Dasineura callistemoni Kolesik, 2017

Hills-Hayes, Brent, 2017, A new species of gall midge (Diptera: Cecidomyiidae) damaging ornamental Callistemon (Myrtaceae) in Australia, Zootaxa 4318 (2), pp. 395-400 : 396-399

Dasineura callistemoni Kolesik sp. nov.

( Figs 1–3 )

http://zoobank.org/urn:lsid:zoobank.org:pub:EA3C80F8-8334-4AEF-9A02-A699ECE856DD

Material examined. Holotype male ( SAMA 29-004722 ), Tynong, Victoria, Australia (38.088°S, 145.638°E), reared between 30.ix and 4.x.2016 from vegetative bud of Callistemon viminalis cultivar “ Little John ” by Andrew G. Manners, collected 19.ix.2016 by Brent Hills-Hayes. Paratypes: 2 males, 3 females, 2 pupal skins, 3 larvae ( SAMA 29-004723 to 29-004732); 2 males, 2 females, 2 pupal skins, 2 larvae ( ANIC 29- 040316 to 29- 040323); collected and emerged with holotype.

Diagnosis and remarks. The new species fits the concept of Dasineura in all characters except the lack of a spatula. It differs from its congeners in the male terminalia which have a serrated tip of the aedeagus, an undivided hypoproct and a dense dorsal row of bristles next to the solid gonostyle tooth, and also in the larva which has the head without posterolateral apodemes and lacks the sternal spatula. While reductions of the spatula and of the posterolateral apodemes in the larva happened independently in many species in several Cecidomyiidae genera and thus might be generic adaptations of otherwise conforming species, the peculiarities of the male terminalia separate the new species from the rest of the genus. In light of these peculiarities being found in a single species which still fits the scope of the genus we decided to keep the new species in Dasineura but should further closely-related species be found in the future, a new genus can be erected to contain them.

Description. Male ( Fig. 1 ). Wing length 1.2 mm (1.1– 1.3 n =5), width 0.5 mm, length/width ratio 2.3 (2.2– 2.3). Abdomen orange, eyes and tarsi dark, rest of body grey. Head. Palpus four-segmented; segment 1 and 2 of equal length, 3 somewhat longer, 4 longest; palpiger present. Eye bridge 3–6 ocelli long. Occipital protuberance absent. Antenna: scape and pedicel wider than long; flagellomeres 12 in number, each consisting of node and neck, first flagellomeres without neck, fused with second; nodes cylindrical, about 2 times longer than wide, with closely appressed connected circumfila comprising one transverse and one oblique band; necks from 1/3 lengths nodes basally to 1/2 terminally. Labellum with small projection distally. Thorax. Wing: C with break at juncture with R4+5; R4+5 slightly longer than 3/4 wing length; Rs rudimentary, in form of bump on R4+5, slightly closer to arculus than to end of R1, wing fold absent. Tarsal claws with large teeth, empodia bulky, longer than claws. Abdomen. Sclerites with pair of sensory setae anteriorly, covered with scales and setae. Setae on sternites in sparse posterior row; on tergites in mesal band, sparse posterior row and sparse lateral group. Terminalia: gonocoxite cylindrical, setose and setulose; gonostyle tapering, setose, covered with setulae to 1/3 length dorsally and 2/3 ventrally, carinate beyond, apically with solid distal claw and dense dorsal row of 10–12 short bristles ( Fig. 1 c); aedeagus slightly longer than mediobasal lobes, wide, serrated apically ( Fig. 1 b); cerci slightly longer than aedeagus, oval to triangular, with 3 setae along posterior edge, covered with regular patches of microtrichia; hypoproct undivided, trapezoid in dorsoventral view, as long as cerci, with pair of setae at apical edge, uniformly covered with microtrichia; mediobasal lobes tightly sheathing aedeagus, basally not expanding into separate lobe, densely covered with long setulae, on distal end of either lobe with four small setose papillae.

Female ( Figs 2 d–h). Wing length 1.2 mm (1.1–1.3, n=5), width 0.5, length/width ratio 2.4 (2.3–2.5). Flagellomeres: 12 in number (except for one specimen with 11); without necks, nodes progressively slightly smaller, about 2x longer than wide except for first and second that are fused and as long as wide; circumfila comprising two transverse and single longitudinal band, interconnected; necks about 1/10 length nodes. Sclerites of tergite 8: more or less parallel, abruptly widened at posterior ends, anterior trichoid sensilla placed at anterior third. Terminalia: ovipositor long, protractile; fused cerci large, evenly covered with microtrichia, and several thin setae, on apical 1/4 with several thick setae; hypoproct 1/6 length cerci, with pair of apical setae. Otherwise as in male.

Pupa ( Fig. 2 a). Length was not measured as all 4 mounted specimens are partially warped. Colour: face, wings, legs black; thorax, abdominal dorsal spines dark brown; abdomen brownish yellow. Antennal base with small triangular projection. Prothoracic spiracle tapering, about 10x longer than wide at base, slightly curved at apical fourth, trachea ending at apex. Cephalic papilla with long firm seta. Frons on either side with one frontal asetose facial papilla. Integument of abdominal segments with spiculae, segments 2–8 each with field of large dorsal spines on anterior half.

Larva ( Figs 2 b–c, 3). Length was not measured as all 5 mounted specimens are partially warped. Colour orange. Integument smooth, with extensive fields of spiculae ventrally and dorsally on thoracic and abdominal segments. Head: antennae cylindrical, about 2.5 times longer than wide at base; posterolateral apodemes absent. Thoracic segment 1: sternal spatula absent; on either ventral side: one sternal papilla, asetose; one ventral papilla, asetose; one pleural papilla, setose; two triplets of lateral papillae, two of each setose and one asetose; on either dorsal side: three dorsal papillae, setose. Setation on thoracic segments 2 and 3 as on segment 1 except two pleural papillae, setose. First seven abdominal segments on either side: one ventral, three dorsal, two pleural papillae, all setose; two sternal papillae, both asetose. Abdominal segment 8 on either side: one dorsal, two pleural, two ventral papillae, all setose. Terminal segment on either side with three terminal papillae, setose.

Etymology. The name of the new species refers to the generic name of the host plant.

Biology ( Fig. 3 ). Larvae of the new species were feeding gregariously within vegetative buds of Callistemon viminalis plants, cultivars “Little John” and “Captain Cook”, grown in a production greenhouse at Tynong in Victoria, Australia, in September 2016. Infested buds stopped developing and, following the departure of the larvae for the soil, turned necrotic and died. Pupation took place within the soil and sometimes on the soil surface. Young potted plants were infested and severely retarded in their overall growth.

Figures

FIGURE 1. Dasineura callistemoni male. (a) Terminalia in dorsal view, with attached gonostyle in ventral view; (b) terminal parts of aedeagus and mediobasal lobes ventrally; (c) terminal part of gonostyle dorsally; (d) wing; (e) palpus with palpiger; (f) 6 th flagellomere ventrally; (g) 6 th flagellomere dorsally; (h) tarsal claw with empodium; (i) antennal segments: scape to 2 nd flagellomere.

FIGURE 2. Dasineura callistemoni; a pupa; b – c larva; d – h female. (a) Face ventrally; (b) 8 th and terminal abdominal segments dorsally (8 th segment is artifactually warped around terminal segment); (c) head dorsally; (d) end of terminalia laterally; (e) 6 th flagellomere ventrally; (f) 6 th flagellomere dorsally; (g) 8 th tergite (anterior part facing up); (h) antennal segments: scape to 2 nd flagellomere.

FIGURE 3. Infestation by Dasineura callistemoni of Callistemon viminalis cultivar “ Little John ”. Left (top & bottom): infested vegetative buds with front leaves removed to reveal larvae. Right: potted sapling with infested main vegetative bud necrotised after departure of larvae for pupation in soil. Arrows indicate larvae.