A new genus and species of Macrosiphini (Hemiptera, Aphididae) from China, living on Isodon eriocalyx

Abstract The aphid genus Nigritergaphis gen. n. is described, and N. crassisetosa sp. n. on Isodon eriocalyx (Dunn) Kudô (Lamiaceae) from Yunnan, China is described and illustrated. The new species curls and distorts the leaves of this important traditional Chinese medicinal plant, and is evidently specific to this host. Holotype and paratypes are deposited in the National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.


Introduction
Isodon eriocalyx (Dunn) Kudô (Lamiaceae) is an important traditional Chinese medicine plant, and has been used as a folk medicine to treat inflammation as well as reducing blood pressure. Over the past twenty years, plants in the genus Isodon have received consider-acute at apex, with 4 setae. Genital plate with 2 anterior setae and 10-12 posterior setae. In alatae: Abdominal tergites each with one pair of marginal patches and an imperfect spino-pleural dark band. Antennae 6-segmented, segments III-V with large and round secondary rhinaria. Fore wing median vein with two-forks, hind wing with two obliques, all veins without fuscous borders.
Taxonomic notes. Nigritergaphis belongs to the tribe Macrosiphini of the family Aphididae, but has a unique combination of features justifying the erection of a new genus. Compared with other aphid genera associated with Lamiaceae, it differs by having numerous, thick long and stiff dorsal setae arising from tuberculate bases, and first tarsal chaetotaxy: 2, 2, 2. It is similar to Roepkea Hille Ris Lambers in the shape of the cauda, dorsal ornamentation and lack of marginal tubercles, but differs from that genus as follows: siphunculi only with weak imbrications (in Roepkea: ornamented with transverse rows of small spicules); body dorsum completely sclerotic and smooth (in Roepkea: usually dark, sclerotic, but with pale patches on the marginal areas, and with numerous small spicules).The new genus resembles Brachycaudus van der Goot in the shape of cauda, and in dorsal sclerotization, but may be distinguished from that genus by the following: lack of marginal abdominal tubercles (in Brachycaudus these are frequently present on several body segments); spiracular pores oval or reniform (in Brachycaudus they are circular and large); siphunculi imbricated and without a sharply limited subapical constriction (in Brachycaudus rather smooth, and with a sharply limited constriction below the flange).The new genus resembles Dysaphis Börner in the shape of spiracular pores and the shape of the cauda, but differs from Dysaphis as follows: abdomen of apterae with a complete sclerotic shield (in Dysaphis dorsal sclerotization never forms a complete shield); without spinal and marginal tubercles (in Dysaphis spinal and marginal tubercles are characteristically present). Etymology. The specific name, crassisetosa is composed of the Latin words "crassis" (= thick) and "setosa" (= covered with hairs), due to the long and thick setae of body.
Mounted specimens. Body. Dorsum brown. Antennal segments I-II dark brown, segment V and base of segment VI brown, others pale. Siphunculi dark brown. For morphometric data see Table 1.
Apterae with 5-segmented antennae and 6-segmented antennae occur at different times of year, the former in October, the latter in December. Seemingly, there is a seasonal effect on morphology in this species. No sexual morphs were observed.
Taxonomic notes. Eastop (2006, 2013) provided a key to all apterous viviparous females on the plant genus Isodon. The new species can be inserted as an additional couplet (couplet 3a) in their key: 1 SIPH strongly swollen, with maximum diameter of swollen part more than 2 × minimum diameter of stem, smooth except for a small subapical polygonal reticulation. SIPH 5. Couplets 4 to 20 without modification.