Research Article |
Corresponding author: Wanzhi Cai ( caiwz@cau.edu.cn ) Academic editor: James Zahniser
© 2017 Xinyu Luo, Wanzhi Cai, Gexia Qiao.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Luo X, Cai W, Qiao G (2017) Half-jumping plant lice – a taxonomic revision of the distinctive psyllid genus Togepsylla Kuwayama with a reassessment of morphology (Hemiptera, Psylloidea). ZooKeys 716: 63-93. https://doi.org/10.3897/zookeys.716.13916
|
Togepsyllinae is a distinctive group within Psylloidea, with its systematic status treated variously by different authors. Of the only two known genera, Togepsylla is better known and distributed in temperate and tropical East Asia. In this study, the taxonomy and morphology of Togepsylla was studied in detail. Keys to adults and fifth instar immatures of the genus are provided. Togepsylla glutinosae sp. n. is described, and T. matsumurana, T. takahashii, and T. tibetana are redescribed. Syncoptozus is compared with Togepsylla for differences in morphology. Modern psyllids have evolved their jumping hind legs via the elongation of the dorsal edge of coxa, the broadening of coxal wall, the thickening of meron, the backward twisting of the plane of trochanter, femur, and tibia, and the enlargement of trochanteral tendon. However, in Togepsylla, this modification has progressed halfway. The metapleuron of Togepsylla is arranged in a different way than other psyllids. The pleural sulcus is short, and the metepisternum and trochantin are not divided. Wax-secreting fields on abdominal sternites, resembling those of whiteflies, are found on all Togepsylla species, and described for the first time. Other distinctive characters of the genus are also revealed, e.g. frons completely fused with gena, a pair of extra sclerites present behind the base of thoracic furca, one-segmented aedeagus, and absence of a flag lobe on valvula dorsalis of ovipositor. Based on various similarities in morphology, Togepsyllinae may have a close relationship with Aphalaridae-Rhinocolinae and is possibly related to Homotomidae, Liviidae-Liviinae and Atmetocranium (Calophyidae). All the distinctive characters of Togepsyllinae suggest that the current placement of the group is doubtful, and the phylogeny of Aphalaridae needs to be resolved.
Aphalaridae , morphological characters, Oriental region, Togepsyllinae
Psylloidea, the superfamily of jumping plant lice, is a group of phloem-sucking insects with strict host specificity. Among all its subordinate taxa, the Oriental and Palaearctic genus Togepsylla is undoubtedly one of the most distinctive. Named after the symmetrical and articulated thick ‘spines’ on the dorsum of head and thorax, it is readily diagnosed by these spine-like setae and wings held flat over its dorsum instead of roof-wise, in addition to the more intrinsic characters identified in this article. The genus contains only three known species to date: Togepsylla matsumurana Kuwayama, 1949, T. takahashii Kuwayama, 1931 (type species), and T. tibetana (Yang & Li, 1981). The few known species develop exclusively on Lauraceae plants, often inducing pit galls or leaf-rolling galls (
Togepsyllini was established by
Based on a synthesis of fossil studies, the defining character of Psylloideasensu stricto is the mutual modification of the metacoxa and furca of the metathorax (
A new species, Togepsylla glutinosae sp. n., has been collected on Litsea glutinosa from tropical China recently. During the taxonomic work on Chinese Aphalaridae, many previously overlooked characters of Togepsylla were revealed, including the half-modified metacoxae which do not provide sufficient jumping force, and wax secreting fields on abdominal sternites first found on a psyllid. Based on an integration of East Asian collections, this study aims to revise the taxonomy of the genus Togepsylla, and reassess the distinctive morphological characters of it.
This study is based on the collections of the Entomological Museum of China Agricultural University (
Slides were prepared following this protocol: whole insect soaked in boiling potassium hydroxide (KOH) solution for 10 minutes, naturally cooled down after heating stopped, washed in distilled water, and finally mounted on a slide in glycerine. All drawings and examinations were undertaken with an Olympus BX41 microscope. One dry-mounted adult of each Togepsylla species was coated with gold using a Leica EM SCD050 Super Cool Sputter Coater and prepared for Scanning Electron Microscope (SEM) examination and photography, using an FEI® Quanta 450 Environmental Scanning Electron Microscope.
Measurements were taken with a Keyence VHX-1000 digital microscope using the measuring function and are given in millimeters (mm). For adults:
HW head width,
AL antennal length,
SL length of the posterior pair of prickly setae on the median of the vertex,
TW mesoscutum width,
WL fore wing length,
TL metatibial length.
For fifth instar immatures:
BL total body length,
AL antennal length,
HW head width,
FL fore wing pad length, measured as the distance between the transverse tangents of the anterior angle and posterior margin.
Total body length of adults was not determined because most dry-mounted specimens examined were in distinct positions and therefore incomparable.
Comparisons of morphological characters were based on direct observations of specimens, drawings, SEM photos, measurements, and sometimes on the literature. Putatively homologous characters were compared across the concerned taxa. Diagnostic characters are described for each species, with emphasis on the differences. Characters potentially useful for systematic studies are noted and are referred to in the discussion.
Terminology primarily follows
Scientific names of plants follow the
Togepsylla Kuwayama, 1931: 121. Type species: Togepsylla takahashii Kuwayama, 1931, by original designation.
Togepsylla
Kuwayama:
Hemipteripsylla
Yang & Li, 1981: 182. Type species: Hemipteripsylla tibetana Yang & Li, 1981, by original designation. Synonymized by
Body relatively flat. Vertex, thoracic dorsum and most of fore wing veins with symmetrical long and thick setae, which possess tiny spinules on the surface (Fig.
Adult. Body flat, with abdomen significantly wider than tall. Body dorsum with symmetrical prickly setae on the surface, situated on bulges or projections, distribution as: 4+4 on vertex, 4+4 on pronotum, 1+1 on mesopraescutum, 4+4 (Fig.
Head slightly inclined from longitudinal body axis. Vertex lacking median suture; two tubercles present along the median line, each bearing a pair of prickly setae. Base of lateral ocelli moderately bulging, each bearing two prickly setae. Vertex consistent with gena. Plane of torulus about perpendicular to that of the vertex. Frons completely fused with vertex and gena, only moderately raised from the surface. Gena not divided into two lateral parts, but firmly compact as one, with roughly symmetrical simple setae (Fig.
Preepimeron significantly wider than preepisternum. Notopleural sulcus of prothorax well developed. Mesopraescutum near semicircular, not protruding forward to force pronotum to arch. Pleural sulcus of mesothorax reduced, with pleural apophysis relatively small; posterior margin of mesopleurite directed forward. Mesepisternum rather narrow and bulging (Fig.
Legs long and slender. The three sensory pores on femora ventrum arranged in a row. Plane of hind legs almost parallel with that of middle legs. Metacoxa with rather large tubercle above apical opening, and lacking meracanthus (Fig.
Fore wing narrowest in the base and gradually becoming much wider apically, usually widest at subapex or apical 1/4. Costal break present. Pterostigma absent. Vein Rs reaching anterior margin instead of apical margin. Cell cu1 rather long and flat. Veins A1 and A2 touching in the middle. Anal break adjacent to the apex of vein Cu1b.
Hind wing with partially thickened anterior margin. Veins A1 and A2 combined or one is lost (probably A1), leaving a thickened vein A; cell a1 lost (Fig.
Tergite of abdominal segment 1 better developed, with a median sclerite present (Fig.
Male terminalia: In natural status, proctiger, aedeagus and parameres all oriented caudally instead of upwards. Posterior aspect of proctiger enveloped. Aedeagus uni-segmented and simple, sometimes with tiny spines on dorsum. Sperm pump with only basal end plate, lacking apical end plate (Fig.
Female terminalia: Subgenital plate placed much more proximal than proctiger and simple, lacking tip sometimes. Proctiger lacking rows of long setae on the dorsum. Valvula dorsalis of ovipositor without flag lobe. Median valve slender and placed more terminal, apex touching the subapex of ovipositor.
Fifth instar immature. Body dorsum with symmetrical sectasetae. Antennal 7- or 9-segmented, with three rhinaria. Compound eyes with 1+1 or 2+2 ocular setae. Postocular setae present in 2+2 or more. Fore wing pads simple, without humeral lobe. Legs long and slender, lacking specialized seta. Both tarsal segments differentiated. Tarsal claws with pulvilli and without arolium. Apical setae of tarsus both long and capitate. Abdominal sclerites firm, not broken in the middle. Abdominal apex with a pair of bulges. Circum anal pore field lacking additional rings.
1 | Mesoscutum with 5+5 prickly setae (Fig. |
2 |
– | Mesoscutum with 4+4 prickly setae (Fig. |
3 |
2 | Fore wing colorless, with one prickly seta on the base of vein M3+4 (Fig. |
Togepsylla tibetana (Yang & Li) |
– | Fore wing with black sections on veins, without prickly setae on vein M3+4 (Fig. |
Togepsylla matsumurana Kuwayama |
3 | Fore wing with yellow bands, with rather long prickly setae on veins but M3+4 (Fig. |
Togepsylla takahashii Kuwayama |
– | Fore wing without color patterns, with relatively short prickly setae on veins including M3+4 (Fig. |
Togepsylla glutinosae sp. n. |
1 | Body dorsum with acute-tipped sectasetae (Figs |
Togepsylla takahashii Kuwayama |
– | Body dorsum with truncate sectasetae. Circum anal ring simple, both outer and inner rings composed of single row of pores. | 2 |
2 | Outer margin of head and fore wing pad with closely packed sectasetae (Fig. |
Togepsylla matsumurana Kuwayama |
– | Outer margin of head and fore wing pad with fewer and scattered sectasetae (Figs |
Togepsylla glutinosae sp. n. |
Vein M3+4 of fore wing with 3 prickly setae (Fig.
Adult coloration. Ground color yellow. Long and thick setae on dorsum black. Compound eyes grey. Ocelli yellow. Antennae yellow, with black apices on segments IV, VI, VIII; segments IX-X entirely black. Pronotum, meso- and metascutum each with one pair of orange markings. Legs yellow. Fore wing hyaline and colorless (Fig.
Structures: Setae on dorsum of body relatively long (Table
Adults | HW | AL | SL | TW | WL | TL | |||
Togepsylla glutinosae | 4♂♂ | 0.34–0.36 | 0.36–0.47 | 0.65–0.92 | 0.32–0.35 | 1.00–1.08 | 0.40–0.45 | ||
2♀♀ | 0.36–0.38 | 0.40–0.48 | 1.04–1.06 | 0.38–0.39 | 1.23–1.24 | 0.46–0.48 | |||
Togepsylla matsumurana | 4♂♂ | 0.42–0.44 | 0.71–0.76 | 0.80–0.88 | 0.49–0.50 | 1.84–1.92 | 0.70–0.72 | ||
4♀♀ | 0.44–0.46 | 0.65–0.73 | 0.83–0.95 | 0.52–0.56 | 2.10–2.23 | 0.59–0.67 | |||
Togepsylla takahashii | 4♂♂ | 0.36–0.38 | 0.87–0.92 | 1.37–1.54 | 0.36–0.38 | 1.38–1.41 | 0.56–0.59 | ||
3♀♀ | 0.39–0.41 | 0.92–0.96 | 1.47–1.58 | 0.42–0.44 | 1.53–1.62 | 0.67–0.69 | |||
Togepsylla tibetana | 4♂♂ | 0.42–0.43 | 0.77–0.80 | 0.74–0.81 | 0.40–0.48 | 1.80–2.01 | 0.64–0.72 | ||
4♀♀ | 0.42–0.44 | 0.71–0.85 | 0.83–0.88 | 0.45–0.48 | 1.98–2.20 | 0.60–0.64 | |||
Fifth instar immatures | BL | AL | HW | FL | |||||
Togepsylla glutinosae | n = 5 | 0.89–0.99 | 0.34–0.38 | 0.29–0.33 | 0.30–0.35 | ||||
Togepsylla matsumurana | n = 2 | 1.14–1.30 | 0.38–0.47 | 0.35–0.42 | 0.42–0.51 | ||||
Togepsylla takahashii | n = 5 | 1.32–1.46 | 0.56–0.61 | 0.40–0.41 | 0.46–0.52 |
Mesoscutum with four pairs of prickly setae. Metatibia with three short rows of thick setae, lacking a tightly packed row of short setae on the dorsum (Fig.
Pore fields on abdominal ventrum small oval; pores loosely packed (Fig.
Male terminalia: Proctiger slightly curved backwards (Fig.
Female terminalia (Fig.
Fifth instar immature. Body dorsum strongly sclerotized, ventrum weakly sclerotized. Dorsum of head, thorax and abdomen with symmetrical truncate sectasetae varying in size, mixed with a few simple setae (Fig.
Holotype: ♂, CHINA: Hainan, Danzhou, Nada, 131 m, 19°30.878'N, 109°31.085'E, ex Litsea glutinosa, 12.iv.2016, Xinyu Luo (
Litsea glutinosa (Lour.) C. B. Rob. (Lauraceae)
China: Hainan.
Named after the scientific name of the host plant.
Based on a brief observation in the field, this species was found free living, both immatures and adults are sparsely scattered across the abaxial surface of leaves (no preference for young leaves or shoots is displayed). The immatures do not induce any form of gall or leaf rolling, and from the sectasetae on body margin they produce wax threads of varying lengths, of which the ones from the terminal bulges of abdomen are longest (Fig.
Togepsylla
matsumurana
Kuwayama, 1949: 48;
Togepsylla
matsumurai
Kuwayama:
Hemipteripsylla
matsumurana
(Kuwayama):
Togepsylla
zheana
Yang, 1995: 109. Synonymized by
Dorsum of head and thorax brown with large areas of brown patterns. Antennal segments VI and VIII each with two additional rhinaria (Fig.
Adult coloration. Head yellow, vertex with brown patterns. Long and thick setae on dorsum black. Compound eyes light brown. Ocelli yellow. Antennae yellow, segments I-II light brown, apices of segments III, IV, VI, VIII black, segments IX-X entirely black. Thoracic dorsum brown, except for bases of setae which are yellow. Thoracic pleurites light brown. Legs yellow, with apical half of femora light brown, apex of tibiae brown. Fore wing membrane hyaline and colorless; R1, apices of Rs and M1+2 black (Fig.
Structures: Setae on dorsum of body relatively short (Table
Mesoscutum with 5 pairs of prickly setae (Fig.
Pore fields on abdominal ventrum large oval, with pores loosely packed (Fig.
Male terminalia: Proctiger slightly curved backwards apically (Fig.
Female terminalia (Fig.
Fifth instar immature. Body dorsum firmly sclerotized, with sclerites of thorax and abdomen almost unseparated; body ventrum weakly sclerotized (Fig.
Male terminalia of Togepsylla spp. 19–21 Togepsylla glutinosae sp. n. 22–24 Togepsylla matsumurana 25, 26 Togepsylla takahashii 27, 28 Togepsylla tibetana 19, 22, 25, 27 Male terminalia, in profile 20, 23, 26, 28 Paramere, inner surface 21 Paramere, posterior view 24. Apical half of aedeagus. Scale bar: 0.2 mm.
Fifth instar immature of Togepsylla spp. 33–37 Togepsylla glutinosae sp. n. 38–42 Togepsylla takahashii 33, 38 Half of head, dorsal view 34, 39 Antenna, dorsal view 35, 40 Wing pads, dorsal view 36 Claws, showing pulvilli and apical setae of tarsus 37 Circum anal ring, ventral view 41 Claws, showing pulvilli 42 Circum anal ring, dorsal view on the left half, ventral view on the right half. Scale bar: 0.2 mm (33–35, 37, 38–40, 42), 0.05 mm (36, 41).
CHINA: 2 ♀, Zhejiang, Qingyuan, Baishanzu, 1300-1500 m, ex Litsea cubeba, 24.ix.1993, Hong Wu (
Litsea cubeba (Lour.) Pers. (
China: Guangxi, Taiwan, Yunnan, Zhejiang (
Togepsylla
takahashii
Kuwayama, 1931: 121;
Togepsylla
minana
Yang & Li, 1981: 179. Synonymized by
Fore wing with yellow bands (Fig.
Ground color yellow. Compound eyes grey. Long and thick setae on dorsum black. Ocelli yellow. Antennae yellow, with black spices on segments III-VIII; segments IX-X entirely black. Fore wing hyaline, with four obliquely transverse yellow stripes (Fig.
Structures: Setae on dorsum of body relatively long (Table
Mesoscutum with four pairs of prickly setae (Fig.
Pore fields on abdominal ventrum long, narrow and curved; pores tightly packed (Fig.
Male terminalia: Distal 1/3 of proctiger with posterior surface split and replaced with membranous tissue (Fig.
Female terminalia (Fig.
Fifth instar immature. Body dorsum firmly sclerotized, with sclerites of thorax and abdomen almost unseparated; body ventrum weakly sclerotized. Dorsum of head, thorax, and abdomen with symmetrical acute sectasetae varying in size (Fig.
Comparison of coxa of different psyllid taxa. 54, 55 Cacopsylla sp. 56 Togepsylla takahashii 54 Mesocoxa and trochanter 55 Metacoxa and trochanter; 56. Metacoxa. Scale bar: 0.2 mm. Abbrevations: atc = anterior trochanteral condyle; de = dorsal edge; mr = meron; mrc = meracanthus; ptc = posterior trochanteral condyle; tct = trochanter; td = trochanteral tendon.
CHINA: 18 ♂, 21 ♀, 10 fifth instar immatures, Fujian, Shaxian, ex Lindera communis, 1.ix.1974, Chikun Yang and Fasheng Li (
Lindera communis Hemsl., L. megaphylla Hemsl. (= L. oldhamii) (Lauraceae) (
China: Fujian, Guangxi, Taiwan.
Biology:
Hemipteripsylla
tibetana
Yang & Li, 1981: 182;
Togepsylla
tibetana
(Yang & Li):
Paramere with large area of netlike grains covering the inner surface of apical half, anterior margin serrated (Figs
Adult coloration. Ground color yellow. Long and thick setae on dorsum yellow. Compound eyes grey. Ocelli yellow. Antennae yellow, with black spices on segments IV, VI, VIII; segments IX-X entirely black. Fore wing hyaline and colorless (Fig.
Structures: Setae on dorsum of body relatively short (Table
Mesoscutum with five pairs of prickly setae. Metatibia with one row of thick setae ventrally, and with a tightly packed row of long setae on the dorsum. Pulvilli narrow. Fore wing with broad cell r1, cell cu1 tallest in the middle; vein M3+4 with one seta on the base; surface spinules rather minute, widely spread across a large area in distal cells; fields of radular spinules unclear (Fig.
Pore fields on abdominal ventrum large oval, with pores loosely packed.
Male terminalia: Proctiger completely sealed, with apex slightly thickened (Fig.
Female terminalia (Fig.
Lateral aspect of thorax. 57 Togepsylla takahashii 58 Cacopsylla sp. Scale bar: 0.2 mm (57), 0.5 mm (58). Abbrevations: aac = anterior axillary cord; abas = anterior basalare sclerite; acl = anapleural cleft; adk = anepimeral disk; aepm = anepimeron; aeps = anepisternum; apwp = anterior pleural wing process; cx = coxa; cxc = coxal condyle; epm = epimeron; eps = episternum; hepm = heel of epimeron; kepm = katepimeron; keps = katepisternum; nt = notum; pa = pleural apophysis; pac = posterior axillary cord; pbas = posterior basalare sclerite; pcb = precoxal bridge; pbr = prealar bridge; pls = pleural suture; pnt = postnotum; ppt = parapteron; ppwp = posterior pleural wing process; psc = praescutum; sc = scutum; scl = scutellum; tems = transepimeral suture; tg = tegula; trn = trochantin.
Fifth instar immature. Unknown.
CHINA: 49 ♂, 69 ♀, Tibet, Nyingchi, Mafenggou, 3050 m, ex Litsea sericea, 1.vi.1978, Fasheng Li (
Litsea sericea (Nees.) Hook. f. (Lauraceae)
China: Tibet.
The similarities and differences of the two genera have been listed by
Hind legs
Psyllids jump powerfully, then cast a mid-air rotation. Such a somersault, however, involves not only the strong muscles supported by the specialized metathoracic furca, enlarged metatrochanteral tendon and expanded meral part of the metacoxa but also a kicking of both hind legs on parallel planes (
To discuss the formation of the enlarged and twisted metacoxa, one must seek reference from the mesocoxa. Mid and hind legs are both appendages of winged thoracic segments; additionally, in immature psyllids, they are equal in every detail, although differing from the forelegs in some aspects, indicating that hind legs of adults emerged from the model of mid legs. An undescribed Cacopsylla species is used as example:
The mesocoxa (Fig.
Compared with mesocoxa, the metacoxa (Fig.
By contrast, Togepsylla possesses half-modified metacoxae (Fig.
Lateral aspect of thorax
Most psyllids possess an apophysis on meso- and metepisternal complex, termed ‘trochantinal apodeme’ (
According to
Wax-secreting fields on abdominal sternites
Togepsylla possesses three pairs of fields of pores on sternites of abdominal segments 4–6, in both sexes. Wax secretions from these pores have been observed on T. matsumurana (Fig.
All the four members of Sternorrhyncha are known to secrete wax through integumental wax gland/pores. In scale insects whose wax glands are studied the most, these structures are highly variable in ultrastructure (shape and number of loculars of each pore) and distribution (all over the body or restricted to a certain region) (
Psyllid immatures possess wax-secreting pores on their caudal plates. These pores are arranged in various patterns, mostly with a basic circum-anal ring (possibly homologous with the circum-anal ring of female adults), and on many occasions with extra pore fields (Brown and Hodlinson 1985). Extra pore fields can sometimes be succeeded by the adults, appearing on their more terminal (usually segments 7 and/or 8) abdominal tergites, e.g. Agonoscena pegani Loginova, 1960 and A. sabulisa Li, 1994 (in
This is the first time that a psyllid adult is found with such fields of wax-secreting pores. Compared with those of whiteflies, wax pore fields of Togepsylla are strongly constricted, and the segment correspondence is different. It is uncertain whether these structures of Togepsylla and Aleyrodoidea are homologous or not.
Togepsyllinae displays great differences with all the other psyllid taxa in external morphology. These include: frons completely fused with gena; gena firmly compact instead of being bisected; ‘conical sensoria’ absent from apex of labium; metapleuron distinctively arranged; metacoxa ventral aspect of metathorax as a compact sclerite; wax plates present on sternites of abdominal segments 4–6; male terminalia oriented caudally; male proctiger completely enveloped, instead of having a basal major part, which is sclerotized anteriorly and laterally, whereas membranous posteriorly, with a median suture; aedeagus one-segmented; sperm pump with only basal end plate, lacking the apical end plate; median valve of female terminalia simple, slender and placed more terminal, apex touching the subapex of ovipositor; fifth instar immatures without tarsal arolium, instead with pulvilli on claws. These traits make the current systematic position of Togepsyllinae doubtful.
Alternatively, Togepsyllinae share many similar characters with fossil pan-psyllids [extinct taxa included in Psyllomorpha by
Comparison of characters among whiteflies, fossil pan-psyllids, Togepsyllinae, and other psyllids sensu stricto.
Aleyrodoidea | Protopsyllidae | Liadopsyllidae | Togepsyllinae | Other Psylloideasensu stricto | |
---|---|---|---|---|---|
Median suture of vertex | Absent | Absent | Absent | Absent (Togepsylla) or present in the anterior half of vertex (Syncoptozus) | Present (with a few exceptions such as Pseudophacopteron and Atmetocranium) |
Frons | Completely fused with gena | Completely fused with gena | Independent from gena | Completely fused with gena | Independent from gena |
Clypeus | Fused with gena | Fused with gena | Attached to gena by a pair of sclerites | Attached to gena by a pair of sclerites | Attached to gena by a pair of sclerites |
Labium | Long, originated before prosternum | Long, originated before ventrum of prothorax | Long, originated between procoxae | Shortened (two-segmented), originated between procoxae | Shortened (pseudo-three-segmented), originated between procoxae |
Extra sclerites posterior to base of thoracic furca | Present | - | - | Present | Usually absent, but present in Rhinocolinae |
Modification of metapleurite | - | - | - | Incomplete | Complete |
Modification of metacoxa | Slight enlargement | Slight enlargement | Slight enlargement | Significant enlargement, slight backwards twist | Significant enlargement, backwards-twisted at 90° |
Enlargement of trochanteral tendon | None | - | - | Slight | Significant |
Reduction of tergite of abdominal segment 1 | Tergite complete | - | - | Consistent in the middle | Reduced to two separate small lateral sclerites |
Wax plates | Present | - | - | Present | Absent |
Aedeagus | One-segmented | One-segmented | - | One-segmented | Double-segmented |
Male proctiger | Fused with subgenital plate | Fused with subgenital plate | - | Posterior aspect completely sclerotized and finely enveloped | Posterior aspect membranized |
Valvulae dorsales of ovipositor | Without flag lobe | - | - | Without flag lobe | With flag lobe (except for Apsylla) |
Ocular setae of last instar immature | Absent | - | - | Present | Present or absent |
Tarsal arolium of last instar immature | Absent | - | - | Absent | Present |
In the schematic phylogenetic tree (
In addition to the obvious synapomorphies of Aphalarinae members, i.e., mesothoracic trochantinal apodeme present on the anterior margin of the pleurite and metatibia with an open crown of apical spurs, Togepsyllinae and Rhinocolinae share other characters. They both have: a short clypeus; a pair of extra sclerites posterior to the base of thoracic furca; meracanthus absent or rather small; and the tubercle above the apical opening of metacoxa prominent. Most notable is the extra pair of sclerites posterior to the base of thoracic furcae. These shared characters may suggest a relatively close relationship between Togepsyllinae and Aphalaridae-Rhinocolinae.
Another species, Atmetocranium myersi (Ferris and Klyver) (Calophyidae: Atmetocraniinae), the sole member of the genus, is somewhat in resemblance with Togepsyllinae. Referring to a dry-mounted specimen and to the original description (
Phylogeny of Togepsyllinae seems unsolvable in the current situation, given the clear fact that there are only two known genera which are distinct from each other in many traits, indicating the possible existence of further extinct members of the group. On a greater scale, the current definition of Aphalaridae needs a phylogeny-based revision, to resolve its internal relationships and to test if Togepsyllinae is an independent taxon.
Thanks are due to Dr. Yorio Miyatake of Osaka Museum of Natural History, Japan and Dr. Hiromitsu Inoue of Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization, Japan, for their kind loans of specimens of Togepsylla matsumurana, and the information of collections of this species in Japan; to Dr. David Ouvrard of Natural History Museum, UK, for his loan of psyllid specimens from London; to Prof. Yunzhi Yao of Capital Normal University, China, for his sharing of knowledge and literatures on fossils of pan-psyllids. SEM examination and photographing was supported by Dr. Kuiyan Zhang of Institute of Zoology, China Academy of Science. This manuscript has been linguistically reviewed by American Journal Experts. This research was supported by National Natural Sciences Foundation of China (No. 31561163002) and grants from the Ministry of Science and Technology of the People’s Republic of China (Nos. 2013FY111200, 2014FY210200, 2014FY110100).