Phylogenetic Analysis of the Genus Planaphrodes Hamilton (Hemiptera, Cicadellidae, Aphrodinae) Based on Morphological Characteristics, with Revision of Species from China, Korea and Japan

Simple Summary Planaphrodes is a genus of Aprhodinae distributed in the Palaearctic region from Portugal to Japan. This paper reconstructs phylogenetic relationships among species of Planaphrodes based on morphological characteristics for the first time, elucidates the phylogenetic status of the genus and describes two new species found in China. Abstract A morphology-based phylogeny of the Holarctic leafhopper genus Planaphrodes Hamilton is reconstructed for the first time based on 39 discrete male adult morphological characters. The results support the monophyly of Planaphrodes, with the included species forming two monophyletic lineages defined mainly by the number and location of aedeagus processes. The position of Planaphrodes in the Aphrodini was resolved as follows: (Stroggylocephalus + (Anoscopus + (Planaphrodes + Aphrodes))). The fauna of Planaphrodes from China, Japan and Korea are reviewed and six species are recognized, including two new species: P. bifasciatus (Linnaeus), P. sahlbergii (Signoret), P. nigricans (Matsumura), P. laevus (Rey), P. baoxingensis sp. nov. (China: Sichuan) and P. faciems sp. nov. (China: Hubei). Acocephalus alboguttatus Kato, 1933 syn. nov. and Aphrodes daiwenicus Kuoh, 1981 syn. nov. are considered junior synonyms of Planaphrodes sahlbergii (Signoret, 1879). Planaphrodes bella Choe, 1981 is a junior synonym of Planaphrodes nigricans (Matsumura, 1912). A checklist and key to species of Planaphrodes are provided.


Introduction
Aphrodini (subfamily Aphrodinae) is a small group of leafhoppers comprising four genera and fifty-eight species in the world, distributed primarily in the Palaearctic realm [1]. Leafhoppers of the tribe are common on herbaceous plants, usually in meadows and pastures, and some species live and feed on roots beneath the surface litter [2]. Some species also breed on leguminous crops, e.g., alfalfa [3,4]. Two species, Anoscopus albifrons (Linnaeus) and Aphrodes bicincta Schrank, are known vectors of phytoplasma plant pathogens [5,6]. Unfortunately, little is known about the ecology of most species of the group, partly due to their cryptic lifestyles, which make them seldom encountered in routine collecting [7]. Species of Aphrodini may be recognized by their dorsally flattened produced heads with ocelli on the anterior margin distant from the eyes and lateral frontal sutures extended ventromesad of the ocelli and by the basally narrow male subgenital plates and slender,

Phylogenetic Analysis
The data matrix was analyzed using TNT1.1 [37] initially using the traditional search method. The equal weighting analysis with 1000 replicates (trees to save = 10, random seed = 0) was used to produce the final phylogenetic estimate, and character changes were mapped using WinClada 1.0 [38]. The branch support was calculated by using TNT to search for suboptimal trees and calculating decay indices (Bremer support) as the difference in length between the original MP trees and the shortest trees incompatible with each resolved branch. Bootstrap replicates [39] were analyzed to assess node support with 1000 replicates and 50% was used as the cut off value. The illustrated cladograms were edited using Adobe illustrator CS 6.0. and Adobe Photoshop CS6.0.
Ancestral area probabilities were estimated in RASP v.4.0 [40] using the Bayesian binary MCMC (BBM) method and default parameter settings. The tree from Figure 1 inferred from the morphological matrix by TNT was used to infer the ancestral distribution of each clade. The following biogeographic regions were assigned to extant taxa based on known distributions: (A) Europe, (B) Middle East and Western Asia, (C) Central Asia (including western China), (D) Eastern Asia (including central and eastern China, Korea and Japan). Taxa that occur in multiple areas were assigned multiple states.

Phylogeny
Maximum parsimony analysis yielded four most parsimonious trees of length = 110, consistency index (CI) = 0.79 and retention index (RI) = 0.82. To simplify the presentation of results, only one of the MP trees is shown, with decay indices and boostrap support indicated for branches in Figure 1. Character state changes are indicated in Figure 2. All MP trees are consistent with the previous genus-level classification, with all genera of Aphrodini recovered as monophyletic based on the included species. Three branches with no support values indicated in Figure 1 collapsed in the strict consensus of all MP trees. Our analysis indicates that Aphrodes and Planaphrodes are sister groups (bb = 77, Br = 3), supported by the following synapomophies: crown and pronotum finely striate (char. 0: 1), crown flat, with distinct medial carina and two slightly rising keels behind the ocelli (char. 5: 1), forewings opaque and leathery (char. 6: 1), valve depressed and trapezoidal (char. 13: 2), styles crescent-shaped (char. 16: 0) and style apophysis obliquely truncate and broadened (char. 17: 4). The positions of Stroggylocephalus and Anoscopus relative to each other were not consistently resolved by our analysis. Broader analyses of this group including a larger taxon sample and more distantly related outgroups are needed to fully resolve the phylogenetic status of this tribe.  Planaphrodes received relatively strong branch support (bootsrap, bb = 83; Bremer, Br = 3) and is supported by the following synapomorphies: crown strongly produced (char. 2: 2), crown anterior margin with numerous small bright spots (char. 4: 1), aedeagal shaft significantly flattened laterally (char. 21: 1), aedeagal shaft partial widened in lateral view: (char. 23: 4,5,6), teardrop-shaped gonopore: (char. 37: 3) and gonopore situated at shaft proximal 1/3 (char. 38: 2). Among these synapomorphies, the flattened aedeagal shaft is unique to Planaphrodes species, which corroborates the monophyly of the genus. Relationships among Planaphrodes species are also stable and all but one species of the genus grouped into two sister clades.
Planaphrodes vallicola is sister to the remaining Planaphrodes (bb = 83; Br = 3). The other Planaphrodes species grouped into two clades. P. vallicola is unique in having the posterior pair of aedeagal processes situated more dorsally than in other species of the genus, in this respect more closely resembling species of Aphrodes. Nevertheless, P. vallicola shares the compressed aedeagal shaft present in other Planaphrodes, supporting its retention in this genus.
The clade comprising the rest of the species of Planaphrodes isunited by the presence of more than four processes on the aedeagal shaft (char. 25: 3) and the position of the gonopore near the base of the shaft (char. 38: 4). Planaphrodes received relatively strong branch support (bootsrap, bb = 83; Bremer, Br = 3) and is supported by the following synapomorphies: crown strongly produced (char. 2: 2), crown anterior margin with numerous small bright spots (char. 4: 1), aedeagal shaft significantly flattened laterally (char. 21: 1), aedeagal shaft partial widened in lateral view:(char. 23: 4,5,6), teardrop-shaped gonopore: (char. 37: 3) and gonopore situated at shaft proximal 1/3 (char. 38: 2). Among these synapomorphies, the flattened aedeagal shaft is unique to Planaphrodes species, which corroborates the monophyly of the genus. Relationships among Planaphrodes species are also stable and all but one species of the genus grouped into two sister clades.
Planaphrodes vallicola is sister to the remaining Planaphrodes (bb = 83; Br = 3). The other Planaphrodes species grouped into two clades. P. vallicola is unique in having the posterior pair of aedeagal processes situated more dorsally than in other species of the genus, in this respect more closely resembling species of Aphrodes. Nevertheless, P. vallicola shares the compressed aedeagal shaft present in other Planaphrodes, supporting its retention in this genus.
The clade comprising the rest of the species of Planaphrodesisunited by the presence of more than four processes on the aedeagal shaft (char. 25 Figure 1 showing character state changes. Numbers above the circles refer to characters and those below refer to character state. Filled and open circles represent synapomorphies and homoplasious character changes, respectively. Lateral and ventral views of aedeagus from relative specimen have also been provided. Clade 1 comprises six species. Planaphrodes bifasciatus is separated based on aedeagal shaft with apical denticles (char. 24: 1) and lateral processes and caudal processes almost at the same level (char: 33: 2). The sub-branch is supported by aedeagal shaft with more than four pairs of processes (char. 25: 4) and tiny tooth caudal processes (char. 31: 3). These species also have the aedeagal shaft distinctly broadened in lateral view. P. nigricans, P. baoxingensis and P. faciems are supported as a monophyletic group by the presence of tiny lateral processes (char. 29: 2) and lateral processes lower than caudal processes (char. 33: 3). The triangular dorsal processes (char. 34: 2) and ventral orientation of the dorsal aedeagal processes (char. 35: 0) are synapomorphic for the P. baoxingensis and P. faciems sister pair.
Biogeographic analysis from the BBM method based on the MP tree in Figure 3 suggests that widespread Palearctic ancestors gave rise to lineages of Planaphrodes with more restricted distributions. The ancestor of Clade 1 was inferred to have a wide distribution across Eurasia but gave rise to a lineage of three species restricted to East Asia (P. nigricans, P. baoxingensis and P. faciems). In contrast, Clade 2 was inferred to have arisen in Europe and six species of this clade are still largely restricted to Europe. However, a lineage comprising two species (P. elongatus and P. iranicus) expanded its range into Western Asia, even Central Aisa.
Aphrodini are similar to other Aphrodinae in the position of the ocelli and orientation of the lateral frontal sutures and structure of the male terminalia but differ in the relatively robust, depressed body form and elevated forewing veins ( Figure 11A).
Hamilton [7] provided a key to genera of Aphrodini, as presently defined, which he treated as a subtribe of Aphrodini. Hamilton's broad definition of Aphrodinae included most genera now included in Deltocephalinae [41], but Hamilton's tribal classification was not adopted by subsequent authors. Dietrich [27] restricted the definition of Aphrodinae to include only Aphrodini, Portanini and Xestocephalini based on front femur row AV with single stout seta near midlength and female with ovipositor distinctly arcuate and later [42,43] added Sagmatiini and Euacanthellini to this subfamily as well. Further analyses are needed to confirm the monophyly of the subfamily and its included tribes.
Diagnosis. Planaphrodes differs from other genera of Aphrodini as follows: crown strongly depressed and produced, horizontal in profile ( Figures 4A-G Body robust, rugulose or shagreen. Head produced, longer medially than pronotum. Crown strongly flattened between ocelli, slightly to distinctly depressed laterally, anterior margins slightly upcurved, angularly rounded or parabolic in dorsal view and carinate to foliaceous in lateral view (Figures 4A-G, 5A-D and 8A-H). Coronal suture not reaching anterior margin, lateral frontal sutures extended to anterior margin of crown. Eyes broadly, shallowly notched next to antennal pit. Ocelli on anterior margin, visible dorsally, distant from eyes (Figures 4A-G, 5A-D and 8A-H). Face with frontoclypeus to anteclypeus flat to slightly inflated, frontoclypeus longer than wide with lateral margins expanded dorsad; lateral frontal sutures directed toward middle of ocelli; anteclypeus elongate with lateral margins slightly expanded medially and tapered apically ( Figure 5I-O). Antennal ledges short, antennal pits moderately deep ( Figure 5I-O). Pronotum with anterior margin roundly produced and posterior margin shallowly concave, sides short; surface shagreen. Scutellum and exposed part of mesonotum triangular, wider than long, slightly longer than pronotum ( Figures 4A-G, 5A-D and 8A-H).
Female abdominal sternite VII broader than long, caudal margin concave medially ( Figure 10C). Female pygofer with scattered setae over most of surface ( Figure 10A,B). First valvulae, in lateral view, with dorsal margin nearly straight through most of length, somewhat narrowed near apex and tapered to apex, with dorsal preapical sculpture irregularly strigate, apical sculpture oblique, rugulose ( Figure 10H,I). Second valvulae, in lateral view, with distal toothed blades occupying approximately two-fifths of total length, dorsal margin slightly elevated at apex of fused area, followed by slight concavity and second slight elevation at based of toothed distal part, teeth small and somewhat irregularly spaced over dorsal margin of evenly tapered distal section ( Figure 10F,G). Third valvulae, in lateral view, with basal half narrow and apical half distinctly expanded, apex prominently rounded and extended slightly beyond pygofer, with sparse small setae ventrally ( Figure 10D,E).
Distribution. Palaearctic region from Portugal to Japan. Notes. We recognize the sixteen species, including two described as new, in the following checklist. Six species from China, Japan and Korea are described or re-described below based on comparative morphological study, and we propose three new synonymies. This study improves knowledge of the geographical distribution of the genus. As suggested by previous authors (e.g., Hamilton [7], Tishechkin [21]), the aedeagus is the most reliable character for distinguishing species. The key for the male genitalia of the Planaphrodes have been studied. Lateral processes of aedeagus situated higher than caudal processes ( Figure 14F)...     Male: crown dark brown, with several small yellow spots near anterior margin ( Figure 8A-H). Face brown, anteclypeus with rather indistinct dark mottling. Eyes grey. Pronotum dark brown with broad ivory white transverse band in posterior margin. Scutellum dark brown ( Figure 5N,O). Forewings pale brown, opaque, veins dark brown, with a large irregular whitish or yellowish transverse band and a whitish or yellowish cloudy patch situated in subapical and basal 1/3 region, respectively, apex yellowish; some whitish or yellowish coloration quite extended ( Figure 8A-H). Abdomen pale brown. Legs pale brown, with brown macrosetae ( Figure 8K). Female: yellowish brown, above and below more or less densely dark mottled ( Figure 8I,J).

Checklist of Species of Planaphrodes
Pygofer well sclerotized, taller than long, caudal margin slightly concave, with distinct posteroventral lobe covered with tiny setae and hook-like process arising at middle of caudal submargin directed medially with apical denticles (Figure 9A-C). Subgenital plates broad, curved, parallel-sided at basal half in ventral view, narrowed to rounded apex, with numerous irregularly arranged short setae ( Figure 9D). Styles slender, with long paddle-shaped apical lobe evenly broadened and denticulate on ventromesal margin. Connective nearly as wide as long ( Figure 9E,F). Aedeagal shaft straight, with caudal margin slightly concave, bearing three pairs of retrorse processes, apical processes tiny, directed caudally and then curved ventrally; ventral spines tapering apically and directed caudoventrally, moderately long and slightly divergent; lateral processes short, directed ventrally ( Figure 9G,H). Gonopore slit-shaped, on ventral surface at basal 1/3 above caudal spines ( Figure 9I,J).
Crown dark brown, with some small yellow spots near anterior margin ( Figure 5A). Face brown, anteclypeus with rather indistinct dark mottling. Eyes grey. Pronotum dark brown with broad ivory white transverse band on posterior margin( Figure 5I). Scutellum dark brown with a shallow spot at apex ( Figure 5A). Forewings pale brown, opaque, veins dark brown, with large irregular yellowish transverse band and yellowish cloudy patch situated in subapical and basal 1/3, respectively, apex yellowish ( Figure 11A). Abdomen pale brown. Legs pale brown, with brown macrosetae ( Figure 5E). Female yellowish brown, above and below more or less densely dark mottled.    Aedeagal shaft broad in lateral view, with three pairs of retrorse processes of same length, including two pairs of processes near caudal margin in central section (a pair of dorsal processes and a pair of caudal processes) and a pair of processes on sides closer to anterior margin (lateral processes); apex simple, rounded.
Diagnosis. This species is widely distributed in the Palearctic Region. Oshanin [22] first recorded this species from China. Recently, Zhang [89] recorded this species from China based on one male specimen and provided the illustrations of external habitus and aedeagus. Unfortunately, we cannot provide photos of the male genitalia but refer to the illustration of the male genitalia from Ribaut [36] as the dissection of the only male Chinese specimen is missing the male genitalia. It closely resembles the Palaearctic species Planaphrodes nigritus (Kirschbaum) from which it differs in the shape of the aedeagus and apical process of the shaft. that P. grisea Mitjaev, the type of which has the styles fused to the aedeagus, is probably an abnormal form of P. laevus. Aphrodes turkestanicus described by Dubovsky [93] from Fergana Valley (Uzbekistan) is also a synonym of the species. Different individuals of P. laevus may have the base of the caudal processes of the aedeagus fused or separated [4,19].
Diagnosis. It was originally named trifasciatus, but Koçak [95] discovered that this name was a homonym and proposed the replacement name laevus. Hamilton [7] suggested that P. grisea Mitjaev, the type of which has the styles fused to the aedeagus, is probably an abnormal form of P. laevus. Aphrodes turkestanicus described by Dubovsky [93] from Fergana Valley (Uzbekistan) is also a synonym of the species. Different individuals of P. laevus may have the base of the caudal processes of the aedeagus fused or separated [4,19].   Figure 5C). Face brown, with distinct dark brown mottling especially on genae, anteclypeus and base of frontoclypeus. Eyes black ( Figure 5K). Pronotum black, with brown band on posterior margin. Scutellum dark. Forewings dark brown, opaque, veins indistinct, with narrow irregular yellowish transverse band situated in subapical region interrupted with dark brown and yellowish cloudy patch situated in basal 1/3, apex yellowish ( Figure 5C). Abdomen dark brown ( Figure 5G).
Pygofer well sclerotized, taller than long, caudal margin slightly concave, with distinct round posteroventral lobe covered with tiny setae and short hook-like process at middle of caudal submargin directed medially with preapical denticle (Figure 15A,B). Subgenital plates broad, curved, parallel-sided at basal half in ventral view, narrowed to rounded apex, with numerous irregularly arranged short setae ( Figure 15C). Styles slender, with long crescent-shaped apical lobe denticulate on ventral margin. Connective short, Y-shaped ( Figure 15D). Aedeagal shaft strongly compressed, in lateral view narrowed near base, widened near middle, gradually narrowing in its distal part, with four pairs of retrorse processes, apical processes tiny and hook-like; dorsal processes tapering apically and directed posteriorly, moderately long and slightly divergent; caudal processes tapering apically and directed ventrally; lateral processes small, directed ventrally ( Figure 15E,F). Gonopore slit-shaped, on ventral surface near basal 1/3 above caudal spines ( Figure 15E Etymology. The species name refers to the type locality. Diagnosis. This new species is very similar to P. nigritus (Kirschbaum), which is widely distributed in the Palaearctic region but can be distinguished from the latter by the posteriorly directed dorsal spines and smaller lateral spines of the aedeagus ( Figure 15F).  Figure 5D). Face brown, frontoclypeus with distinct dark brown mottling and oblique striations on both sides. Eyes black ( Figure 5L). Pronotum black with indistinct dark brown mottling in posterior margin. Scutellum black, a shallow spot at apex. Forewings brown, opaque, veins indistinct, with a large irregular yellowish transverse band situated in subapical region and yellowish cloudy patch situated in basal 1/3 ( Figure 5D). Abdomen brown. Legs brown ( Figure 5H).
Pygofer well sclerotized, taller than long, caudal margin slightly concave, with distinct posteroventral lobe covered with tiny setae and hook-like process at middle of caudal submargin directed medially with a denticle ( Figure 16A,B). Subgenital plates broad, curved, parallel-sided at basal half in ventral view, narrowed to rounded apex, with numerous irregularly arranged short setae ( Figure 16C). Styles slender, with long crescentshaped apical lobe denticulate on ventral margin. Connective short, Y-shaped ( Figure 16D). Aedeagal shaft in caudal view strongly compressed( Figure 16E), in lateral view narrowed in its basal portion, widened in its middle part, gradually narrowing in its distal part, with five pairs of retrorse processes, apical processes tiny and directed caudally; dorsal processes triangular and directed caudally, moderately long and slightly divergent; caudal processes tapering apically and directed ventrally; between dorsal and caudal spines, with pair of small spines; lateral processes tiny and short, directed ventrally ( Figure 16F). Gonopore slit-shaped, on ventral surface at basal 1/3 above caudal spines ( Figure 16E Etymology. This specific epithet is derived from the Latin word "faciem", referring to the facelike color pattern of the forewings. Diagnosis. This species is very similar to P. nigricans, P. nigritus and P. faciems but can be distinguished by the caudal spines directed caudally and presence of a pair of small spines between the caudal and ventral spines ( Figure 16F).  Figure 5D). Face brown, frontoclypeus with distinct dark brown mottling and oblique striations on both sides. Eyes black ( Figure 5L). Pronotum black with indistinct dark brown mottling in posterior margin. Scutellum black, a shallow spot at apex. Forewings brown, opaque, veins indistinct, with a large irregular yellowish transverse band situated in subapical region and yellowish cloudy patch situated in basal 1/3 ( Figure 5D). Abdomen brown. Legs brown ( Figure 5H).
Pygofer well sclerotized, taller than long, caudal margin slightly concave, with distinct posteroventral lobe covered with tiny setae and hook-like process at middle of caudal submargin directed medially with a denticle (Figure 16A,B). Subgenital plates broad,

Discussion
This study is the first attempt to elucidate relationships among genera of Aphrodini and within species of Planaphrodes using explicit phylogenetic methods. Our results support Hamilton's recognition of four genera within the tribe and agree to some extent with his intuitive phylogeny based on aedeagal structure. Our phylogeny is difficult to compare to Hamilton's because his tree diagram implies that various extant species are directly ancestral to others. Nevertheless, our results are consistent with Hamilton's suggestion that P. vallicola, alone among Planaphrodes species, retains the ancestral position of the aedeagal spines, making it the most plesiomorphic species in the genus. Hamilton [7] also suggested that P. nigricans and P. monticola form a lineage characterized by having two pairs of spines close together on the caudal margin of the aedeagus and that this lineage

Discussion
This study is the first attempt to elucidate relationships among genera of Aphrodini and within species of Planaphrodes using explicit phylogenetic methods. Our results support Hamilton's recognition of four genera within the tribe and agree to some extent with his intuitive phylogeny based on aedeagal structure. Our phylogeny is difficult to compare to Hamilton's because his tree diagram implies that various extant species are directly ancestral to others. Nevertheless, our results are consistent with Hamilton's suggestion that P. vallicola, alone among Planaphrodes species, retains the ancestral position of the aedeagal spines, making it the most plesiomorphic species in the genus. Hamilton [7] also suggested that P. nigricans and P. monticola form a lineage characterized by having two pairs of spines close together on the caudal margin of the aedeagus and that this lineage is sister to the lineage, giving rise to most of the remaining species, characterized by a slender, parallel-margined aedeagal shaft. Within the latter group, P. sahlbergii and P. angulaticeps have the apical shaft spines projecting caudally in lateral aspect. These views are consistent with our phylogenetic results.
More broadly, our analysis provides morphological support for the sister-group relationship of Planaphrodes to Aphrodes. These genera share a strongly produced head, flat vertex between ocelli and sharp transition of vertex to face but differ in the coloration of the forewing (spotted or banded in Planaphrodes versus unmarked in Aphrodes) and the shape of the aedeagal shaft (strongly compressed in Planaphrodes but cylindrical in Aphrodes). The other two genera of Aphrodini are also supported as monophyletic by our analysis, with Stroggylocephalus supported by two unique synapomorphies (crown parallel-margined; flat ellipse gonopore shape) and Anoscopus supported by one homoplasious character change (aedeagus with apical spines oriented anteroventrad).
Our morphology-based phylogenetic estimate shows some large-scale biogeographic structure within Planaphrodes and suggests that regional faunas in Europe and East Asia may have arisen from widespread Eurasian ancestors. For example, Clade 2 includes a subclade containing three species (P. nigrigans, P. faciems and P. baoxingensis) restricted to East Asia that is successively sister to P. nigritus, P. monticola and P. bifasciatus; these three widespread species occur across Eurasia. Similarly, Clade 1 includes widespread species P. laevus that is sister to a clade comprising species with more restricted distributions in Europe or Asia. Paraphrodesvallicola, which is sister to the clade comprising the remaining species of the genus, occurs in Kazakhstan and adjacent parts of southern Russia, supporting a possible Central Asian origin for the genus. Planaphrodes is the only genus of Aphrodini well represented in East Asia. Other genera of Aphrodini are largely or entirely restricted to Europe and western Asia, with a few species apperantly adventive in the Nearctic region.
Some changes to the taxonomy of Planaphrodes suggested by our results will need to be confirmed through further study. Based on published descriptions and figures [17,31], P. iranicus and P. nisamiana are similar in appearance and male genitalia and occur in neighboring countries (Azerbaijan and Iran). Although they differ in three characters included in our matrix pertaining to small details of aedeagal structure (Figure 2), their overall morphological similarity suggests that they may be synonyms. This should be confirmed through study of the types and other specimens from those countries and analysis of molecular data. P. laevus and P. lusitanicus differ in only one character scored in our matrix (Figure 2), so we also suspect these two taxa may be synonyms. The former is recorded from several Eurasian countries, while the latter has been reported only from Portugal. P. modicus also resembles P. laevus in aedeagal structure (with base of caudal aedeagal processes fused) except for the poorly developed caudal processes. This species was described by Logvinenko [28] based on a single male specimen from Moldavia and there have not been further reports of this species in the literature. Additional study is needed to confirm whether the type of P. modicus is a malformed individual of P. laevus. The relationships within subclade ((P. sahlbergii + P. angulaticeps) + (P. araxicus + P. modicus)) are not consistently resolved among equally parsimonious trees.
Due to the limited numbers of specimens available, we were not able to test the validity of morphology-based species concepts in Planaphrodes, so further studies are needed to address this issue. Although the recent acoustic studies of Tisheshkin [21] have provided some corroboration of morphology-based species concepts currently used in Planaphrodes, further collecting throughout the known range of the genus and additional comparative morphological study are needed to elucidate the extent of morphological variation in species currently known from a few or single individuals. Ultimately, molecular phylogenetic and phylogeographic studies as well as acoustic studies of species not recorded by Tishechkin [21] will be needed to validate current species concepts.