Stigmella multispicata Rocienė & Stonis

Nieukerken, Erik J. van, Gilrein, Daniel Owen & Eiseman, Charles S., 2018, Stigmellamultispicata Rociene. & Stonis, an Asian leafminer on Siberian elm, now widespread in eastern North America (Lepidoptera, Nepticulidae), ZooKeys 784, pp. 95-125 : 95

Stigmella multispicata Rocienė & Stonis Figures 1, 2, 5-6, 7-9, 12, 14, 16, 18, 19-25, 26, 28, 29

Stigmella multispicata Rocienė & Stonis in Stonis & Rocienė, 2014: 205. Holotype ♂, Russia, Primorskiy Kray, 20 km E Ussuriysk, Gornotayezhnoe, Biological Station, 8.viii.2011, leg. A. Rocienė, genitalia slide no. AG427 (ZIN) [not examined].

Stigmella multispicata ; van Nieukerken et al. 2016: 106, 173 [moved to S. ulmivora group].

Diagnosis.

In North America S. multispicata is the only Stigmella species with the combination of black frontal tuft, white collar, and single fascia. Stigmella quercipulchella (Chambers, 1882) is relatively similar, but has an additional silver patch at tornus, is slightly larger and has more strongly purple reflections across the forewings. This combination of characters is also diagnostic in East Asia, but there remains a possibility that similar species will be discovered. From the closely related European S. ulmivora it differs by the white collar (dark in ulmivora ) and the entirely dark antennae (those of S. ulmivora have the distal 7-8 flagellomeres white); S. ulmivora is also slightly larger and has more antennal segments. The female of S. multispicata differs from all more or less similar species by the obvious long ovipositor, visible even without dissection.

Male genitalia differ from those of S. ulmivora in the shallowly indented uncus and the very short sublateral processes of the transtilla; the female genitalia are easily recognized by the long apophyses; the ductus spermathecae has no spines in contrast to S. ulmivora . Some species in the S. rhamnella group have superficially similar male genitalia, but they have no juxta, and the moths are externally very different.

Stigmella multispicata leafmines are characterized by the egg placement on the leaf underside in vein axils, larval exit on leaf underside, and green to blue-green larval color.

Redescription.

Male (Figs 1, 5, 6). Forewing length 1.8-1.9 mm (1.8 ± 0.1, 9), wingspan 3.7-4.1 mm. Head: frontal tuft black, collar cream white. Scape cream white. Antenna fuscous, short, with 21-24 segments (22.8 ± 1.1, 5), ratio to forewing length 12-13 segments/mm. Thorax and forewing shining fuscous bronze, in some lights appearing greenish, a silver fascia at 2/3, apex darker fuscous, terminal cilia concolorous, underside dark fuscous. Hindwing grey-brown. Abdomen brown, without visible anal tufts.

Female (Figure 2). Forewing length 1.8-2.2 mm (1.9 ± 0.2, 7), wingspan 4.0-4.3 mm. Antenna with 18-20 segments (18.3 ± 0.8, 6), ratio to forewing length 8-11 segments/mm. Otherwise as male, abdomen with conspicuous long protruding ovipositor, with small anal tufts.

Male genitalia (Figs 7-9, 12). Capsule length 190-235 μm (215.6 ± 23.0, 3), 1.1 –1.2× as long as wide. Vinculum anteriorly with pointed and anteriorly protruding lateral corners. Uncus with shallow lobes, widely separated. Gnathos with widely separated posterior processes, running parallel. Valva length 170-185 μm (177.2 ± 5.0, 3), narrow, 2.5 –3.0× as long as wide, distally becoming narrower, slightly curved inwards, transtilla with pointed corners, sublateral processes almost absent (Figure 12). Juxta present, haltere-shaped, with triangular point distally. Phallus 320-330 μm (323.4 ± 4.8, 3), 2.3 –2.9× as long as wide; vesica with many relatively stout cornuti, varying from long-pointed to broadly triangular, with anterior cornuti smaller.

Female genitalia (Figs 14, 16, 18). No anal papillae; T8 narrow, anterior and posterior apophyses long and narrow, anterior ones longer (ca 290 μm) than posterior (ca 235 μm). Bursa length ca 810 μm; accessory sac strongly curved. Corpus bursae completely covered with relatively distinct pectinations; accessory sac and vestibulum without sclerotizations. Ductus spermathecae originating from accessory sac, with many narrow and indistinct convolutions.

Larva (Figs 23, 25, 26). Head-capsule length 290 μm, width 315 μm.

Biology.

Host plants. Ulmus pumila L. ( Ulmaceae ), Siberian elm, a widespread tree in East Asia, cultivated globally in temperate climates, widely planted in North America. Vacated mines presumably representing this species were also collected in China on Ulmus macrocarpa Hance, Large-fruited elm.

Leafmine (Figs 19-22). Egg always deposited in vein axils on leaf underside, beneath the trichomes; leafmine a long narrow upper side gallery or corridor mine, running through leaf, usually not along veins and not crossing midrib; slightly curved, but many mines make a U-turn near the end. Frass initially in narrow medial black line, later becoming contorted, brown and almost filling mine. Larval exit on leaf underside.

Larva (Figs 23, 25, 26). Bright green to blue-green, probably feeding with venter upwards (analogy with S. ulmivora , but not positively observed); head capsule translucent brown. Larvae descending by silken threads, sometimes en masse, spinning a brown cocoon on debris.

Life history. Larvae and leafmines found in China in October; in North America larvae were observed from 15 June to mid-July and from 19 October to 6 November. Moths were found on 26 May and from 8 July throughout August to 6 September (with a peak between 10 and 15 August), a few late records from 22 and 26 September and 2 October. Moths reared from October mines emerged in the laboratory between 25 March and 19 May. The species has at least two annual generations, maybe more. Adults are frequently found at light.

Distribution

(Figs 28, 29). Presumed to be native in Russia: Primorye and China: Beijing. Almost certainly introduced in North America: Canada: Ontario, Québec; United States: Illinois, Indiana, Iowa, Maryland, Massachusetts, Minnesota, New York, Ohio, Tennessee, Wisconsin. The species has been found in the urban environment, in farmland and in more natural habitats. Table 1 lists the online photographs that we recognized as representing S. multispicata .

DNA barcodes.

All eight barcodes belong to BINBOLD:ACP7362. All North American barcodes are 100% identical; the single Chinese one differs in 11 basepairs (1.7%). The nearest neighbor, at 6.3%, is Stigmella ulmivora (Figure 44).

Remarks.

The extensive collections of Chinese microlepidoptera of Nankai University were searched in vain for this species (Li Houhun, personal communication to EvN). It is possible that specimens can be found in other collections in China, such as the Zoological Institute in Beijing.

Material examined.

19♂, 26♀, 3 sex undetermined, 5 larvae, mines. China: 1 larva (green, dried out, destructively extracted for DNA), China, Beijing, Beijng Botanical garden - Wofosi, E.J. van Nieukerken & S. Richter, 17.x.2013, EvN no 2013117-M, Ulmus pumila , N40.00417, E116.20419, 108 m, RMNH.INS.30070; 1 mine from which previous larva was taken, RMNH.INS.43922; 1 mine with dead larva, same data, EvN no 2013117-H, RMNH.INS.43923 (all RMNH).

Canada: 1♂,1♀ (in ethanol 96%), Ontario, Toronto, Etobicoke School of the Arts, EQP–CLL– 602, Brad Schumacher, 22-28.ix.2014, GMP#05745, Malaise trap, N43.631, W79.504, 109 m, BIOUG16150-E04, BIOUG16150-E05 (BIOUG); 1 vacated leafmine, Ontario, Ottawa, Bayview Rd., E.J. van Nieukerken, 12.vii.2018, U. pumila , amidst 100's of mines of Orchestes steppensis , EvN no 2018080H, N45.40819, W75.72474, RMNH.INS.45003 (RMNH); 4 vacated mines, Québec, Montreal, Old Montreal, Avenue de l’Hotel de Ville, E.J. van Nieukerken, 1.viii.2018, U. pumila , EvN no 2018101-H, N45.50894, W73.55604, RMNH.INS.45004 (RMNH).

United States: 1♀, Indiana, St. Joseph Co., J. Vargo, 26.v.2010, N 41.37 ’46.2”– W 86.08 ’13.9”, [N41.62950, W86.13719] (USNM); 1♂, same locality, 2.viii.2010 (USNM); 5♂, 4♀, same locality, 10.viii.2010, genitalia slides JCK8416, JCK8417 (♂), JCK8617, RMNH.INS.15499 (RMNH, MEM, USNM); 1♂, same locality, 13.viii.2010, genitalia slide EvN4511, RMNH.INS.24511 (RMNH); 1♂, same locality, 11.viii.2010 (MEM); 1♀, same locality, 13.viii.2010 (USNM); 5♂, 16♀, same locality, 15.viii.2010 (MEM, RMNH); 1♀, same locality, 28.viii.2010 (MEM); 1♂, 2♀, same locality, 6.ix.2010 (USNM); 1♂ (abdomen missing), Indiana, Pulaski Co., Jasper-Pulaski FWA, J. Vargo, 4.viii.2010, 41 09' 31.0" N 086 58' 42.6"W [N41.15861, W86.9785] (USNM); 1♂, Iowa, Winneshiek Co., Plymouth Rock, Black light in a planted prairie near woodlands along the Upper Iowa River, M.J. Hatfield, 26.ix.2014, N43.4376, W92.0041, Genitalia slide EvN5052, RMNH.INS.25052 (RMNH); 14 leafmines (13 vacated, 1 with dead larva), Massachusetts, Franklin Co., Sunderland, N42.498380, W72.544853, C.S. Eiseman, 22.vii.2018, U. pumila (CSEC); 4 larvae (in Tissue collection, ethanol 96%, -80°, 1 preparation), New York, Suffolk Co., Sagaponack, Ms. Lee Foster, 21.x.2015, U. pumila , N40.93, W72.28, RMNH.INS.30697, RMNH.INS.30698 (extracted), larval preparation RMNH.INS.30698.P, RMNH.INS.30699, RMNH.INS.30700 (RMNH); 3 adults (in capsule), same data, emerged 25.iii & 19.v.2016, (RMNH); 1♂, Ohio, Franklin Co., Hillard, D.J. Shetlar, 21.vii. 2016, N40.007, W83.1738, Genitalia slide EvN4901, RMNH.INS.24901; 1♂, same locality, 1.ix.2016, RMNH.INS.15533 (RMNH).

Tentative ID, most likely this species.

China: 4 tenanted mines (rearing failed), Beijing, Xiangshan, Wofosi and botanical garden, E.J. van Nieukerken & J.W. van Driel, 1.x.1984, EvN no 18 –1– 1K, Hills with deciduous shrub and low trees, U. macrocarpa , N39.983, E116.2, 100-500 m, RMNH.INS.44328; 1 vacated mine, same data, EvN no 18 –1– 1H, RMNH.INS.44330.

Other data, material not examined.

Canada (Data from BOLD, barcode identification): 1 adult, Ontario, Waterloo region, Kitchener, Crestview Public School, EQP-CLL-863, Sherrie Cochrane, 2.x.2015, GMP#08378, N43.454, W80.44, 334m, BIOUG25491-E12 (BIOUG); 1 adult, Ontario, Toronto, Eastdale CI, EQP–CLL– 605, David Servos, 2.x.2015, GMP#08428, N43.666, W79.349, 89, BIOUG25505-D03 (BIOUG).

United States (Observations, personal communications to authors): 4 larvae/mines, Indiana, St. Joseph Co., J. Vargo, 15-29.vi.2018; 120 adults, St. Joseph Co., Mishawaka, J. Vargo, 8.vii.2018, light trap; larvae descending en masse from trees, New York, Suffolk Co., Sagaponack, Ms. Lee Foster, 21.x.2015, U. pumila , N40.93, W72.28; larvae still present, same locality, 8.xi.2015; larvae, same locality, Mike Harmon, 16.vii.2016; larvae, same locality, 19.x.2016; larvae descending en masse from trees, New York, Suffolk Co., Wainscott, 3.xi.2015, Mike Harmon, U. pumila , N40.94, W72.24.