Yamatochaitophorus yichunensis, a new species of aphid (Aphididae: Chaitophorinae) from northeast China

Abstract Yamatochaitophorus yichunensis sp. n. is described from specimens collected in northeast China on Acer tegmentosum (Aceraceae). Yamatochaitophorus is also a new generic record for China. Type specimens are deposited in the National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing, China (NZMC) and the Natural History Museum, London, UK (BMNH).


Introduction
The genus Yamatochaitophorus was erected by Higuchi (1972) for Trichaitophorus albus Takahashi, 1961, which was described from an unidentified Acer sp. in Japan. The alata and embryo of Y. albus were described by Chakrabarti and Mandal (1986) from several Acer spp. in India. The genus has until now been monotypic (Favret 2016). Here, a second species, Yamatochaitophorus yichunensis sp. n. is described based on the specimens collected in northeast China on Acer tegmentosum (Aceraceae); the genus is newly recorded in China.
In the Chaitophorinae, three genera are associated with the plant family Aceraceae; Periphyllus van der Hoeven, Trichaitophorus Takahashi and Yamatochaitophorus Higuchi. Yamatochaitophorus is closely related to Trichaitophorus, also distributed in Eastern Asia (China, Japan and India), but can be distinguished from Trichaitophorus by the larger number of marginal setae and fewer eye facets, as well as by the shape and length of the dorsal setae (Higuchi 1972;Chakrabarti and Mandal 1986). Yamatochaitophorus is similar to Periphyllus on the same host plants; cauda always rounded, anal plate entire, siphunculi with reticulations in alatae etc. However, it may be distinguished from Periphyllus by the following characters: eyes with approx. 25 facets (the latter: many eye facets), antennae 5-segmented in apterae (the latter: 6-segmented); first tarsal segments with 3 ventral setae (the latter: first tarsal segments with 5-7 ventral setae); body small, elongate oval, less than 1.36mm in apterae (the latter: body relatively large, mostly elliptical); without "aestivales" form in summer (the latter: with "aestivales" form, modified first-instar larvae of resting stage) (Higuchi 1972;Richards 1972;Junkiert et al. 2011).

Materials and methods
Reliable aphid taxonomy requires slide-mounted specimens that are undistorted, but with the body contents fully cleared to make it possible to see surface details clearly. Specimens were placed in a 10% solution of potassium hydroxide and heated for 10-20 minutes or until body contents have softened. They were taken successively through distilled water, 70% EtOH and 95% EtOH, then transferred to clove oil for a minimum of 5 minutes, and finally mounted in Canada balsam. The descriptions and drawings provided here were produced from slide-mounted specimens using a Leica DM4000B and drawing tube. The photomicrograph images were prepared with a Leica DM2500 using DIC illumination, and processed with Automontage and Photoshop software.
Specimens of Yamatochaitophorus albus from Japan and India were obtained on loan from the Natural History Museum, London, UK, (BMNH) for comparison with our material.
Aphid terminology in this paper generally follows that of Higuchi (1972) and Chakrabarti and Mandal (1986). The units of measurement in this paper are millimetres (mm). The holotype and some paratypes are deposited in the National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing, China (NZMC); the other paratypes are deposited in the Natural History Museum, London, UK (BMNH).
Embryo (Fig. 14): Dorsal setae of body long thick and acute. Head with two pairs of frontal setae and two pairs of mid-dorsal setae. Pro-, meso-and metanotum each with a single pair of spinal setae and two pairs of marginal setae. Abdominal tergites I-VII each with one pair of spinal and one pair of marginal setae; tergite VIII with two pairs of fine and short dorsal setae. Siphunculi short, truncated. Eyes with 6-7 facets.
Host plant. Acer tegmentosum (Aceraceae). The species infested the underside of leaves of the host plant, and population density was low, with less than 20 individuals dispersed on the underside of a leaf (Figs 28, 29).

1
Abdominal tergites I-VII each with 3-10 spino-pleural (one occasionally), and 1-5 pairs of marginal shorter setae with flattened apices, besides 1 pair of spinal and 1 pair of marginal long and thick setae; ultimate rostral segment with 1 or 2 accessory setae; in embryos, dorsal body with long, thick and acute spinal setae, similar to marginal setae in shape ..