Periphyllus acerihabitans Zhang

Periphyllus acerihabitans Zhang

(Figs 1–5; Tables 1 –2)

Periphyllus acerihabitans Zhang, 1982 in Zhang & Zhong 1982: 73.

Re-description of apterous viviparous female (based on 15 specimens) (Figs 1,5a–c; Table 1). Colour. In life: light green (Fig. 5 a–c); in mounted specimens: yellowish with apices of ANT III–V, ANT VI, legs, pleural and spinal setae on abdominal tergites VII–VIII dusky. Morphological characters. Body oval (Fig, 1a). Frons flat. Head with numerous fine, pointed setae, which are 0.075–0.240 mm long. ANT 6-segmented, long, reaching abdominal segment II, 0.58–0.68 × BL and 0.32–0.36 × HW. ANT IV slightly longer than ANT V; ANT V always shorter than ANT VI; PT 1.50–2.00 × BASE (Fig. 1 b); other antennal ratios: VI:III 0.70–0.86, V:III 0.51–0.56, IV:III 0.49–0.57. ANT I with 5–9 setae, ANT II with 4–6 setae, ANT III with 9–14 setae (Fig. 1 c), ANT IV with 2– 4 setae, ANT V with 2–3 setae, BASE with 2 setae. ANT setae fine, pointed, 0.03–0.16 mm long; some setae on ANT IV and V slightly forked. LS ANT III 4.0–5.3 × BD III (Fig. 1 c). BASE with 5 accessory rhinaria. Rostrum reaching middle coxae. ARS with 2 accessory setae (Fig. 1 d), 0.21–0.25 × ANT III and 0.63–0.70 × HT II. Legs setose, with numerous stout, pointed setae, which are 0.11–0.23 mm long; some tibial setae with slightly forked apices. Hind tibiae with rows of short spinules; empodial setae spatulate; first tarsal chaetotaxy 5:5:5. Abdominal tergites membranous, with numerous pale, pointed setae, which are 0.09–0.15 mm long, sometimes with slightly forked apices; stout setae in marginal, pleural and spinal positions on abdominal tergites I–VI longer, 0.19–0.25 mm long; stout setae in pleural and spinal positions on abdominal tergites VII–VIII longest, 0.26–0.30 mm long (Fig. 1 a). Siphunculi truncate with 3–4 rows of reticulations and well developed flange (Fig. 1 e). Cauda broadly rounded with 9–14 setae.

Re-description of alate viviparous female (based on 8 specimens) (Figs 2,5d; Table 1). Colour. In life: greenish with head, wing veins light brown and ANT, knee area, tibiae, tarsi and thoracic sclerotized plate dark brown (Fig. 5 d); in mounted specimens: yellowish with head, apices of ANT III–V, BASE, thoracic sclerotized plate, wing veins, knee area, distal part of tibiae, siphunculi, pleural and spinal setae on abdominal tergites VII– VIII dusky. Morphological characters. Body elongate. Frons flat. Head with numerous fine, pointed, setae, which are 0.075–0.210 mm long (Fig. 2 a). ANT 6-segmented, reaching abdominal segment I, 0.58–0.72 × BL and 0.27– 0.32 × HW. PT 1.67–2.17 × BASE (Fig. 2 c); other antennal ratios: VI:III 0.70–0.80, V:III 0.50–0.54, IV:III 0.48– 0.60. ANT I with 4–9 setae, ANT II with 4–5 setae, ANT III with 9–14 setae (Fig. 2 d), ANT IV with 3–5 setae, ANT V with 2–3 setae, BASE with 1–2 setae. ANT setae fine, pointed, 0.045–0.14 mm long; some setae on ANT IV and V slightly forked. LS ANT III 4.3–5.6 × BD III. ANT III with 12–19 secondary rhinaria (Fig. 2 d), BASE with 5–7 accessory rhinaria. Rostrum reaching middle coxae. ARS with 2 accessory setae, 0.19–0.22 × ANT III and 0.66–0.69 × HT II. Fore wings with normal venation (Fig. 2 b). Legs setose, with numerous stout, pointed setae, which are 0.08–0.23 mm long; some tibial setae with slightly forked apices. Hind tibiae with rows of short spinules; empodial setae spatulate; first tarsal chaetotaxy 5:5:5. Abdominal tergites membranous, with numerous pale, pointed setae, which are 0.09–0.14 mm long (only few setae with slightly forked apices); stout setae in marginal, pleural and spinal positions on abdominal tergites longer, 0.17–0.26 mm long (Fig. 2 e). Siphunculi truncate, wholly reticulated, with well-developed flange (Fig. 2 f). Cauda broadly rounded with 9–11 setae.

Description of dimorph (based on 3 specimens) (Figs 3,5e,f; Table 2). Colour. In life: yellowish white (Fig. 5 f); in mounted specimens: yellowish with dusky tip of ARS. Morphological characters. Body small, flattened. Head with a longitudinal suture continuous with abdomen. Posterior part of head fused with prothorax. Vertex wrinkled with 2 broad foliate setae, without serrated margins. ANT 4-segmented. ANT I with swollen anterior processes, from which 2 curved, oval foliate setae arise; ANT II with 1 stout seta; ANT III distinctly wrinkled, with primary sensorium and 1 flattened seta opposite to sensorium; BASE with a small spine near primary sensorium; PT with 2 apical setae, 0.4–0.54 × BASE. Rostrum reaching middle coxae. ARS with 2 accessory setae. Dorsum wrinkled. Meso- and metanotum, and abdominal tergites I–VI each with one pair of spinal and lateral plates; each spinal plate with one spinule placed obliquely. Meso- and metanotum each with small, oval foliate setae marginally; abdominal tergites I–VII each with large, broad foliate setae marginally (the largest ones on abdominal tergites I–IV); tergite VIII with leaf-like setae marginally; posterior segment with a pair of elongated leaf-like setae. Fore and middle tibiae with 5 and 7 leaf-like setae, respectively; hind tibiae with long, stout pointed setae.

Description of oviparous female (based on 2 specimens) (Fig. 4; Table 2). Colour. In life: yellowish with head, thorax and abdominal sclerotized plate dark brown; in mounted specimens: yellowish with frons, ANT, legs, siphunculi, marginal, pleural and spinal sclerites and setae on abdominal tergites dusky. Morphological characters. Body oval with being restricted between abdominal segments VI and VII. Frons flat. Head with numerous fine, pointed setae, which are 0.09–0.26 mm long. ANT 6-segmented, long, reaching abdominal segment II, 0.54 × BL and 0.4 × HW. PT 1.69–1.76 × BASE; other antennal ratios: VI:III 0.70–0.75, V:III 0.44–0.46, IV:III 0.43–0.44. ANT I with 6–7 setae, ANT II with 4–5 setae, ANT III with 13–14 setae, ANT IV with 2–3 setae, ANT V with 1– 2 setae, BASE with 2 setae. ANT setae fine, pointed, 0.04–0.14 mm long. LS ANT III 3.71–4.67 × BD III. BASE with 5 accessory rhinaria. Rostrum reaching middle coxae. ARS with 2 accessory setae, 0.22 × ANT III and 0.73– 0.78 × HT II. Legs setose, with numerous stout, pointed setae, which are 0.09–0.20 mm long; some tibial setae with slightly forked apices. Hind tibiae visibly swollen with 152–208 oval or 8-shaped pseudosensoria on almost whole length (Fig. 4 c); empodial setae spatulate; first tarsal chaetotaxy 5:5:5. Abdominal tergites each with large, oval marginal and small, oval spinal sclerites. Abdominal setae numerous, pale, pointed, 0.04–0.13 mm long, sometimes with slightly forked apices; setae in marginal, pleural and spinal positions on abdominal tergites I–VIII distinctly longer, 0.21–0.29 mm long. Siphunculi truncate with 4-6 rows of reticulations and well developed flange (Fig. 4 b). Cauda broadly rounded with 8–11 setae.

Life cycle and host plant. Field observations were conducted in Shimane, Ehime and Fukuoka Prefectures, western Japan. Periphyllus acerihabitans is a monoecious, holocyclic species exclusively associated with Acer buergerianum Miq. (trident maple). Aphids live on the underside of leaves, leaf stems and young shoots of the host plant (Fig. 5 a,b). Large colonies are formed at the end of March and are usually attended by ants (Fig. 5 b). Apterous and alate viviparous females were observed from the end of April to the end of June, but at the end of June only a few individuals were found. Dimorphs (aestivating nymphs) were found along the leaf veins of the host plant (Fig. 5 e). Dimorphs began to appear at the end of April and were observed in June and July; only dimorphs were found during July. Oviparous females are produced in October and November; in the beginning of November both viviparous and oviparous females were observed. Males are unknown. Periphyllus acerihabitans and P. californiensis were sometimes found on the same host-plant tree.

Distribution. China (Zhejiang Province); Japan (Honshu: Tochigi Pref., Ibaraki Pref. and Shimane Pref.; Shikoku: Ehime Pref.; Kyusyu: Fukuoka Pref.) (Fig. 6). This species is recorded from Japan for the first time. Acer buergerianum is native to eastern China, but was introduced into Japan as an ornamental tree. Thus, it is likely that P. acerihabitans is an adventive species in Japan. A. buergerianum is widely cultivated in Japan, and it is possible that P. acerihabitans occurs more widely in Japan, as well as other countries where A. buergerianum is grown.

Remarks. P. acerihabitans clearly differs from other East Asian species of the genus Periphyllus (Sorin 1990; Park & Park 1995) by terminal process very short, less than twice the length of the base of antennal segment VI. However, Zhang and Zhong (1982) pointed out that it is most similar to P. v i r i d i s, and they presented differences in some morphometric characters of the spring viviparous generation of both species. Despite both species have similar colour in life, P. acerihabitans is much smaller than P. v i r i di s (and especially its subspecies P. viridis osugensis, also recorded from Japan) in all known morphs, even when both spring and autumnal viviparous generations are compared. In apterous and alate females the first tarsal chaetotaxy of P. acerihabitans is 5:5:5 (7:7: 7 in P. v i r i d i s), the cauda is broadly rounded (helmet-shaped in P. vi ridis), the siphunculi are much shorter with a few rows of reticulations in wingless morphs (elongated with 8–9 rows of reticulations in P. v i r i d i s). The differences in the body and the length of antennal segments are also visible in dimorphs. Moreover, the last abdominal segment of the dimorph of P. acerihabitans has a pair of elongated, leaf-like setae whereas in P. v i r i d i s those setae are rather short and broadly rounded. The compared species are both monophagous— P. acerihabitans is associated with A. buergerianum, P. vi r i d i s with A. pictum subsp. mono (Maximowicz) H. Ohashi (= A. mono).

Material examined. Holotype—Hangzhou, Zhejiang, China, 5.V.1975, Acer buergerianum, Zhong & Zhang leg., (NZMC) No. 5595-1-1—1 apterous viviparous female. Paratypes—the same data as the holotype, (NZMC) No. 5595—5 apterous viviparous females; the same locality as the holotype, 11.V.1975, (NZMC) No. 5577, 5688—3 alate viviparous females. Non-type material—Nasu, Tochigi Pref., Japan, 20.V.2000, A. buergerianum, T. Fukatsu leg., MNHN(EH) 12691, 12693, 12694—4 apterous and 1 alate viviparous females; Tsukuba, Ibaraki Pref., Japan, 7.V.1999, A. buergerianum, T. Fukatsu leg., MNHN(EH) 12690, 12692—2 apterous and 1 alate viviparous females; St. 88 Ochiai, Haikimi-cho, Masuda-shi, Shimane Pref., Japan, 2.XI.2013, A. buergerianum, H. Yoshitomi leg., (UŚ) 13/11/28—2 oviparous females; Minami-machi, Matsuyama, Ehime Pref., Japan, 12.X.2011, A. buergerianum, H. Yoshitomi leg., (UŚ) 11/10/24, 11/10/25—2 apterous and 2 alate viviparous females; the same locality, 18.X.2011, A. buergerianum, H. Yoshitomi leg., (UŚ) 11/10/26, 11/10/27—2 apterous and 1 alate viviparous females; the same locality, 30.IV.2015, A. buergerianum, H. Yoshitomi leg., (UŚ) 15/6/29, 16/6/30—1 apterous viviparous female, 3 dimorphs; Tachibana, Ômuta-shi, Fukuoka Pref., Japan, 3.V.2011, A. buergerianum, H. Yoshitomi leg., (UŚ) 11/5/22, 11/5/23—1 apterous and 1 alate viviparous females.

P. viridis viridis: Primorski Kraj, 27.V.1980, A. mono, Pastchenko leg., MNHN(EH) 22490—2 alate viviparous females, 2 dimorphs; Takihara, Mie, Japan, A. mono, 10.V.1976, M. Sorin leg., MNHN(EH) 12826—1 apterous viviparous female, 1 dimorph; Nasu Tochigi, Japan, A. mono, 20.V.2000, T. Fukatsu leg., MNHN(EH) 12827, 12828—1 apterous viviparous female, 2 alate viviparous females, 2 dimorphs.

P. viridis osugensis: Holotype - Osugidani, Mie Pref., Japan, A. mono, 5.V.1987, M. Sorin leg., MNHN(EH) 22491—1 alate viviparous female.

P. californiensis: Misugi, Mie Pref., Japan, 13.XI.1968, Acer sp., A. Kitamura leg., MNHN—2 apterous viviparous female, 2 alate viviparous females, England, Surrey, Acer palmatum, 17.VI.1979, J.H. Martin leg., No 2406 BMNH—8 dimorphs; Poland, Ustroń, A. palmatum, 17.X.2010, J. Junkiert leg., UŚ 10/10/87, 10/10/88 —3 apterous viviparous females, 2 alate viviparous females.