Glyphochaitophorus cristaphis Qiao, 2021

Chen, Jing, Li, Zhaoxu, Jiang, Liyun & Qiao, Gexia, 2021, Glyphochaitophorus, a new genus of Chaitophorini (Hemiptera: Aphididae: Chaitophorinae) from China, Zootaxa 4975 (3), pp. 581-591 : 582-590

Glyphochaitophorus cristaphis Qiao , sp.nov.

(Figs 1–51, Table 1 )

Etymology. The name of the new species refers to the ridge-like spinal area of the body, “ crista ” (Latin) meaning “ridge” or “crest”.

Description. Apterous viviparous females (based on 10 specimens): Body ellipsoid; with a conspicuous mid-dorsal ridge, pleuro-marginal areas being thinner, and venter flat; dirty yellowish green in life. For morphometric data see Table 1 .

Mounted specimens. Body pale brown, antennae and legs brown; eyes, apex of rostrum, siphunculi and second tarsal segments dark brown; cauda and anal plate dark brown. Head fused with prothorax, meso- and metathorax fused, abdominal segments I–VII fused, abdominal segment VIII free. Dorsal cuticle with very well-developed “O”- and “C”-shaped or irregularly shaped wart-like sculpturing (Figs 1,16-17, 21, 26). Frontal setae (Figs 1, 5, 17, 19) and dorsal setae on abdominal tergite VIII (Figs 6, 7, 26) long thick and blunt, arising from distinct tubercles. Dorsal and marginal setae on other segments hardly discernible (Fig. 16).

Head. Frons convex between tubercles at bases of the two pairs of frontal setae (Figs 1, 17). Frontal setae (Figs 1, 5, 19) 4.0-5.3 times as long as basal diameter of antennal segment III. Eyes multi-faceted (Figs 1, 17), but facets fewer than 20, with ocular tubercles. Antennae 5-segmented (Figs 2, 18), 0.25-0.28 times as long as body; segments I-II have inner sides rugose, distal two-thirds of segment III and segments IV-V with imbrications. Except antennal segments I-II each with one thicker large seta, other antennal setae mostly very short, sometimes indistinct, segments I-V each with 3-5, 2-3,1-4, 0-1, and 1-2 setae, respectively; length of setae on segment III 0.20-0.30 times as long as the basal width of this segment; processus terminalis with 4 short and pointed apical setae. Primary rhinaria round, non-ciliated. Rostrum short, reaching mid-coxae; ultimate rostral segment with rounded apex (Figs 3, 20),1.70-2.05 times as long as its basal width, 0.81-0.93 times as long as hind second tarsal segment; with 3 pairs of primary setae and 1 pair of accessory setae.

Thorax. Mesosternal furca with two arms separated (Fig. 4). Legs normal (Figs 22-24), rather short. Hind femur 4.07-4.50 times as long as its widest diameter, 1.14-1.33 times as long as antennal segment III; setae on femora sparse, short and pointed. Hind tibia 0.37-0.41 times as long as body; distal halves of tibiae with spinules on outer side. Tibial setae mainly distributed on distal two-thirds and varying greatly in form and length, with longest setae towards the end; inner setae on tibiae sharply pointed; outer setae with tubercles at bases, distal setae long, thick and pointed, other outer setae expanded at apices; tibiae at lateral middle part with 5 or 6 thick short pointed setae on distinct tubercles; the longest setae on hind tibia 0.93-1.38 times as long as mid-width of this segment. First tarsal segments with 5 long fine and pointed ventral setae. Second tarsal segments with imbrication. Empodial setae flabellate.

Abdomen. Abdominal tergite VIII with four setae (Figs 7-8, 26), 4.3-5.0 times as long as basal diameter of antennal segment III. Siphunculi short, truncated, with spinulose transverse striae (Figs 8-9, 25); 0.23-0.30 times as long as their basal width, 0.13-0.22 times as long as cauda. Cauda knobbed, covered with spinules; with mosaic-like ornamentation on base near constricted part (Figs 10, 26-27); 0.52-0.73 times as long as its basal width, with 12-17 setae. Anal plate entire, broadly rounded (Figs 11, 27), covered with spinules, with 13-22 setae. Genital plate transverse oval; posterior margin with weak corrugations, anterior part with short spinulose striae; with 3 or 4 anterior (discal) setae and 7 or 8 posterior setae. Two gonapophyses, each with 5 or 6 short pointed gonosetae.

Alate viviparous female (based on one specimen). Body elliptical; head and thorax dark brown, abdomen green, costal and subcostal veins thick and dark brown, antennae and legs brown in life (Fig.49). For morphometric data see Table 1 .

Mounted specimens. Head and thorax blackish brown, antennae and legs dark brown, abdomen pale brown; siphunculi pale brown, cauda and anal plate dark brown, apex of rostrum blackish brown (Fig.37).

Head. Head dorsal cuticle rugose (Fig.39). Head with two pairs of frontal setae, one pair of anterior spino-pleural setae and two pairs of pleural setae between eyes. Frontal setae thick, long and pointed, with tubercles at bases (Figs 13, 38); other cephalic setae short and blunt at apex (Fig. 39). Frontal setae about 4 times as long as basal width of antennal segment III. Antennae 6-segmented (Fig. 40), 0.62 times as long as body; antennal segments I-II with short wrinkles, segments III-VI with developed imbrications; base of segment III distinctly constricted (Figs 12, 40-41); processus terminalis 0.92 times as long as base of the segment (Fig.42); primary rhinaria small round, ciliated; secondary rhinaria small and round, 9 or 10 ones only on segment III. Antennal setae very short and pointed, segments I-VI each with 6, 2, 3-4, 2, 1, 1 setae, respectively; processus terminalis with 4 apical setae; length of setae on segment III one third of its basal width. Rostrum reaching mid-coxae (Fig.43), ultimate rostral segment thick and stout, 3.11 times as long as its basal width, 1.04 times as long as hind second tarsal segment, with 3 pairs of primary setae and 1 pair of accessory setae.

Thorax. Dorsal setae on thorax short and stout, similar to dorsal setae on head. Legs normal. Femora with short transverse stripes on distal half; hind femur 6.62 times as long as its widest width, 1.39 times as long as antennal segment III. Distal third of tibia with developed spinules; hind tibia 0.45 times as long as body; setae on tibia longer than those on femora, stiff and sharp, and distal outer one third of tibia with more setae; setae on hind tibia 1.57 times as long as its mid-width. First tarsal chaetotaxy 5, 5, 5. Second tarsal segments with short imbrications.

Abdomen. Abdominal tergites I and VIII with spinulose transverse striae, which are weaker on other tergites. Spinal and pleural setae very short and stout, marginal setae long and thick or short and stout. Abdominal tergite I with 14 setae, including one pair of slightly longer marginal setae which are 0.83 times as long as basal width of antennal segment III. Tergite VIII with four long and rather thick dorsal setae (Fig. 14), arising from basal tubercles; longest dorsal setae on tergite VIII 3.00 times as long as basal width of antennal segment III. Fore wings with median vein twice-branched, costa and subcosta thick and brown, pterostigma long and broad; hind wings with two obliques (Fig.37). Siphunculi truncated (Fig. 44), with spinulose striae; 0.57 times as long as its basal width and 0.29 times as long as cauda. Cauda knobbed (Figs 15, 45), covered with spinules, 0.39 times as long as its basal width, with14 setae. Anal plate entire, transverse oval (Fig. 45), covered with spinules, with 22 setae. Genital plate broadly transverse oval with spinulose striae, with 2 anterior setae and 7 posterior setae. Two gonapophyses, each with 5 or 6 short and fine gonosetae.

The fourth instar nymph (based on one specimen). For morphometric data see Table 1 . Body spindle-like (Fig.28); head and prothorax fused (Fig. 29), meso-thorax to abdominal segment VII fused, abdominal segment VIII free (Fig. 28). Dorsum of head and prothorax, and abdominal tergite VIII ornamented as in adult aptera, dorsum of other segments with weak or indistinct reticulations or irregular sculpturing (Fig.28).

Head. Head with two pairs of long thick frontal setae (Figs 28-29), 4.25 times as long as basal width of antennal segment III. Antennae 5-segmented (Figs 28-29), 0.40 times as long as body; segments III-V with short imbrications; antennal setae very short, those on segment III 0.25 times as long as its basal width; processus terminalis 1.06 times as long as base of segment V. Rostrum reaching mid-coxae, ultimate rostral segment 1.60 times as long as its basal width, 0.84 times as long as hind second tarsal segment (Fig.30).

Thorax. Hind femur 1.40 times as long as antennal segment III, setae on femora short and stout. Distal half of hind tibia slightly expanded (Fig. 32), hind tibia 0.27 times as long as body; inner setae on pro- and mid-tibia short and pointed, outer setae stout, longer than inner setae, longest towards the end (Figs 28-29, 32). Inner setae on hind tibia similar to those of fore- and mid-legs, fine and pointed; outer basal one third of hind tibia without setae; outer distal two-thirds with well-developed spinules, and with long and pointed setae with basal tubercles; median third with five short thick and stout setae; longest setae on hind tibia 1.50 times as long as its midlength width.

Abdomen. Spinal and pleural setae on abdominal tergites I-VII hardly discernible, marginal setae short and stout, becoming longer from tergite I to VII; marginal setae on tergite I 0.010mm long, 0.50 times as long as basal width of antennal segment III; lengths of marginal setae on tergites V-VII 0.012mm, 0.015mm, and 0.017mm respectively. Abdominal tergite VIII (Figs 28, 31) with one pair of long thick and one pair of short dorsal setae, the long setae 0.027mm, 3.60 times as long as the short ones, and 4.50 times as long as basal width of antennal segment III. Siphunculi short truncated, with densely spinulose striae (Figs 28, 31). Cauda semi-circular, with 12 setae. Anal plate transverse oval, with 15 setae. Cauda and anal plate with spinules.

Young nymph (the first or second instar nymph (based on one specimen). For morphometric data see Table 1 . Body oval (Fig.33); head and prothorax separated (Figs 33-34), and every segment of body distinctly separated on marginal area (Fig. 33). Dorsum of head (Fig. 34), prothorax and abdominal tergites VII-VIII with distinct short wrinkles, rest of dorsum only with weak or indistinct wrinkles (Fig.33).

Head. Head with two pairs of long thick frontal setae with tuberculate bases (Figs 33-34), and with two pairs of very short dorsal setae between eyes. Eyes with about 10 facets. Antennae 4-segmented (Fig.33), segments III-IV with short imbrications; 0.49 times as long as body; antennal setae very short, those on segment III 0.38 times as long as its basal width; processus terminalis 1.23 times as long as base of this segment. Rostrum reaching hindcoxae, ultimate rostral segment thick and stout, 1.71 times as long as its basal width, 0.86 times as long as second hind tarsal segment (Fig.30).

Thorax. Dorsal setae on thorax with -tubercles at bases, spino-, pleural and sub-marginal setae very short. Setae on pronotum very short, with one pair of anterior spinal and 2 pairs of marginal setae. Mesonotum with one pair of spinal, one pair of pleural and one pair of submarginal setae, and with one pair of thick long sword-like posterior marginal setae. Metanotum with one pair of spinal and one pair of submarginal setae; and with a pair of thick long flattened posterior marginal setae. Legs normal. Hind femur 1.06 times as long as antennal segment III. Setae on femora very short and stout, sparse; inner setae on pro-and mid-tibia short and fine, outer setae long and thick. Inner setae on hind tibia similar to those on pro-and mid-legs, outer setae thick long and pointed, longer towards the end; median part with seven short stout setae; longest setae on hind tibia 1.73 times as long as its mid-width. Outer distal two-thirds of hind tibia with well-developed spinules. Hind tibia 0.26 times as long as body (Figs 33, 35).

Abdomen. Abdominal tergites I-VI each with one pair of very short spinal setae arising from round sclerites, and a pair of sword-like marginal setae; marginal setae on tergite I are 1.88 times as long as basal width of antennal segment III (Figs 33, 36). Tergite VII with one pair of sword-like spinal setae and one pair of sword-like marginal setae (Figs 33, 35-36). Tergite VIII with one pair of sword-like spinal setae, 2.50 times as long as basal width of antennal segment III (Figs 33, 35-36). Siphunculi shorter truncated, with densely spinulosa stripes (Figs 33, 35-36). Cauda semi-circular, with six setae. Anal plate transverse oval, with 10 setae. Cauda and anal plate with spinules.

Specimens examined. Holotype: apterous viviparous female, CHINA: Tibet (Yadong County, Xiayadong Town ), 25.vi.2016, No. 37412-1-6-2, on Acer palmatum Thunb. , coll. FF Niu ( NZMC) . Paratypes: 7 apterous viviparous females, 1 alate viviparous female, 1 fourth instar nymph and 1 young nymph (first or second instar nymph, with the same collection data as holotype ( NZMC); 2 apterous viviparous females, No. 37412-1-4, with the same collection data as holotype ( NHM).

Distribution. China (Tibet).

Host plant. Acer palmatum Thunb.

Biology. The aphids were found feeding in small numbers on the basal parts of the samaras of Acer palmatum Thunb. But , the life-cycle is unknown (Figs 46–51).

Comments. The new genus is unique in Chaitophorini by having apterae with a conspicuous median dorsal ridge, by the wart-like sculpturing of the entire dorsal cuticle, and by the siphunculi with spinulose striae. The apterae share several characters with Trichaitophorus and Yamatochaitophorus , such as head and prothorax fused, eyes with approx. 25 facets or less, abdominal tergites I-VII completely fused, inner and outer setae on distal half of tibiae distinctly differentiated, flattened empodial setae, siphunculi short and truncated, and anal plate entire and broadly rounded. However, the new genus differs from them as follows: except for the long frontal setae and dorsal setae on abdominal tergites VII-VIII, the dorsal setae of Glyphochaitophorus are hardly discernible, whereas in Trichaitophorus there are short and long, thick or dilated marginal setae at least on the thorax and abdominal tergites I-VI, and Yamatochaitophorus has long thick spinal, pleural and marginal setae with knobbed or blunt apices on all body segments. Tibial setae of Glyphochaitophorus are mainly distributed over distal two-thirds of tibia, and show considerable differences in size and form, with the most distal setae longest, and the outer setae expanded apically and arising from basal tubercles. In Trichaitophorus and Yamatochaitophorus setae are distributed over the whole length of the tibiae, all the outer setae being long thick and pointed. Other differences are the siphunculi with spinulose striae (in Trichaitophorus they are corrugated or striate but without any spinules, and in Yamatochaitophorus they have only with weak transverse imbrications); the distinctly knobbed cauda (in the other two genera the cauda is rounded).

Besides the new genus, there are three other genera of Chaitophorini associated with Acer ; Periphyllus , Trichaitophorus and Yamatochaitophorus . These four genera are differentiated by the key that follows: