Anim. Syst. Evol. Divers. Vol. 36, No. 2: 185-191, April 2020 https://doi.org/10.5635/ASED.2020.36.2.020 Short communication A New Record of the Cosmopolitan Species Caprella mutica (Crustacea: Amphipoda: Caprellidae) from Korean Waters, with Comparison to Caprella acanthogaster Jun-Haeng Heo1, So-Yeon Shin1, Chang-Mok Lee2, Young-Hyo Kim1,* 1Department of Life Sciences, Dankook University, Cheonan 31116, Korea 2Hanmin High School, Paju 10955, Korea ABSTRACT A newly recorded species Caprella mutica Schurin, 1935 belonging to the family Caprellidae Leach, 1814 was collected from the East Sea, Korea. Caprella mutica is native to the north-east Asia but is a well-known cosmopolitan and invasive species in many areas. This species is morphologically highly similar to C. acanthogaster Mayer, 1890. However, it is distinguished from a combination of the characteristics of the head, pereonites 1-2, and gnathopod 2. In this study, the Korean C. mutica is fully illustrated based on the mature specimens and compared to C. acanthogaster. Keywords: Amphipoda, Caprellidae, Caprella mutica, new record species, Korea INTRODUCTION particles from the water column (Nauwelaerts et al., 2007). However, C. mutica have been confused morphologically The genus Caprella Lamarck, 1801 is one of the 95 genera with C. acanthogaster Mayer, 1890 because they have mixed belonging to the family Caprellidae Leach, 1814 and contains characteristics. Caprella acanthogaster was newly recorded 184 species (Horton et al., 2020). This genus is characterized in Korean waters with a brief description by Kim and Lee with (1) biarticulate flagellum in the antenna 2; (2) mandib- (1978). Thus, we suggest illustrations of C. mutica and C. ular palp absent; (3) pereonites 3-4 with gills; (4) pereopods acanthogaster, and compare the two species through their 3-4 absent; and (5) abdomen with a pair of appendages and morphological characteristics in this paper. Specimens were a pair of lobes in the male (McCain, 1968; Arimoto, 1976). collected by SCUBA diving and light trapping from the shal- Among them, Caprella mutica was first described as a type low and subtidal waters in Korea (Fig. 1) and were deposited locality in Peter the Great Bay by Schurin (1935). After, in the National Institute of Biological Resources (NIBR), Vassilenko (1967, 1974) and Arimoto (1976) dealt with this Incheon, Korea and the Marine Amphipod Resources Bank species more specifically. This species has a wide range of of Korea (DARBK), Dankook University, Cheonan, Korea. distribution globally and is well-known as a cosmopolitan and invasive species by navigation development, indigenous to north-east Asia (Schurin, 1935; Willis et al., 2004; Cook SYSTEMATIC ACCOUNTS et al., 2007; Ashton et al., 2007, 2008; Frey et al., 2009; Schückel et al., 2010; Boos et al., 2011; Almón et al., 2014; Order Amphipoda Latreille, 1816 Peters and Robinson, 2017). It is associated with macro-algae Family Caprellidae Leach, 1814 in shallow water (Fedotov, 1991; Ashton et al., 2007). Addi- Genus Caprella Lamarck, 1801 tionally, C. mutica is known predominantly as a detritivore (Guerra-García and De Figueroa, 2009) capable of swaying 1*Caprella acanthogaster Mayer, 1890 (Figs. 2A, 3) their bodies through the water using a setose antennae to filter Caprella acanthogaster Mayer, 1890: 80, Pl. 7, figs. 52, 53; This is an Open Access article distributed under the terms of the Creative *To whom correspondence should be addressed Commons Attribution Non-Commercial License (http://creativecommons.org/ Tel: 82-41-550-3442, Fax: 82-41-559-7861 licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, E-mail: [email protected] and reproduction in any medium, provided the original work is properly cited. eISSN 2234-8190 Copyright The Korean Society of Systematic Zoology Jun-Haeng Heo, So-Yeon Shin, Chang-Mok Lee, Young-Hyo Kim 1903: 78, Pl. 3, fig. 3; Vassilenko, 1974: 204, figs. 120, 36°43′15.25″N, 129°43′09.38″E, 14 Aug 2018, Kim YH, Lee 121; Arimoto, 1976: 169, figs. 91, 92; Martin, 1977: 154, SG; 3♂♂, Pohang-si, Nam-gu, Guryongpo-eup, Janggil-ri, fig. 3; Kim and Lee, 1978: 2, fig. 2; Guerra-García and 35°56′58.65″N, 129°32′48.66″E, 5 Mar 2019, Lee SG; 3♂ Takeuchi, 2004: 996, figs. 21-26; Vassilenko, 2006: 110, ♂, Uljin-gun, Pyeonghae-eup, Jiksan-ri, 36°43′24.32″N, Pl. 16; Lee and Hong, 2011: 14, fig. 3. 129°28′35.51″E, 6 Mar 2019, Lee SG. Description. Male (DARBK-203): Body (Figs. 2A, 3A) long Material examined. 3♂♂, Korea: Jeollanam-do: Jangheung- and slender, 15.3 mm long, covered with tiny tubercles. Head gun, Hoejin-myeon, Duksan-ri, Noryeoksin Port, 34°26′40.5″ unarmed, except a pair of tiny tubercles in middorsally. Eye N, 126°57′53.2″E, 15 Sep 2015, Kim SH, Heo JH; 1♂, small and round. Pereonite 1 elongate and fused with head, Gyeongsangbuk-do: Uljin-gun, Pyeonghae-eup, Hupo-ri, 0.80 times shorter than pereonite 2; pereonite 2 longest, with several spines posterodistally; pereonite 3 slightly longer than pereonite 4, with dorsal and lateral spines, elongated gills; pereonite 5 subequal to pereopod 4, with dorsal and lateral spines; pereonites 6-7 short, with dorsal spines; length ratio of pereonites 2-7 1.00 : 0.70 : 0.65 : 0.60 : 0.27 : 0.31. Antenna 1 (Fig. 3B) 0.73 body length; peduncular articles = 1-3 thick, with sparse short setae and covered with tiny tu- × bercles; peduncular article 3 slightly widening distally; length ratio of peduncular articles 1-3 1.00 : 1.71 : 1.43; flagellum slender, 21-articulate, 0.54 peduncle, eac h article with 1 = aesthetasc ventrodistally. × Antenna 2 (Fig. 3C) setose, much shorter than antenna 1, not reaching the distal end of peduncular article 2 of anten- na 1; peduncular articles 4-5 and flagellum article 1 with many long swimming setae ventrally; length ratio of pedun- cular articles 3-5 1.00 : 3.66 : 3.90; flagellum biarticulate, 0.84 peduncular article 5. = Gnathopod 1 (Fig. 3D) small, basis expanded posteriorly, Fig. 1. Collecting sites of Caprella mutica (●) and Caprella × acanthogaster (■) in this study. 1, Jiksan-ri, Uljin-gun; 2, No- with anterodistal process; merus subequal to ischium, with ryeoksin Port, Jangheung-gun; 3, Jimak-ri, Jindo-gun; 4, Dae- simple setae distally; carpus short, subtriangular, with ex- jukdo Island, Gochang-gun; 5, Janggil-ri, Pohang-si, Korea. pending rounded lobe and long simple setae ventrodistally; A B Fig. 2. Caprella acanthogaster Mayer, 1890 (A) and Caprella mutica Schurin, 1935 (B). A, Mature male, 15.1 mm, habitus; B, Ma- ture male, 19.1 mm, habitus. Scale bars: A 3.0 mm, B 2.0 mm. = = Korean name: 1*가시투성바다대벌레 186 Anim. Syst. Evol. Divers. 36(2), 185-191 A New Record of Caprella mutica from Korea B A C D E F G H Fig. 3. Caprella acanthogaster Mayer, 1890, mature male, 15.1 mm. A, Habitus; B, Antenna 1; C, Antenna 2; D, Gnathopod 1; E, Gnathopod 2; F, Pereopod 5; G, Pereopod 6; H, Pereopod 7. Scale bars: A 2.0 mm, B, E, H 1.0 mm, C, D, F, G 0.4 mm. = = = Anim. Syst. Evol. Divers. 36(2), 185-191 187 Jun-Haeng Heo, So-Yeon Shin, Chang-Mok Lee, Young-Hyo Kim propodus subtriangular, narrowing distally, palm slightly con- out process. Eye small and round. Pereonite 1 elongate and vex, with unequal setae, proximal projection conspicuously fused with head 0.86 times shorter than pereonite 2; pereonite provided; dactylus falcate, slightly exceeding palm; length 2 longest, covered with numerous hair, with a pair of small ratio of 6 articles 1.00 : 0.31 : 0.35 : 0.53 : 1.39 : 1.37. spines posterodistally; pereonite 3 slightly longer than pere- Gnathopod 2 (Fig. 3E) attached to rather distoventral por- onite 4, with dorsal and lateral spines and elongated gills; = tion of pereonite 2, long and slender, covered with tiny tu- pereonite 5 subequal to pereonite 3, narrowed both lateral bercles; basis, ischium, merus with process on each distal margins, with dorsal and lateral spines; pereonites 6-7 short, portion, propodus elongate, nearly as long as basis, width with dorsal spines; length ratio of pereonites 2-7 1.00 : 0.51 : 0.50 length, covered with unequal setae, palm with triangu- 0.46 : 0.51 : 0.22 : 0.22. = lar projection near distal margin, poison tooth situated nearly Antenna 1 (Fig. 4B) 0.81 body length; peduncular ar- × triangular projection, and a grasping spine; dactylus falcate, ticles 1-3 thick, with rare short setae; peduncular article 3 × strongly curved; length ratio of 6 articles 1.00 : 0.14 : 0.28 : slightly widening distally; length ratio of peduncular arti- 0.09 : 1.42 : 0.89. cles 1-3 1.00 : 2.14 : 1.64; flagellum slender, 19-articulate, = Pereopod 5 (Fig. 3F) regenerated form; basis with small 0.35 peduncle, each article with 1 aesthetasc ventrodistally. = triangular process posterodistally; ischium short; merus ex- Antenna 2 (Fig. 4C) setose, much shorter than antenna 1, × panded posteriorly with simple setae; carpus with simple se- not reaching the distal end of peduncular article 2 of anten- tae on both margins; propodus longest, with long simple setae na 1; peduncular articles 4-5 and flagellum article 1 with posteriorly, distal margin with long setae, palm definded by a many long swimming setae ventrally; length ratio of pedun- pair of grasping spines midanteriorly; dactylus falcate, slight- cular articles 3-5 1.00 : 4.07 : 4.44; flagellum biarticulate, ly exceeding grasping spines; length ratio of 6 articles 1.00 : 0.65 peduncular article 5. = 0.18 : 0.89 : 0.62 : 1.85 : 1.15. Gnathopod 1 (Fig. 4D) small, basis expanded posteriorly, = × Pereopod 6 (Fig. 3G) similar to pereopod 5, but merus with anterodistal process; merus subequal to ischium, with more stout and elongated than that of pereopod 5; length ratio simple setae distally; carpus short, subtriangular, with ex- of 6 articles 1.00 : 0.29 : 1.17 : 0.66 : 2.29 : 1.69. pending rounded lobe and long simple setae ventrodistally; Pereopod 7 (Fig. 3H) similar to pereopod 5, but merus nar- propodus subtriangular, narrowing distally, palm slightly con- = rower and more elongated than that of pereopod 5; length ra- vex, with unequal setae, proximal projection conspicuously tio of 6 articles 1.00 : 0.24 : 1.18 : 0.90 : 1.69 : 1.30. provided; dactylus falcate, slightly exceeding palm; length Distribution. North-Pacific Ocean (Mayer, 1890; Vassilenko, ratio of 6 articles 1.00 : 0.38 : 0.38 : 0.58 : 1.08 : 1.12. = 1974; Arimoto, 1976), South America (Martin, 1977). Gnathopod 2 (Fig. 4E) attached to rather distoventral por- = tion of pereonite 2, long and slender, covered with dense 1*Caprella mutica Schurin, 1935 (Figs. 2B, 4) hair; basis, ischium, merus with process on each distal Caprella mutica Schurin, 1935: 198, fig. 1; Vassilenko, 1974: portion, propodus elongate, nearly as long as basis, width 201, figs. 118, 119; Arimoto, 1976: 111, fig. 59; Faasse, 0.30 length, palm with triangular projection near distal mar- 2005: 22, figs. 1-3; Turcotte and Sainte-Marie, 2009: 1, fig. gin, poison tooth situated nearly triangular projection, with a × 1; Boos et al., 2011: 129, fig. 2; Daneliya and Laakkonen, grasping spine, unequal simple setae on palmar margin; dac- 2012: 1, figs. 2, 3. tylus falcate, strongly curved; length ratio of 6 articles 1.00 : 0.13 : 0.25 : 0.03 : 1.20 : 0.71. = Material examined. 1♂, Korea: Jeollanam-do: Jindo-gun, Pereopod 5 (Fig. 4F) stout; basis with large triangular pro- Gogun-myeon, Jimak-ri, 34°28′19.36″N, 126°21′48.27″E, 1 cess posterodistally; ischium short; merus expanded posterior- Jul 2004, Kim YH, Yu CJ; 1♂, Jeollabuk-do: Gochang-gun, ly with simple setae; propodus longest, with long simple setae Simwon-myeon, Mandol-ri , Daejuk-do Island, 35°32′17.4″N, posteriorly, palm defined by a pair of grasping spines midan- 126°29′00.8″E, 26 Jun 2014, Hong SS, Kim SH; 1♂, Jeolla- teriorly; dactylus falcate, slightly exceeding grasping spines; nam-do: Jangheung-gun, Hoejin-myeon, Duksan-ri, Noryeok- length ratio of 6 articles 1.00 : 0.39 : 1.18 : 1.08 : 2.50 : 2.09. sin Port, 34°26′40.5″N, 126°57′53.2″E, 15 Sep 2015, Kim Pereopod 6 (Fig. 4G) similar to pereopod 5, but merus = SH, Heo JH; 1♂, Gyeongsangbuk-do: Uljin-gun, Pyeonghae- more elongated than that of pereopod 5; length ratio of 6 arti- eup, Jiksan-ri, 36°43′24.32″N, 129°28′35.51″E, 6 Mar 2019, cles 1.00 : 0.57 : 1.70 : 1.35 : 2.85 : 2.38. Lee SG. Pereopod 7 (Fig. 4H) regenerated form; similar to pereopod = Description. Male (cat no. NIBRIV0000865950): Body (Figs. 5, but basis elongated; length ratio of 6 articles 1.00 : 0.18 : 2B, 4A) long and slender, 17.7 mm long. Head smooth with- 0.59 : 0.44 : 1.08 : 0.90. = Korean name: 1*털손가시투성바다대벌레 (신칭) 188 Anim. Syst. Evol. Divers. 36(2), 185-191 A New Record of Caprella mutica from Korea A B D C F G E H Fig. 4. Caprella mutica Schurin, 1935, mature male, 17.7 mm. A, Habitus; B, Antenna 1; C, Antenna 2; D, Gnathopod 1; E, Gna- thopod 2; F, Pereopod 5; G, Pereopod 6; H, Pereopod 7. Scale bars: A, B 2.0 mm, C, D, F-H 0.4 mm, E 1.0 mm. = = = Anim. Syst. Evol. Divers. 36(2), 185-191 189 Jun-Haeng Heo, So-Yeon Shin, Chang-Mok Lee, Young-Hyo Kim Distribution. North-East Asia, Pacific and Atlantic Ocean of tute of Biological Resources (NIBR), funded by the Ministry North America, Europe, New Zealand (reviewed in Ashton et of Environment (MOE) of the Republic of Korea (NIBR2008 al., 2007), South Africa (Peters and Robinson, 2017). and NIBR201928201). Remarks. Caprella mutica is markedly similar to C. acan- thogaster and the congeneric characteristics are as follow: (1) antenna 1, peduncular article elongate and peduncular article REFERENCES 3 slightly widening distally; (2) antenna 2, peduncular articles 4-5 and flagellum article 1 with many long swimming setae; Almón B, Pérez J, Bañón R, Trigo J, 2014. First record of Ca- (3) gnathopod 2 elongated, with poison tooth and a grasping prella mutica from the Iberian Peninsula: expansion south- spine; (4) pereonites 3-4 with elongated gills; (5) pereopods wards in European waters. 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The Capreillidae (Crustacea: Amphipoda) the United Kingdom, 84:1027-1028. https://doi.org/10.1017/ of the Western North Atlantic. Bulletin of the United States S0025315404010355h National Museum, 278:1-147. https://doi.org/10.5479/ si.03629236.278 Received March 23, 2020 Nauwelaerts S, Michel K, Stamhuis E, Boos K, 2007. Is the Jap- Revised April 22, 2020 anese skeleton shrimp Caprella mutica a filter feeder? II. Accepted April 22, 2020 Anim. Syst. Evol. Divers. 36(2), 185-191 191