Liriomyza euphorbiella, Eiseman & Lonsdale, 2019

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: 11-12

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Liriomyza euphorbiella

spec. nov.

Liriomyza euphorbiella   spec. nov.

( Figs. 14, 15 View FIGURES 14–26 , 44, 45 View FIGURES 34–45 , 93–96 View FIGURES 93–96 )

Holotype. OKLAHOMA: Payne Co., Mehan , 36.014339° N, - 96.996744° W, 5.x.2016, em. 27.iii.2017, M.W. Palmer, ex Euphorbia cyathophora   , #CSE3730, CNC939924 View Materials (³). GoogleMaps  

Paratypes. Same data as holotype, #CSE3730, CNC939925 View Materials (1♀); em. by 3.iv.2017, #CSE3739, CNC939926 View Materials , CNC939927 View Materials (2♀), #CSE3742, CNC939920–939922 View Materials (2♀, 1 unemerged in puparium), CNC939923 View Materials (empty pu- paria)   .

Etymology. The specific epithet refers to the host plant, Euphorbia L.  

Host. Euphorbiaceae   : Euphorbia cyathophora Murray.  

Leaf mine. ( Figs. 44, 45 View FIGURES 34–45 ) Pale green with dark green frass; initially narrow and linear with the frass in alternating strips, expanding to an elongate blotch with irregular and more or less diffuse frass. According to M. Palmer (in litt.) most mines contain two larvae.

Puparium. ( Fig. 15 View FIGURES 14–26 ) Yellow; formed outside the mine.

Distribution. USA: OK.

Adult description. Wing length 1.8mm (³♀). Length of ultimate section of vein CuA 1 divided by penultimate section: 1.8–2.3. Eye height divided by gena height: 4.8–5.9. First flagellomere small, rounded. Thorax with light pruinosity.

Chaetotaxy: Two ors, two ori. Four dorsocentrals, becoming shorter anteriorly with anterior three pairs weaker; second seta 3/5 length of first, third half length of first, fourth only slightly shorter than third. Acrostichal seta absent. Acrostichal setulae in six irregular rows; posterior one or two pairs incurved.

Coloration: ( Fig. 14 View FIGURES 14–26 ) Setae black. Pigment relatively pale, appearing faded as if bleached. Head mostly light yellow; back of head brown with venter yellow, ocellar tubercle dark brown, joined to back of head by wider light brown patch; orbital plate very faintly brownish laterally along eye margin, especially lateral to setae; posterolateral corner of frons brown almost to base of outer vertical, light brown to base of inner vertical; clypeus dark brown. Notum dark brown with complete lateral yellow stripe excluding brownish tint above alar base; scutellum dark brown laterally. Metatergite brown, anatergite paler brown and katatergite yellow with paler brown posterior and ventral regions; pigment on pleuron paler brown, including markings on ventral 2/3 of anatergite, katepisternum below (and not including) seta base, meron excluding dorsal margin, and extensive mottling on anepimeron. Calypter margin gray, hairs light brown with slight golden shine. Legs mostly light yellow in male; fore coxa light brown on basal half, mid and hind coxae mottled light brown on basal half excluding anterior surface of mid coxa; fore tibia faintly brownish, mid tibia light brown with venter yellow, hind tibia brown with venter yellow; hind tarsus light brown; female differs in having fore tibia and tarsus light brown and mid and hind tibiae and tarsi brown. Abdomen brown with lateral margin of tergites paler.

Genitalia: ( Figs. 93–96 View FIGURES 93–96 ) Epandrium with one posteroventral spine. Surstylus with two closely spaced apical spines. Phallophorus with shorter venter. Apical section of ejaculatory duct pigmented and swollen. Basiphallus sclerotized along left lateral and anterodorsal surfaces. Paraphallus narrow, lightly sclerotized. Hypophallus narrow, with apical “hairs”. Mesophallus fully fused to distiphallus; composite structure nearly as long as basiphallus, with complete ventral suture that is marginally swollen at base and on distal half; narrow basal stem slightly wider than swollen section of ejaculatory duct, distal half slightly angled dorsally; with one pair of short tubules enclosed within short apical chamber; apical chamber twice as wide as stem, with thick lateral walls and nearly complete sclerotized apical ring. Ejaculatory apodeme with base not distinct from apically narrowing stem; blade ill-defined, rounded; sperm pump with large, irregular sclerotized base.

Comments. Liriomyza euphorbiella   is a relatively pale, unremarkable species externally, typical of many congeners with a dark spot on the frons to the base of the inner vertical, a subshining scutum, four rows of acrostichal setulae, yellow femora and a broad yellow dorsal band on the anepisternum and katepisternum. The following characters of the male genitalia must be examined for diagnosis: surstylus with two small apical spines; mesophallus fully fused to distiphallus; mesophallus+distiphallus nearly as long as basiphallus, with basal stem and wide, shallow apical chamber that is angled dorsally and with a strong apical ring; sperm sac with broad ventral sclerotized plate. This morphology is very similar to that seen in the Asclepias   ( Apocynaceae   ) feeders L. asclepiadis Spencer   ( Lonsdale 2017: Figs. 217–219) and L. subasclepiadis Spencer   ( Spencer & Steyskal 1986: Figs. 796, 797), but in these species the distiphallus is darker and straighter with only the apical chamber much more sharply angled dorsally, the stem of distiphallus is more constricted medially in the former species and thicker in the latter, and the apical ring is narrower in the latter.

Liriomyza euphorbiella   keys approximately to couplet 59 in Lonsdale (2011), but can be differentiated from L. specifica Spencer   and L. venegasiae Spencer   using the above characters. Note that there is a minor error in the key that prevents proper usage in the second half. The second half of couplet 39 states “ At least base of outer vertical bristle surrounded by brown… 48 ”, but the couplet it refers to should be the following one, couplet 49.

This is the first North American record of an agromyzid reared from Euphorbia   . Spencer (1969) reported a mine on E. marginata Pursh   in Quebec attributed to an undetermined genus of Agromyzidae   , but he did not describe or illustrate it. We found a single white blotch mine of an unknown agromyzid on E. cf. brachycera Engelm.   in Colorado. After mining mostly on the upper leaf surface, the larva switched to the lower surface for a short distance and then succumbed to a parasitoid.