Triozidus yangorum Liao & Percy, 2025

Liao, Yi-Chang, Inoue, Hiromitsu & Percy, Diana M., 2025, The psyllid genus Triozidus Li, 1994 stat. rev. sensu novo (Hemiptera: Psylloidea: Triozidae) in East Asia is redefined with the addition of two new species from Taiwan inducing galls on the leaflet petiolules of Eleutherococcus trifoliatus (Araliaceae), Zootaxa 5727 (1), pp. 113-139 : 129-133

Triozidus yangorum Liao & Percy sp. nov.

( Figs 1C–F , 12–15 )

Type material. Holotype: TAIWAN • ♂; Taipei City, Shilin, Guzhen ; 25°08’06.4”N, 121°35’28.1”E; 17 Jan 2023; Y. C. Liao leg.; Eleutherococcus trifoliatus ; NCHU, dry mounted . Paratypes: TAIWAN • 15♂, 19♀, 15 immatures; same data as for holotype . 2♂, 2♀; same data as for holotype, but NHMB . 7 immatures; Nantou Co., Meifeng ; 24°05’21”N, 121°10’23”E; 23 Sep. 2008; M. M. Yang leg.; Eleutherococcus trifoliatus ; NCHU, dry, slide mounted and in ethanol . Other material examined: TAIWAN • 1♂, 14 immatures; Nantou Co., Sitou Forest Recreation Area ; 23.66513 N, 120.79718 E; 1295 m; 26 Jan. 2010; D. M. Percy leg.; Eleutherococcus trifoliatus ; DMPC, slide mounted .

Description. Adult ( Figs 1C , 12–14 ). Coloration. Body color yellowish brown ( Figs 1C , 12 ). Newly emerged individuals light green. Entire head and abdominal tergites mid-brown. Antennae yellow with apices of segments 4, 6 and 8 dark brown, and entire segments 9 and 10 black. Compound eyes dark brown. Ocelli orange. Legs brown. Forewing pale yellow, transparent, with dark brown patch around clavus. Hindwing transparent, except clavus dark brown.

Structure. Body large-sized, length from anterior head margin to tip of folded forewing 5.3–6.1 mm, female generally larger ( Fig. 12 ); covered in short fine setae. Head ( Figs 12 , 13A ) slightly narrower than thorax. Vertex width 1.8–2.0 x length, minutely pubescent. Genal processes prominent, length along mid-line 0.7-0.8 x vertex length, divergent, conical, blunt at apex, medium-long pubescence. Antenna ( Figs 13B–C ) length 1.8–1.9 x head width, antennal segment 3 approximately double length of segment 4, relative length of flagellar segments as 1.0: 0.5: 0.3: 0.3: 0.3: 0.3: 0.2: 0.2; two unequal terminal setae: longer seta 1.1 x, and shorter, truncate seta 0.2 x segment 10 length. Thorax moderately arched dorsally, minutely pubescent. Hind leg ( Fig. 13F ) metatibia length 1.0–1.1 x head width. Forewing broad ( Fig. 13D ), length 6.1–6.8 x head width, and 2.4–2.6 x width, widest slightly distal to the middle; wing apex acute; vein Rs moderately long, gradually curved to fore margin; vein M evenly curved with bifurcation at or slightly anterior to line connecting apices of veins Rs and Cu 1a; cell m 1 larger than cell cu 1; vein Cu 1a evenly curved, vein Cu 1b more or less straight; veins minutely pubescent. Hindwing ( Fig. 13E ) 0.6 x as long and 0.5 x as wide as forewing.

Male terminalia ( Figs 14A–C ). Proctiger short, with moderate posterior lobes reaching maximum extension in the apical half, covered in long setae except for basal third laterally ( Fig. 14A ). Subgenital plate subglobular, with medium long setae laterally and ventrally; posterior dorsal margin slightly convex. Paramere ( Figs 14A–B ) about as long as proctiger; in profile broader at base, sinuous, before narrowing to apex which is acute and directed inward and rearward; inner face beset with long setae, outer surface with shorter setae. Distal aedeagus segment ( Fig. 14C ) about as long as paramere ( Figs 14A , 16 ), angled medially with thumb-shaped projections, apical portion inflated into a shallow hook with blunt apex; sclerotized end tube of ductus ejaculatorius short, slightly sinuous. Female terminalia ( Fig. 14D ) cuneate, short; proctiger dorsal margin slightly sinuate with medial depression and acute apex, only slightly longer than subgenital plate, with long setae in the apical half, anal ring length approximately one third proctiger length, consisting of a single row of pores. Subgenital plate, in profile, triangular, apex acute, beset with long hairs laterally and ventrally. Ovipositor dorsal valvulae cuneate, ventral valvulae straight with several shallow serrations apically.

Measurements (range, mean±SD) in mm ( 5 males, 5 females). Body length (including forewing) ♂ 5.38–5.81, 5.63±0.17; ♀ 5.25–6.06, 5.81±0.32. Head width ♂ 0.74–0.78, 0.76±0.02; ♀ 0.76–0.80, 0.77±0.02. Vertex width ♂ 0.41–0.43, 0.42±0.01; ♀ 0.38–0.43, 0.41±0.02 Vertex length ♂ 0.23–0.30, 0.26±0.03; ♀ 0.28–0.29, 0.28±0.01. Genal cone length ♂ 0.19–0.22, 0.20±0.01; ♀ 0.20–0.23, 0.21±0.01. Antenna length ♂ 1.40–1.50, 1.44±0.04; ♀ 1.33–1.35, 1.34±0.01. Metatibia length ♂ 0.80–0.85, 0.82±0.03; ♀ 0.73–0.88, 0.81±0.06. Forewing length ♂ 4.58–4.93, 4.76±0.20; ♀ 4.85–5.56, 5.18±0.38. Forewing width ♂ 1.89–1.98, 1.93±0.04; ♀ 1.96–2.19, 2.06±0.11. Aedeagus length 0.30 (n =1). Paramere length 0.30 (n =2). Proctiger length ♀ 0.45–0.50 (n =2). Subgenital plate length ♀ 0.46–0.50 (n =2).

Fifth instar immature ( Figs 1D , 15 ). Coloration. General color yellow. Forewing pad and thorax pale brown. Body ( Fig. 15A ) length 1.3–1.4 x width. Body surface, including margin of head, wing pads ( Fig. 15C ), caudal plate and legs covered with medium dense, long simple setae. Antenna ( Fig. 15E ) relative length of antennal segments 3 to 8 as 1.0: 0.85: 0.3: 0.4: 0.3: 1.8. Legs ( Figs 15A–B ) as for generic description. Forewing pad length 2.8–3.2 x width, and 2.4–2.8 x antenna length. Caudal plate length 0.8–1.0 x width. Circumanal ring ( Fig. 15D ) heart-shaped (medial constriction mainly from anterior); width 0.3 x caudal plate width; outer ring mostly composed of a single row of elongate pores, with occasional convolutions and intermittent multi-pore sections; inner ring composed of a mixture of small and irregular pores.

Measurements (range, mean±SD) in mm ( 5 immatures). Body length 2.53–2.88, 2.70±0.15. Head width 0.80– 0.85, 0.81±0.02. Antenna length 0.53–0.61, 0.57±0.03. Metatibiotarsus length 0.71–0.80, 0.76±0.04. Forewing pad length 1.36–1.60, 1.48±0.11. Caudal plate length 0.90–1.25, 1.01±0.14. Caudal plate width 1.08–1.18, 1.16±0.06. Circumanal ring width 0.30–0.35, 0.32±0.02.

Etymology. The specific name honours both Prof. Chung-Tu Yang and Dr. Man-Miao Yang for their enormous contribution to the systematics of Psylloidea .

Distribution. Taiwan; only found in the central and northern part.

Host plant. Eleutherococcus trifoliatus ( Araliaceae ).

Biology. Univoltine with adults emerging December to January. Immatures develop within large, fully enclosed round galls that are positioned just below the base of leaflets on the petiolules. Occasionally galls are seen on the leaflet base, but this seems to be a secondary oviposition preference. Each gall consists of a single gall chamber with usually a single immature ( Fig. 1D ). Galls are found individually or in aggregates of two to four galls per leaf, often with a gall on each of the three petiolules ( Figs 1E–F ). The host plant, E. trifoliatus , is found in montane zones ( 500 to 1,500 m elevation) as an understory forest plant with prickly stems and a sprawling or scandent habit.

Genetic resources. Adult and immature sequences were identical: annotated mitochondrial genome: Genbank PQ826428.

Figures

FIGURE 1. Triozidus burckhardti sp. nov. and Triozidus yangorum sp. nov. adults, immature and galls on the host plant, Eleutherococcus trifoliatus. A, T. burckhardti female; B, closed galls of cf. T. burckhardti with a single gall on each petiolule of the trifoliate leaf; C, T. yangorum male; D, T. yangorum fifth instar immature within gall chamber; E, close up showing three petiolule galls of T. yangorum on a single leaf, the upper already opened; F, the scandent host, E. trifoliatus, showing distribution of petiolule galls.

FIGURE 12.Adults of Triozidus yangorum sp. nov. A, Holotype, male, dorsal view; B, Holotype, male, lateral view; C, female, dorsal view; D, female, lateral view. Scale bars: 1 mm.

FIGURE 13. Adult Triozidus yangorum sp. nov. A, head; B, antenna; C, terminal antennal segments showing uneven length terminal setae (arrowed); D, forewing; E, hindwing; F, hind leg. Scale bars: 0.1 mm (A, B, C, F); 1 mm (D, E).

FIGURE 14. Terminalia of Triozidus yangorum sp. nov. A, male terminalia (lateral view); B, paramere (inner surface); C, distal portion of aedeagus, showing medial narrow thumb-like projections (arrowed); D, female terminalia (lateral view). Scale bars: 0.1 mm.

FIGURE 15. Fifth instar immature of Triozidus yangorum sp. nov. A, habitus; B, tarsal arolium showing asymmetric development of tarsal claws (vestigial claw arrowed); C, forewing pad marginal simple setae; D, circumanal ring showing intermittent irregular pore shape (inset); E, antenna. Scale bars: 0.1 mm.

FIGURE 16. Phylogenetic placement of Triozidus in family Triozidae is indicated by a black square representing a subgroup within Group B (see Percy et al. 2018), the related genera are expanded on in the text. An asterix indicates the placement of the type species of Heterotrioza, H. chenopodii in Group D, and Trioza, T. urticae in Group M, and Dyspersa sensu Cho et al. (2022) in Group A. Configuration of the three Triozidus taxa to one another based on the 714 bp COI fragment data (unique haplotypes only) is shown, with T. burckhardti placement indicated based on the backbone analysis (see text); taxon placements within Triozidus are uncertain in both analyses due to short internal branches and low to moderate bootstrap support, with a slightly different taxon configuration recovered in the ML backbone constraint analysis (see text). Illustrations of forewing, paramere and aedeagus are shown for all six Triozidus species to indicate comparative sizes; an asterisk by T. ceratophorus and T. eleutherococci indicates the illustrations are redrawn with reference to Li (2011) and Konovalova (1980, 1988) respectively, and in these cases paramere and aedeagus may not be to scale, plus the apex of the aedeagus is partly obscured in the illustration for T. eleutherococci. The annotation of the mitogenome of T. yangorum is graphically represented at top right.