Phytomyza nemophilae,

Eiseman, Charles S. & Lonsdale, Owen, 2019, New State and Host Records for Agromyzidae (Diptera) in the United States, with the Description of Ten New Species, Zootaxa 4661 (1), pp. 1-39: 19

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Phytomyza nemophilae

spec. nov.

Phytomyza nemophilae  spec. nov.

( Figs. 29View FIGURES 27–33, 61View FIGURES 57–63, 105–109View FIGURES 105–109)

Holotype. OREGON: Lane Co., Blue River , 12.iv.2017, em. 26.iv.2017, M.W. Palmer, ex Nemophila parviflora  , #CSE3778, CNC939967View Materials (1³). 

Paratypes. Same data as holotype, CNC939968–939973View Materials (1³ 5♀), same except em. 28–30.iv.2017, #CSE3733 (1♀)  .

Etymology. The specific epithet refers to the host plant, Nemophila Nutt. 

Host. Boraginaceae  : Nemophila parviflora Douglas ex Benth. 

Leaf mine. ( Fig. 61View FIGURES 57–63) A long, narrow, highly contorted, whitish linear mine. The black frass is deposited in discrete, well-spaced grains.

Puparium. Details not recorded.

Distribution. USA: OR.

Adult description. Wing length 2.8–3.1 mm (³), 3.0– 3.2 mm (♀). Crossvein dm-cu absent. Eye height divided by gena height: 3.3–3.8. First flagellomere small, rounded. Posterior ocelli widely spaced, intervening region three times diameter of ocellus; ocellar triangle subrectangular, wider posteriorly. Body with light brownish pruinosity that is dense and gray on thorax.

Chaetotaxy: Two ors, one ori, slightly decreasing in length anteriorly; ors inset. Postvertical subequal to ors; ocellar seta thin, slightly shorter than ori. Four strong dorsocentral setae, decreasing in length anteriorly. Acrostichal seta absent.Acrostichal setulae in two rows between anterior dorsocentral and midpoint of scutum. Intra-alar setulae few, scattered suturally and presuturally.

Coloration: ( Fig. 29View FIGURES 27–33) Setae black. Head mostly light yellow; antenna, ocellar triangle and posterolateral corner of frons (not including base of inner vertical seta) dark brown; ocellar triangle connected to dark posterolateral region on frons by paler brown intervening patch; back of head dark brown with venter paler; clypeus and palpus brown. Body mostly dark brown with light brownish pruinosity that is dense and gray on thorax with slight blue and coppery tints. Calypter margin pale, hairs golden-brown. Legs paler brown than thorax; apices of femora light yellow with spot as long as wide; base of tibiae light yellow. Abdomen paler brown than thorax.

Genitalia: ( Figs. 105–109View FIGURES 105–109) Posteromedial margin of epandrium extended as thin, short plate. Surstylus small, rounded, mostly fused to epandrium. Hypandrium broadly arched, with short, thin apical apodeme; inner lobe weak, wide, with two setae. Pregonite well-developed. Phallophorus flanked by one pair of weak lateral bars; cylindrical with dorsal margin extending as large, irregular plate fused to basiphallus. Basiphallus with one pair of arms that are fused basally. Hypophallus broad and membranous with recurved medial tubule that opens into phallic membrane. Paraphalli dark, adjacent; base tapered, inner-distal margin curved inwards, fusing to ventromedial surface of mesophallus. Mesophallus slightly longer than wide, base broadly rounded and apex fused to (and indistinguishable from) distiphallus; narrowly sclerotized along ventromedial margin where it meets paraphalli; dorsum with one pair of narrow sclerotized bands that diverge on distiphallus, wrapping around that segment laterally to produce a dark serrated ridge. Distiphallus undivided, narrow basally and widest medially, mostly membranous (but see above), minutely wrinkled longitudinally, and with wide ventral suture and large apical opening. Ejaculatory apodeme not found.

Comments. Phytomyza nemophilae  will key to P. carbonensis Spencer  using Spencer & Steyskal (1986), but the male genitalia are unlike any other described Nearctic species and will readily differentiate it. The genitalia of other borage-feeders in the Palaearctic P. obscura  subgroup (part of the P. obscura  group)—a likely unrelated lineage of darker species without gray thoracic pruinosity and more numerous acrostichal setulae—share a distant similarity in having incurved paraphalli and an apically broad distiphallus, but in the new species, the hypophallus is entirely membranous, the paraphallus is much shorter, the mesophallus is short, rounded, almost entirely clear and indistinguishable from the distiphallus, and the distiphallus tubules are fused, broadest medially and mostly clear with an irregularly sclerotized band bearing a raised serrated ridge.