Neothelaxes pileata Qiao, 2021

Jiang, Li-Yun, Zhang, Xiao-Lu, Chen, Jing, Zhao, Yi-Fang & Qiao, Ge-Xia, 2021, Neothelaxes pileata, a new species from China (Hemiptera, Sternorrhyncha, Aphididae, Thelaxinae), ZooKeys 1076, pp. 1-8 : 1

Neothelaxes pileata Qiao sp. nov.

Figures 1-11 , 12-22 , 23-28

Specimens examined.

Holotype: apterous viviparous female, China: Tibet Autonomous Region ( Linzhi City : Motuo County, 29.697°N, 95.556°E, altitude 2678 m), 25 July 2019, No. 46755-1-1-1, on Pilea martinii coll. X.L. Zhang. Paratypes: 2 apterous viviparous females and 3 first instar nymphs with the same collection data as the holotype; 1 apterous viviparous female, No. 46755-1-2, with the same collection data as the holotype (NHMUK); 2 fourth instar apterous nymphs, China: Tibet Autonomous Region ( Linzhi City : Motuo County, 29.697°N, 95.556°E, altitude 2678 m), 17 June 2021, No. 51097-1-1-1, on Pilea martinii coll. M. Qin and X.L. Zhang.

Etymology.

The specific name Neothelaxes pileata is an adjective based on the feminine generic name of the host plant.

Description.

Apterous viviparous female: Body small, oval (Figs 12 , 23 ). Adults light dirty green, or dirty yellowish green, nymphs yellowish green, covered with white waxy powder in life (Fig. 23 ), and found in irregularly spherical galls on the leaves of the host plant. For morphometric data see Table 1 .

Mounted specimens.

Body dorsum pale brown (Fig. 12 ). Antennae, legs, cauda, anal plate, and genital plate brown, siphunculi and apex of rostrum dark brown. Head to abdominal segment VII fused, sometimes with intersegmental boundary on spinal area between head and pronotum and pronotum and mesonotum, and on spino-pleural areas of abdominal tergites; abdominal segment VIII free (Fig. 12 ). Dorsal setae of body spine-like (Figs 6 , 7 ). Wax plates large, with many minute wax pores (Figs 15 , 17-19 ). Vertex with one pair of wax plates, pronotum to abdominal tergites I-VII each with one pair of spinal and one pair of marginal wax plates, tergite VIII with a spino-pleural wax plate (Figs 15 , 17-19 ). Spiracles small and round, spiracular plates small and oval, brown.

Head. Frons convex, eyes 3-faceted (Figs 1 , 12 , 15 ). Head dorsum with indistinct median suture. Dorsal setae on head short, fine and pointed (Figs 1 , 15 ). Cephalic setae with two pairs, head with one pair of posterior spinal setae and three pairs of marginal setae; cephalic setae 0.78-1.13 × basal diameter of antennal segment III (Figs 1 , 4 , 15 ). Eyes 3-faceted. Antennae 5-segmented (Figs 2 , 13 ), segments III and IV with sparse spinulose imbrications, segment V with spinulose imbrications; 0.29-0.33 × body; processus terminalis 0.30-0.40 × base of the segment. Antennal setae sparse, very short and pointed; segments I-V with 2 or 3, 2, 1-4, 3, 2 setae, respectively; processus terminalis with five setae. Length of setae on segment III 0.50-0.80 × basal diameter of the segment. Primary rhinaria ciliated (Figs 2 , 13 ). Rostrum (Figs 3 , 14 ) reaching mid-coxae; ultimate rostral segment elongate wedge-shaped, stout at apex, 2.50-3.14 × its basal width, 1.18-1.33 × second hind tarsal segment, with two pairs of primary setae and two accessory setae, accessory setae longer than primary setae.

Thorax (Fig. 12 ). Pronotum with one pair of posterior spinal setae and two pairs of marginal setae; meso- and metanotum each with two pairs of marginal setae. Mesosternal furca with two arms separated (Fig. 5 ). Legs normal. Femur and trochanter fused (Fig. 12 ); hind femur and trochanter 4.52-5.61 × widest width of this segment; 2.41-2.74 × antennal segment III. Distal 1/3 of tibiae slightly expanded, with spinulose transverse stripes (Fig. 16 ); hind tibia 0.21-0.25 × body. Setae on legs fine and pointed, length of setae on hind tibiae 0.43-0.73 × middle diameter of the segment. First tarsal segments spinulose, segment II with spinulose short stripes (Fig. 16 ). First tarsal chaetotaxy: 4, 4, 2 or 3.

Abdomen. Abdominal tergites with two or three pairs of spinal and one pair of marginal setae; tergite VII with one pair of spinal and one pair of marginal setae (Fig. 19 ); tergite VIII with one pair of spinal and two pairs of marginal setae (Fig. 21 ). Length of marginal setae on tergite I 0.50-0.63 × basal diameter of antennal segment III; dorsal setae on tergite VIII 0.56-0.75 × basal diameter of antennal segment III. Siphunculi almost poriform (Figs 8 , 18 , 20 ), on tergite VI surrounded by three hair-like setae; 0.23-0.32 × its basal width, 0.42-0.60 × cauda. Cauda knob-shaped (Figs 9 , 21-22 ), with spinulose short stripes; 0.27-0.38 × its basal width, with six to eight long and short, finely pointed setae. Anal plate transversely oval (Figs 10 , 21-22 ), indistinctly bilobed, with spinulose short stripes. Genital plate (Figs 11 , 22 ) transverse oval, with sparse spinulose transverse lines; with two anterior setae and seven or eight posterior setae. Two gonapophyses, each with five shorter and pointed gonosetae.

First instar nymph: Body oval, pale when macerated. Head and pronotum fused (Fig. 23 ). Vertex arc-shaped, head dorsum smooth, with distinct median suture (Fig. 24 ). Dorsal setae on head short and pointed, head with one pair of cephalic setae, two pairs of setae between antennae, three pairs of marginal setae and one pair of anterior spinal setae between eyes; length of cephalic setae 0.83 × basal diameter of segment III. Eye 3-faceted. Antennae 5-segmented (Fig. 25 ), segments I-IV smooth, segment V with spinulose imbrications; antennal setae slightly long and pointed, segments I-V each with 2, 2, 0, 2-3, 2+5 setae, respectively; length of setae on segment IV 1.0 × basal diameter of antennal segment III; segment III 0.032 mm, respective length in proportion of segments I-V as follows: 100, 100, 100, 77, 154+77; processus terminalis 0.50 × base of the segment. Primary rhinaria round and ciliated. Rostrum reaching abdominal segment IV; ultimate rostral segment elongate wedge-shaped (Fig. 26 ), 2.82 × its basal width, 1.35 × hind second tarsal segment; with one pair of accessory setae and two pairs of primary setae. Dorsal setae of thorax and abdomen spine-like, similar to adults. Thorax dorsum each with one pair of spinal and one pair of marginal wax plates, respectively. Pronotum with one pair of spinal and one pair of marginal setae, mesonotum and metanotum each with one pair of spinal, one pair of pleural and two pairs of marginal setae. Trochanter fused with femur. Distal half of tibiae and tarsi with spinulose stripes, the other half of tibiae smooth (Fig. 27 ). First tarsal chaetotaxy: 2, 2, 2. Abdominal tergites I-VII each with one pair of spinal and one pair of marginal wax plates (Fig. 28 ); tergite VIII covered with wax plate (Fig. 28 ). Abdominal tergites I-VII each with one pair of spinal and one pair of marginal setae (Fig. 28 ); tergite VIII with two dorsal setae (Fig. 28 ); length of marginal setae on tergite I and dorsal setae on tergite VIII 0.83 × and 0.33 × basal width of antennal segment III, respectively. Siphunculi invisible. Cauda circular at apex, with two setae (Fig. 28 ). Anal plate broadly circular, with four setae (Fig. 23 ). Cauda and anal plate with spinules.

Embryo (in an aptera): Eye 3-faceted. Antenna 5-segmented, segments I-IV smooth, segment V with spinulose imbrications. Frontal setae hair-like, the remainder of dorsal body setae stout, acute, almost spine-like. Vertex on each side with three anterior and two posterior setae. Pronotum with three pairs of marginal and one pair of spinal setae, anterior spinal setae missing. Meso- and metanotum each with two pairs of marginal, one pair of spinal, and one pair of pleural setae. Abdominal tergites I-VII each with one pair of spinal and one pair of marginal setae; tergite VIII with one pair of dorsal setae. Siphunculi hardly visible. Antennal segments I-IV with 2, 2, 0, 2 or 3 and 2+4 setae, respectively.

Host plant.

Pilea martinii (H. Lev.) Hand-Mazz. ( Urticaceae ).

Biology.

The specimens were found within an irregularly spherical gall on the leaves. Compared to the other two species in Neothelaxes , which are not known to form galls, the biology of this new species is unusual, interesting, but less well known.

Comments.

According to some morphological features-3-faceted eye in apterae; fused head and thorax; 5-segmented antenna; processus terminalis shorter than base of the segment; antennal segment V, tarsi, and apices of tibiae spiculose; siphunculi poriform and surrounded by setae; cauda knob-shaped-the new species is regarded as belonging to the subfamily Thelaxinae . This new species is similar to those of Neothelaxes based on dorsum of body with waxy plates, dorsal body setae short and spine-like, and primary rhinaria ciliated. However, it differs from the type species of the genus, N. viticola , as follows: first tarsal segment chaetotaxy: 4, 4, 2 or 3 (in N. viticola first tarsal segments with 5-5-7 setae); dorsum of body pale brown, without distinct sclerites (in N. viticola vertex and spinal, marginal, and pleural sclerites of body dorsum distinct); antennae at most 1/3 of body length (in N. viticola 1/2 of body length); antennae of embryo 5-segmented (in N. viticola 4-segmented); infesting plants of Pilea ( Urticaceae ) ( N. viticola infests the genus Parthenocissus ( Vitaceae )).

Of the four known genera of Thelaxinae (sensu Remaudière and Stroyan 1984), Thelaxes , Glyphina , and Kurisakia are associated with woody trees ( Fagaceae , Betulaceae , Juglandaceae ), wheras Neothelaxes is known only from climbing woody rattan ( Vitaceae : Parthenocissus ) (Chakrabarti & Quednau, 1996). No species of Thelaxinae was previously known to live in galls. The new species is associated with an herbaceous plant and was found in leaf galls. These traits are very different from those of other species of Thelaxinae . The association with the galls is unusual and needs further confirmation from a full colony of aphids in a gall.

In view of the present findings on its host association and gall inducing nature as well as several other characters, the new species is placed in the genus Neothelexes . Further surveying and research on its biology, for example the rearing of additional adults (especially alatae) from additional galls, will be necessary to elucidate the appropriate taxonomic placement of the new species.

Figures

Figures 1 - 11. Neothelaxes pileata Qiao sp. nov. Apterous viviparous female: 1 dorsal view of head 2 antennal segments I-V 3 ultimate rostral segment 4 cephalic seta 5 mesosternal furca 6 marginal seta on abdominal tergite I 7 spinal seta on abdominal tergite VIII 8 siphunculi 9 cauda 10 anal plate 11 genital plate. Scale bars: 0.05 mm.

Figures 12 - 22. Neothelaxes pileata Qiao sp. nov. Apterous viviparous female: 12 dorsal view of body 13 antenna 14 ultimate rostral segment 15 dorsal view of head, with antennal segments I-II and dorsal setae 16 distal part of hind tibia and hind tarsal segment 17 marginal setae and marginal waxy plates on abdominal tergites II-V 18 siphunculus and marginal setae and marginal waxy plate on abdominal tergite V 19 spinal setae and waxy plates on abdominal tergite VII 20 siphunculus and dorsal view of abdominal tergites VI-VIII 21 dorsal setae on abdominal tergite VIII, cauda, and anal plate 22 cauda, anal plate and genital plate. Scale bars: 0.10 mm (12, 17); 0.05 mm (13 - 16, 19 - 21); 0.02 mm (18, 22).

Figures 23 - 28. Neothelaxes pileata Qiao sp. nov. First instar nymph: 23 dorsal view of body 24 dorsal view of head, with antennal segments I-II and dorsal setae 25 antenna 26 ultimate rostral segment 27 hind tibia and hind tarsal segment 28 dorsal setae and waxy plates on abdominal tergites V-VIII, showing cauda. Scale bars: 0.10 mm.