Ishigakidiplosis Elsayed, 2024

Elsayed, Ayman Khamis, 2024, Integrative taxonomy reveals a new gall midge genus and species (Diptera: Cecidomyiidae) developing in the flower buds of Pongamia pinnata (Fabaceae) in Japan, Zoological Journal of the Linnean Society 202, pp. 1-13 : 3-10

Ishigakidiplosis Elsayed , gen. nov.

LSID: urn:lsid:zoobank.org:act:7C7C95AB-19FE-41F3-9E70-3E2C134A4F31

Type species: Ishigakidiplosis karamae Elsayed * sp. nov. designated here.

Diagnosis

The new genus Ishigakidiplosis belongs to the supertribe Cecidomyiidi because of the presence of an occipital dorsal protuberance on the adult head ( Fig. 2A * B)* the cylindrical female flagellomeres* the binodal male flagellomeres ( Fig. 2C–F )* and the loss of setae on the ventral papillae of the larval abdominal segment VIII ( Gagné 1994 * Gagné and Jaschhof 2021). Ishigakidiplosis differs from all genera of Cecidomyiidi by the following combination of characters: the palpus is four-segmented ( Fig. 2A * G* H); the tarsal claws are toothed and bent after the basal third ( Fig. 3A ); the wing vein R 5 joins C posteriad of the wing apex ( Fig. 3B ); the ovipositor is protrusible; the female cerci are separated* and each cercus bears ventral and apicoventral setae slightly thicker and longer than the surrounding ones ( Figs 3C * 4); the gonocoxal mediobasal lobes are absent ( Fig. 5F ); the male hypoproct is bilobed* and the lobes are large and splayed and connected dorsomedially to a central* triangular* microtrichose lobe ( Fig. 5C * D* F); the aedeagus has a remarkable dorsal slit ( Fig. 5F * G); the pupation takes place in soil and the pupal exuviae is mostly hyaline ( Fig. 6 ); the larval spatula is bilobed ( Fig. 7A ); and the larval terminal abdominal segment bears six corniform and two setiform papillae ( Fig. 7B * C). In particular* Ishigakidiplosis is unique among known gall midges for its triangular lobe connecting the hypoproctal lobes dorsomedially ( Fig. 5C * D* F). This lobe has been reported rarely in some taxa of Cecidomyiinae * but it is usually smaller than that of Ishigakidiplosis and situated basally on the hypoproct (Peter Kolesik* pers. comm.* 2023). It can be present either ventrally* as in Odontodiplosis Felt and some species of Lestodiplosis Kieffer (Gagné and Lill 1999* Gagné 2018)* or dorsally* as in Stomatosema gagnei Kolesik (Kolesik and Halling 2022; Peter Kolesik* pers. comm.* 2023).

Description

Adult& head: Eyes connate. Occiput with dorsal protuberance ( Fig. 2A * B). Antenna: female flagellomeres cylindrical* with two connected bands of circumfila* with short necks ( Fig. 2C * D); male flagellomeres binodal* with looped circumfila ( Fig. 2E * F). Palpus four-segmented ( Fig. 2A * G* H).

Adult& thorax: Anepimeron with setae; anepisternum with scales; katepisternum bare. Tarsomere I without ventroapical extension. Acromere ( Fig. 3A ): claws toothed basally* bent after basal third. Wing ( Figs 1E * F* 3B): R 1 joining C slightly before mid-length of wing; Sc pigmented; R S slightly closer to end of R 1 than arculus; R 5 joining C posteriad of wing apex; C broken after conjunction with R 5; wing fold present; M 4 forked with CuA.

Female abdomen: Ovipositor ( Figs 3C * 4): protrusible portion bare dorsally* mostly covered with short and a few long setae ventrally and laterally; cerci separated* each with several ventral and apicoventral setae slightly thicker and longer than surrounding ones; hypoproct with two apical setae.

Male abdomen: Terminalia ( Fig. 5C–G ): cercal lobes oval; hypoproct bilobed* lobes large* ellipsoid* splayed* concave ventrally* with microtrichose surface and several subapical dorsal setae* lobes connected dorsomedially to central* triangular* microtrichose lobe; aedeagus cylindrical* slightly wider at base* with remarkable dorsal slit; gonocoxite without mediobasal lobe* setose; gonostylus microtichose basally* carinate and setose distally.

Pupal exuviae: Mostly Hyaline* except prothoracic spiracle and enlarged dorsal abdominal spines ( Fig. 6 ). Prothoracic spiracles ( Fig. 6C ) elongate* slightly curved* with trachea extending to tip. Abdominal segments II–VI with tiny stigma-like spiracles. Terga II–VIII with enlarged spines on anteromedian third ( Fig. 6D ).

Larva& third instar: Spatula bilobed ( Fig. 7A ). Ventral and dorsal papillar pattern largely in accordance with the basic pattern in Cecidomyiidi ( Möhn 1955) but with the following peculiarities: ventral papillae asetose on thoracic and abdominal segments I–VIII; two pairs of pleural papillae* asetose on thorax* setose on abdominal segments I–VIII; six dorsal papillae* asetose on thorax* setose on abdominal segments I–VII; two setose dorsal papillae on abdominal segment VIII. Terminal segment with two setose and six corniform papillae ( Fig. 7B * C).

Etymology

The name combines ‘Ishigaki’* the island where the gall midge was collected* with ‘diplosis’* the commonly used suffix for Cecidomyiini that means double* referring to the binodal male flagellomeres.

Figures

Figure 1. Ishigakidiplosis karamae and its host plant.A* Pongamia pinnata (Fabaceae) growing behind mangroves on Ishigaki Island* Japan. B* flower buds of P.pinnata infested with I.karamae (red arrows). C* immature larvae in a flower bud that has been cut open. D* mature larva in a flower bud that has been cut open. E* freshly emerged female.F* freshly emerged male (terminal tarsal segments are lost).

Figure 2. Adult head of Ishigakidiplosis karamae. A* head. B* occiput with dorsal protuberance bearing two setal bases.C* ventral view of female antennal flagellomere V. D* female antennal flagellomeres.E* dorsal view of male flagellomere III. F* male antennal flagellomeres.G* dorsolateral view of mouthparts. H* lateral view of mouthparts. Scale bars:50 µm.

Figure 3. Ishigakidiplosis karamae. A* tarsomere I and acromere.B* wing.C* female terminal abdominal segments. Scale bars: 50 µm.

Figure 5. Male abdomen of Ishigakidiplosis karamae. A* tergites VI–VIII. B* sternites VI–VIII. C* ventral view of hypoproct. D* dorsal view of hypoproct. E. ventral view of gonostylus. F* dorsal view of terminalia (hypoproctal setae not shown). G* dorsal view of aedeagus. Scale bar: 50 µm.

Figure 6. Pupal exuviae of Ishigakidiplosis karamae. A* exuviae of freshly emerged adults in soil. B* ventral view of head. C* prothoracic spiracle. D* dorsal view of abdomen.Scale bars: 50 µm.

Figure 7. Third instar larva of Ishigakidiplosis karamae. A* spatula.B* abdominal segment VIII and terminal segment Ventrally.C* abdominal segment VIII and terminal segment dorsally.Scale bars:50 µm.