Libnotes (Libnotes) byersiana, Podenas & Byun, 2018

Podenas, Sigitas & Byun, Hye-Woo, 2018, Libnotes crane flies (Diptera: Limoniidae) from Jeju Island (South Korea), Zootaxa 4483 (2), pp. 375-384 : 379-381

Libnotes (Libnotes) byersiana sp. nov.

( Figs. 4–9 )

Diagnosis. Head dark brown, dusted with gray, thorax obscure yellow, mesonotal prescutum with brown median stripe, lateral stripes missing. Abdominal segments brown with widely yellow posterior margins. Wing unpatterned except stigma, vein Sc1 reaches frontal wing margin slightly before branching point of Rs, R3 and R4+5 strongly curved towards posterior wing margin. Membranous area behind ninth tergite with two triangle-shaped plates, gonocoxite elongate with subglobular ventro-mesal lobe, outer gonostylus short and nearly straight, inner gonostylus small, oval with large unarmed rostral prolongation, ventral side of stylus extended into short sculptured spine at base of rostral prolongation.

Examined material. Type specimens 2 males.

Holotype: male (pinned) ( Fig. 4 ), S. Korea, #35, Cheju Island , [Halla San (volcano), altitude 1500 ft.], September 9, 1954, G. W. Byers ( USNM).

Paratypes: male (pinned, wing slide mounted in euparal ( Fig. 7 ), genitalia ( Fig. 8 ) in microvial filled with glycerol on same pin), S. Korea, #36, Cheju-do , Halla San (volcano), altitude 1500 ft., September 10, 1954, G. W. Byers ( SMEK).

Description ( Figs. 4–9 ). Adult ( Fig. 4 ), male (N =2). General body color brownish yellow. Body length 4.6–4.7 mm, wing length 5.7–6.2 mm.

Head. Dark brown to blackish, covered with silvery gray pruinosity. Anterior vertex narrow, silvery gray. Dorsally head with longitudinal line of ground blackish color, sides of which marked with gray pruinosity, oval, less intense spot laterally. Eyes big, nearly reaching each other dorsally and ventrally. Antenna reaching base of wing, if bent backward. Scape brown with yellowish distal part, sparsely dusted with gray, elongate, nearly cylindrical. Pedicel dark brown, twice as short as scape. Flagellum dark brown at base, brown at apex, basal flagellomeres oval with apical pedicels, decreasing in length apically, apical segment twice as long as preceding. Verticils twice as long as respective segments. Flagellomeres covered with whitish pubescence. Rostrum brown, semi-polished. Palpus dark brown, mouth parts paler.

Thorax. Obscure yellow. Cervical sclerites dark brown. Pronotum obscure yellow with dark brown dorsal stripe. Ground color of mesonotal prescutum yellow, median stripe brown, dark brown at frontal margin of sclerite. Lateral stripes missing, lateral margin of sclerite indistinctly brownish. Scutal lobe brown, area between lobes yellowish. Scutellum pale, mediotergite obscure yellow. Pleuron obscure yellow, semi-polished. Wing ( Fig. 7 ) subhyaline, brownish, unpatterned except light brownish stigma. Veins light yellowish-brown. Venation: Sc long, Sc1 ending slightly before branching point of Rs. Sc2 at tip of Sc1. Rs medium-long, slightly arched. R1 short, nearly transverse, indistinct at wing margin. R2 at tip of R1, oblique. R3 and R4+5 long, distinctly arched, getting closer to each other towards wing margin. Cross-vein r-m distinct, beyond base of discal cell. Discal cell elongate, 2.6 times as long as wide. Basal deflection of CuA1 at middle of discal cell. Second anal vein medium-long, slightly arched subapically. Cell a2 medium wide, anal angle widely rounded. Halter 0.8–1.0 mm long, with pale stem and dark brown knob. Coxae obscure yellow, just fore coxa frontally darkened. Trochanters obscure yellow. Femora pale at base turning brown distally with yellow apical ring. Tibiae light brown, basal tarsomeres brown, two distal tarsomeres dark brown. Femur I: 4.6–5.7 mm long, III: 6.2–6.5 mm, tibiae I: 5.9–6.6 mm, III: 6.2–6.5 mm, tarsus I: 5.6 mm, III: 4.7–4.9 mm. Claw with subbasal spine.

Abdomen. Tergites dark brown at base with widely yellow posterior margin. Four basal sternites generally yellow, third and fourth indistinctly brown at base, remaining sternites distinctly dark brown at base widely yellow at distal margin. Male genitalia ( Fig. 8 ) yellow. Ninth tergite simple, posterior margin nearly straight, membranous area behind ninth tergite with two triangle-shaped finely setose plates ( Fig. 8 pl). Gonocoxite elongate with subglobular ventro-mesal lobe at middle ( Fig. 9 ). Outer gonostylus ( Fig. 5 ) narrow, comparatively short, slightly arched. Inner gonostylus short, oval, 2.25 times as short as gonocoxite with large, slightly curved, unarmed rostral prolongation. Ventral side of stylus with short acute-pointed sculptured lobe at base of rostral prolongation ( Fig. 6 ). Paramere with long and narrow blade-shaped point-apexed distal prolongation ( Fig. 8 ). Penis elongate, turning narrower before apex, reaching slightly beyond middle of gonocoxite.

Habitat. Unknown.

Elevation. Nearly 500 m.

Period of activity. Beginning of September.

Distribution. Currently known only from Jeju Island, South Korea.

Remarks. Distinguished from other species in the genus by small size, body coloration, wing venation and male genitalia. The structure of the male genitalia of L. byersiana n. sp. are unique among East Palearctic Libnotes . One such feature is the unusually shaped membranous area with two large plates below the ninth tergite (behind the ninth tergite in KOH cleared terminalia ( Fig. 8 )), which are remains of the 10th segment. These plates are derivates of semi-membranous structures that are sometimes present in other Libnotes (Libnotes) , for example, two elongate darkened lobules are ventral to the posterior margin of the ninth tergite in L. divaricata . The inner gonostylus of L. byersiana has a small acute lobe on the ventral surface which is also unique among species of L. ( Libnotes ). Overall, the male genitalia of L. byersiana resembles that of L. (Neolibnotes) biprotensa ( Alexander, 1972) from Palau Islands, but the wing venation of both species is very different. Among East Palearctic species, L. divaricata is most similar to L. byersiana . Both species are the smallest among Korean Libnotes , and resemble most Dicranomyia Stephens, 1829 with unpatterned wings, similar wing venation, an unarmed rostral prolongation of the inner gonostylus and a complicated tip of the penis.

Etymology. This species is named after Dr. George W. Byers, who, as a military entomologist in post-war Korea in 1954, collected lots of crane flies together with this species.

Figures

FIGURES 4–9. Libnotes (Libnotes) byersiana sp. nov. 4: holotype, general view; 5: gonostyles of paratype, dorsal view; 6: inner gonostylus of paratype, ventral view; 7: wing of paratype; 8: male genitalia of paratype, dorsal view; 9: gonocoxite of paratype, lateral view. Abbreviation: pl–setose plate on membranous area behind ninth tergite.