Agromyza soka,

Eiseman, Charles S. & Lonsdale, Owen, 2018, New state and host records for Agromyzidae (Diptera) in the United States, with the description of thirty new species, Zootaxa 4479 (1), pp. 1-156: 13-14

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Agromyza soka

spec. nov.

Agromyza soka  spec. nov.

( Figs. 5–6View FIGURES 1–6. 1, 78View FIGURES 75–82, 230–233View FIGURES 230–233)

Holotype. USA. VIRGINIA: nr. Plummers Isl. , 20.v.1914, R.C. Shannon (1♂, USNM). 

Paratypes. USA. CONNECTICUT: Hartford Co.  , East Hartford, Two Rivers Magnet Middle School,, em  . 27–29.iv.2017, C.S. Eiseman, ex Robinia pseudoacacia  , #CSE3574, CNC939943–939946 (3♂ 1♀, CNC); NORTH CAROLINA: Scotland Co., Laurinburg, St. Andrews University , 24.iv.2015, em  . 16–18.iii.2016, T.S. Feldman, ex Robinia pseudoacacia  , #CSE2248, CNC653954, CNC653955 (1♂ 1♀, CNC); 4.iv.2016, em. 18.iv – 3.v.2017, T.S. Feldman, ex Wisteria floribunda  , #CSE3518, CNC939744–939747 (1♂ 3♀, CNC).

Etymology. The specific epithet (Gr. sokos —“stout, strong”) refers to the complex, heavily-sclerotized phallus.

Hosts. Fabaceae  : Robinia pseudoacacia  L., Wisteria floribunda (Willd.)  DC.

Leaf mine. ( Fig. 78View FIGURES 75–82) A broad, green track, contorted to form a secondary blotch that occupies most of the leaflet surface. Frass is in discrete, rather closely spaced, black grains.

Puparium. ( Fig. 6View FIGURES 1–6. 1) Reddish-brown; formed outside the mine.

Distribution. USA: CT, NC, VA. We have found larvae producing similar leaf mines in MA, and these have also been reported from NY, PA, VA, and WV (see Comments).

Adult description. Wing length 2.3–2.5mm (♂), 2.3–3.0mm (♀). Length of ultimate section of vein CuA1 divided by penultimate section: 0.6–0.7. Eye height divided by gena height: 6.9–9.2. Ocellar triangle relatively small and rounded. First flagellomere small and nearly circular or slightly longer than high, with nearly indistinct apical tuft of pale hairs. Notum pruinose.

Chaetotaxy: Two ors, two or three ori (anterior seta small if present). Ocellar and postvertical setae subequal to outer vertical seta. Five dorsocentrals, strongly decreasing in length anteriorly. Eight irregular rows of acrostichal setulae. Mid tibia with one (male paratype) or two posteromedial setae.

Coloration: ( Fig. 5View FIGURES 1–6. 1) Setae dark brown with light brown reflection. Body predominantly dark brown (female darker) with light pruinosity; antenna dirty orange with distal half of first flagellomere infuscated (more so dorsally) in holotype, entirely brown in paratypes, with antenna entirely dark brown in female; frontal vitta, gena and postgena paler; apices of fore or all femora narrowly yellow; tarsi yellow; fore tibia light brown, fading to yellow at base. Calypter white with hairs brown. Haltere white.

Genitalia: ( Figs. 230–233View FIGURES 230–233) Surstylus not distinct from epandrium, barely visible laterally, flat on inner surface and with four large spines. Cerci narrow and convergent. Hypandrium broad with thick arch, small apical process, and large inner lobe with two distal setae and several minute basal pits. Postgonite lobate and downturned. Proepiphallus and metepiphallus strongly reduced, flattened. Phallophorus elongate on left side. Halves of basiphallus strongly diverging from, and partially fused to phallophorus; lateromedially with lightly sclerotized membranous lobe; apex folded inwards, with pointed basal process and elongate distal process that is fused to mesophallus. Hypophallus broad, flat and heavily sclerotized; apically split in dissected NC male. Mesophallus cylindrical, dark, basally rounded, slightly longer than wide, fused to distiphallus. Distiphallus broad, black, ventrally tilted and cup-like with constricted opening enclosing haired inner process. Ejaculatory apodeme welldeveloped with blade paler, no medial rib evident.

Comments. Reminiscent of those species related to Agromyza bispinata  , the surstylus of A. soka  has few pronounced spines ( Fig. 231View FIGURES 230–233) and there is a subcircular first flagellomere, but the flagellomere is not much longer than the pedicel and any longer hairs on the segment are restricted to an ill-defined apical tuft. Furthermore, the calypter has darker hairs, there are five dorsocentrals, the cercus is narrow, the epandrium is not darkly pigmented around the base of the spines, and the phallus is very dark and highly derived. Due to the variably colored antennae of this species, it will not readily key in Spencer & Steyskal (1986), although most specimens will be identified as A. parca  , which has entirely dissimmilar male genitalia.

The leaf mines of this species (as “an unidentified dipterous leaf-miner ( Agromyzidae  )”) were described and illustrated by Weaver & Dorsey (1967) from material collected in West Virginia, but no adults were reared. Valley (1982) described Phytoliriomyza robiniae (Valley)  from adults caught on Robinia pseudoacacia in Harrisburg  , Pennsylvania between 22 and 30 April of 1979, 1980, and 1981, attributing to this species the leaf mines studied by Weaver & Dorsey. Valley reported collecting the larvae in New York (16–30 May), Pennsylvania (1–19 May), Virginia (26 April –10 May), and West Virginia (10 May). The paratypes of Agromyza soka  were collected in North Carolina on 24 April; we have found larvae in Connecticut on 3 June, and our photographs from 14 June 2013 in Massachusetts show mostly brown, abandoned mines, but one is still green and appears to contain a healthy larva. As stated by Valley, there is just one generation per year, with pupae overwintering. While there is strong circumstantial evidence associating P. robiniae  with R. pseudoacacia  , we are skeptical that the larvae are leafminers on this plant, and we consider the larval records presented by Valley (1982) to represent A. soka  .

The undetermined Agromyza  reared from Robinia pseudoacacia  by Scheffer & Lonsdale (2018) in New York is presumably also referable to this species. They also reported Phytoliriomyza robiniae  from New York, but based only on the leaf mine, “a pale green-yellow blotch that forms at the leaf margin midway between the leaf tip and base” (the Agromyza  mine was described as a “darkish blotch encompassing much of the distal half of the leaf”). The leaf mines they illustrate for P. robiniae  resemble those of A. soka  and were likely misidentified.


Smithsonian Institution, National Museum of Natural History