The unusual Afrotropical and Oriental leafhopper subfamily Signoretiinae (Hemiptera, Cicadellidae): taxonomic notes, new distributional records, and description of two new Signoretia species

Abstract The leafhopper subfamily Signoretiinae is redescribed and includes two tribes: Signoretiini Baker and Phlogisini Linnavuori. Redescriptions of included tribes, diagnoses and a taxonomic key to genera are provided. New records for genera of Signoretiinae are as follows: Phlogis in Central African Republic, Malaysia and Thailand; Preta in Thailand; and Signoretia in the Republic of the Congo, Zambia, Thailand, Vietnam, and Taiwan (China). Signoretia pacifica is newly recorded from Cameroon. In addition, detailed illustrations of the male genitalia of the previously described species, Chouious tianzeus, Preta gratiosa,and Signoretia yangli are provided; the male genitalia of Signoretia malaya are described for the first time; and two new species of Signoretia are described, Signoretia delicata sp. n. from the Philippinesand Signoretia kintendela sp. n. from the Republic of the Congo.


Taxonomy, distribution, morphology, new species introduction
Signoretiinae is a small, poorly known subfamily of leafhoppers apparently restricted to tropical forests in the Afrotropical and Oriental regions. The group is represented by few specimens in collections and is easily distinguished from nearly all cicadellids by the deeply punctured and enlarged pronotum (see subfamily remarks); other striking morphological features include: face strongly convex with cibarial muscle scars prominent; forewing outer anteapical cell present (vein s present); and hind femur macrosetal formula 2+0+0. Some of these morphological features have led to difficulties in placing the included genera in the Cicadellidae higher classification scheme. Baker (1915) first recognized the group as a subfamily of Stenocotidae (including members of current subfamilies Evacanthinae, Megophthalminae, and Tartessinae) and later (1923) treated Signoretiidae as a family of the Jassoidea. Evans (1947) subsequently placed Signoretiini as a tribe of Aphrodinae. Linnavuori (1978) highlighted the many unusual or unique features present in the group and recognized it as a separate subfamily. For similar reasons, Linnavuori (1979) subsequently recognized an additional subfamily, Phlogisinae, based on a single female specimen of Phlogis mirabilis Linnavuori from west Africa. Dietrich (2005) treated Phlogisinae as a junior synonym of Signoretiinae based on the enlarged, punctate pronotum extended to the scutellar suture in both groups. Subsequent morphology and DNA sequence-based phylogenetic analyses (Dietrich et al. 2010;unpublished data) indicate that these two taxa are sister groups, i.e., together form a monophyletic group. Although the relationship of Signoretiinae sensu lato to other cicadellid subfamilies was poorly resolved by these analyses, the results indicate that the group belongs to a lineage comprising Cicadellinae, Evacanthinae, and Typhlocybinae.
Signoretiinae sensu lato are variable for some morphological characters generally used to define taxa at the subfamily-level in Cicadellidae. For example, the position of the ocelli differs between the two included tribes: in Signoretiini they are found on the crown margin close to the eyes; in Phlogisini they are found on the crown, far from the margin. Similarly, Phlogisini have hind tibiae with macrosetae in row PD, and forewings with crossveins at the bases of the inner and median anteapical cells; while Signoretiini lack these features. Finally, Phlogisini have a distinct maxillary suture and Signoretiini have a complete longitudinal carina on the frontoclypeus, traits fairly uncommon in leafhoppers. Due to all above-mentioned morphological differences found in these taxa, Phlogisini and Signoretiini are herein treated as valid tribes within Signoretiinae.
Signoretiini, as treated herein (Fig. 1), includes Preta Distant with two species restricted to the Oriental region and Signoretia, occurring both in the Afrotropical and Oriental regions, with 27 species. Phlogisini includes the monotypic genera Phlogis Linnavuori from Africa and Chouious Yang from China. Although the African Signoretiini were revised by Anufriev (1971) and Linnavuori (1978), the male genitalia have been illustrated and described for only a few species of Oriental Signoretiini. In the present study, we review morphological characters to separate the included tribes and genera of Signoretiinae and a taxonomic key to genera is given. Further taxonomic notes on genera and species of Signoretiinae, new distributional records, descriptions of the male genitalia of Signoretia malaya and of two new species of Signoretia are also given.

Material and methods
Morphological terminology follows Dietrich (2005). Specimens examined are deposited in the following institutions: American Museum of Natural History, New York, USA (AMNH); The Natural History Museum, London, UK (BMNH); Field Museum of Natural History, Chicago, USA (FMNH); Illinois Natural History Survey, Champaign, USA (INHS); Muséum national d'Histoire naturelle, Paris, France (MNHN); Northwest Agriculture and Forestry University, Yangling, China (NWAF); Royal Ontario Museum, Toronto, Canada (ROM); Taiwan Agricultural Research Institute, Taiwan (TARI); and United States National Museum, Washington, DC, USA (USNM). In quotations of type-material labels, a backslash (\) separates lines on a label.
Habitus images were taken with a Digital Lab XLT system by Microptics using a Nikon D1x digital SLR camera and genitalia images were taken with a Q Imaging Micropublisher 3.3 digital camera mounted on an Olympus BX41 compound microscope. Multiple images were combined using the CombineZP software (Hadley 2010). Photographs were modified with Adobe Photoshop and vector illustrations based on the photographs produced with Adobe Illustrator.
Female ovipositor (Figs 26,27) elongate, variable in shape and dentition. Distribution. Afrotropical and Oriental. Notes. With the exception of the proconiine sharpshooter genus Tretogonia Melichar, 1926 and the recently described dikraneurine (Typhlocybinae) genus Sweta Viraktamath & Dietrich, 2011, Signoretiinae are the only leafhoppers with fully developed wings that have the pronotum extended to the scutellar suture. Viraktamath and Dietrich (2011) discussed several characters supporting the placement of Sweta in Typhlocybinae rather than Signoretiinae. Interestingly all these leafhoppers have the long pronotum distinctly punctate.
Nothing is known about the ecology or feeding behavior of Signoretiinae, although the strongly convex or inflated face suggests that they preferably feed on xylem sap. Pronotum with complete paired longitudinal carinae (Fig. 8); forewings with claval veins fused for one-third of their distance (Fig. 17)  with distinct depression laterad of each ocellus; transition from crown to face rounded; antennal ledges not prominent, evenly rounded; frontoclypeus without median longitudinal carina; anteclypeus with apex emarginated; maxillary suture present. Pronotum (Figs 2-5, 7) evenly convex, without carinae or deep depressions. Forewings ( Fig. 15) with or without R1 and crossveins r-m1 and m-cu2 present. Hind wings with crossvein m-cu perpendicular to CuA; submarginal vein not extended onto jugum. Forefemora with intercalary row strongly arcuate. Hind tibiae with row PD with macrosetae and row PV with some setae blunt-tipped. Male terminalia (Figs 21-24) with pygofer with apical two-thirds distinctly more sclerotized than base, without posteroventral process; valve fused laterally to pygofer; subgenital plates not extended posteriorly as far as pygofer lobe apex; style without preapical teeth or denticuli; with distinct dorsal connective (separate sclerite connecting aedeagus to anal tube); anal tube segment X with (Phlogis) or without (Chouious) posterolateral processes.  (Yang 1991). It is similar to Phlogis in external morphology, including wing venation and leg chaetotaxy, but differs in the structure of the head, as indicated in the key.

Chouious tianzeus
Notes. Phlogis was originally described based on the single female type specimen of P. mirabilis from Cameroon (Linnavuori 1979). The genus is readily distinguished from Chouious based on the head morphology, as indicated in the key. Three new specimens are herein studied and assigned to this genus, including a male considered to be conspecific to P. mirabilis and undescribed females from the Oriental region.
Distribution. Afrotropical: Cameroon (Linnavuori 1979) Linnavuori, 1979 http://species-id.net/wiki/Phlogis_mirabilis Phlogis mirabilis Linnavuori, 1979: 684. Notes. Previously, the only known specimen of Phlogis mirabilis was the female type from Cameroon. A male specimen from Central African Republic is tentatively considered as conspecific to the type-specimen, based on distribution, external morphology, and size (7.4 mm). The male genitalia of this specimen agree with those of Chouious in the characters described for Phlogisini. However, this male can be easily distinguished from Chouious because its: (1) pygofer lobe lacks the deep concavity on the dorsal margin, (2) aedeagus lacks ventral atrial processes, but has paired apical recurved processes; and (3) anal tube segment X has posterolateral paired processes.

Phlogis mirabilis
Distribution. Cameroon (Linnavuori 1979) 15,16,[25][26][27][28] Notes. The only other known specimens of Phlogis are two females from the Oriental region, Malaysia and Thailand, examined for this study. Both specimens studied herein (Figs 4-7) agree in most respects with Linnavuori's original description of the genus, but differ in size (6.4 and 9.5 mm vs. 7.5 mm for P. mirabilis) and in some details of body form, indicating that they represent two additional, presumably new species. However, we do not provide formal descriptions, given the meager material available at present. The specimen from Malaysia (Figs 4-6) closely resembles P. mirabilis, but is longer (overall length 9.5mm vs. 7.5mm) and differs in the shape of the seventh sternite (Fig. 25). The specimen from Thailand is smaller (6.4mm) and has the shape of the seventh sternite (Fig. 28) Distant, 1908). Head (Figs 8-17) with crown bearing prominent medial, lateral and posterior carinae, margins elevated, punctations indistinct; ocelli closely adjacent to eyes, laterad of submarginal carinae, directly above antennal ledges; transition from crown to face sharp, indicated by transverse carina; antennal ledges prominent, with anterior depression; frontoclypeus with complete median longitudinal carina; anteclypeus with apex truncate; maxillary suture absent.
Female ovipositor sigmoid, broadened near midlength; first valvulae with dorsal sculpturing strigate; second valvulae with dorsal teeth numerous, close-set, and bidentate; toothed area occupying more than half entire length of valvula.
Male terminalia  with pygofer with well-developed posteroventral process; valve articulated laterally to pygofer; subgenital plates extended posteriorly beyond pygofer lobe apex; style with preapical teeth or denticuli; dorsal connective absent; anal tube segment X with or without lobes and/or processes at base or more apically; aedeagus divided into ventral paraphyses-like structure articulated to connective consisting of basal preatrium and paired robust processes and dorsal shaft, dorsal and ventral parts may be loosely connected by membrane (all Oriental species) or completely fused to eachother (some African species).
Notes. Preta is restricted to the Oriental region and currently includes two species, P. gratiosa and P. luzonensis Baker, 1923, the latter known only from the Philippines. It can be easily distinguished from Signoretia by its complete paired longitudinal carinae on the pronotum (Fig. 8) and medially fused claval veins of forewings (Fig. 17), as indicated in the key.

Preta gratiosa
Notes. Signoretia currently includes 10 Oriental species and 15 Afrotropical species, in addition to the new species described herein. Members of Signoretia can be easily distinguished from Preta by the lack of paired complete longitudinal carinae on pronotum (Figs 10, 13) and separate claval veins on forewings (Fig. 19). Several nominal species do not have the male genitalia described and illustrated, specially the Oriental ones.
Etymology. The species epithet refers to the relatively small size of this species and its delicate habitus.
Notes. This species is described as new because it does not agree with any of the ten previously described Oriental species based on the following combination of characteristics: (1) stramineous dorsal coloration with two pairs of dark markings on crown; (2) median carina on crown absent; (3) each ocellus close to eye for distance of approximately its own diameter; (4) frontoclipeal longitudinal carina not continuing on clypellus; and (5) pronotum longer than wide and without paired incomplete longitudinal carinae on anterior portion, but with very faintly elevated median longitudinal carina. Exceptionally, the above-mentioned characteristics, will not separate Signoretia delicata sp. n. from S. tagalica Baker, 1915 (another Philippine species described from Luzon and Banahao), with which shares other morphological characters, such as the less produced crown, making the frontoclypeus appear more inflated, and very short outer anteapical cell. Nevertheless, based on the original illustrations and description, S. tagalica is larger (male is 6.5 mm) and has a much longer pronotum (more than 4 times the median length of crown) than the species described herein.
The short crown of this new species, shared with other described Signoretia, could be viewed as sufficient diagnostic characteristics to place this group in a new genus. Considering that at the moment only a small fraction of Oriental Signoretia have the male genitalia described, it would be premature to erect a new genus without reviewing all other described Oriental Signoretia.

Signoretia errans
Notes. Linnavuori (1978) included this species in his key and provided illustrations of the male genitalia, but did not include a formal description or list of material examined. However, his figure captions indicate that he examined specimens from the Democratic Republic of Congo (Dingila and Mongbawu). The species is considered valid because Linnavuori (1978) satisfied the criteria of availability by including the species in his identification key for African Signoretia and providing illustrations of features that distinguish the species from its congeners.
Notes. Signoretia kintendela sp. n. shares with other members of the pacifica group (Linnavuori 1978) the fusion of the aedeagal shaft to the paraphyses-like structure consisting of the robust and sclerotized paired basal aedeagal appendages and elongate preatrium. If the robust process interpreted herein as arising from the membrane between the anal tube and pygofer lobe was viewed as an anal tube appendage by Linnavuori (1978), then in the pacifica group, the new species is more similar to S. congoensis and S. augur because these species share a single pair of processes at base of the anal tube. Nevertheless, the new species can be distinguished from these and all other Signoretia by the shorter ventrocaudal processes of the pygofer lobe and very long and slender rami of basal appendages with sinuous and foliaceous apex.
Type material. Male terminalia. Pygofer (Fig. 37) with caudal margin of lobe membranous; ventrocaudal process elongate evenly curved and tapered, spiniform, produced posteriorly beyond pygofer lobe apex. Subgenital plates (Fig. 37) extending posteriorly beyond pygofer lobe apex by approximately one-third of lobe length, dorsal surface with numerous long, fine setae evenly distributed throughout length and three macrosetae in longitudinal row near midlength. Connective (Fig. 38) H-shaped, arms subparallel; without dorsal median keel or median anterior lobe. Style (Fig. 38) slender and elongate; apex globose, directed laterally, with few small denticuli. Aedeagus (Fig. 38,39) with ventral paraphyses-like structure with pair of robust, tapered, recurved distal processes; dorsal part consisting of pair of round basolateral lobes and tubular shaft. Anal tube ( Fig. 37) with segment X without basal processes and distal margin thickened, terminating ventrally in short lobe.
Distribution. Cameroon [new record]; Democratic Republic of Congo, Guinea, Liberia (Linnavuori 1978); Ivory Coast, Nigeria, and Sierra Leone (Anufriev 1971 Signoretia yangi Li, 1995: 6. Notes. Identification based on illustrations in original description, although male specimens studied differ from original illustration in the shape of the connective. Additionally, distinctive features not mentioned or illustrated in the original publication include the: highly membranous, small and tubular aedeagal shaft; ventral aedeagal processes being separately articulated and densely clothed with microtrichia; and pair of slender ventral spines on segment X extending basad. Distribution. China: Fujian (Li 1995) and Taiwan

Discussion
As mentioned in the introduction, despite sharing some features unique among Cicadellidae, the two recognized tribes of Signoretiinae show striking differences in major characters of the external morphology. Likewise, the male genitalia also show differences between the two groups. All described Signoretiini have the valve not fused laterally to the pygofer, a strongly developed ventrocaudal process on the pygofer lobe, and long subgenital plates. Males of Phlogisini have, on the other hand, the valve fused laterally to the pygofer, pygofer without processes, and shorter subgenital plates. Furthermore, the aedeagus is articulated with the anal tube by an additional sclerite, the dorsal con-nective (Hamilton 1983). Signoretiines tend to have one or two pairs of processes arising from the ventral margin of segment X of the anal tube. The presence of these processes is variable within the tribes, and they can originate in different positions and have different shapes, which indicate they may not be homologous structures. For example, all African Signoretia and Preta gratiosa have processes at the base, while Signoretia aureola and Phlogis mirabilis bear modifications at a more apical position. However, Chouious tianzeus and the remaining Oriental Signoretiini with male genitalia described, S. delicata sp. n. and S. malaya, have processes strongly reduced or absent. Linnavuori (1978) in his revision of the African Signoretiini (as Signoretiinae) divided the species of Signoretia into two groups: the pacifica group including species with the aedeagus shaft "reduced, membranous and more or less concealed by the fused, scoop-shaped appendages" and the karaseki group including species with the aedeagus shaft "long and sclerified, distinctly separated from the appendages". Furthermore, in the key to species, Linnavuori (1978) added that in species of the karaseki group the paired basal appendages are long and separate, while in the pacifica group they are fused both to each other and, more or less, to the membranous shaft. The definition of these groups based on the sclerotization of the shaft can be confusing, because the degree of apparent sclerotization can vary due to differences in procedures used for preparing the genitalia for study. However, whether the paraphyses-like structure (=basal appendages) is completely fused or not to the base of the shaft seems to be an important taxonomic character, as previously noted by Anufriev (1971). At that the time Anufriev published his study, this character would separate Oriental signoretiines (with an articulated shaft to the basal appendages) from the Afrotropical ones (with a fused shaft and basal appendages). The genitalia of at least some of Linnavuori's (1978) species from the karaseki group do resemble the genitalia of Oriental Signoretiini because of the membranous connection of the highly sclerotized basal appendages to the lightly sclerotized aedeagus shaft. In Oriental species, the shaft can be so short and lightly sclerotized that previous authors have not illustrated it in their genitalia descriptions (Anufriev 1971, Li 1995. Although the membranous shaft of members of the Linnavuori's (1978) African pacifica group can be variable, the complete fusion of the paraphyses-like structure to the aedeagal shaft (Fig. 29), seems to be a better character to define this group and has not so far been found in Oriental signoretiines. Additional paired sclerotized cuticular processes were seen associated to this membranous connection in S. yangi as triangular tooth-like projections (Fig. 35) and in P. gratiosa (Fig. 23) as curved elongate spiniform projections.
Shih (TARI). Additionally, recently collected material from Cameroon was made available to us by J. Cryan (North Carolina Museum of Natural Sciences), Zambia by J. Zahniser (INHS), and from Republic of Congo and Thailand by M. Sharkey (University of Kentucky). M. Webb kindly reviewed preliminary versions of this manuscript and sent us images of P. mirabilis type, currently on loan to him. Y. Cao (NWAF) helped us obtain and translate part of the Chinese bibliography. Travel to Illinois by the senior author was funded in part by a Conselho Nacional de Desenvolvimento Científico e Tecnológico grant (CNPq PROTAX proc. 562303/2010-3).