The genus Paracymus Thomson contains 81 described species worldwide (Hansen, 1999; Short and Fikáček, 2011) and nine species in Palaearctic region (Hansen, 2004; Minoshima, 2014). One species have been recorded in China, two species in Japan and two species in the Far East of Russia (Hansen, 2004; Minoshima, 2014).

Members of Paracymus are characterized by the combination of the following features: dorsal surface of body black; antenna with eight antennomeres; maxillary palpus as long as or shorter than antenna; mesoventrite with a projection pointed apically; elytra with sutural stria and without rows of serial punctures; five abdominal sternites visible (Minoshima, 2014).

In this paper, we report two Paracymus species [Paracymus aeneus (Germar) and P. zaitzevi Shatrovskiy] for the first time in Korea. Habitus and SEM photographs, distribution map, key and diagnoses of the species are provided.

Materials and Methods

To identify Korean Paracymus species more reliably, we compared them with voucher specimens in the Natural History Museum (NHM), London, United Kingdom. The specimens used in this study are deposited in Chungnam National University Insect Collection (CNUIC), Daejeon, Korea. The terms and measurements of specimens mainly followed Komarek (2004) and Archangelsky et al. (2005).

Systematic accounts

Family Hydrophilidae Latreille

Subfamily Hydrophilinae Latreille

Key to the species of the Paracymus in Korea

Paracymus aeneus (Germar, 1824) 염전꼬마검정물땡땡이 (신칭) (Figs. 1A, 2, 4)

Hydrophilus aeneusGermar, 1824: 96.

Hydrobius punctulatusSturm, 1836: 15.

Hydrobius salinusBielz, 1851: 152.

Laccobius cupreusDalla Torre, 1877: 68.

Diagnosis. Length 2.5-3.0 mm. Ventral surface of body most reddish brown. Width of frons about 3.5 times as wide as eye. Mentum (Fig. 2A) subquadrate, 1.5 times as wide as long. Maxillary palpomere (Fig. 2B) 2 about 4.0 times as long as 1, broad apically. Profemur (Fig. 2D) with pubescence on basal two-third. Mesoventral process (Fig. 2C) falcon-shaped, protrude; carina protrude, rounded in lateral view. Mesofemur (Fig. 2E) with pubescence on basal half. Sternite VII (Fig. 2H) rounded apical margin, without a row of spines. Median lobe (Fig. 2I) of aedeagus slender, gradually narrowed apically, shorter than paramere, widest at base; apical part rounded. Paramere (Fig. 2I) broad, widest at base; inner margins nearly straight; outer margins straight; apical part protrude and rounded.

Material examined. KOREA: Chungnam Prov.: 7 exx, Taean-gun, Nam-myeon, Sinon-ri, N36°51′49.23″ E126°12′ 23.75″ 7 m, 30 VII 2013, DH Lee, pond on abandon salt farm (2♂♂1♀, on slides); Gyeonggi Prov.: 8 exx, Ansan-si, Danwon-gu, Daebudong-dong, Dongju-salt farm, N37°14′ 05.60″ E126°36′19.55″ 4 m, 7 XI 2013, DH Lee, IS Yoo, SG Lee, saline pond near salt farm.

Distributions: Asia: Korea, Japan, Russia (East Siberia, Far East), Iran, Israel, Kyrgyzstan, Kazakhstan, Mongolia, Tajikistan, Turkmenistan, Turkey, Europe: Albania, Austria, Bulgaria, Croatia, Czech Republic, Denmark, France, Great Britain, Germany, Greece, Ireland, Italy, The Netherlands, Norway, Poland, Romania, Russia (South European Territory), Slovenia, Spain, Sweden, Ukraine; North Africa: Egypt, Tunisia.

Remarks. This species can be distinguished from P. chalceolus (Solsky) by protarsal claw as long as tarsomere 1 in male and median lobe elongate.

Paracymus zaitzeviShatrovskiy, 1989 꼬마검정물땡땡이 (신칭) (Figs. 1B, 3, 4)

Paracymus zaitzeviShatrovskiy, 1989: 190. Fig. 1, Fig. 4,

Diagnosis. Length 1.6-1.8 mm. Ventral surface of body most dark brown. Width of frons about 3.0 times as wide as eye. Mentum (Fig. 3A) transverse subquadrate, 2.0 times as wide as long. Maxillary palpomere (Fig. 3B) 2 about 4.0 times as long as 1, widest at apical third. Profemur (Fig. 3D) with pubescence on basal half. Mesoventral process (Fig. 3C) falconshaped, protrude; carina weakly protrude, broadly rounded in lateral view. Mesofemur (Fig. 3E) with pubescence on basal two-third. Sternite VII (Fig. 3H) rounded apical margin, with a row of spines. Median lobe (Fig. 3I) of aedeagus slender, broad subapical part, shorter than paramere, widest at base; apical part rounded. Paramere (Fig. 3I) slender, widest at base; slightly curved at apical third; apical part rounded.

Material examined. KOREA: Gyeonggi Prov.: 12 exx. Yeoncheon-si, Yeoncheon-eub, Dongmak-ri, N38°06′45.13″ E127°06′45.13″ 104 m, 26 IX 2014, DH Lee, SG Lee, JS Lee, pond (2♂♂, on slides).

Distribution. Korea, Russia (Far East).

Remarks. This species can be distinguished from P. chalceolus (Solsky) by the small size (less than 2.0 mm) and from P. orientalis Orchymont by the subapical part of median lobe broad.