Anim. Syst. Evol. Divers. Vol. 37, No. 3: 249-254, July 2021 https://doi.org/10.5635/ASED.2021.37.3.021 Short communication The First Record of the Genus Hemiaegina (Crustacea, Amphipoda, Caprellidae) from Jeju-Island, Korea So-Yeon Shin, Jun-Haeng Heo, Young-Hyo Kim* Department of Life Sciences, Dankook University, Cheonan 31116, Korea ABSTRACT Hemiaegina minuta Mayer, 1890 belonging to the family Caprellidae was collected from Jeju Island in Korea. This species has extensive habitats worldwide but it is the first record of the genus Hemiaegina from Korean waters. This monotypic species of the genus Hemiaegina has the following characteristics: gnathopod 1, propodus with a roundly swollen proximal projection; gnathopod 2, propodus with a bilobed triangular process; pereonite 2 with a pair of projections ventrally; and pereopod 7, propodus with a serrated palm. In this study, H. minuta is fully illustrated based on the mature specimens. Keywords: Crustacea, Amphipoda, Caprellidae, Hemiaegina, Korea INTRODUCTION the subtidal waters of Jeju Island and were deposited into the National Institute of Biological Resources (NIBR) in Incheon, The genus Hemiaegina Mayer, 1890 belongs to a very large Korea and the Marine Amphipod Resources Bank of Korea group, the family Caprellidae Leach, 1814, but contains (MARBK) in Cheonan, Korea. only one species, Hemiaegina minuta Mayer, 1890. This is a monotypic species with a wide global distribution (McCain, 1968; Müller, 1990; Guerra-García and Lowry, 2009; Guer- SYSTEMATIC ACCOUNTS ra-García et al., 2010; Zeina and Guerra-García, 2016; Horton et al., 2021, see the details in the distribution section below). Order Amphipoda Latreille, 1816 The genus Hemiaegina is characterized by having (1) a bi- Family Caprellidae Leach, 1814 articulate flagellum in antenna 2; (2) pereopods 3 and 4 with 1*Genus Hemiaegina Mayer, 1890 uniarticulate appendages at the base of the gills; and (3) an abdomen with a pair of biarticulate appendages. Three spe- 2*Hemiaegina minuta Mayer, 1890 (Figs. 1-3) cies of the genus Hemiaegina were previously reported (May- Hemiaegina minuta Mayer, 1890: 40, Pl. 1, figs. 25, 27, Pl. 3, er, 1890; Sundara Raj, 1927; Quitete, 1972), but the morpho- figs. 32-35, Pl. 5, figs. 52-53, Pl. 6, figs. 13, 33-34, Pl. 7, logical differences between the three species were recognized fig. 4; Steinberg and Dougherty, 1957: 281, figs. 8-11, 13, as intraspecific variations, so they were synonymized (Serejo, 29; McCain, 1968: 61, figs. 29-30; Utinomi, 1969: 297, 1997; Guerra-García et al., 2010). Thus, they were revised fig. 2; Arimoto, 1976: 58, fig. 26; Serejo, 1997: 630, figs. to a single species, H. minuta (Horton et al., 2021). Previous 11-16; Guerra-García, 2003a: 105-106, fig. 10; 2003b: studies of this species have reported insufficient descriptions 6-7, fig. 3; 2004: 39, fig. 32; Díaz et al., 2005: 249, fig. 9; or illustrations, so we provide redescription of Korean Hemi- Krapp-Schickel and Guerra-García, 2005: 50, fig. 3; Guer- aegina minuta, including illustrations of the appendages. This ra-García and Lowry, 2009: 295, fig. 3; Zeina and Abou study is the first record of the genus Hemiaegina from Ko- Zaid, 2013: 228, figs. 5-6; Paz-Ríos et al., 2014: 2517, fig. rean waters. Specimens were collected by SCUBA diving in 9; Zeina and Guerra-García, 2016: 233, fig. 3. Korean name: 1*작은아가미다리바다대벌레속 (신칭), 2*작은아가미다리바다대벌레 (신칭) 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 So-Yeon Shin, Jun-Haeng Heo, Young-Hyo Kim A B Fig. 1. Hemiaegina minuta Mayer, 1890. A, Male, 4.5 mm; B, Female, 4.0 mm. Scale bars: A, B 1.0 mm. = Hemiaegina quadripunctata Sundara Raj, 1927: 126, Pl. 18. ing distally; propodus massive, width 0.55 length, with a Hemiaegina costai Quitete, 1972: 165, figs. 1-2. small grasping spine on proximal projection, palm irregular × and mesial margin concave, with a poison tooth mesially Material examined. 7♂♂, 7♀♀, Korea: Jeju-do: Jeju-si, and a large bilobed process distally; dactylus falcate, inner Gujwa-eup, Jongdal-ri, 33°28ʹ57.41ʺN, 126°54ʹ52.96ʺE, 5 margin serrated; length ratio of 6 articles 1.00 : 0.07 : 0.25 : Oct 2015, Park YC; 14♂♂, 17♀♀, 3 Nov 2015, Park YC; 0.17 : 1.07 : 0.56. = 1♂, Seogwipo-si, Seogwi-dong, Mun Island, 33°13ʹ34.50ʺN, Pereopod 3 (Fig. 2F) very small, rudimentary, 0.1 gill, 126°34ʹ11.10ʺE, 18 May 2017, Kim SH. uniarticulate, oval shape with a setule. × Description. Male (cat no. NIBRIV0000888148): Body Pereopod 4 (Fig. 2G) similar to pereopod 3. (Figs. 1A, 2A) slender and smooth, 4.5 mm long. Head Pereopod 5 (Fig. 3A) long and normal; palm of propodus smooth without process. Eye small and round. Pereonite concave with small setae, defined by a grasping spine with 1 fused with head, suture not present; pereonite 2 longest, accompanied slender seta; length ratio of 6 articles 1.00 : with a pair of projections ventrally between gnathopod 2; 0.12 : 0.59 : 0.50 : 0.57 : 0.46. = pereonites 3-4 with small uniarticulate pereopods and oval Pereopod 6 (Fig. 3B) similar to pereopod 5, but palm of to elliptical gills; pereopod 5 subequal to pereopod 6; pereo- propodus more concave than that of pereopod 5; length ratio pod 7 shortest; length ratio of pereonites 2-7 1.00 : 0.88 : of 6 articles 1.00 : 0.16 : 0.61 : 0.43 : 0.55 : 0.48. 0.75 : 0.80 : 0.80 : 0.37. Pereopod 7 (Fig. 3C), propodus broad and peculiar, palm = = Antenna 1 (Fig. 2B) slender, 0.63 body length; pedun- greatly concave, with a large proximal projection by a lined cular article 1-3 unarmed; peduncular article 3 short; length several teeth, grasping spine absent; length ratio of 6 arti- × ratio of peduncular articles 1-3 1.00 : 2.64 : 0.54; flagel- cles 1.00 : 0.20 : 0.67 : 0.50 : 0.61 : 0.51. lum 11-articulate, 1.58 peduncle, each article with 1 aes- Abdomen (Fig. 3D) with a pair of biarticulate appendag- = = thetasc ventrodistally. es, dorsal lobe bilobed. × Antenna 2 (Fig. 2C) much shorter than antenna 1, exceed- Female (cat no. NIBRIV0000888149): Body (Figs. 1B, 3E) ing the distal end of peduncular article 3; length ratio of pe- 4.0 mm long, generally as in male including abdominal ap- duncular articles 3-5 1.00 : 3.53 : 3.65; flagellum biarticu- pendages, but pereonites 3-4 with rounded brood pouches. late, swimming setae absent; 0.20 peduncular articles 3-5. Antenna 1 (Fig. 3F) slender, 0.48 body; length ratio of = Gnathopod 1 (Fig. 2D) small; propodus elongate-ovate, peduncular articles 1-3 1.00 : 3.07 : 0.59; flagellum 13-ar- × × palm nearly straight with unequal simple setae and grasping ticulate, 1.39 peduncle, each article with 1 aesthetasc ven- = spine on medial surface of semicircular proximal lobe; dac- trodistally. × tylus falcate, fitting palm; length ratio of 6 articles 1.00 : Antenna 2 (Fig. 3G) much shorter than antenna 1; length 0.23 : 0.42 : 0.42 : 0.89 : 0.76. ratio of peduncular articles 3-5 1.00 : 3.75 : 4.00; flagellum = Gnathopod 2 (Fig. 2E) attached to midposterior portion biarticulate, 0.20 peduncular articles 3-5. = of pereonite 2; basis elongate, subequal to propodus, widen- Gnathopod 1 (Fig. 3H) very similar to that of male. × 250 Anim. Syst. Evol. Divers. 37(3), 249-254 A New Record of Hemiaegina Species from Korea B A C D G F E Fig. 2. Hemiaegina minuta Mayer, 1890. Male, 4.5 mm. A, Habitus; B, Antenna 1; C, Antenna 2; D, Gnathopod 1; E, Gnathopod 2; F, Gill and Pereopod 3; G, Gill and Pereopod 4. Scale bars: A 1.0 mm, B, E-G 0.4 mm, C, D 0.2 mm. = = = Gnathopod 2 (Fig. 3I) similar to that of male, but distal bi- two genera by its lack of a mandibular palp (Dana, 1853; lobed process on palm of propodus blunt than that of male. Mayer, 1890, 1903; McCain, 1968; Quitete, 1972). Although Remarks. The genus Hemiaegina Mayer, 1890 is similar to this species is widely distributed from temperate to tropical the genera Protella Dana, 1852 and Monoliropus Mayer, 1903 waters, it shows very little intraspecific variation among the recorded in Korean waters, having uniarticulate pereopods localities (Zeina and Guerra-García, 2016). The newly record- 3-4. However, Hemiaegina is easily distinguished from those ed species is consistent with the original description by May- Anim. Syst. Evol. Divers. 37(3), 249-254 251 So-Yeon Shin, Jun-Haeng Heo, Young-Hyo Kim C F E A B G H D I Fig. 3. Hemiaegina minuta Mayer, 1890. A, Pereopod 5; B, Pereopod 6; C, Pereopod 7; D, Abdomen. Female, 4.0 mm; E, Habitus; F, Antenna 1; G, Antenna 2; H, Gnathopod 1; I, Gnathopod 2. Scale bars: A-C, F, I 0.4 mm, D, H 0.1 mm, E 1 mm, G 0.2 mm. = = = = er (1890) with the following characteristics: (1) gnathopod gnathopod 2, palm of the propodus with bilobed triangular 1, propodus with a roundly swollen proximal projection; (2) process; (3) pereonite 2 with a pair of projections between the 252 Anim. Syst. Evol. Divers. 37(3), 249-254 A New Record of Hemiaegina Species from Korea bases of gnathopod 2; and (4) pereopod 7, propodus with a tacea: Amphipoda: Caprellidae) from shallow waters of serrated palm. the Caribbean coast of Venezuela. Organisms, Diver- Habitat. This species has been found on many different sub- sity and Evolution, 5:249-251. https://doi.org/10.1016/ strates on the Great Barrier Reef: green, brown, and red algae, j.ode.2004.11.010 Guerra-García JM, 2003a. Caprellids (Crustacea: Amphipoda) sponges, tunicates, seagrass, dead corals encrusted with algal from Papua New Guinea, with the description of a new spe- turf, and under small boulders, but at Lizard Island the spe- cies. Helgoland Marine Research, 57:100-109. https://doi. cies has been only found on hydroids (Guerra-García, 2006). org/10.1007/s10152-003-0144-4 Type locality. Off Amoy, China (Mayer, 1890). Guerra-García JM, 2003b. The Caprellidea (Crustacea: Amphi- Distribution. Red Sea, West coast of United States, Venezu- poda) from Mauritius Island, Western Indian Ocean. Zoot- ela, Colombia, Gulf of Mexico, South Africa, Hawaii, Bora axa, 232:1-24. https://doi.org/10.11646/zootaxa.232.1.1 Bora, Japan, Papua New Guinea, Australia, India, Mauritius, Guerra-García JM, 2004. The Caprellidea (Crustacea, Amphi- South Arabian coast, Indonesia, Korea (for details of the poda) from Western Australia and Northern Territory, Aus- localities see McCain, 1968, McCain and Steinberg, 1970; tralia. Hydrobiologia, 522:1-74. https://doi.org/10.1023/ Guerra-García, 2003a, 2003b, 2004, 2006; Díaz et al., 2005; B:HYDR.0000029929.07691.a7 Krapp-Schickel and Guerra-García, 2005; Guerra-García et Guerra-García JM, 2006. Caprellidae (Crustacea: Amphipoda) al., 2006; Zeina and Abou Zaid, 2013; Paz-Ríos et al., 2014; from the Great Barrier Reef and adjacent localities. Re- cords of the Australian Museum, 58:417-458. https://doi. Zeina and Guerra-García, 2016). org/10.3853/j.0067-1975.58.2006.1451 Guerra-García JM, Ganesh T, Jaikumar M, Raman AV, 2010. Caprellids (Crustacea: Amphipoda) from India. Helgoland ORCID Marine Research, 64:297-310. https://doi.org/10.1007/ s10152-009-0183-6 So-Yeon Shin: https://orcid.org/0000-0002-1175-5447 Guerra-García JM, Krapp Schickel T, Müller HG, 2006. Caprel- Jun-Haeng Heo: https://orcid.org/0000-0003-0942-7126 lids from the Caribbean coast of Colombia, with description Young-Hyo Kim: https://orcid.org/0000-0002-7698-7919 of three new species and a key for species identification. Boletín de Investigaciones Marinas y Costeras, 35:149-194. https://doi.org/10.25268/bimc.invemar.2006.35.0.222 CONFLICTS OF INTEREST Guerra-García JM, Lowry JK, 2009. Caprellidae. Zootaxa, 2260:290-327. Horton T, Lowry J, De Broyer C, Bellan-Santini D, Coleman No potential conflict of interest relevant to this article was CO, Corbari L, Costello MJ, Daneliya M, Dauvin JC, Fišer reported. C, Gasca R, Grabowski M, Guerra-García JM, Hendrycks E, Hughes L, Jaume D, Jazdzewski K, Kim YH, King R, Krapp-Schickel T, LeCroy S, Lörz AN, Mamos T, Sen- ACKNOWLEDGMENTS na AR, Serejo C, Sket B, Souza-Filho JF, Tandberg AH, Thomas JD, Thurston M, Vader W, Väinölä R, Vonk R, We cordially thanks Dr. S.H. Kim of the In The Sea Inc., White K, Zeidler W, 2021. World Amphipoda Database. Korea for providing valuable specimen. This work was sup- Hemiaegina Mayer, 1890 [Internet]. World Register of Ma- ported by a grant from the National Institute of Biological rine Species. Accessed 5 Jul 2021, <https://www.marine- Resources (NIBR), funded by the Ministry of Environment species.org/aphia.php?p=taxdetails&id=206026>. (MOE) of the Republic of Korea (NIBR202102203 and Krapp-Schickel T, Guerra-García JM, 2005. Littoral Caprelli- dae (Crustacea: Amphipoda) from Indonesia, with the de- NIBR202130202). scription of a new species. Bolletino del Museo Civico di Storia Naturale di Verona, 29:47-62. 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