Borysthenes undulatus, Lyu, 2025

Borysthenes undulatus sp. nov.

Fig. 1K–L View FIGURE 1 , 3Q–X View FIGURE 3 , 5C–D View FIGURE 5 , 6D View FIGURE 6

Materials examined: Holotype: ♂, 50m outside the entrance of Wuzhishan National Reserve , Wuzhishan, Hainan Island, China (中国¾南ẑ五DZƜ保ae区ƛ口外 50m), 25.iii.2024, leg.: Tianlang Lyu.

Paratypes: 6♂ 1♀, same data as holotype ; 1♀, near Boliwan reservoir along road X437 , Qiongzhong, Hainan Island, China (中国¾南ẑDz中OiKĤAENJ 437 乡Dzãũ), 8.viii.2021, leg.: Tianlang Lyu.

Diagnosis: This species can be distinguished by the following combined characters: a) Coastal margin of tegmina with wavy undulations, b) tegmina markings light yellow, c) near base of coastal cell with a barbell-shaped spot, d) aedeagus with two ventral processes sharing a common stem.

Description: Body length: 6.9–7.4mm (male, n=6).

Coloration: generally light-colored. Head and thorax light-yellow, eyes claret. Abdomen dark brown. Legs light yellow except tarsi and apical spines of tibia, black. Tegmina milky white, decorated with yellow markings ( Fig. 1K–L View FIGURE 1 , Fig. 6D View FIGURE 6 ): base of coastal cell yellow, a bit further but before midpoint with a barbell-shaped yellow spot; at about the same level, a transverse yellow band extend from Sc+RA into clavus, with vague and clouded margins; at middle of tegmina, a transverse yellow band arise near the apex of coastal cell, extending to the apex of claval suture, covering r-m, 1 st and 2 nd m-cu, icua and icu, with well-defined margins; stigmal cell with a large yellow spot, reaching RP; along the subapical margin a twisted yellow band start from apical angle and becomes clouded when extending posterior; at the inner margin of this band, a small black spot between RP1+2 and RP3+4.

Structures: Head and thorax: compound eyes well developed. Coastal margin of tegmina with wavy undulations. RP and Sc+RA share a common stem, RP with 3 terminals. One examined specimen with CuA1 bifurcate apically. Hindwing with RP bifurcate. Coastal margin of tegmina and hindwings often with dense wax secretion.

Male genitalia ( Fig. 4Q–X View FIGURE 4 ): pygofer ( Fig. 4W–X View FIGURE 4 ) generally symmetrical. From lateral view, caudal margins of lateral lobes with subangulate apex. From ventral view, medioventral process large, campaniform, apex with a small sharp prominence.

Anal segment ( Fig. 4U View FIGURE 4 ) generally symmetrical, short. From dorsal view, caudal margin truncate. From lateral view, ventrolateral lobes moderately extended ventrally.

Aedeagus ( Fig. 4R–T View FIGURE 4 ) with 6 processes in total, all visible from left lateral view. Left side near apex with a short process, slightly curved downward, pointing cephalic; a long process raised from left of endosoma, curved rightward; a short dorsal process at the base of endosoma, first directed leftward and cephalic, and curved for ca. 180 degrees, pointing caudally; right side near apex with a long process, directed cephalic; slightly away from apex, two ventral processes share a common stem, with the right one curved dorsally immediately after diverged, and the left one strait, pointing ventrocephalic.

Gonostyli ( Fig. 4V View FIGURE 4 ) symmetrical. Ventral margins smoothly curved, without prominent keel angle. Apex taper, without bifurcation or emargination or strong concavity. Basal half of inner surface bares dense setae.

Female genitalia ( Fig. 5C–D View FIGURE 5 ): Ovipositor gently curved. Posterior vagina with dorsal sclerotization extending further cephalically than ventral sclerotization, structure as shown in Fig. 5D View FIGURE 5 , slightly longer than wide. Bursa copulatric cephalad to vagina. Ductus receptaculi ventral to vagina, not twisted into a helix, with a finger-like transparent lobe near base.

Remarks: This species has such unique appearance that are hardly confused with other known species.

Wings of female specimens are folded due to soak of ethanol; female body length weren’t measured. Females are about the same size as males.

Habitat and Behavior: This species is so far only recorded in the mountainous area of Hainan Island. Most of the type specimens were collected at night in a hotel garden near the entrance of Wuzhishan National Reserve , where the majority of vegetation was artificially planted and specimens dispersed throughout them. One specimen was collected during the daytime using a sweep net, near Boliwan reservoir along road X437, about 40 km from the previous location.

Distribution: Hainan Island (Mt. Wuzhishan).

Etymology: The specific epithet comes from Latin, indicating “with undulations”, referring to the special twist in the coastal margin of their tegmina. The epithet is a masculine adjective.