The genus Stomaphis Walker, 1870 comprises of 37 Palaearctic species, feeding on trunks or roots of various deciduous trees and conifers (Blackman and Eastop 2020;Favret, 2020). This genus is morphologically distinguished from other female aphids by the large body length and rostrum much longer than the body (Depa and Mróz, 2013). To date, four species of Stomaphis have been documented from Korea: Stomaphis asiphon Szelegiewicz, 1975; S. japonica Takahashi, 1960; S. sinisalicis Zhang and Zhong, 1982; S. yanonis Takahashi, 1918. Here, we report Stomaphis matsumotoi on Juglans mandshurica Maxim. (Juglandaceae) for the first time in Korea.

Materials and Methods

Colonies of Stomaphis matsumotoi individuals were found on the trunks of Juglans mandshurica Maxim. (Juglandaceae) in 2019. The fresh aphid samples were preserved in 95% alcohol and slide glass specimens were mounted on Canada balsam, following Blackman and Eastop’s (2000) methods. Measurements and digital images were taken using Leica DMC 5400 (Leica Z16 APO) and Leica DM 4000B (Active Measure version 3.0.3; Mitani Co. Ltd., Japan). The samples examined in this study are deposited in the College for Agri- culture and Life Sciences, Seoul National University (Korea). The synonym information of the plant follows The Plant List (2013). Abbreviations used for descriptions are as follows: apt., apterous viviparous female; Ant, antennae; Ant I, Ant II, Ant III, Ant IV, Ant V, Ant VIb, and PT, antennal segments I, II, III, IV, V, base of VI, and processus terminalis of antennomere VI respectively; BL, body length; HW, greatest head width across compound eyes; GP, genital plate; HT Ⅰ, first segment of hind tarsus; HT II, second segment of hind tarsus; MT II, second segment of middle tarsus; SIPH, siphunculi; URS, ultimate rostral segment (segment IV+V); AbdT I–VIII, Abdominal tergites I–VIII respectively.

Systematic Accounts

Stomaphis (Stomaphis) matsumotoiSorin, 1995 가래나무주둥이왕진딧물(신칭) (Table 1; Figs. 1, 2)

Stomaphis (Stomaphis) matsumotoiSorin, 1995: 148, 152.

Stomaphis (Stomaphis) matsumotoiSorin, 1995: Remaudière and Remaudière, 1997: 205; Sorin, 2012: 30; Matsumoto, 2017: 71–73.

Description. Apterous viviparous female. Color (alive): Body dark brown with slightly white wax. Head and pronotum dark brown. Antenna brown with bases of Ant III light brown. Legs brown, hind femora and hind tibiae brown with darker knee area, hind tarsi brown. URS, SIPH sclerites, GP, cauda, and ventral plates dark brown (Fig. 1). (mounted specimens): Body brownish, head dark brown. Antennae brown with bases of Ant III light brown. Legs brown, hind femora and hind tibiae brown with darker knee area, hind tarsi brown. URS, SIPH sclerites, GP, cauda, and ventral plates dark brown (Fig. 2A– H). Morphology: Antennae 0.459–0.540×BL and 1.771– 1.907×HW, Ant IV/III 0.413–0.437, Ant V/III 0.483–0.526, Ant VI/III 0.691–0.696, PT/Ant VIb 0.201–0.204. Ant III a little curved with 0–7 circular, secondary rhinaria, Ant IV with 2–7 secondary rhinaria (Fig. 2H). Rostrum longer than BL, telescopic, URS 0.672–0.794×Ant III, URS 0.860–1.006×HT II (Fig. 2E, F). Labrum covered with 53–75 accessory setae. HT II 2.260–2.263×MT II. Head and pronotum sclerotized, mesonotum with spinal and marginal sclerites, and metanotum with spinal sclerites. AbdT I, II, and VII with a pair of spinal sclerites, AbdT III–VI without sclerites. AbdT VIII with a sclerotic band, divided at the middle. Abdominal segment VIII with latero-ventral processi. Cauda rounded (Fig. 2C). Ventral side of the abdomen with 5 long barrel-shaped sclerotized patches. SIPH pore surrounded by sclerite plate (Fig. 2D). Other measurements and morphological differences are given in Table 1.

Specimens examined. 3 apt., Coll. 20190730-LMH-1, Soheul-eup, Pocheon-si, Gyeonggi-do, Korea, 30. vii. 2019, on Juglans mandshurica Maxim. (Juglandaceae), leg. Hong-yul Seo; 8 apt., Coll. 20190919-LMH-1, Soheul-eup, Pocheon-si, Gyeonggi-do, Korea, 19. ix. 2019, on Juglans mandshurica Maxim. (Juglandaceae), leg. Euiyoung Kang, Heungyoon Oh.

Host plants. Juglans mandshurica Maxim. (Juglandaceae) (Sorin, 1995).

Distributions. Korea (new record), Japan.

Remarks. According to Masato Sorin’s description (1995), body color is dark brown in life. In this study, we found dark brown with slightly white wax from Korean samples (Fig. 1).

Key to species of Stomaphis in Korea