Asiphonipponaphis, a new genus of Hormaphidinae (Hemiptera, Aphididae) causing galls on Distylium chinense from China, with description of a new species

Abstract The aphid genus Asiphonipponaphis gen. n. from China is new to science. Asiphonipponaphis vasigalla sp. n. causing galls on Distylium chinense from Hunan, China is described and illustrated. Holotype and paratypes are deposited in the National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing, China (NZMCAS) and Kogakkan University, Japan.


introduction
The aphid tribe Nipponaphidini in subfamily Hormaphidinae (Hemiptera: Aphididae) occurs in East and Southeast Asia, with Distylium as the primary host, on which different shaped and sized galls are produced, and Fagaceae, Lauraceae and Moraceae as the secondary hosts (Ghosh 1988). Pergande (1906) described the first nipponaphidine species causing galls on Distylium from Japan. Since then, many gallforming species on Distylium have been described (Matsumura 1917, Monzen 1934, 1954, Takahashi 1958, 1962, Hille Ris Lambers 1959, Noordam 1991, Sorin 1996. Takahashi (1962) and Sorin (1987) reviewed the species which cause galls on Distylium in Japan. Blackman and Eastop (1994) keyed the aphid species on Distylium, including free-living apterae and alatae emerging from galls. Sorin (2003) keyed the aphid species living on Distylium racemosum in Japan based on the galls and their detailed life cycles.
Up to now, at least eighteen species and one subspecies in twelve genera are known to induce galls on Distylium. Thirteen species and one subspecies are recorded on Distylium racemosum, viz. Dinipponaphis autumna (Monzen) In this study, a new genus and a new species, Asiphonipponaphis vasigalla sp. n. causing galls on Distylium chinense is described from Hunan, China, further enriching the group of aphid species forming galls on Distylium.

Materials and methods
All specimens examined in this study were collected from Jishou University (Jishou City) by X. T. Li.
Aphid terminology in this paper generally follows Ghosh (1988) and Noordam (1991). The unit of measurements in this paper is millimeters (mm).
In Table 1, the following abbreviations have been used: Ant.I, Ant.II, Ant.III, Ant. IV, Ant.Vb, for antennal segments I, II, III, IV and the base of antennal segment V, respectively; PT, processus terminalis; Ant.IIIWD, the widest diameter of antennal segment III; URS, ultimate rostral segment; BW URS, basal width of ultimate rostral segment; 2HT, second hind tarsal segment; MW hind tibia, mid-width of hind tibia; BW Cauda, basal width of cauda; AP, anal plate; GP, genital plate. Specimen depositories: the holotype and ten paratypes of the new species are deposited in the National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing, China (NZMCAS), and two paratypes in Kogakkan University, Japan.
Generic diagnosis. In alatae, antennae 5-segmented, secondary rhinaria annular. Rostrum short, ultimate rostral segment shorter than second hind tarsal segment, with 2 pairs of primary setae and 1 pair of accessory setae. Abdomen with 5 pairs of spiracles, present on abdominal segments II-VI. Siphunculi absent in both fundatrix and emigrant alatae. Cauda knobbed, distinctly constricted at base. Anal plate bilobed. Legs normal. Tarsi 2-segmented, claws normal, first tarsal chaetotaxy of alatae 3, 3, 3. Fore wings of emigrant alatae with pterostigma narrow and long, distal margin of pterostigma forming almost a straight line with the hind margin, media unbranched, not united with cubitus, and two cubitus veins fused at base; hind wings with 2 obliques.
Comments. This new genus is unique in Nipponaphidini by its peculiar galls and morphological characters. Different from other saccate galls on Distylium, e.g. galls of Nipponaphis, its galls are located on the midrib of leaves and split at the tip when mature, forming a flower-shaped opening, while galls of Nipponaphis are located on twigs and usually open on the lateral wall of the galls when mature. It is related to Quadrartus Monzen for sharing several characters in alatae, such as spiracles present on abdominal segments II-VI (i.e. 5 on each side of abdomen), distal margin of pterostigma forming almost a straight line with the hind margin, but differs from the latter as follows: antennae 5-segmented (in Quadrartus: 4-segmented); media of fore wings unbranched (in Quadrartus: once branched); siphunculi absent (in Quadrartus: present). It is also related to Indonipponaphis Ghosh & Raychaudhuri. Both of them possess 5-segmented antennae in alatae and induce galls on the midrib of leaves of Distylium. But the new genus differs from Indonipponaphis as follows: abdomen with 5 pairs of spiracles (in Indonipponaphis: 4 pairs); media of fore wings unbranched (in Indonipponaphis: once branched); siphunculi absent (in Indonipponaphis: present).
Taxonomy of Nipponaphidini is mostly based upon the apterae on secondary hosts. The identification of alatae is much more difficult because of the vague descriptions and limited diagnostic characters. But not all species are known by both alate and apterous morphs. Thus identification of alatae, although confusing, is still very important to the classification of Nipponaphidini. Further observations of life cycles will probably reveal more gall causers on Distylium, and acquisition of more morphs will facilitate the taxonomic study and clear up the confusion. Etymology. The new species is named for the shape of gall. "Vas" (Latin) means "vase", "galla" (Latin) means "gall".

Asiphonipponaphis vasigalla
Description. Fundatrix: Body oval, nearly round (Fig. 8), reddish brown and covered with thin white wax in life. For morphometric data see Table 1.
Mounted specimens. Body lightly sclerotized, pale in color. Antennae, ultimate rostral segment and legs brown. Head, thorax and abdominal segments I-VII completely fused. Dorsum smooth. Abdominal tergite VIII with dense spinulose imbrications. Spiracles oval, closed, on abdominal segments II-IV, spiracular plates light brown. Dorsal setae of body little, short and pointed. Head with 1 pair of cephalic, 1 pair of spinal, 1 pair of pleural and 1 pair of marginal setae; thoracic nota each with 1 pair of spinal, 1 pair of pleural and 2 pairs of marginal setae; abdominal tergites I-VI each with 1 pair of spinal, 1 pair of pleural and 1 pair of marginal setae; tergite VII with 1 pair of marginal setae; tergite VIII with 4 setae. Cephalic setae, marginal setae on abdominal tergite I and setae on tergite VIII 0.68 times, 0.61 times and 1.01 times as long as widest diameter of antennal segment III, respectively. Front straight. Eyes 3-faceted. Antennae 3-or 4-segmented (Fig. 1); 0.14 times as long as body. Length in proportion of segments I-III: 35 : 26 : 100+16, respectively. Processus terminalis 0.16 times as long as base of the segment III; very thin, basal width 0.47-0.57 times as long as apical width of base of the segment III. Setae on antennae sparse. Segments I-III each with 2, 2, 0+0 setae, respectively. Processus terminalis with 4 apical setae. Primary rhinaria small, round, protuberant and placed wide apart. Rostrum short and thick, not reaching mid-coxae. Ultimate rostral segment blunt wedge-shaped, 1.43 times as long as its basal width, 0.88 times as long as second hind tarsal segment; with 2 pairs of primary setae and 1 pair of accessory setae. Legs normal. Trochanters and femora fused. Hind trochanter and femur 2.11 times as long as the base of antennal segment III, hind tibia 0.15 times as long as body. Setae on legs sparse, fine and pointed. Setae on hind tibia 0.68 times as long as its mid-diameter. First tarsal chaetotaxy: 2, 2, 2. Siphunculi absent. Cauda, anal plate and genital plate with dense spinulose imbrications. Cauda knobbed, indistinctly constricted at base, 0.74 times as long as its basal width, with 9 setae. Anal plate bilobed, each with 9 or 10 setae. Genital plate broad round, with 2 anterior setae and 11 setae along the posterior margin. Two gonapophyses each with 3 or 4 short setae.
Alate viviparous females (emigrants from galls): Body oval (Fig. 9), cephalothorax black, abdomen dark reddish brown and pterostigma black in life, wings flat in repose. For morphometric data see Table 1.
Host plant. Distylium chinense. Biology. The aphids live in galls on the upper side of leaves of Distylium chinense. In early March, small galls start to grow on young leaves, often rise from or near the midrib, spherical, pale green, sometimes with a pinkish tinge due to the dense soft hairs on the surface (Fig. 16). Usually one leaf bears only one gall. After about 30 days, the galls when fully developed are large, long, saccate, approximately 3.2 cm in length and 1.1 cm in diameter (Fig. 17). Later, they split at the tip, forming a flower-shaped opening (Figs. 19,20), through which large honeydew droplets coated with much wax are expelled (Fig. 18). The galls are vase-shaped when mature (Fig. 20). The alate viviparous females mature in the galls in late April and fly to an unknown secondary host.