Neostenoptera appalachiensis Plakidas and Ferro, 2016

Plakidas, John D., Nguyen, Nhu H. & Ferro, Michael L., 2022, A new species of Neostenoptera Meunier (Diptera: Cecidomyiidae: Winnertziinae) from Hawai‘i, Insecta Mundi 2022 (941), pp. 1-12 : 9-11

Neostenoptera appalachiensis Plakidas and Ferro, 2016

Neostenoptera appalachiensis has been sighted or collected three times since it was described ( Plakidas and Ferro 2016) (Maps 1–2) each resulting in a new state record. Two photos were placed on bugguide.net by Jonathan Burishkin (bugguide.net/node/view/1271455; bugguide.net/node/view/1271456) of specimens that “came to moth lights at night” in GEORGIA, new state record. The photos were taken during 6 August 2016, at USA: Georgia: Bartow Co.: Cartersville (approximately N 34.16°, W −84.79°). The flies are clearly on the light sheet well above the ground and appeared to have flown there .

Curt Harden collected N. appalachiensis emergent from sweetgum limbs collected from his yard in SOUTH CAROLINA, new state record, ( USA: South Carolina, Pickens Co., Central, 115 Cedar Creek Circle, N 34.7146°, W −82.7804°). A large sweetgum limb fell from a tree during fall 2020, pieces were placed in an emergence chamber early 2021 and a sample taken 14 May 2021 contained specimens—“there were tons (top of the liquid was thick with them)” (pers. com.)—specimens are deposited in CUAC.

Astonishingly, five female specimens of N. appalachiensis were collected in HAWAI‘I, new state record, from samples containing Neostenoptera hawaiiensis . All specimens were from material collected at the same locality but emerged over multiple sampling dates: USA: Hawaii: Honolulu Co.: Waimea Arboretum and Botanical Garden: N 21.6203°, W −158.01466° C-MĀIKI Institute, dead wood emergence, A-4-1: 1 F, 29 May–4 June, slide, USNM; 2 F, 12–18 June, slides, CUAC, BPBM; 1 F, 18–25 June, slide, JPPC; 1 F, 25 June–2 July, alcohol, UHM.

Neostenoptera appalachiensis is now known from the following states: Alabama, Georgia, Hawai‘i, North Carolina, South Carolina, and Tennessee.

Discussion. While not impossible, it seems improbable that any Neostenoptera are native to Hawaii. For example, if adults were blown from the nearest mainland, California —approximately 3850 km (2390 miles) away, at an average speed of 50 kph (31 mph) they would be airborne for 77 hours and would probably freeze, starve to death, or desiccate in that time. Similarly, if carried on a log or structure floating from any mainland, eggs, larvae, and/ or adults, would have to keep from overheating, drying out, being blown to sea, or poisoned with saltwater for at least several weeks. Given these circumstances it would be unlikely that Neostenoptera could arrive at Hawai‘i other than by human aid.

Maps 1–2. Neostenoptera collection localities. 1) Neostenoptera spp. collection localities on O‘ahu Island, Hawai‘i. Neostenoptera hawaiiensis site 1 (sample codes A-1-1, B-1-1, C-1-1), site 2 (sample codes A-2-1, C-2-1), site 3 (sample codes A-4-1). Neostenoptera appalachiensis site 3 (sample code A-4-1). Neostenoptera sp. ( Evenhuis et al. 2018) sites 4, 5, and 6. 2) Neostenoptera appalachiensis collection localities (by county) in the continental United States.

Neostenoptera hawaiiensis and N. appalachiensis were both collected within the Waimea Arboretum and Botanical Garden. Sites where woody materials were collected were either within the Botanical Garden itself, or the forest of predominately introduced plants beyond the garden, deeper into the valley. The garden has sections that focus on plants native to Hawai‘i, Polynesia, and other island ecosystems, but it also contains many plants from Central America, South America, and Africa.

While the larvae of Neostenoptera are unknown, the larvae of three eastern North American paedogenetic species are known to live and reproduce in decaying substrates and mushrooms ( Plakidas 2018; Yukawa 2021), and it’s likely Neostenoptera does the same. Both Neostenoptera species, like many other non-native species, probably “hitch-hiked” a ride aboard exotic plants introduced to the island and are unintentional introduced species to Hawai‘i from other parts of the world. Micro-dipterans can easily go undetected in plant shipments since their minute larvae are embedded in decaying plant tissue. Neither species have been found to be economically harmful since their larvae are strictly fungivorous.

The above speculation calls into question the ultimate origin of N. appalachiensis which itself may have been introduced to Eastern North America, possibly from Central America, South America, or Africa. Recent collections of Neostenoptera have come from citizen science, monitoring, and by-catch (residues) from collections made using emergence chambers. As these techniques continue to be used, more observations and specimens should become available and the biogeographic mysteries presented by the genus may be solved.