New Baltic amber leafhoppers representing the oldest Aphrodinae and Megophthalminae (Hemiptera, Cicadellidae)

Three fossil leafhopper inclusions from Eocene Baltic amber, representing three new extinct genera and species, are described and illustrated. Eomegophthalmus lithuaniensis gen. et sp. nov. is tentatively placed in Megophthalminae, although it may represent the stem group from which Megophthalminae, Ulopinae, and Membracidae arose. Xestocephalites balticus gen. et sp. nov. and Brevaphrodella nigra gen. et sp. nov. are placed in Aphrodinae: Xestocephalini based on the structure of the head, leg chaetotaxy, and male genital capsule. These new genera and species represent the oldest known representatives of their respective subfamilies and the latter is the oldest known brachypterous adult leafhopper.


Introduction
The fossil record of leafhoppers (Cicadellidae), as reported in the literature, is very sparse, consisting of a few reports of rock fossils from the lower Cretaceous of Brazil, Eurasia and Australia (Shcherbakov 1986;Hamilton 1990Hamilton , 1992)), a single wing impression from the upper Cretaceous of western North America (Oman 1937), several genera and species from Eocene Baltic amber (Keilbach 1982;Spahr 1988, Szwedo 2002) and several genera and species from Oligo-Miocene Dominican amber (Dietrich & Vega 1995).Several fossil leafhoppers from Miocene deposits in Europe and North America have also been described (Metcalf & Wade 1966).Known Cretaceous leafhopper fossils are mostly either too poorly preserved to facilitate placing them to subfamily or, with the exception of two Brazilian fossils placed in Ledrinae (Shcherbakov 1992), have generalized morphology without distinctive features that would allow them to be placed with certainty in modern subfamilies.In contrast, representatives of several extant subfamilies have been reported from Baltic and Dominican amber.The cicadellid subfamilies (sensu Dietrich 2005) reported thus far from Baltic amber (reviewed by Szwedo 2002) are Bathysmatophorinae, Macropsinae, Mileewinae, Ledrinae, and Typhlocybinae (sensu Dietrich 2005Dietrich , 2011;;Wei et al. 2010).An extinct subfamily, Nastlopiinae, description based on a fi rst instar nymph (Szwedo & Gebicki 2002), needs more study to determine its status and relationship to other groups.Oligo-Miocene Dominican amber has yielded representatives of Aphrodinae (Xestocephalini), Cicadellinae (Cicadellini), Deltocephalinae (Athysanini), Evacanthinae (Nirvanini), Iassinae (Krisnini), Megophthalminae (Agalliini), Neocoelidiinae (Krocodonini) and Typhlocybinae (Dikraneurini; Dietrich & Vega 1995 and unpublished observations).While Dominican amber fossils are mostly referable to modern genera, most of the fossil leafhoppers present in the older (Eocene) Baltic amber appear to belong to extinct genera and, in some cases, cannot be assigned with confi dence to modern tribes.This suggests that much tribe-and genus-level diversifi cation in leafhoppers occurred during the Paleogene.Thus, Eocene Baltic amber documents an important stage in the evolution of the major lineages of Cicadellidae.Germar & Berendt (1856) were the fi rst authors to report on Cicadellidae from Baltic amber, describing seven species and placing two of these in Typhlocyba Germar, 1833, two in Jassus Fabricius, 1803, two in Tettigonia Fabricius, 1775, and one in Bythoscopus Germar, 1833.Unfortunately, the type material for these species was apparently destroyed during World War II and the original descriptions and illustrations are not suffi ciently detailed to allow for their proper placement although, as noted by Szwedo (2002), the two species of Typhlocyba are probably correctly placed in subfamily Typhlocybinae, and Bythoscopus may be placed with reasonable confi dence in Macropsini, but they cannot be placed to genus based on the information available at present.The original illustrations of Tettigonia proavia Germar-Berendt, 1856 and T. terebrans Germar-Berendt, 1856(Germar & Berendt 1856) indicate that they belong to Bathysmatophorinae.Tettigonia terebrans appears to be similar to Ambericarda skalskii Szwedo & Gebicki, 1998, so far the only other bathysmatophorine formally described from Baltic amber.Germar & Berendt mentioned that their two "Jassus" species were somewhat similar to modern European species of Deltocephalinae (Speudotettix Ribaut, 1942 andThamnotettix Zetterstedt, 1840), but they did not mention or illustrate characters that would unequivocally place these species in that subfamily.Their drawings and descriptions of these two taxa are consistent with Deltocephalinae, but they could also apply to other subfamilies; thus these two "Jassus" species should be treated as species incertae sedis.
Based on the original descriptions and illustrations, additional cicadellid species described from Baltic amber by Bervoets (1910) may be tentatively placed as follows: Bythoscopus punctatus Bervoets, 1910 andPediopsis minuta Bervoets, 1910 belong in tribe Macropsini; Eupteryx minuta Bervoets, 1910 belongs in subfamily Typhlocybinae (tribal placement uncertain); Acocephalus resinosus Bervoets, 1910 may belong in Bathysmatophorini, but the original description and illustration are not suffi cient to confi rm this placement.
More recently described cicadellids from Baltic amber (Szwedo & Gebicki 1999;Gebicki & Szwedo 2001) were placed in Ledrinae and Mileewinae, respectively.Although the subfamily placements of these fossils appear to be correct, the placement of the two ledrine nymphs in the modern genus Camptelasmus Spinola, 1850 is questionable, given that the type material of the type species of this genus is lost, and nymphs of modern representatives have not been previously described (Jones & Deitz 2009).Jones & Deitz (2009) excluded Camptelasmus from Ledrinae and considered the genus to be of uncertain position within Cicadellidae.The nymphs described and illustrated by Szwedo and Gebicki (1999) do not resemble those of other known members of Ledrini (sensu Jones & Deitz 2009, = Petalocephalini), which are much more strongly fl attened with lamelliform extensions of the tergites but, nevertheless, are consistent with Ledrinae in having the frontoclypeus narrower than the distance between the frontoclypeus and the eye, and in having setal row AD of the hind tibia with enlarged, spiniform bases.These fossils should be considered unplaced within Ledrinae until the nymphs of modern ledrines are better known.
The fossil taxa from Eocene Baltic amber described herein are remarkable in that they represent the oldest known representatives of Aphrodinae and Megophthalminae and exhibit morphological character combinations not found in modern representatives of their respective groups.The geologic age of Baltic amber is generally considered to be Late Eocene (37.7±3Ma; Perkovsky et al. 2007) although some evidence suggests that a Middle Eocene (44.1±1Ma) or even older origin is possible (reviewed by Szwedo & Sontag 2009;Weitschat & Wichard 2010).

Material and Methods
All specimens studied were obtained by the fi rst author from amber dealers in Palanga, Lithuania, where the material was originally collected.The specimens are deposited in the Insect Collection of the Illinois Natural History Survey (INHS).Digital photographs were taken using a Q-Imaging digital camera attached to an Olympus SZX-12 stereomicroscope.

Diagnosis
Same as for Eomegophthalmus lithuaniensis sp.nov., due to monotypy of this genus.

Etymology
The genus name, a feminine Latinized Greek noun, combines eos ("dawn") with Megophthalmus, the name of a related modern genus, and refers to the apparent position of the genus as the earliest known representative of its lineage.

Diagnosis
This species resembles extant members of the tribe Megophthalmini in having the crown of the head short and broad, the eyes relatively large and extended well laterad of the pronotum, the ocelli on the face distant from the eyes, and lateral frontal sutures of the head distinctly carinate.It is however easily distinguished by its relatively large and more dorsally placed ocelli, elongate wings, and short, broad second valvulae.

Etymology
The species name refers to the country in which the holotype was collected.

Age and occurrence
Baltic region.Baltic amber, Middle Eocene, ca.44 Ma.

Remarks
The structure of the head (crown absent, ocelli on face distant from eyes) places this leafhopper within the lineage comprising Eurymelinae, Megophthalminae, Ulopinae, and treehoppers.The carinate facial sutures extended ventrad of the ocelli suggest that it is closest to Megophthalmini but, unlike Eomegophthalmus gen.nov., modern members of that tribe have the gena expanded and concealing the proepisternum and the wings reduced in size.The presence of macropterous forewings with supernumerary crossveins suggests a relationship to Adelungiini, but modern members of the latter tribe have the head smoothly rounded and shagreen in texture (except in Adelungia Melichar, 1902, which has a compressed, bladelike median dorsal process), and lack conspicuous transverse rugae on the pronotum.
The broad second valvulae are more membracid-like than those of modern Megophthaminae, which have the second valvulae relatively narrow with serrations restricted to the distal half.The relatively dorsal position of the ocelli also suggests a relationship with Ulopinae and Membracidae.Thus, the subfamily placement must be considered tentative until the relationship of Eomegophthalmus gen.nov. to other leafhoppers can be elucidated by phylogenetic analysis.

Specimen notes
The type specimen, embedded in a clear piece of orange-yellow polished amber with most aspects of the body visible, apparently underwent considerable decay prior to fossilization.The abdomen is missing except for most of the fi rst and second valvulae of the ovipositor, which are exposed and situated in their original resting position near the apex, beneath the wings.The rest of the exoskeleton is remarkably well preserved, although there is some distortion of the head and thorax due to compression, and the forewing integument has numerous small fractures that appear as white areas and give the specimen the appearance of having reticulate forewing venation.Close examination suggests that only a few of these fractures correspond to veins.

Diagnosis
Same as for Xestocephalites balticus sp.nov., due to monotypy of this genus.

Etymology
The genus name, a masculine Latin noun, was formed by replacing the suffi x of Xestocephalus, a related modern genus, with -ites ("stone"), a common suffi x used to designate fossil taxa.

Diagnosis
This species resembles the modern genus Xestocephalus Van Duzee, 1892 in the structure of the head and in the leg chaetotaxy but differs in having the head wider than the pronotum, the crown more strongly depressed, the forewing elongate, and the front femur lacking an enlarged ventral seta near the midlength.

Etymology
The species name refers to the Baltic region, where the holotype originated.

Age and occurrence
Baltic region.Baltic amber, Middle Eocene, ca.44 Ma.

Remarks
This genus is referable to Aphrodinae based on the position of the ocelli on the crown slightly posterad of the anterior margin and distant from the eye.Among modern aphrodines, it most closely resembles Xestocephalus (Xestocephalini) in the structure of the head.Xestocephalus differs in having the head less strongly depressed and narrower than the pronotum with the gena broader and the anteclypeus strongly fl attened.Xestocephalites gen.nov.also differs from most modern aphrodines in having the wings fully macropterous.Species of the related tribe Portanini also have fully developed wings, but differ in having the head narrower, the ocelli on the margin of the crown, and the lorum greatly enlarged.

Specimen notes
The type specimen is embedded in a clear orange-yellow piece of amber but it is partly degraded with the left front leg (femur and segments distad) detached, and parts of the dorsum, including the forewings, largely concealed by air bubbles such that the wing venation is not visible.The anterior margin of the head is obscured by a horizontal fracture plane.

Diagnosis
Same as for Brevaphrodella nigra sp.nov., due to monotypy of this genus.

Etymology
The genus name, a feminine Latin noun, combines brevis ("short"), Aphrodes (the name of a related extant leafhopper genus), and -ella (a diminutive suffi x), refering to the small size and short forewings of the genus.

Diagnosis
Although the placement in Aphrodinae is somewhat tentative because the ocelli are not visible on the specimen, the overall structure of the head (fl attened, produced crown; broad, fl attened face with wide, angulate gena); leg chaetotaxy (2+2+1 hind femoral macrosetal formula); and male genital capsule (with numerous, scattered macrosetae and ligulate subgenital plates) are consistent with Aphrodinae.The presence of a single enlarged ventral seta near the midlength of the front femur suggests that the new genus is related to Xestocephalus and supports its placement in tribe Xestocephalini.

Etymology
The species name refers to the black overall coloration of the holotype.

Age and occurrence
Baltic region.Baltic amber, Middle Eocene, ca.44 Ma.

Remarks
Placement of Brevaphrodella gen.nov. in Aphrodinae is somewhat tentative because the ocelli are not visible on the specimen.Either they are absent or greatly reduced (as in some modern brachypterous leafhoppers), or they are on the anterior margin of the head and not visible due to the presence of a fracture plane concealing this part of the head in the only available specimen.Nevertheless, the overall structure of the head (fl attened, produced crown; broad, fl attened face with wide, angulate gena); leg chaetotaxy (2+2+1 hind femoral macrosetal formula); and male genital capsule (with numerous, scattered macrosetae and ligulate subgenital plates) are consistent with Aphrodinae.The presence of a single enlarged ventral seta near the midlength of the front femur suggests that the new genus is related to Xestocephalus and supports its placement in tribe Xestocephalini.This appears to be the oldest known example of a brachypterous adult leafhopper, along with the specimen of an undescribed species and genus from Baltic amber illustrated by Szwedo (2002: fi g. 24).

Specimen notes
The holotype is a specimen in excellent condition with apparently very little decomposition or loss of original color, embedded in a clear, light yellow piece of amber with dorsum and venter clearly visible but with numerous air bubbles concealing parts of the venter and a fracture plane obscuring the view of the anterodorsal margin of the head.The abdomen appears to have longitudinal pale stripes but these are asymmetrical and appear to be caused by pockets of air between the integument and the matrix.

Discussion
Although, to date, very few fossil Cicadellidae from Eocene Baltic amber have been described and illustrated adequately, leafhoppers are quite common in the Baltic amber fauna and the fossil taxa described so far from this source appear to be of great importance to the study of leafhopper phylogeny.
The species represented by these fossils lived during a time when modern subfamilies and tribes were fi rst beginning to appear; thus the fossils document evolutionary changes in morphology that were associated with the transition from the more morphologically generalized leafhoppers recorded from the Cretaceous period (Hamilton 1990(Hamilton , 1992) ) and the thoroughly modern leafhoppers recorded from the more recent Dominican amber (Dietrich & Vega 1995).Because the preservation of Baltic amber fossils is often very good, detailed study of their morphology is beginning to yield insights into the evolution of characters important for inferring the ecology and behavior of leafhoppers as well as for diagnosing higher taxa.
Eomegophthalmus gen.nov.exhibits a unique combination of features shared with some modern leafhopper subfamilies, as well as the treehopper families Aetalionidae, Melizoderidae and Membracidae.This provides further support for phylogenetic results suggesting that treehoppers arose from within a lineage comprising Megophthalminae and Ulopinae (Dietrich et al. 2001).
Xestocephalites gen.nov.and Brevaphrodella gen.nov.reveal that diversifi cation of the lineage, that eventually gave rise to the large modern leafhopper subfamily Deltocephalinae, involved parallel acquisition of characters such as brachyptery and specialized leg chaetotaxy that now occur in several independent lineages of leafhoppers.
These recent discoveries, in addition to those recently published by Szwedo and colleagues, suggest that Baltic amber may soon yield representatives of other modern leafhopper subfamilies and tribes, most of which remain undocumented in the fossil record.
Episternum divided by suture into anepisternum and katepisternum, without processes.Front femur with numerous scattered, poorly undifferentiated setae on dorsal and anterior surface, ventral rows poorly differentiated, AM1 slightly enlarged; tibia slender, dorsal surface fl at, longitudinal rows present but poorly differentiated and surfaces of tibia between rows with numerous scattered fi ne setae, ventral setae scattered and short.Middle leg similar to front leg in shape and chaetotaxy.Hind femur apical macrosetae 2+0; hind tibia compressed, with setal rows PD, AD, AV and PV with 15, 10, 11, and ~53 setae, respectively; with PD and AD closer to each other than distance from AD to AV; PD setae slightly smaller than those of AD; AD macrosetae with bases enlarged but not spinelike, intercalary setae absent; AV extended from basal third to apex; PV setae fi ne and subequal in length with macrosetae of similar lengths; pecten with single row of macrosetae with spinelike bases, 2 lateral setae longer than 4 medial setae; tarsus ca.1/3 length of tibia; tarsomere I without dorsoapical pair of setae, ventral setae CuA connected to submarginal vein slightly distad of apex of clavus; clavus occupying ~3/4 total wing length; appendix absent.Hind wing macropterous but not well preserved in holotype.FEMALE GENITALIA.Ovipositor with fi rst valvulae sculpturing imbricate; second valvulae abruptly broadened near base and tapered distally, with 2 large teeth near base and several smaller serrations more distad.
5, tarsus 1.1; forewing length 7.1; ovipositor length 2.0.STRUCTURE.Body elongate, somewhat depressed, uniformly dark brown.Head broad and short, much wider than pronotum; eyes bulbous; crown very short and poorly developed, coronal suture not visible, posterodorsal margin of head elevated and forming vertical rim above pronotum; ocelli large, slightly closer to midline than to eyes, in depressions near dorsal margin of face; antennal ledges oblique, fl attened, slightly extended over antennal pits; antenna nearly as long as width of head; frontoclypeus narrow, rugulose, elevated and shelfl ike ventrolaterally in relation to gena, concave dorsomedially, extended to dorsal margin of face in anteroventral view, evenly tapered from antennal pit to anteclypeus; lateral frontal sutures complete, weakly carinate, extended from antennal pit to midline; ocellocular area broad; clypeal suture complete; anteclypeus tapered, slightly convex, apex rounded, extended slightly beyond lower margin of gena; lorum fl at, well separated from genal margin, ventral 2/3 bordering anteclypeus; gena very narrow; maxillary cleft absent.Proepisternum small, fl at, largely exposed.Pronotum depressed, transversely rugulose, anterior margin roundly produced but not extended anterad of eyes, lateral margin short, carinate.Exposed part of mesonotum and scutellum depressed, scutellum acuminate.scattered, pecten with 3 platellae.Forewings elongate, macropterous, with venation poorly delimited, texture glabrous except rugulose near base of clavus; vein R branched in basal 1/3, with 6 branches, 4 extended to costal margin with basal branch arising near midlength, crossvein s present; M with 2 branches; only distal r-m crossvein visible; inner apical cell long, tapered in distal 3/4, not extended to wing apex; MALE.Unknown.
AD and PD with approximately equal numbers of macrosetae extended from near base to apex, without short intercalary setae between successive large macrosetae, AV with 3 stout preapical macrosetae in addition to numerous close set, slender setae of approximately equal length; tarsomere I elongate, with conspicuous dorsoapical pair of macrosetae and well differentiated ventral longitudinal row of short, stout setae.Forewings macropterous, venation not visible in holotype; clavus occupying ¾ length of wing, appendix absent.Male subgenital plates short and broad, somewhat compressed, fused along midline, with numerous conspicuous long, fi ne setae along dorsal and apical margins and few stout setae ventromedially, apices obliquely truncate.
STRUCTURE.Body elongate, weakly depressed, dark brown colored, without conspicuous pattern.Head slightly wider than pronotum; crown well developed, roundly produced, longer medially than next to eye, uniformly shagreen; ocelli well developed but small, on crown just posterad of anterior margin, slightly closer to midline than to eye; transition from crown to face rounded; antennal ledges oblique, weakly developed; antennal pits deep; antenna shorter than half width of head; frontoclypeus weakly convex; lateral margins evenly tapered ventrad from antennal pits to just dorsad of clypeal suture, thence abruptly narrowed; clypeal suture weakly delimited; lateral frontal sutures extended dorsomesad from antennal pits to near dorsal margin of face; anteclypeus parallel-sided, weakly convex, apex rounded, extended slightly beyond genal margin; lorum fl at, narrowly separated from genal margin ventrally, bordering anteclypeus for half length; gena broadly rounded; rostrum extended to just beyond base of hind legs.Pronotum depressed smooth, with sparse fi ne punctures and very inconspicuous transverse striations lateral margin less than half-length of eye, carinate.Exposed part of mesonotum and scutellum together slightly shorter than broad.Front femur chaetotaxy poorly visible in holotype, without conspicuous large ventral setae, tibia without conspicuous dorsal preapical macrosetae, ventral rows with several conspicuous macrosetae.Hind femur macrosetae 2+1+1; hind tibia fl attened and bowed, with setal rows PD, AD, AV with 12, 11, and 17 setae, respectively (PV not visible on specimen); with macrosetae of dorsal rows approximately equal in length, FEMALE.Unknown.
STRUCTURE.Body small, depressed, ovoid, entirely black.Head triangularly produced; crown weakly convex, shagreen; coronal suture not visible; eyes small, anterior margin slightly emarginate adjacent to antennal base; ocelli not visible.Antennal pits deep, pedicel enlarged, base of fl agellum divided into 5 subsegments.Lorum large, fl at, narrowly separated from gena ventrally; gena angulate below eye, concealing proepisternum.Anteclypeus fl at, tapered distally, apex rounded, extended slightly beyond gena.Rostrum long, extended to base of hind coxae.Pronotum with lateral margins divergent posteriorly, long, carinate.Mesonotum reduced, almost completely concealed by pronotum, scutellum small.Forewing short, coriaceous, elytralike, apex truncate, extended nearly to posterior margin of abdominal tergite IV, venation not delimited.Front femur with AM1 small, near midheight of femur, intercalary row well differentiated with 5-6 setae; AV with single long stout seta near midlength; hind tibia with setal rows PD, AD, AV and PV with 15, 10, 11, and ~53 setae, respectively; with dorsal preapical macrosetae 1+2, row AV with 13 setae becoming longer from base to apex, basal 5 abruptly shorter than others.Middle trochanter with stout ventroapical seta; femur with 4 AV and 1 PV setae, tibia with pair of dorsal setae near base and another near apex, AV with several setae.Hind femur macrosetae 2+2+1, penultimate pair close-set with posterior seta much smaller than anterior; tibia rows AD and PD with approximately equal numbers of macrosetae; AD macrosetae each with one intercalary seta, AD1 slightly offset toward middle of dorsal surface and distad of PD1, pecten with two pairs of shorter setae between two longer lateral and on long medial seta; tarsomere I with dorsoapical pair of macrosetae and two well differentiated rows of short, stout ventral setae; pecten with 5 tapered setae, medial seta longest.Male pygofer with numerous large macrosetae scattered over distal half.Valve concealed by sternite VIII.Subgenital plates ligulate, boatlike, with numerous large macrosetae scattered over most of length, mesal margins straight and closely appressed, apex evenly tapered. FEMALE.Unknown.