Dixa calciphila sp. nov. (Figs 3–4, 10, 15–17, 23) Type material. HOLOTYPE ♂, labeled: “ USA: TN: MARION COUNTY / Spr @ US 64/TN41 opposite Raccoon Mtn/ N35°03′31″ W85°29′08″, 243 m / 24.iv.2014 / J.K. Moulton”; “ HOLOTYPE / Dixa / calciphila / J.K. Moulton [red label]” (CNC). PARATYPES: Same data as holotype, 5♂ and 2♀ each to CNC and USNM. Additional material examined. USA: KENTUCKY: EDMONSON COUNTY, Mammoth Cave NP, Cinnamon Fern Bog, UV light trap, 7.vi.2007, C. Parker & J. Robinson (1♂, USGS); Thru Sprs, UV light trap, 15– 16.viii.2006, C. Parker & J. Robinson (3♂, USGS). HART COUNTY, Three Hundred Sprs nr Munfordville, N37°17′29.85″ W85°43′45.70″, 29.ix.2008, JKM—1♂. Unnamed trib Lynn Camp Crk, 10.iv.2008, JKM—1♂. TAYLOR COUNTY, Little Angel Spr, Trib Craig’s Crk, N of Campbellsville, N37°26′40″ W83°21′18″, 9.vi.2005, JKM; 1.vii.2004, Malaise trap, G.K. Weddle—2♂. 17.iv.2005, JKM—1♂, 1♀, 1L; 15.ix.2005 —1♂. TENNESSEE: FRANKLIN COUNTY, Trib Turkey Crk, ex TN Rt 16 (Old Turnpike Rd.), Walls of Jericho SNA, N34°59′40.77″ W86°03′38.98″, 23.v.2008, JKM—1♂. MARION COUNTY, Spr @ US 64/TN41 opposite Raccoon Mtn, 243 m, N35°03′31″ W85°29′08″, 24.iv.2014, JKM—20♂, 7♀; 4.ix.2015 —5♂, 2♀. Daniel Cave Spr, N36°26′00″ W85°48'00.00″, 8.ix.2010, JKM—3♂. MORGAN COUNTY, Frozen Head SP, Flat Frk, N36°07′10.91″ W84°27′52.67″, 20.vi.2014, JKM—1♂. Obed Wild and Scenic R NP, Melton Mill Br @ Footbridge, Point Tr. below Lilly Bluff Overlook, 357 m, UV light trap, 6.ix.2005, C. Parker (2♂, USGS). PUTNAM COUNTY, Tayes Hollow Spr. @ TN Rt. 84, S of Monterrey, 498 m, N36°08′12″ W85°17′28″, 17.iv.2010, JKM—1♂, 2♀, 1L; 7.iii.2009 —4♂ & 2♀; 10.iii.2009 —3♂, 1♀, 6L; 31.iii.2013 —6♂, 4♀, 4L, 2P. D. calciphila sp. nov.; 11, D. inextricata. Scale bar = 50 µm. Diagnosis. This species can be distinguished from D. appalachiensis sp. nov. and D. inextricata by the following characters: Morphological. Ventral margin of gonostylus strongly convex; basal gonocoxal lobe with apex noticeably acuminate; cercus narrow, acuminate, as long as lateral width of proctiger. Molecular. Among the most significant differences within the 66 nucleotides (22 codons) shown (Fig. 38) that serve to distinguish this species from the other two are amino acid substitutions at the following codon positions: 2 (valine/methionine), 3 (alanine/proline), 14 (asparagine/serine), 18 (asparagine/serine), 19 (arginine-CG)/arginine-AG or lycine), and 21(glycine/absent). Description. Male (Fig. 3). Same as D. appalachiensis sp. nov., except as follows: Wing length (n =13) 2.6– 3.1 (avg=2.9) mm. Wing darker smoky gray. Thorax generally darker brown (Fig. 3), most distinctly differing in katepisternum concolorous with head, anepisternum, and anepimeron and contrasting sharply against whitish to straw-colored mesocoxa. Meron brown, nearly as dark as katepisternum. Terminalia (Figs 10, 15–17, 23): 9S lightly sclerotized, with straight anterior margin. Proctiger heavily sclerotized (Figs 15–17, 23). Cercus narrow, acuminate, as long as lateral width of proctiger (Figs 10, 15). Basal gonocoxal lobe directed posterodorsally in lateral view with apex distinctly falcate (Fig. 10), appearing rectangular in ventral (Fig. 16) and terminal views (Fig. 17). Apical gonocoxal lobe blunt, directed mediolaterally, in lateral view appearing ca. 1/ 5X or less of gonostylus length (Figs 10, 15). Gonostylus triangular in lateral view, ca. 1.3–1.5X longer than greatest depth, ventral margin noticeably convex, bulbous (Fig. 10). Female (Fig. 4). Wing length (n =4) 2.9–3.2 (avg=3.0) mm. Not reliably separated from D. appalachiensis sp. nov. or D. inextricata. Etymology. Named for the karst geography (calc - = lime + - phil = loving) that largely defines the region in which it occurs. Distribution. Currently known only from Kentucky and Tennessee (Fig. 37). Remarks. This species is known from streams ranging from small first order hillside trickles (Fig. 33) to raging torrents (Fig. 34) originating from underground streams. In central Tennessee adults are already on the wing by early March, earlier than other dixids found in the region. This species has been collected in association with Dixa fusca, D. modesta sensu Peters, Dixa nr. repanda Peters, and a member of the Dixella indiana complex. This species is expected to occur in northeastern Alabama and possibly, southern Indiana. Morphologically and molecularly, this species is more distantly related to the other two species in the group than they are to one another.

Published as part of Moulton, John K., 2016, The Dixa inextricata Dyar & Shannon (Diptera: Dixidae) species group, with two new cryptic species from the eastern Nearctic Region, pp. 458-472 in Zootaxa 4121 (4) on pages 463-466, DOI: 10.11646/zootaxa.4121.4.6, http://zenodo.org/record/265286