Megophthalmidia occidentalis Johannsen

Kerr, Peter H., 2014, The Megophthalmidia (Diptera, Mycetophilidae) of North America including eight new species, ZooKeys 386, pp. 29-83 : 49-55

Megophthalmidia occidentalis Johannsen Figs 51-61

Megophthalmidia occidentalis Johannsen, 1909: 89

Type material examined.

♂, "Friday Harbor, Wash., July 6.05" / "OAJohannsen, Lot 114, Sub + slide, Cornell U." / "♂ HOLOTYPE Megophthalmidia occidentalis Johannsen" [white label with edge colored red] / "HOLOTYPE Cornell U. No. 1999" [red label]. Specimen double-mounted. Left wing dissected and slide-mounted, marked "HOLOTYPE Cornell U., No. 1999"; male genitalia dissected, ethanol-preserved, in glass microvial within stoppered glass vial marked "MYCETOPHILIDAE, O.A. Johannsen, LOT 114, Cornell U., HOLOTYPE No. 1999." [CUIC].

Additional material examined: CALIFORNIA: 2 ♂♂, 3 ♀♀, "USA: CA: Alpine Co; GroverHotSprings SP, nr. Hoffman house, 38°41.997'N, 119°50.805'W, 1800masl, 14. viii– 3.ix.2006 PH Kerr & M Hoffman 06LOT476" [CSCA]; 4 ♂♂, 4 ♀♀, "USA: CA: Amador Co.: Indian Grinding Rock St. Pk., dry wash nr. S.Nature trail, MT#2, 38°25' N, 120°38' W ', 715masl, 24. v– 10.vi.2007 P. Kerr & M. Hauser 07LOT096" [CSCA; locality Fig. 104; specimen numbers 07Y273 (♂, Fig. 51), 07Y274 (♂, dissected), and # 07Z068 (♀)]; ♂, "USA: CA: Amador Co.: Indian Grinding Rock St. Pk., firebreak nr. envtl camp, MT#3, 38°25.7' N, 120°38.6' W ', 715masl, 24. v– 10.vi.2007 P. Kerr & M. Hauser 07LOT097" [CSCA]; 26 ♂♂, 46 ♀♀, "USA: CA: Amador Co.: Indian Grinding Rock St. Pk., dry wash nr. S.Nature trail, MT#2, 38°25' N, 120°38' W ', 715masl, 10-29.vi.2007 P. Kerr & M. Hauser, 07LOT315" [CSCA, 25 ♂♂, 45 ♀♀, including specimen numbers 07Z048 (♀, Fig. 51) and 07Z049 (♀, dissected); UAIC, ♂, ♀]; 6 ♂, 13 ♀♀, "USA: CA: Amador Co.: Indian Grinding Rock St. Pk., dry wash nr. S.Nature trail, MT#2, 38.4216°N,-120.645°W 715masl, 15. v– 18.vi.2008 P. Kerr CSCA08L596" [CSCA, 4 ♂, 11 ♀♀; LACM, ♂, ♀; SBNM, ♂, ♀]; 6 ♂♂, 2 ♀♀, "USA: CA: Amador Co., Indian Grinding Rock SHP, 25.vi.2008, P. Kerr CSCA09L616" [CSCA; in alcohol]; 13 ♂♂, 16 ♀♀, "USA: CA: Calaveras Co., Calaveras Big TreesSP, South Grove old fire rd., 38°14.9'N, 120°15.45'W ~1400masl, 8-26.vii.2005, A.R. Cline & S.D. Gaimari, 06LOT289" [CSCA, 10 ♂♂, 13 ♀♀; LACM, ♂, ♀; SBNM, ♂, ♀; UAIC, ♂, ♀;]; ♂, "USA: CA: Calaveras Co., BigTreesSP, S. Grove, Sequoia tree #298 (Creek), canopy trap (153'), 38.2415°N, 120.2554°W 1405masl, 27. vi– 18.vii.2009, P. Kerr & R. Frizzell CSCA09L428" [CSCA; in alcohol, specimen # 09D638]; ♂, "USA: CA: Calaveras Co., BigTreesSP, S. Grove, Sequoia tree #282 (Stellar), canopy trap (129'), top bottle, 38.2407°N, 120.2546°W 1425masl, 27. vi– 18.vii.2009, P. Kerr & R. Frizzell CSCA09L433" [CSCA; specimen # 09D656, in alcohol]; ♂, "USA: CA: Calaveras Co., BigTreesSP, S. Grove, Sequoia tree #282 (Stellar), canopy trap (129'), bottom bottle, 38.2407°N, 120.2546°W 1425masl, 27. vi– 18.vii.2009, P. Kerr & R. Frizzell CSCA09L434" [CSCA; specimen # 09D656, in alcohol]; 4♀♀, "USA: CA: Calaveras Co., BigTreesSP, S. Grove, Sequoia tree #282 (Stellar), canopy trap nr. ground, top bottle, 38.2407°N, 120.2546°W 1425masl, 27. vi– 18.vii.2009, P. Kerr & R. Frizzell CSCA09L435" [CSCA; in alcohol]; 2 ♂♂, "USA: CA: Calaveras Co., BigTreesSP, S. Grove, Sequoia tree #282 (Stellar), canopy trap nr. ground, bottom bottle, 38.2407°N, 120.2546°W 1425masl, 27. vi– 18.vii.2009, P. Kerr & R. Frizzell CSCA09L436" [CSCA; specimen numbers 09D665, 09D666, both in alcohol]; ♂, "USA: CA: Calaveras Co., BigTreesSP, S. Grove, Sequoia tree #317 (Neighbor), canopy trap (4'), top bottle, 38.2406°N, 120.2563°W 1410masl, 27. vi– 18.vii.2009 P. Kerr & R. Frizzell CSCA09L441" [CSCA; specimen # 09D718, in alcohol]; ♂, "USA: CA: Del Norte Co, SixRiversNF, ForestRd17N05, 2miSE Rt.199, 41.8737°N, 123.8135°W, 620masl, 3. vi– 24.vii.2009 P. Kerr & O. Lonsdale, 2m MT, CSCA09L524" [CSCA; Figs 56-58]; 2 ♂♂, "CALIF. Madera Co., Meadow near locked gate, road to Mark Mine, SE. slope of Green Mt. 7600 ft., 20.VIII.71 H. Leech" [CAS]; 6 ♂♂, "CAL. Mono Co., Alt. 7200 ft, Leavitt Meadow / 12- VIII -1963, flight trap, H. B. Leech" [CAS]; ♂, "McBride Spgs., Mt. Shasta, CALIF., 4800' 22.VII.1965, Malaise trap" [CNC]; ♂, "Loop Trail nr, Phillipsville, Alt Hwy 101 CAL, 5-VII-1968, B. V. Peterson" [CNC]; ♂, "U.S.A.: CALIFORNIA: Siskiyou County, McBride Springs, 8 –VIII– 1967 1524m., Paul H. Arnaud, Jr." [CAS]; ♂, "U.S.A.: CALIFORNIA: Siskiyou County, Elk Creek, ca. 6 km. E. McCloud, 29 –VII– 1974, Paul H. Arnaud, Jr., Calif. Acad. Sci. Coll." [CAS]; ♂, "U.S.A.: CALIFORNIA: Siskiyou County, Big Flat Public Camp, South Fork Salmon River, 20 –VIII– 1980, 1510m, Paul H. Arnaud, Jr." [CAS]; 10 ♂♂, 2 ♀♀, "USA: CA: Sonoma Co., Annadel SP, 0.9mi from park lot, Richardson trail, 38°26.11'N, 122°36.67'W 220masl, 6m MT#3, 17. v– 7.vi.2007 P. Kerr & S. Blank 07LOT196" [CSCA; including # 13M284 (♂, Fig. 52), 7 males in alcohol]; ♂, "USA: CA: Sonoma Co., Annadel SP, swept from exposed roots overhanging dry creekbed, 38°26.11'N, 122°36.67'W 220masl 7.vi.2007 P. Kerr 07LOT094" [CSCA]; ♂, "CAL. Trinity Co., S. Fork Van Horn, creek 2 mi. from, mouth at upper, Mad river. Alt. 3000' 9.VIII.70 / moss-edged rock pools in running stream, open area. Collector Hugh B. Leech" [CAS]; ♂, "USA: CA: Tulare Co.: Whitaker Forest, E. Eshom Crk. Drainage, nr. tree #142, 36.7062N, 118.9319W, 1650masl, MT, 3. vi– 16.vii.2010 P.H. Kerr CSCA10L174" [CSCA; specimen #12J131, in alcohol]; 3 ♂♂, "USA: CA: Tulare Co.: Whitaker Forest, E. Eshom Crk. Drainage, nr. tree #142, 36.7062N, 118.9319W, 1650masl, MT, 16. vii– 12.viii.2010 P.H. Kerr CSCA10L286" [CSCA; # 12J955 (dissected, Figs 53-55, 59-61); 2 ♂♂ in alcohol]. IDAHO: ♂, "USA: IDAHO: Bonner County, Sandpoint KOA, 0.4 km W. Sagle, 18-VII-1974, Paul H. Arnaud, Jr., Calif. Acad. Sci. Coll." [CAS (dissected)]. NEVADA: ♂, "Clear Creek Cpgd., Ormsby Co., NEV., 6500' 27.VII.1968, D. D. Munroe" [CNC]. OREGON: 12 ♂♂, "USA: ORE.: Deschutes Co., DeschutesRiver, 1 mi. SW. Pringle Falls 31-VII-1970, Paul H. Arnaud, Jr., 4250' Flight Trap" [CAS]; ♂, "USA: OREGON: Crook County, Cougar Campground, Marks Creek, 24 –VII– 1974, Paul H. Arnaud, Jr., Calif. Acad. Sci. Coll." [CAS]; ♂, "USA: OREGON: Jackson County, Union Creek Campground, Rogue River 17.3 km N. Prospect, 975m / 24 –VII– 1974, Paul H. Arnaud, Jr., Calif. Acad. Sci. Coll." [CAS]. WYOMING: ♂, "U.S.A.: WYOMING:, Lincoln County, between Grover and, Thayne 16 –VIII– 1981, Paul H. Arnaud, Jr" [CAS]. CANADA (B.C.): ♂, "12km. NE Pemberton, B.C., 28-VII-1990, A. Borkent CD1236" [CNC]; ♂, "No. 62-1256-04, Date 8.VII.62, F.I.S.1962 / light trap, Langford, B.C." [CNC]; ♂, "CANADA: BC: Nanaimo, 49.13°N, 123.97°W, 4-6 June 2004, B. Brown, Malaise 06LOT435" [CSCA; specimen # 13N141].

Diagnosis.

Megophthalmidia occidentalis is most easily separated from Megophthalmidia mckibbeni sp. n. and all other Nearctic congeners by its yellow body that contrasts its dark brown head (Fig. 51). This species is most similar to Megophthalmidia mckibbeni in the morphology of its male reproductive structures, particularly the aedeagus, which features a pair of long lateral processes (= "aedeagal fork", Fig. 60) that bear a short recurved ventral hook (Fig. 59). This feature distinguishes these two species from all other Megophthalmidia in North America. Independent of body coloration, Megophthalmidia occidentalis may be distinguished from Megophthalmidia mckibbeni by having the epandrium posterior margin emarginate medially only (Fig. 55; not entire margin angled inward, toward center), aedeagus bearing lateral processes that have s-curvature (tip pointing upward) in lateral view (Fig. 59) and are subtended by a short process that extends about 1/3 length of lateral process before hook (Fig. 59; in Megophthalmidia mckibbeni , this subtending process is clearly longer (Fig. 38)). In the dorsal view, the aedeagal lateral processes of Megophthalmidia occidentalis are thicker and exhibit noticeable bends (Fig. 60), as opposed to being largely straight (as in Megophthalmidia mckibbeni , Fig. 39).

Description.

Male. Body length: 2.3-3.0, 2.7 [2.9] mm (n=10). Wing length: 2.2-2.7, 2.5 [2.6] mm (n=10).

Coloration (Fig. 51). Head dark brown; antennal scape and pedicel pale cream-colored to pale yellow, flagellomeres brown; face and clypeus light brown to brown; palps and labellum cream-colored to pale yellow. Thorax pale yellow to yellow throughout; scutum setae brown. Legs cream-colored to pale yellow becoming gradually darker apically, to light brown at tarsi; hind tibial comb yellowish, preceded by 0-3 (usually 3) dark brown setae. Wing hyaline without markings, wing veins yellowish brown; haltere stem and knob pale yellow. Anterior abdominal segments yellow to yellowish brown, posterior segments darkening successively; all abdominal segments bear dark brown setae. Terminalia pale yellow to light brown at base, gradually becoming darker brown apically.

Head. Ocelli slightly raised, median ocellus in line with anterior margin of lateral ocelli, median ocellus approx. 0.5 × size as lateral ocelli; lateral ocellus located approx. 1 –1.3× diameter of ocellus from eye margin, separated from median ocellus by approx. twice its own diameter. Eyes with microsetae, which are approximately as long as width of facet. Frons microtrichose, without setae, flattened. Antennal length 0.8-1.1, 1.0 [1.0] mm (n=10) (approx. 1 × length of head and thorax). Face clearly longer than wide, setose; clypeus and labrum microtrichose, without setae. Palpus with four palpomeres; palpomere 1 without setae, other palpomeres with golden brown to dark brown setae, palpomere 2 bearing inconspicuous, small pocket of sensilla; palpomeres 1 and 2 subequal in length, palpomere 3 length subequal to or shorter than combined length of palpomeres 1 and 2, palpomere 4 length 1 –1.25× combined lengths of palpomeres 1-3. In female, palpomere 4 appx. length of palpomeres 2-3.

Thorax. Dorsum with evenly-distributed, short, appressed setae, bearing longer setae only along lateral and posterior margins. Antepronotum, proepisternum, and laterotergite bearing setae; remaining lateral thoracic sclerites bare. Costal wing vein extends beyond R5, one-half to approx. two-thirds distance between R5 and M1; R1 approximately the same length as r-m; cubital fork proximad of r-m base (Fig. 52); R1, M1, M2, CuA1, and CuA2 with setae on upper surface (lacking setae on M1 + M2). Wing veins A1 and CuP absent.

Male genitalia (Figs 53-61). Epandrium dorsal surface flat or nearly so, with or without setae medially, posterior broadly but shallowly emarginate at center (Fig. 55). Posterior processes of epandrium greater than 7 × longer than wide, separated at base by approx. 3 × width of process, length of setae at base of epandrial processes ~2 × width of process (Figs 54). Gonocoxites as in Figs 56-58. Aedeagal fork with short recurved hook, bearing subtending process approx. 1/3 length of base to tip of hook (Fig. 59).

Female. Body length: 2.4-3.0, 2.7 mm (n=10). Antennal length: 0.6-0.8, 0.7 mm (n=10). Wing length: 2.4-2.7, 2.6 mm (n=10).

Coloration (Fig. 51). Same as male, except generally lighter at apex of abdomen.

Head and thorax. Same as male, except antenna length shorter; 0.6-0.8, 0.7 mm (n=10).

Discussion.

Where sympatric, Megophthalmidia occidentalis and Megophthalmidia mckibbeni demonstrate clear color differences of both males and females that make distinguishing them in the field routine (Figs 31, 51). Interestingly, the male genitalia of these two species are remarkably similar however - to the point where additional study was necessary to make sure that they aren’t simply color morphs of the same species. This wouldn’t be expected, given that both sexes of each type are found in sympatry, but it was still worth considering. As a test in a ‘double-blind’ format, I examined dozens of dissected and disassociated male genitalia from both Megophthalmidia mckibbeni and Megophthalmidia occidentalis throughout their respective geographic ranges, to see if differences in the structure of the male genitalia are consistent with the more obvious, non-genitalic differences between these species, such as body color. It was found that the genitalia of these two species do exhibit consistent morphological differences, in addition to differences of body color, and this test corroborated a separate species hypothesis for each (i.e., they can be distinguished reliably by their genitalia alone). If specimens are not critically-point dried, however, specimens of Megophthalmidia occidentalis tend to darken to an orange-brown color and in Southern California, I have seen a male Megophthalmidia occidentalis that retains a similar body color to Megophthalmidia mckibbeni [#12K748], so specific morphology of the male terminalia remains the more reliable arbiter for proper species recognition. The original holotype of Megophthalmidia occidentalis has darkened somewhat, but is consistent with Fig. 51.