Limnophyes spp.

Eiseman, Charles S., Namayandeh, Armin, Linden, John Van Der & Palmer, Michael W., 2023, Metriocnemus erythranthei sp. nov. and Limnophyes viribus sp. nov. (Diptera: Chironomidae: Orthocladiinae): leafminers of monkeyflowers, speedwells, and other herbaceous plants, with new observations on the ecology and habitats of other leaf-mining Chironomidae, Zootaxa 5249 (1), pp. 41-68 : 61-62

Limnophyes spp.

( Fig. 7b )

Material examined. USA: IOWA: Winneshiek Co., Twin Springs Park , 11.vi.2017, em. ~ 21.vi.2017, J. van der Linden, ex Veronica anagallis-aquatica (2♀); same data but collected 29.i.2018 (1 larva). These specimens were examined by A. Namayandeh in 2018 and their current location is unknown.

Biological notes. Each of the collections listed above consisted of a few Veronica stems with attached leaves in which chironomid larvae were forming linear mines. The only larva photographed from the first collection was consistent with M. erythranthei . The two female Limnophyes adults emerged about ten days after the first collection. One of these was light reddish-brown and was identified as Limnophyes cf. carolinensis Saether, 1975 (https:// bugguide.net/node/view/1396485). The other was grayish-black and appeared to be L. viribus (https://bugguide. net/node/view/1396495). The only other insect to emerge from this collection (about a day earlier) was an adult of Scaptomyza pallida (Zetterstedt, 1847) (Drosophilidae) , a saprophagous species that sometimes develops as an inquiline in mines made by other fly larvae, including Zygoneura calthella Eiseman, Heller & Rulik, 2016 (Sciaridae) on marsh marigold ( Ranunculaceae : Caltha palustris L.) ( Eiseman et al. 2016) and Agromyza parvicornis Loew, 1869 (Agromyzidae) on corn ( Poaceae : Zea mays L.) (C. Eiseman, unpublished). Whether the Limnophyes adults arose from the observed leaf-mining larvae or were themselves inquilines or contaminants was not known with certainty.

About two weeks after the second collection of Veronica leaf mines (on 12 February 2018), actively wriggling Metriocnemus pupae were observed in the leaf mines, and in one case, in a stem. On the same date, an adult male of another orthocladiine, Corynoneura lobata Edwards, 1924 , was found dead in the rearing container; its pupal exuviae were not located and the larval habits of this individual are unknown. Corynoneura lobata has an aquatic larva inhabiting mainly fast-flowing waters ( Cranston 1982). Also on this date, the now preserved Limnophyes larva, which was initially identified as L. cf. carolinensis but appears consistent with L. viribus , was observed moving within an existing linear mine that was substantially wider than its body, consuming small patches of mesophyll here and there along the margins ( Fig. 12b ; video: https://youtu.be/0h3Bvc0DfgE). The following day, the first adult Metriocnemus emerged from one of the pupae in the mines.

Based on the available evidence, we believe that the Limnophyes species we have reared do not establish their own mines but feed as inquilines in mines created by Metriocnemus larvae.

Figures

FIGURE 7. Metriocnemus sp. “Oregon”, larva (a–c). a. habitus; b. antenna; c. labrum and premandible; d. mandible; e. mentum; f. posterior portion of the larva.

FIGURE 12. Secondary inhabitants in leaf mines of Metriocnemus erythranthei on Veronica sp. a., larva of M. eurynotus (upper left) and two larvae of M. erythranthei (center and upper right); b., larva of Limnophyes sp. (prob. L. viribus) (lower left) in vacated mine.