Burnilia japonica, Asche, Manfred, Hayashi, Masami & Fujinuma, Satoshi, 2016

Asche, Manfred, Hayashi, Masami & Fujinuma, Satoshi, 2016, Enigmatic distribution: first record of a hitherto New World planthopper taxon from Japan (Hemiptera, Fulgoroidea, Delphacidae, Plesiodelphacinae), Deutsche Entomologische Zeitschrift 63 (1), pp. 75-88 : 76-78

Taxon classification Animalia Hemiptera Delphacidae

Burnilia japonica sp. n. Colour plate 1, Figs 1, 2, 3, 4, 5, 6

Description.

Slender, medium-sized delphacid species of delicate appearance with strongly pale-dark contrasting colouration of the head.

Length (from tip of head to apex of tegmina): Males (n=20): 4.0-4.4 mm (mean 4.2 mm); Females (n=20): 4.3-4.7 mm (mean 4.5 mm)

Colouration: Ground colour pale yellow to orange. Vertex pale yellow, with a narrow transverse dark brown to blackish stripe across the posterior margin of the anterior compartment; lateral margins, posterior corners and converging anterior carinae blackish brown; transition to frons as well as dorsal part of median frontal carina blackish. Frons pale yellow, lateral margins blackish, median carina centered in a narrow black-brown stripe. Post- and anteclypeus orange, median carina of postclypeus brownish. Rostrum orange with black tip. Antennae sordid orange-brown; scape distally fringed blackish-brown; pedicel anteriorly with a broad oblique brown stripe which is distally darker. Sides of head in front and dorsally of compound eyes broadly marked black, posterior corners above compound eyes blackish; compound eyes bright red; sides otherwise pale yellow to orange; ocelli centered in a brown spot; oblique genal carina anteriorly fringed brown; lower part of genae pale yellow; lamina mandibularis (lorae) orange. Pronotum sordid pale yellow, carinae of disk and posterior margin brownish, sides behind compound eyes anteriorly brown; laterodistal part of pronotum pale yellow, anteriorly with a blackish fringe. Mesonotum and tegulae sordid orange-brown. Tegmina translucent, smokey pale yellow or light sordid brown, veins light brown. Hind wings hyaline with brown veins. Legs orange to pale yellow, distal outer margin of tibiae brown. Abdominal tergites and sternites as well as male and female genitalia, mostly orange; ovipositor and posteromedian parts of tergite IX brown, anal style in males brownish, and females blackish.

Head and thorax: Head with large compound eyes, narrow vertex and frons; head including compound eyes about 3 times wider than vertex at base, about 0.8 times narrower than maximum width of pronotum. Vertex elongate, narrow, medially about 1.87 times longer than wide at base, distinctly projected in front of compound eyes; lateral margins subparallel, slightly converging towards apex, apex in dorsal view truncate; compartments of vertex concave, limited by faint but well recognizable carinae; basal compartments elongate, anteriorly limited by anteriorly diverging carinae; anterior compartment rhomboid, lateral carinae converging towards apex and medially continuing as median frontal carina; transition of vertex to frons in lateral view in an almost right angle, apically slightly rounded. Frons elongate, apically rather narrow, continuously widening towards frontoclypeal suture, medially about 2.1 times longer than maximally wide, widest at frontoclypeal suture, basally about 3 times wider than apically, frons medially about 1.3 times longer than post- and anteclypeus together; lateral frontal carinae ridged, very slightly convex, in parts nearly straight, diverging from apex towards base; median frontal carina distinctly ridged, frontal surface in upper part shallowly concave, in lower part almost plain or slightly convex; frontoclypeal suture almost straight. Postclypeus vaulted, median carina ridged, lower part forming a nose-like projection (best seen in lateral view). Antennal joints subcylindrical, elongate, terete; pedicel about 2.8 times longer than scape, furnished with about 16 sensory plaques, arranged in 7 groups, partly in rows. Compound eyes large, in lateral view flat kidney-shaped, mediobasal incision above antennal base distinct, ocelli well developed; oblique genal carina sharply ridged. Pronotum about 3.6 times wider than medially long, carinae of disk sharply ridged, attaining posterior margin, lateral carinae slightly convex, diverging posteriorly; surface of disk shallowly concave. Mesonotum medially about 2.6 times longer than pronotum, carinae ridged, lateral carinae very slightly concave, diverging towards and attaining the posterior margin, median carina vanishing before reaching scutellum; surface of disk nearly plane. Tegulae well developed, in dorsal view about as long as wide. Tegmina elongate and narrow, about 4.5 times longer than maximally wide, widest shortly distad of nodal line, the latter in distal third; subapical cells small and narrow, inner cell (C5) slightly longer than outer one (C1), in membrane M branched into M1 and M2. Margin of hind wing with distinct notch at A1, M distally branched. Legs slender; hind leg with tibia about 1.25 times longer than tarsal joints together, laterally furnished with 2 spines, one close to base, the other shortly below midlength, distally with 5 spines: 2 rather small ones inside, 3 increasingly longer ones towards outside; post-basitarsus about twice as long as 2nd and 3rd post-tarsal joints together, distally with 5 spines: 4 in a row, one spine positioned anteriorly out of row; 2nd post-tarsal joint distally with 4 spines: the 3 inner ones forming an oblique row, the outer one distinctly longer.

Abdomen slightly depressed, hypopleurites subrectangular with straight outer margin. Male drumming organ with paired apodemes of the second abdominal sternite elongate, erect, slightly widening dorsally, nearly attaining tergites.

Male genitalia: Genital segment in lateral view trapezoidal, ventrally about 1.3 times longer than dorsally, laterodorsal corners slightly produced, caudal margin nearly straight; in ventral view medially slightly longer than wide, mediocaudal margin straight with a small central knob; in caudal view ovoid, slightly higher than wide; diaphragm narrow, median sclerotized portions lobe-like with median membranous interruption. Aedeagus relatively short, when exposed hardly surpassing tip of anal segment, in lateral view curved dorsally; central sperm-conducting tube (sheath sensu Yang and Chang 2000) strongly sclerotized and ending in an apical phallotreme which is fringed by a crown of grooves and exposed to the left side; no free suspensorium: base of phallotheca connecting to anal segment strongly sclerotized forming phallobase sensu Yang and Chang (2000), otherwise phallotheca membranous, subapically on dorsal side slightly dilated and very finely serrate, on ventral side with a stronger sclerotized patch, in one of the examined individuals subapically on right dorsal side with a small sclerotized tooth directed dorsally; dorsally, immediately below the phallotreme on the left side, with a slender, apically pointed flag-like process which is almost semicircularly curved over the dorsal towards the right side, process subapically with small teeth. Anal segment, elongate, robust, shaft in ventral view about 1.7 times longer than maximally wide, widest caudally, ventrocaudal corners projected ventrally forming ear-like lobes, slightly asymmetrical; ventral surface membranous; anal style subconical, ventral side slightly concave, about 4 times shorter than anal segment, mostly gently curved ventrally. Genital styles distinctly shorter than anal segment, in repose not attaining dorsolateral edges of genital segment, arising from a broad base and continuously narrowing towards apex, narrowest subapically, apically dilated into a bilobate tip; the inner apical lobe shorter than the outer one, apically rounded and pointing medially; the outer lobe ventrally and dorsally pointed, in lateral view forming a wide trapezoidal tip with nearly straight caudal margin.

Female genitalia: as in all Plesiodelphacinae ditrysic with clear separation of copulation and oviposition duct ( Asche 1985a, b). Ovipositor slender, compressed, slightly curved dorsally, not surpassing the lateral edges of tergite IX; at base of ovipositor a sclerotized groove into the vagina guiding and supporting the aedeagus during copulation; gonoplacs large and relatively wide, fully enclosing gonapophyses VIII and IX, gonapophysis IX dorsally in distal third finely serrate; gonocoxae VIII elongate, slightly dilated and rounded at base; tergite IX laterocaudally slightly pointed; anal segment short and depressed, about as long as wide, anal style about as long as anal segment, ventrally concave and membranous.

Diagnosis.

Burnilia japonica sp. n. can easily be distinguished from the New World species of the genus by the colouration of the frons: median carina broadly bordered by a blackish stripe versus frons entirely devoid of colour patterns, or frons furnished by one or two transverse blackish stripes in Neotropical species. In Burnilia japonica sp. n. the vertex displays a faint but distinct carination separating the two posterior from the anterior compartment; in the Neotropical species at least the median carina separating the basal compartments is strongly reduced or absent, in some species also the basal carinae limiting the anterior compartment are absent. Burnilia japonica sp. n. is also unique by the possession of a relatively short and sturdy aedeagus (usually distinctly more slender and elongate in Neotropical species), by a flag-like semicircular subapical aedeagal process (forming a straight, slender spine in Neotropical species, if present), and by an anal segment with large ear-shaped lateroventral lobes (no such lobes are observed in the Neotropical species).

Distribution.

Japan: Kyushu (south-westernmost area), Yakushima Island of the Osumi Isles and Okinawa Island (northern part) of the Ryukyus, endemic.

Hostplant, ecology, and biology

(see Colour plate 2). In the extent of our field investigations on Yakushima Is. south of Kyushu, the host plant is restricted to a wild perennial zingiberaceous plant, Alpinia intermedia Gagnep. ( Zingiberaceae : gingers) distributed in Japan and the East Orientalis growing on shady and wet forest floors of cedar afforestation or sometimes laurophyll forests. The occurrence of this Burnilia -species is usually strongly confined to narrow spots even in a same forest. Although two other species of Zingiberaceae , Alpinia formosana K.Schum. and Alpinia zerumbet (Pers.) (apparently introduced) are also found in same area, and are rather dominant at sunny forest edges or at roadsides, Burnilia japonica has never been found on these plants, but exclusively on Alpinia intermedia .

In the field, both nymphs and adults are found near the ground, on stems of the host plant below the level of fallen cedar leaves. Adults may appear from late July with a probable peak at mid- and late August on Yakushima Is.

Since late summer of 2013, M. Hayashi had been rearing several adults collected by Fujinuma, on potted ginger-lilies ( Alpinia intermedia ) at his home near Tokyo. Adults were never observed to hibernate; thus it is assumed that overwintering occurs as eggs. Some nymphs were recognized in the following June, and a first adult appeared on July 5, 2014. The nymphs in every instar are wholly red, becoming vivid in last (5th) instar. On stems of the host plant, both adults and nymphs stand still with their heads directing upward and antennae fully stretching right laterally. Adults just after emerging are carmine red, gradually changing their colouration to yellowish with grey tinge. The compound eyes, however, remain brightly red with a black pseudopupil.

Etymology.

The specific name refers to the geographical occurrence in Japan.

Material examined.

Holotype ♂ macropterous, Japan, Kagoshima Pref., Osumi Isles, Yakushima, Yudomari, 20.VIII.2013, S. Fujinuma (TUA). The holotype is deposited in the Laboratory of Entomology, Tokyo University of Agriculture, Japan.

Paratypes: 3 ♂♂, 4 ♀♀, Kyushu, Kagoshima Pref., Minami-Satsuma, Bonotsu, Akime, 17.VIII.2014, K. Ôhara (TUA). 1 ♀, Kagoshima Pref., Makurazaki, Nishikago, 17.VIII.2014, K. Ôhara (TUA). 2 ♂♂, 6 ♀♀, Kagoshima Pref., Makurazaki, Hinokami, 17.VIII.2014, K. Ôhara (TUA). 25 ♂♂, 36 ♀♀, same data as holotype (TUA, MFNB). 2 ♂♂, 1 ♀, same locality, 19.VIII.2013, S. Fujinuma (TUA). 6 ♂♂, same locality, 18.VII.2014, M. Hayashi (TUA). 2 ♂♂, Yakushima, Kurio, 19.VIII.1983, Sk. Yamane (TUA). 2 ♀♀, Ryukyus, Okinawa Is., Kunigami, Benoki, S. Azuma, no collecting date (RUMF). All specimens macropterous.