercus in dorsal view ( Fig. 25View FIGURES 25 – 30) roughly triangular, with apices slightly divergent; in lateral view ( Fig. 25View FIGURES 25 – 30) cercus rounded. 10 S lobes ( Fig. 26View FIGURES 25 – 30) thin, oblong, comma-shaped, with apices expanded gradually. Spermatheca ( Fig. 27View FIGURES 25 – 30) 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. inextricata  in Figure 29View FIGURES 25 – 30.

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. 37View FIGURE 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, 32View FIGURES 31 – 36). 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. modesta Johannsen 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: A 1 = first anal vein; C = costal vein; CuA = anterior branch of cubital vein; CuP = posterior branch of cubital vein; FV = false vein; h = humeral crossvein; M 1 = first branch of media; M 2 = second branch of media; M 3 + 4 = third branch of media; m–cu = medial-cubital crossvein; m–m = medial crossvein; Rs = radial sector; R 1 = anterior branch of radius; R 2 = first branch of R 2 + 3; R 2 + 3 = second branch of radius; R 3 = second branch of R 2 + 3; R 4 + 5 = fourth branch of radius; r–m = radial – medial crossvein; Sc —subcostal vein.

USNM

USA, Washington D.C., National Museum of Natural History, [formerly, United States National Museum]

NHP

NHP

ISU

USA, Illinois, Normal, Illinois State University

CSU

CSU

FSR

FSR

BRP

BRP

USGS

USGS

CNC

Canadian National Collection of Insects, Arachnids, and Nematodes

USNM

Smithsonian Institution, National Museum of Natural History

ISU

Indiana State University

CSU

Colorado State University

USGS

U.S. Geological Survey

BZF

Forest Research and Development Center and Nature Conservation

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Diptera

Family

Dixidae

Genus

Dixa