First record of the aphid genus Jacksonia Theobald (Hemiptera, Aphididae, Aphidinae) from China, with description of one new species

Abstract The aphid genus Jacksonia Theobald is reported in China for the first time, from Shaanxi, with the description of a new species, Jacksonia gibbera Qiao, Li, Zhang & Su, sp. n., found on an unidentified plant belonging to the Leguminosae/Fabaceae. A key to species of Jacksonia is provided.


introduction
The aphid genus Jacksonia was erected by Theobald (1923), with a description of the type species Jacksonia papillata. It was distinguished by the peculiar shape of the siphunculi, constricted at the middle, without a flange or any reticulation, and welldeveloped antennal tubercles which are converging, rough and very broad. Until now, this genus is represented by only three known species in the world (Ghosh 1986;Heie 1994;Raychaudhuri 1980;Remaudière and Remaudière 1997;Favret 2013). After identifying the specimens from Shaanxi, China, and comparing the original descriptions of the known species, one new species of Jacksonia is reported from China, Jacksonia gibbera Qiao, Li, Zhang & Su, sp. n. It was collected on an unidentified species of Leguminosae (Fabaceae).
In alate viviparous female: Dorsum of head smooth or sparsely to densely spinulose, venter smooth. Frontal setae with acute apices. Antennal segments I-V with normal imbrications, segments III-V with small or large round or transverse oval secondary rhinaria. Fore wings with two-forked medial veins, hind wings with 2 oblique veins. Abdominal tergites with brown or blackish brown spino-pleural and marginal patches, spino-pleural patches on tergites III-V usually fused to form a large dorsal patch. Others similar to apterae.
Host plants. On various species of Poaceae (Dactylis, Deschampsia, Festuca, Poa), but also with species described from Campanula and an unidentified plant belonging to the Leguminosae/Fabaceae. Other recorded hosts are likely to be casual occurrences (Blackman and Eastop 2006).
Comments. This genus is related to Myzus Passerini, 1860, but apterae can be distinguished from the latter by the peculiarly shaped siphunculi and the very broad antennal tubercles. The genus is also very similar to Xenosiphonaphis Takahashi, 1961, in having very broad antennal tubercles and flangeless siphunculi, but in Xenosiphonaphis, the inner apex of the antennal tubercles is only slightly converging. The alatae also differ: in Jacksonia, the basal halves of the siphunculi are without spinules, transverse wrinkles or grooves while those of Xenosiphonaphis have transverse wrinkles or grooves on the basal half.
Description. Apterous viviparous females: Body oval, 1.42-1.62 mm long, 0.82-0.95 mm wide. Green in life. In mounted specimens, body pale; apical parts of base of antennal segment VI and processus terminalis, apex of rostrum and tarsi brown, other parts pale (Fig. 13).
Abdomen: Abdominal tergites I-VI with wrinkles, more distinct toward marginal area of body (Fig. 19); posterior area of siphunculi with distinct spinules, tergites VII-VIII with sparsely spinulose transverse stripes; venter with spinulose transverse stripes. Dorsal setae of body very short, blunt or slightly capitate at apex, ventral setae short and acute. Abdominal tergites I-VII each with one pair of spinal setae, tergites I, V-VII each with one pair of marginal setae, tergites II-III each with two pairs of marginal setae, tergite IV with three pairs of marginal setae; tergite VIII with two dorsal setae. Length of marginal setae on tergite I about as long as dorsal setae on tergite VIII, 0.005 mm, 0.2 of basal diameter of antennal segment III. Siphunculi cylindrical (Figs 9, 20), constricted in middle, inner side of distal half slightly elongated; with dense imbrications, flangeless, ends of siphunculi truncated, with pore in central area; 0.20-0.21 mm long, 0.13-0.14 times as long as body, 3.42-4.32 times as long as its basal width, 2.2-2.3 times cauda. Cauda tongue-shaped, blunt at apex (Figs 10, 25), 0.09-0.094 mm long, 0.075-0.088 mm wide, with 4-5 setae. Anal plate semi-circular (Fig. 11), with 10 setae. Genital plate broadly circular (Figs 12,26), with 10-14 posterior setae and two anterior setae.
Hind tibiae in immatures (third instar) without spinules, smooth (Fig. 27). Host plant. An unidentified plant belonging to the Leguminosae/Fabaceae. It colonises the undersides of the leaves of the host plant.
Taxonomic notes. The new species is similar to the type species Jacksonia papillata Theobald, but apterae differ from this and J. campanulata by the characters given in the key below. The fourth species, Jacksonia sikkimensis Ghosh, Basu & Raychaudhuri, is known only from alate viviparous females.