Myiomma koreana Oh & Lee, 2025

Myiomma koreana Oh & Lee , sp. nov.

( Figs. 1–8 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 )

Myiomma kukai Jung & Lee, 2012: 53 View in CoL (misidentification of M. koreana ).

Diagnosis. This species can be distinguished from its closely allied species, M. takahashii and M. kukai by the combination of following characteristics: dorsum covered with brownish, reclining setae; antennal segment I widely pale brown in male, chestnut brown in female; antennal segment II pale brown except apical 1/ 3 in male, widely dark brown and base and apex narrowly pale in female; hemelytra without reddish tinge, semitransparent and brownish in male and widely dark brown in female; cuneus dark brown, anterior 1/3 pale; all male coxae widely dark brown, all femora dark brown with reddish tinge medially, apically pale; all female coxae and femora widely dark brown, apex of metafemur narrowly pale; inner margin of left paramere sensory lobe with comparatively weak protrusion, outer margin wide and covered with stiff setae.

Description. Male. Body elongated oval, 2.10–2.20; Coloration: Body brown to dark brown, partly tinged with red; Head dark brown, posterior margin yellowish white, posterolateral margin partly reddish brown; vertex and frons partly pale brown along inner margin of compound eye; clypeus tinged with red. Antennae brown; antennal segment I widely pale brown, segment II pale brown, apical 1/3 darkened, segment III and IV brown, apically pale. Labium dark chestnut brown, segment III medially pale. Pronotum entirely dark brown, lateral side partly brown. Mesoscutum dark brown, lateral side widely pale, tinged with orange-red coloration. Scutellum dark brown, apical 1/3 whitish, extreme apex blackish brown. Hemelytra brown, semi-transparent, basal part of corium narrowly pale, with minute reddish tinge; cuneus brown basal 1/3 pale; membrane pale smoky brown, partly darkened along inner side of vein. Legs brownish; coxae dark brown, femora widely dark brown and medially tinged with red; metafemur dorsally pale brown and ventrally dark brown with reddish tinge, apical 1/4 pale; metatibia brown, apically pale; tibial spines pale brown; tarsi brown. Abdomen dark brown, pygophore apically reddish brown. Surface and vestiture: Dorsal surface weakly shiny, covered with pale brown to dark brown simple setae. Head weakly glabrous, frons sparsely covered with reclining pale brown setae; posterolateral margin with stiff, pale brown setae; Antennal segment II covered with suberect, brown setae. Pronotum and scutellum covered with brown, reclining setae; posteromedial margin with long, reclining brown setae. Hemelytra weakly shiny, densely covered with brown, suberect simple setae. Femora sparsely covered with short, pale setae and suberect, simple setae. Structure: Head dorsoventrally elongate, waterdrop-shaped in anterior view; posterior margin of vertex V-shaped. Antennal segment I very short and incrassate, segment II thick, elongated and weakly clavate, segment III and IV short and thin. Labium long, reaching abdominal sterna V–VII. Foreleg and midleg slender, hindleg with thick metafemur and elongated, linear metatibia. Male genitalia as in Figs. 4–6 View FIGURE 4 View FIGURE 5 View FIGURE 6 ; left paramere L-shaped; sensory lobe tumid, inner margin with weak protrusion and outer margin round, sparsely covered with long, stiff setae; Hypophysis smooth and elongated, distinctly curved medially; right paramere small, weakly curved and horn-shaped; basal part of sensory lobe with a minute protrusion; endosoma membranous, with a thin, elongated sclerotized structure; phallotheca conical, tapering apically and inner margin well sclerotized. Female. Body elongate oval, 2.10–2.30; body comparatively ovoid, overall coloration darker than in male; antennal segment I and II dark brown, segment III and IV brown; segment II not clavate, pale at extreme apex; apical half of scutellum with wide, V-shaped white marking; hemelytra dark brown, femora almost entirely dark brown; metafemur dark brown, apical 1/4 pale, mottled with dark brown and reddish tinge; basal 2/3 of metatibia dark brown. Not significantly different from male in surface and vestiture. Female genitalia as in Fig. 7 View FIGURE 7 ; sclerotized rings small and mutually adjacent, weakly sclerotized and ovate, lateral margin pointed at apex; dorsal labiate plate weakly sclerotized, surface somewhat wrinkled; ventral side of bursa copulatrix with a pair of waterdrop-shaped ventral structures; interramal lobe and sclerite weakly sclerotized, surface rugose; gonapophysis I leaflike, ventral margin moderately curved; gonapophysis II smooth, apical margin similar as spoon-style ship bow.

Measurements. Male (n=2)/ Female (n=5). Total body length 2.14–2.17/ 2.16–2.29; head width across eyes 0.42–0.44/ 0.42–0.44; vertex width 0.08–0.09/ 0.08–0.09; lengths of antennal segment I–IV 0.08, 0.64–0.67, 0.10– 0.11, 0.09–0.11/ 0.09–0.10, 0.50–0.52, 0.17–0.18, 0.13–0.14; labial length 1.00/ 0.88–1.02; mesal pronotal length including collar 0.30–0.33/ 0.30–0.32; basal pronotal width 0.83/ 0.83–0.90; width across hemelytron 0.98–1.01/ 0.97–1.10; cuneal length 0.36–0.39/ 0.36–0.38; cuneal width 0.23–0.24/ 0.25–0.27; lengths of metafemur, tibia and tarsus 0.66, 0.88, 0.22/ 0.66–0.73, 0.94–0.97, 0.22–0.23.

Etymology. Named after the type locality, the Korean Peninsula; an adjective.

Distribution. Korea (Gyeonggi-do; Gyeongsangbuk-do; Jeollabuk-do).

Biology. This species was collected from the tree bark of Quercus palustris Münchh. ( Fagaceae ), Zelkova serrata (Thunb.) Makino ( Ulmaceae ), and Salix sp. ( Salicaceae ). In Suwon-si and Gwacheon-si, this species coinhabited the bark surface with I. amurensis , another isometopine species commonly found in deciduous tree bark in Korea. Observed specimens constantly probed the bark surface with its labium stretched forward ( Figs. 1C, D View FIGURE 1 ), and rapidly scuttle away or jump when disturbed.

Type material. Holotype, ♂: South Korea, Gyeongsangbuk–do: Mt. Gaya, Seongju-gun , from light trap, 06.viii.2022, WG Kim ( SNU) . Paratypes: South Korea, Gyeonggi–do: 4♀ Gwanggyo park, Gwanggyosan-ro 159, Jangan–gu , Suwon–si , from Quercus palustris , 26.vi.2024, M. S. Oh & W. Kim ( SNU) ; 1♀, ditto, from Salix sp. , 26.vi.2024, M. S. Oh & W. Kim ( SNU) ; 1♀, Empty lot near Gwacheon civic center , Tongyeong-ro 5, Gwacheon-si , from Zelkova serrata , 28.vi.2024, W. Kim ( SNU) ; 1♀, Garaeul park , Neunggok-dong 793, Siheung-si , from Quercus palustris , 28.vi.2024, W. Kim ( SNU) .

Additional material. 1♂: South Korea, collection information unknown (SNU).

Discussion. Previously, Jung & Lee (2012) added molecular data of Myiomma kukai Yasunaga & Hayashi, 2002 , into their phylogenetic analysis dataset. While preparing the manuscript for Myiomma koreana , we found the voucher specimen which was suspected to be the reference specimen of this sequence at the insect collection at Seoul National University CALS. Despite that this specimen did not bearing a collection label and the exact collection information was not available, we were able to examine it in morphological detail. Although Jung & Lee (2012) did not mention the collection records for each of the analyzed species, most specimens deposited at SNU CALS were collected from South Korea by researchers at Prof. Seunghwan Lee’s lab between the late 2000s and the early 2010s, and this Myiomma sample is also presumed to have been collected in South Korea. Based on the comparison of the external morphology and genital characters, this specimen is conspecific with our new species, Myiomma koreana . Pairwise distance between each sequence is less than 0.2% ( Table 2 View TABLE 2 ), which can be regarded as intraspecific variation based on former barcoding research on Miridae ( Jung et al., 2011; Kim & Jung, 2018). NJ tree results also show a close relationship between ‘ Myiomma kukai ’ from Jung & Lee (2012) and our new species ( Fig. 9 View FIGURE 9 ). M. kukai is endemic to Japan (Honshu and Kyushu) ( Yasunaga 2001, Yasunaga et al. 2017, Shishido et al. 2020), and has never been reported from Korea. We therefore clarify that the ‘ M. kukai ’ sequence provided by Jung & Lee (2012) pertains to our new species, M. koreana , not M. kukai from Japan.

Furthermore, all specimens that were hand-collected by the first and second author from tree bark were female, while a single male was obtained by light trap by the third author. Species of Myiomma exhibit sexual dimorphism regarding eye size and dorsal coloration ( Yasunaga et al. 2017, Sishido et al. 2020), making it hard to properly link males and females by traditional morphological means, except when the male and female are collected at the same locality have been treated as conspecific. With the help of DNA barcoding on the COI region, we were able to confirm that the two morphologically different specimens of the new species represent sexual dimorphism.