Eulonchus smaragdinus Gerstaecker, 1856

Borkent, Christopher J., Gillung, Jessica P. & Winterton, Shaun L., 2016, Jewelled spider flies of North America: a revision and phylogeny of Eulonchus Gerstaecker (Diptera, Acroceridae), ZooKeys 619, pp. 103-146 : 118-121

Taxon classification Animalia Diptera Acroceridae

Eulonchus smaragdinus Gerstaecker, 1856 Figs 10, 11, 12, 16F, 17E, 18E, 19E

Eulonchus smaragdinus Gerstaecker, 1856: 360.

Eulonchus smaragdinus pilosus Schlinger, 1960: 418, syn. n.

References.

Osten Sacken 1877: 276 (California, notes), 1878: 99 (catalogue); Melander 1902: 181 (California); Aldrich 1905: 221 (catalogue); Kertész 1909: 12 (catalogue); Verrall 1909 a: 451 (fig wing); Cole 1919: 34 (key, notes, figs, California); Essig 1926: 559 (descr. note, California); Brunetti 1926: 583 (Uruguay [misidentification]); Sabrosky 1948: 388 (key ref., notes); Schlinger 1953: 220 (LT designation), 1960: 417 (description, distr., figs), 1965: 404 (catalogue), 1987: 320 (host Aptostichus standfordianus ); Paramonov 1955: 20 (comparison with Apsona muscaria ); Cole 1969: 221 (notes); Poole 1996: 36 (checklist).

Common name.

Southern Emerald or Sapphire.

Diagnosis.

Proboscis curved and longer than abdomen apex (as long or longer than wing length); ocellar tubercle nearly flat, weakly bifurcated; legs bright yellow; body colour metallic green, blue or purple; thorax covered in yellowish pile.

Redescription.

Body length: 8.3-12.9 mm, Wing length: 6.9-12.6 mm. Head. Flagellum red-brown or dark brown, male flagellum cylindrical, shorter than head height; scape and pedicel brown; clypeus elongate, length equal to oral cavity; rounded with flat area dorsally, black-brown, surface glossy, glabrous; labial palp brown or yellow, extending anteriorly beyond proboscis at point of attachment; margin of oral cavity (parafacial) glabrous, admixed with pubescence; proboscis length extending beyond abdomen; ocellar tubercle bifurcate (processes short and rounded), tubercle height shorter than width; median ocellus present or greatly reduced; occiput metallic green-blue or blue, pile densely white or yellow. Thorax. Metallic green, blue or purple, pile white or yellow; coxae brown or black with metallic blue (and green) sheen; femora yellow; tibiae dark yellow; tarsi dark yellow (distal tarsomeres often darker); calypter margin yellow or light brown; calypter membrane transparent; haltere entirely light brown to yellow. Abdomen. Metallic green or blue-violet, vestiture white or yellow, dominant setae appressed or erect, pile posteriorly directed, marginal band of laterally directed pile on T2-4. Male genitalia (Figs 17A, 18A, 19A). Epandrium rectangular, wide at the apex, with posterior margin slightly concave; gonocoxite deeply emarginate along anterior margin, fenestrae lacking; aedeagus thinned at the apex, only slightly sclerotized.

Type material examined.

Lectotype male, ZMB, "Californien/ von Müller” [green]; “1251” [white]; “Type” [orange]; " smaragdinus / Gerst.*" [green]; "Californ. v. Müller” [green]; "LECTOTYPE/ Eulonchus / smaragdinus / Gerst./ Designation of. E.I. Schlinger-1952" [blue]; specimen condition: very good, tarsi of both mid legs missing. Body length: 10.0 mm, wing length: 8.6 mm. Paralectotype female, ZMB, "Californien/ von Müller S." [green]; “Type” [orange]; "PARALECTOTYPE ♀/ Eulonchus smaragdinus / Gerstaecker/ Det. C.J. Borkent 2015" [yellow]; specimen condition: fair, head crushed, antennae broken off, tarsi of left mid leg and hind right leg missing.

Eulonchus smaragdinus pilosus Schlinger, 1960: 418; Holotype male, USNM, "S Bernadino/ Co. CAL."[white]; "Coquillet/ Collector" [white]; "Insect Book./ Pl.18 fig 23" [white]; "HOLOTYPE/ Eulonchus / smaragdinus / pilosus / ♂ Schlinger" [orange]; specimen condition: excellent, tarsi of left hind leg missing. Body length: 10.1 mm, Wing length: 9.0 mm.

Other material examined.

Listed in Table 3 (Suppl. material 1).

Distribution

(Fig. 20). Nearctic: northern California (USA) to Baja California (Mexico). Erroneous record of Uruguay, see discussion by Schlinger 1960.

Ecology.

Eulonchus smaragdinus has been recorded visiting the flowers of 11 different plant families and 18 different species (Table 2, Borkent and Schlinger 2008b).

Biology.

Host: Aptostichus standfordianus ( Euctenizidae ) ( Schlinger 1987).

Comments.

Eulonchus smaragdinus is highly variable in size and colour, and is superficially morphologically similar to Eulonchus sapphirinus , most notably in the bright yellow legs. However, it can be easily distinguished from the latter in having a proboscis that is curved (rather than straight) that extends beyond the abdomen, and is often longer than body. Male genitalic characters otherwise indicate a closer relationship to Eulonchus halli , as suggested by Schlinger (1960) (see Fig. 22). Schlinger (1960) erected the subspecies Eulonchus smaragdinus pilosus due to the lighter coloured pile of the individuals he collected. In our study we found that these lighter individuals were just one end of the colouration spectrum (golden pile changing progressively to white pile when moving north to south) of Eulonchus smaragdinus , and therefore do not recognize it as a distinct subspecies.