Neostenoptera hawaiiensis Plakidas, Nguyen, and Ferro, 2022

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 : 2-9

Neostenoptera hawaiiensis Plakidas, Nguyen, and Ferro , new species

Figures 1–12 , 16–17 , Map 1

Diagnosis. Adult, body length (measured from head to end of genitalia) male 1.0– 1.2 mm (n = 10); female 1.4–1.6 mm (n = 5). Color: pale translucent-yellow, the eyes are reddish-brown, with one smaller brown spot below each eye; wings teneral, with only veins R1 and CuA1 present and a fringe of long brown setae along the wing margin except for the proximal 1/4 along the wing base ( Fig. 7 ). Neostenoptera hawaiiensis most closely resembles N. appalachiensis but can be distinguished in the following manner. Female antennae with nine flagellomeres, flagellomere 9 shorter and narrower than 8 and with one long dark brown seta distally ( Fig. 4 ), a species defining trait. In contrast, the female flagellum of N. appalachiensis has ten flagellomeres, flagellomere 10 with a short coniform seta distally ( Fig. 15 ). The male of N. hawaiiensis has the ejaculatory apodeme ( Fig. 8–10 ) lightly sclerotized, as long as the aedeagus, with a forked apex, a species defining trait. The tegmen ( Fig. 9–10 ) is lightly sclerotized laterally and extends to the height of the aedeagus. In contrast, the ejaculatory apodeme of N. appalachiensis has a tubular apex and the tegmen does not reach the full height of the aedeagus ( Fig. 14 ).

Description. Adult. Body length (measured from head to end of genitalia) male 1.0– 1.2 mm (n = 10), female 1.4– 1.6 mm (n = 5). Color, pale translucent-yellow. Head. Eyes situated laterally; eye bridge complete, without facets at vertex. Occiput with two setae. Palpus and labellum absent, frons bare. Antennal scape with one seta; pedicel with horizontal rows of microtrichia, no setae. Female flagellum. Flagellum with nine flagellomeres each with two digitate sensoria on flagellomeres 1–8 ( Fig. 4–5 ), flagellomere 1 with two setae on the node, flagellomeres 2–8 with one or two setae on the node; flagellomere 9 shorter and narrower than 8 and with one long dark brown seta distally, a species defining trait. Male flagellum. Flagellum with eleven flagellomeres, flagellomeres 1 and 2 with single digitate sensoria, flagellomeres 3–11 lack sensoria ( Fig. 1–3 ). Thorax and chaetotaxy. Pronotum with four setae, two dorsocentral setae and two dorsolateral setae, one of which is elongated. Lateral sclerites bare except for a fine covering of microtrichia; scutellum non-setose. Wing ( Fig. 7 ): elongate, narrow, with a row of long light brown setae along the entire wing margin except on the proximal 1/4; membrane entirely microtrichose. Vein R1 closely joined to C, reaching the wing margin before midlength; vein R5 absent; vein CuA1 visible near wing base. Halters translucent yellow, with one seta near the base and one seta on the knob. Legs with fore femur inflated distally, mid and hind leg femora slender or only slightly inflated distally; tarsi four-segmented ( Fig. 6 ); tarsal claws falcate, empodium shorter than claws.

Male abdomen and chaetotaxy. Tergites and sternites membranous; tergite 1 with two lateral setae; tergites 2–7 with two setae situated anteriorly and posteriorly, and two closely approximated trichoid sensillae; tergite 8 ( Fig. 8 ) with two setae and two trichoid sensillae. Sternite 1 without setae; sternites 2–7 with four setae and two closely approximated trichoid sensillae; sternite 8 with two setae and two trichoid sensillae. Sternite 9 extending to the height of the gonocoxites with a few setae along the posterior margin ( Fig. 11 ). Tergite 9 ( Fig. 8 ) with four setae at the posterior lateral margins, no trichoid sensillae; cercus bilobed, longer than tergite 9; hypoproct (sternite 10) not discernable. Gonocoxites fused along the anterior margin, covered with microtrichia and a few setae situated distally. Gonostyli about 2.75× longer than wide, covered with setulae, sparsely covered with setae, the inner margin with longer, stouter hair-like setae forming a light comb of hairs. Ejaculatory apodeme ( Fig. 8–10 ) lightly sclerotized, as long as aedeagus, with forked apex, a species defining trait. Tegmen ( Fig. 9–10 ) lightly sclerotized laterally extending to the height of the aedeagus.

Female abdomen and chaetotaxy. Tergites and sternites 1–7 similar to male. Tergites 8 and 9 with two anterior and two posterior setae; tergite 10 imperceptible; sternite 8 without setae; sternite 9 bilobed each lobe with seven setae; sternite 10 (hypoproct) bilobed with three setae per side. Cercus two-segmented ( Fig. 12 ), disticercus shorter than basicercus, with horizontal rows of microtrichia and two short dorsal setae located at the distal corners. Two circular dark brown sclerotized spermathecae at level of tergites 7 and 8.

Larva and pupa. Unknown.

Type material. Holotype male, labeled: USA: Hawaii, Honolulu Co., GPS 21.63094 -158.04771; Waimea Arboretum & BG. 17-23 April 2018; C-MĀIKI Institute, dead wood emergence, A-2-1. Deposited in USNM.

Designated paratypes ( Table 1). All specimens have label data: USA: Hawai‘i, Honolulu Co., Waimea Arboretum and Botanical Garden, C-MĀIKI Institute, dead wood emergence. Specific emergence dates and sample code numbers are associated with appropriate specimens.

Species concept. The concept of “species” is a human-induced attempt to generalize and simplify a complex and cluttered natural world. J. B. S. Haldane (1956) put it more eloquently: “The concept of a species is a concession to our linguistic habits and neurological mechanisms”. Our concept of species is also a concession to the shortness of a human life in relation to the length of evolutionary time. As such, a “unified” or “universal” species concept may not exist and it’s reasonable to expect future workers will bring about new species concepts or refine old ones. The validity of the species described herein will be assessed and reassessed by future workers whether we explicitly state which species concept is being invoked. Despite these drawbacks there may be some utility in stating outright that the Morphological Species Concept (sensu Mayden 1997) was used when defining this species.

Etymology. The specific name, hawaiiensis , is Latin meaning “from Hawai‘i ”, in reference to the collection site in Waimea Arboretum, Honolulu Co., Hawai‘i.

Bionomics. Specimens were collected using an emergence chamber from dead wood 1–4 cm in diameter. The dead wood samples were sequestered in emergence chambers during March when presumably only larvae were present. The peak of adult emergence was during April and May, with a few more specimens emerging into August. Specimens of Neostenoptera sp. reported by Evenhuis et al. (2018) were collected April, May, August, and September from yellow sticky boards, suggesting that they were also present as adults throughout the summer and flew.

Figures

Figure 12. Neostenoptera hawaiiensis, female abdomen segments: posterior margin of 7 to cercus.

Figures 1–6. Neostenoptera hawaiiensis. 1) Male scape to flagellomere 2. 2–3) Variation in male flagellomeres 10+11. 2) Arrow points to the variation in the stem of flagellomere 10. 3) Arrow points to the longer stem of flagellomere 10. 4) Female flagellomeres 8+9. 5) Female flagellomeres 3+4. 6) Male, four-segmented tarsus, midleg, arrow to empodium.

Figures 7–11. Neostenoptera hawaiiensis. 7) Male wing. 8) Male genitalia, dorsal, arrow points to the apex of the forked ejaculatory apodeme. 9–10) Male genitalia, variation in shape of tegmen and apex of ejaculatory apodeme. 11) Male genitalia, detailing the shape of the ninth sternite, ventral.

Figures 16–17. Neostenoptera hawaiiensis. 16) Neostenoptera hawaiiensis, habitus, male, paratype. 17) Neostenoptera hawaiiensis, habitus, female, paratype.

Figures 13–15. Neostenoptera spp. 13) Neostenoptera kiefferi, male wing (after Meunier 1901: Fig. 19). 14) Neostenoptera appalachiensis, male genitalia, arrow to tubular apex of ejaculatory apodeme. 15) Neostenoptera appalachiensis, female flagellomeres 8–10, arrow to coniform seta at apex of tenth flagellomere.