Eomegophthalmus lithuaniensis, Dietrich & Gonçalves, 2014

Dietrich, Christopher H. & Gonçalves, Ana Clara, 2014, New Baltic amber leafhoppers representing the oldest Aphrodinae and Megophthalminae (Hemiptera, Cicadellidae), European Journal of Taxonomy 74, pp. 1-13 : 4-6

Eomegophthalmus lithuaniensis sp. nov.

urn:lsid:zoobank.org:act:2A1548C9-BC26-4F05-BB99-E0EE5FB55AB9

Figs 1A-B , 2A-F

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.

Material examined

Holotype female, Eocene Baltic amber, Palanga, Lithuania ( INHS).

Description

MEASUREMENTS. (in mm). Body length including forewings at rest 9.0; head width 2.9; pronotum width 2.5; front femur length 1.1, tibia 1.4; middle femur length 1.4, tibia 2.0; hind femur length 2.0, tibia 3.5, 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, flattened, slightly extended over antennal pits; antenna nearly as long as width of head; frontoclypeus narrow, rugulose, elevated and shelflike 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 flat, well separated from genal margin, ventral 2/3 bordering anteclypeus; gena very narrow; maxillary cleft absent. Proepisternum small, flat, 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. 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 flat, longitudinal rows present but poorly differentiated and surfaces of tibia between rows with numerous scattered fine 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 fine 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 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; 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 first valvulae sculpturing imbricate; second valvulae abruptly broadened near base and tapered distally, with 2 large teeth near base and several smaller serrations more distad.

MALE. Unknown.

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 first 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.

Figures

Fig. 1. Habitus in dorsal and ventral view. A-B. Eomegopthalmus lithuaniensis sp. nov. ♀. C-D. Xestocephalites balticus sp. nov. ♂. E-F. Brevaphrodella nigra sp. nov. ♂. Scale bars = 1 mm.

Fig. 2. A-F. Eomegopthalmus lithuaniensis sp. nov. ♀. A. Crown, pronotum, and mesonotum, dorsal view. B. Face, anteroventral view. C. Right forewing, lateral view. D. Prothoracic leg, lateral view. E. Metathoracic leg, dorsal view. F. Second valvulae of ovipositor, general lateral view. G-I. Xestocephalites balticus sp. nov. ♂. G. Face. H. Apical portion of femur, tibia, and first tarsomere of metathoracic leg, lateral view. I. Subgenital plates, ventral view. Scale bars: A-H = 1 mm; I = 0.5 mm.