Nipponaphis hubeiensis Wang & Chen, 2021

Wang, Wei, Cui, Yongzhong, Chen, Xiaoming, Bashir, Nawaz Haider & Chen, Hang, 2021, A new species of aphid of the genus Nipponaphis (Hemiptera: Aphididae: Hormaphidinae) from China, inducing galls on the trunk of a witch-hazel (Hamamelidaceae), Zoologia (e 60598) 38, pp. 1-9 : 2-4

Nipponaphis hubeiensis Wang & Chen , sp. nov.

Figs 1–7

http://zoobank.org/ 4BD49F44-ABC1-4C50-BF41-CE3E06C1C23E

Type material. Holotype: female, apterous viviparous with labeled China: Hubei, Shiyan city, Zhushan County, Tianjiaba Town on S. sinensis , 556 m, 32°11’48”N, 110°4’1”E, 15.VIII.2019, #20190021, coll. Wei Wang, Yongzhong Cui and Kunfang Xiao ( RIRI-CAF) . Paratypes: 14 females, same data as holotype except #20190022–35 .

Diagnosis. Morphological characters which are supported the placement of new species in genus Nipponaphis by normal body, apterae aleyrodiform, antennae 4 segmented, sturdy prosoma with middle and posterior setae, fused abdominal segments except VIII, abdominal tergum VIII with 4 setae, scattered sculptures on dorsum, cauda, tarsi and presence of siphunculus. The new species is similar to other Nipponaphis in having aleyrodiform present, prosoma, abdominal segments, head and thorax relatively longer than abdomen, wax gland plate lacking on dorsum, sculptures on dorsum present, number of setae on abdominal tergite VIII, frontal horns lacking and compound eyes 3-faceted. Nipponaphis hubeiensis sp. nov. may be separated from the closely related N. monzeni based on the following characters (those of N. monzeni between brackets): body oval, more than 1 mm long (body round, less than 1 mm long), antennae 4-segmented (antennae 3-segmented), cauda rectangular (cauda knobbed shape), setae present on antennal segment III (setae absent on antennal segment III) and submarginal setae on abdominal tergites II-VII absent (submarginal setae on abdominal tergites II-VII present). New species can be differentiated from N. distyliicola by four antennal segments, shape of sculptures on dorsum and shape of cauda. From the sympatric N. machili and N. minensis , the new species can be distinguished by antennae four segmented (antennae three segmented in N. machili and N. minensis ), cauda rectangular (cauda knob-like in N. machili and N. minensis ), head and pronotum completely fused (head separated from thorax in N. machili and N. minensis ), primary rhinaria present on antennal segments III and IV (primary rhinaria present on antennal segment III in N. machili and N. minensis ), granular protrusions on the dorsum (circular protrusions on the dorsum in N. minensis , and three dots like marking present on the mid of dorsum in N. machili ).

Description. Body oval, head, thorax, antennae, mouthparts, legs and anal plate brown ( Fig. 5); head and pronotum completely fused ( Fig. 1); dense epandrium on the dorsum of body ( Figs 1, 3). Body average length 1.25 mm (n = 20), width 0.62 mm; head 0.088 mm long, 0.07 times length of body; thorax 0.63 mm, 0.50 times length of body; and abdomen length 0.50 mm, accounting for 0.4 times length of body. Forehead curved, frontal tumor lacking, 5-6 setae on dorsum of head; compound eyes 3-faceted. Antennae short, 4-segmented, basal segment dilated ( Fig. 6), total length 0.20 mm, 0.16 times of body length; 1-2 setae on segments I, II and III respectively, segment IV with 4 short setae; two round primary rhinaria distributed in the segment III and IV, respectively. Rostrum 5-segmented ( Fig. 2), total length 0.26 mm, length of rostral segment IV and V 0.98 mm, 1.48 times longer than tarsus II of hind leg, 3 pairs short setae on segment I and II, segment III with 2 pairs of short setae, 4 terminal sensory setae on segment IV. Six pairs of setae on pronotum, 22 pairs of long and short marginal setae on lateral tergum, long setae on tergum 0.07-0.15 mm in length, 6.25 times of the diameter of antennal segment IV and 2.92 times of their short setae, slightly longer than setae on segment V. Two pairs of marginal setae on pronotum and mesonotum, abdominal tergites with 1 pair of marginal setae, no setae present on abdominal tergites I-VII, and 3-4 setae on VIII. A pair of conical siphunculi present on apex of abdomen ( Fig. 7). Cauda rectangle in shape above anus ( Fig. 4). Hind femur 0.12 mm long, 1.20 times longer than antennal segment IV; hind tibia 0.16 mm long, 0.11 times length of body; tarsus 3-fracted, hind tarsus II 0.07 mm long, tarsus terminal splits into two lateral claws, without paw pad.

Distribution. China (Hubei).

Etymology. The new species is named after the place where specimens were collected. The ‘hubeiensis’ is a toponymic referring to the type locality at Hubei province.

Primary host. Sycopsis sinensis .

Morphology and structure of galls

The morphology, structure and sites where galls grow are important biological characteristics of gall-inducing aphids, which have strong species specificity and are known as ‘extended phenotypic characteristics’ of aphids ( Stern 1995, Stone and Schönrogge 2003, Wool 2004). Consequently, the morphology and characteristics of the galls described in this study can be used in species’ identification.

The gall forms on the trunk ( Figs 8, 9), is oval, and has a closed single-chamber gall ( Figs 10, 11), 30-50 mm in length and 25-35 mm in width. Fresh galls are pale-cyan, but turn brown after they mature. Some have protruding longitudinal veins (vascular bundles below), thick and woody gall chamber wall, hard and brittle texture. A cross section divides into two layers: the outer layer is thin, brown; the inner layer is thick, yellowish white ( Fig. 10). Gall wall is about 3-4 mm thick and has many spindle-shaped pits on the inner surface of gall wall ( Fig. 12). Wax is present inside the gall. At maturity, the galls form round holes as a secondary opening, while there are also round concave holes inside the un-burst galls ( Fig. 11).

We speculated that the secondary opening is formed by the concave hole for aphids’ seasonal migration. This kind of gall is similar to Galla Chinensis, which is caused by the Chinese aphid Schlechtendalia chinensis (Bell, 1851) , on the leaves of Rhus chinensis Mill. ( Lee et al. 1997) . We measure the tannin content of the gall produced by N. hubeiensis sp. nov. and compared it with the tannin produced by the Chinese horned gall ( S. chinensis ). We found that the tannin content in N. hubeiensis sp. nov. is extremely low in comparison, only about 3% ( Fig. 13), which was obviously different from Chinese horned gall. Chen (1991) collected similar galls in Songbai Town, Shennongjia, Hubei Province, and found that the morphology of the ‘woody gallnut’ was similar to resembled Chinese horned gall form on Rhus punjabensis ( Anacardiaceae ) leaves and there is aphid species of Kaburagia Takagi, 1937 ( Pemphigidae : Fordinae) in the region. The ‘woody gallnut’ might be a related to the aphid Kaburagia ovogalIis ( Tsai and Tang 1945). For this reason, we carried out the molecular analysis to differentiate the species of aphids.

Molecular analysis

The topology distance-based clustering graph (NJ-tree) including 13 species of Nipponaphidini, 13 of Cerataphidini and 8 Hormaphidini resulted in robust branch support with the most bootstrap values higher than 70%. The tree is divided into three groups, consistent with the taxonomic classification ( Fig. 14). Nipponaphis hubeiensis sp. nov. clustered in the genus Nipponaphis . Nipponaphis monzeni is the closest species to N. hubeiensis sp. nov. Interspecific K2P genetic distances also indicates the result with its maximum divergence 0.0656 (> 6%) from N. distyliicola , and minimum distance 0.0215 (> 2%) to N. monzeni ( Table 2). Combined with the strong support from molecular evidence and morphological identification, the hypothesis that N. hubeiensis sp. nov. is not a close relative of Fordinae is confirmed and we are confident in erecting a new species for it in Nipponaphis .