Meroplius trifurcus sp. nov.

(Figure 3)

Type specimens. Holotype male: Mt.Jieoksan, Morun-ri, Hwaam-myeon, Jeongseon-gun, Gangwong-do, Republic of Korea, 37.289594°N, 128.780604°E, 30.VII.2023, SJ Suh Coll. (KNU); paratype: 1 male, Mt.Jieoksan, Morun-ri, Hwaam-myeon, Jeongseon-gun, Gangwong-do, Republic of KOREA, 37.300598°N, 128.782214°E, 03.VI.2023, SJ Suh Coll. (KNU)

Diagnosis. This new species, like most species in the genus Meroplius, has a straight distal seta on the male fore femur. However, the male surstylus of this species exhibits a distinctive structure with multiple branches apically, similar to M. vittatus Ozerov, 1985, from the Russian Far East, M. flavofemoratus Ozerov, 2000, from Namibia, and M. mirandus Iwasa, 1994, from Nepal. While M. flavofemoratus and M. vittatus have a two-branched surstylus, this species has a three-branched surstylus, like M. mirandus (Iwasa, 1994; Ozerov, 1985, 2000). Additionally, this new species can be distinguished from M. mirandus by the following characteristics: the mesonotum has short acrostichal setulae in irregularly one to two rows (vs. 3 to 4 pairs of short setae in the acrostichal line); the katepisternum has densely greyish microtomentum along the entire upper margin (vs. only on the posterodorsal margin); the mid and hind femora are broadly yellow basally, at least in the basal third (vs. dark brown with yellow rings basally); and the surstylus is trifurcated, with the distal branch longer than the proximal branch (vs. the distal branch shorter than the proximal branch) (Iwasa, 1994).

Description

Male. Body length: 3.1–3.3 mm; wing length: 2.3–2.4 mm.

Head: Mostly black; frontal vitta and fronto-orbital plate black, subshining; face black with a reddish-brown facial carina; parafacial dark brown; gena black, with height below the eye slightly narrower than 1/10 of vertical diameter of eye; 1 each of orbital, ocellar, inner vertical, outer vertical, postocellar, vibrissae, and some short subvibrissal setae present; outer vertical seta about half of orbital seta, (Figs. 3A–B). Antenna mostly dark; light to reddish brown around the articulation of the pedicel and postpedicel, especially on the posterior margin of the inner surface; postpedicel rounded apically, 1.3–1.4 times as long as wide; arista dark, bare. Palpus: Very small, yellow to reddish brown; proboscis yellow to reddish brown.

Thorax: Black; scutum with delicately greyish microtomentum; proepisternum with greyish microtomentum; anepisternum shining black; anepimeron shining black, with greyish microtomentum on anterior half; katepisternum shining black, with densely greyish microtomentum along the entire upper margin; 1 postpronotal, 2 notopleural, 0+1 supra-alar, 1 postalar, and 0+1 dorsocentral setae present; acrostichal setulae in irregular one to two rows; short setulae dorsocentral, and intra-alar lines; 1 posteromarginal anepisternal seta and 1 seta around the posterior spiracle present; scutellum greyish-dusted, with strong apical seta and fine, short basal setae (Figs. 3B).

Legs: Foreleg yellow with mostly dark tarsus, but basal tarsomere pale; mid and hind legs with coxae and trochanters yellow, femora dark with broadly yellow at least in basal third, knees yellow, tibiae mostly dark but partly yellow apically, tarsi mostly yellow but darkening in distal tarsomeres; fore coxa with 1 preapical dorsal seta; fore femur with 2 black spines ventrally, 1 slender subapical anteroventral seta slightly longer than 3/4 of femur width (Fig. 3C); fore tibia thickened in apical third with protuberance (Fig. 3C); mid and hind femora, and hind tibia without setae; mid tibia with 1 ventral seta in apical third; hind tibia without a distinct osmeterium, occupying most of basal third of tibia.

Wing: Hyaline, covered with microtrichia; veins light brown; calypter and halter white.

Abdomen: Shining black, with some violet reflections; tergites 4–5 with several marginal setae; sternal appendage as in Fig. 3D; surstylus trifurcated and asymmetrical, distal branch longer than proximal branch (Figs. 3E–F). Phallus as in Figs. 3G–H.

Female. Unknown.

Etymology. The specific name is derived from the characteristic of the male surstylus being apically trifurcated, and is based on the Latin word “trifurcus,” meaning “three-branched” (from “tri-” meaning “three” and “furca” meaning “fork” or “branch”).

Distribution. Republic of Korea.

Remarks. This new species was collected using the sweeping method from the herbaceous vegetation below the highland forest at an elevation of about 1100 meters.