Dasineura jujubifolia Jiao & Bu

Jiao, Ke-Long, Han, Pei-Jin, Yang, Ming-Lu, Xiong, Ren-Ci, Wang, Yuan-Hong & Bu, Wen-Jun, 2017, A new species of gall midge (Diptera: Cecidomyiidae) attacking jujube, Ziziphus jujuba in China, Zootaxa 4247 (4), pp. 487-493 : 488-492

Dasineura jujubifolia Jiao & Bu , sp. nov.

Adult. Body. Head and thorax both brown, abdomen yellow brown; length 1.6–1.8 mm in male (n = 22), 1.8–2.2 mm (ovipositor retracted, n = 34) and 2.2–2.8 mm (ovipositor completely exserted, n = 6) in female. Wing length (measured from arculus): 1.4–1.5 mm in male (n = 22); 1.6–1.7 mm in female (n = 40). Wing width: 0.4–0.5 mm in male (n = 22); 0.6–0.7 mm in female (n = 40).

Head. Eye bridge 2 facets long at vertex. Palpus sparsely setose, with 4 segments, last three segments longer than first segment ( Fig. 1 ). Male antenna with 12–13 flagellomeres, female antenna with 13 flagellomeres; pedicel subglobular, smaller than scape; all flagellomeres subcylindrical, somewhat broadened subbasally, neck distinctly shorter; neck of 3rd flagellomere 0.750–0.800 times length of node in male ( Fig. 2 ) and 0.085–0.090 times length of node in female ( Fig. 3 ); each node with 2 horizontal, appressed, bandshaped circumfila, and 2 whorls of long, strong and irregular setae, usually one on basal 1/4 and one subapically; flagellomeres progressively shorter; first and second flagellomeres fused.

Thorax. Wing ( Fig. 4 ) hyaline, setose, sparsely covered by narrow scales, 2.45–2.50 times as long as wide in male and 2.55–2.60 times in female. Vein Rs absent, C, R1 and R5 strong and densely setose; R1 joining C a little before mid-length of wing, R5 arched forward, joining C far before wing apex; vein Cu forked. Legs densely covered by narrow scales and sparse setae; tarsal claws ( Fig. 5 ) toothed on all legs; empodia as long as claws; pulvilli cylindrical, 1/2 length of claws.

Male abdomen. First through sixth tergites entire, rectangular with a single, posterior row of long setae, no lateral setae, uniformly covered by scales, with anterior pair of trichoid sensilla; seventh tergite slightly narrower than sixth, eighth tergite considerably narrower than seventh, both reduced in size, bare except for anterior pair of trichoid sensilla; second through seventh sternites rectangular with irregular but mostly two posterior rows of long setae and two middle rows of long setae, and anterior pair of closely set trichoid sensilla; eighth sternite with irregular but mostly two posterior rows of long setae, and elsewhere evenly covered with scattered, long setae; seventh and eighth sternites reduced in size. Terminalia ( Figs. 6, 7 ): gonocoxite robust with mediobasal lobe divided into 2 parts, a short, rounded dorsal lobe, and an elongate ventral lobe sheathing aedeagus, and covered by short setae; gonostylus stout and strong, straight from subbase to apex, covered by several sparse setae subapically and basally with microtrichia, apically with a blunt apical tooth; cerci deeply separated, and each cercus rounded with a few long apical setae; hypoproct distinctly pigmented, slightly shorter than cerci, deeply divided into two lobes, each with 1–2 short setae; aedeagus elongated, rounded apically, slightly longer than gonocoxite.

Female abdomen. First through sixth tergites as in male, except sixth tergite slightly narrower than fifth; seventh tergite (Fig. 8) 0.12–0.13 mm long, sub-trapezoid, with an irregular but mostly single, posterior row of long setae and anterior pair of trichoid sensilla, sparsely covered by scales, much narrower than sixth tergite; eighth tergite (Fig. 8) 0.29–0.30 mm long, 2.31–2.42 times length of seventh and considerably narrower, divided longitudinally into two separate sclerites, with anterior pair of trichoid sensilla and several scales; second through sixth sternites as in male; seventh sternite reduced in size, covered by several scattered lateral setae and long posterior setae, with anterior pair of closely set trichoid sensilla. Eighth segment without sclerite, with sparse, long setae on distal third. Ovipositor (Figs. 8, 9) long and protrusible; ninth segment 0.18–0.19 mm long in full length (n = 6), 2.80–3.00 times as long as wide, covered by sparse, long setae distally; fused cerci elongate, 3.01–3.20 times as long as wide in mid part, 0.46–0.47 times length of ninth segment, covered by microtrichia distally and few sparse, long setae; hypoproct stout, 2.00–2.20 times as long as wide dorsoventrally, 0.24–0.25 times length of cerci (Fig. 9).

Pupa. Body color orange-brown ( Fig. 12 ). Antennal bases rounded; cephalic setae filiform, long and thin. Prothoracic spiracle obtuse, long and stout, gradually narrowing to apex, somewhat curved distally.

Larva. Third instar ( Fig. 13 ): Light yellow or yellowish white, body 1.5–2.5 mm long (n = 8), elongate ovoid. Antennae tapered, 1.8–2.0 times as long as wide. Sternal spatula (Figs. 10, 14) with 2 anterior teeth, and with one pair of indistinct, reduced and unsclerotized prominences at two sides. Abdominal terminal segment with eight setiform terminal papillae (Fig. 11).

Egg. Spindleform, translucent, white just after deposition, and then gradually turning reddish, 0.2–0.3 mm in length ( Fig. 17 ).

Gall. Rolled leaf galls are at first green, and then gradually turn pink and finally purple or purple-brown as the leaves lengthen ( Figs. 15, 16 ). A rolled leaf gall has 10– 70 larvae or eggs, but sometimes up to 100 ( Fig. 17 ).

Type material. Holotype: male, China, Xinjiang, Alar, Tarim University, Jujube Orchard Gardening Station (40.5423°N, 81.2982°E), 21.XII.2015 (reared in lab), Ming-Lu Yang leg., altitude 1000 m, deposited in Institute of Entomology, Nankai University, Tianjin, China ( NKUM) . Paratypes: 10 males, 22 females, 2 pupae, 8 larvae, same data as holotype ; 11 males, 18 females, ibid., 25–30.VI.2014.

Distribution. Widespread in Xinjiang Uygur Autonomous Region, China. We suspect that the species occurs also in Gansu Province of China, specifically Zhangye City (38.3088– 39.5838°N, 99.5646– 101.1421°E) where gall midges attacking jujube by rolling leaves were recorded ( Lu 2002; Ming-Lu Yang, personal communication).

Etymology. The species name means “ jujube leaves”.

Diagnosis. Dasineura jujubifolia sp. nov. is easily distinguished from the two known Indian jujube gall midge species, Phyllodiplosis jujubae Grover & Bakhshi, 1978 and Silvestrina jujubae Chandra, 1988 by its uninodal male antennal flagellomeres and the presence of mediobasal lobe of gonocoxite developed and sheathing aedeagus. The two Indian species have binodal male antenna flagellomeres and mediobasal lobe of gonocoxite indistinct, reduced and not sheathing aedeagus.

Compared to the two Indian gall midges species above, the biology of Dasineura jujubifolia sp. nov. is similar to Phyllodiplosis jujubae with both species causing the jujube leaves to curl, but different from the latter by inducing the rolled leaf galls gradually turn pink and finally purple or purple-brown as the leaves lengthen. P. jujubae causes the rolled leaf galls to lose their color ( Gangwar 1983), however, in contrast to the two gall makers above, S. jujubae is highly possible to be a predator of coccids, which is obviously not phytophagous.

The rolled leaf galls of jujube by this new gall midge species present the first known association of the cosmopolitan genus Dasineura with Ziziphus jujube . We consider the galls as an extended phenotype that will allow rapid identification of this new gall midge pest.

As for other Dasineura spp. in China, D. jujubifolia sp. nov. is similar to Dasineura citrigemina Yang & Tang, 1991 and D. citrigemmia Yang & Tang, 1991 by having a divided mediobasal lobe of male genitalia, but distinctly differs from the latter two above by the gonostylus being distinctly longer than half of gonocoxite and antenna with 12–13 flagellomeres. In the two citrus gall midge species, the gonostylus is a little shorter than half of gonocoxite and antenna with 14 flagellomeres in both sexes. The new species is similar to Dasineura heterophylla Jiao & Bu in Jiao et al. (2011) by the gonostylus being distinctly longer than half of gonocoxite, but different from the latter by gonostylus stout and strong, straight from the base to apex, as opposed gonostylus slender, and gradually tapering from the base to apex in D. heterophylla . And this new jujube gall midge has terminal papillae absent on ventral lobe of mediobasal lobes on gonocoxite, which is different from most typical Dasineura spp..

Biology. In Alar, Xinjiang, China, this species has 4–5 or more generations per year. All the generations form cocoons below the litter layer in the topsoil, less than 50 mm deep. Each generation lasts 12–14 days except for the overwinter generation. Mature larvae of the overwintering generation drop to the soil beginning from middle August and form cocoons, when most of young leaves have matured. Adults begin to emerge in early April of the following year, with peak eclosion in mid June.

In Xinjiang, almost all jujube trees in cultivated orchards and wild forests have been damaged by this gall midge, with the ratio of damaged trees often easily reaching to 100%. All known varieties of Ziziphus jujuba grown in Xinjiang can be attacked by this gall midge pest. Interestingly, the variety Ziziphus jujuba var. spinosa can relatively reduce the damage by the young green leaves turning yellow, dry and dying quickly to induce increased mortality of larvae inside the rolled leaf galls.

Figures

FIGURES 1 – 7. Dasineura jujubifolia sp. nov.: 1, Female palpus (lateral view). 2, 3 rd male flagellomere (dorsal view). 3, 3 rd female flagellomere (dorsal view). 4, Male wing (dorsal view). 5, Male fore acropod (lateral view). 6, Male genitalia (dorsal view, one gonopod removed). 7, Male genitalia (ventral view, one gonopod removed)

FIGURES 12 – 17. Dasineura jujubifolia sp. nov.: 12, Pupa (ventrolateral view). 13, Mature larva (ventral view). 14, Sternal spatula on mature larva (ventral view). 15, Rolled leaf galls on young green leaves. 16, Rolled leaf galls on older purple-brown leaves. 17, A rolled young leaf gall cut open to show reddish and translucent eggs.