Stylocheiron abbreviatum (Euphausiacea, Crustacea): A New Record from the Korean Waters
Stylocheiron abbreviatum (Euphausiacea, Crustacea): A New Record from the Korean Waters
Fisheries and aquatic sciences. 2012. Sep, 15(3): 255-257
Copyright ©2012, The Korean Society of Fisheries and Aquatic Science
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
  • Received : May 08, 2012
  • Accepted : June 25, 2012
  • Published : September 30, 2012
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Hae-Lip, Suh

The euphausiid crustacean Stylocheiron abbreviatum G. O. Sars, 1883 has been found in the southern waters of Jeju Island, Korea. This species is the third member of the genus Stylocheiron and the twelfth of the family Euphausiidae identified in Korean waters. Using descriptions of this species, a key to Korean euphausiids is presented.
Eupahusiid crustaceans are of major importance in temperate and polar oceans, where they support the food web of phytoplankton, fishes, birds, and marine mammals (Mauchline 1980). The order Euphausiacea comprises two families: Bentheuphausiidae and Euphausiidae. The family Bentheuphausiidae has only one species, Bentheuphausia amblyops . The more abundant family Euphausiidae contains 10 genera with a total of 85 species (Siegel 2011). In the Korean waters, 4 genera with 11 species of euphausiids have been reported (Hong 1969; Suh 1990): Euphausia mutica, E. nana, E. pacifica, E. recurva, E. similis, E. tenera, Pseudeuphausia latifrons, P. sinica, Thysanoessa longipes, Stylocheiron affine , and S. carinatum . No euphausiid species has been added to the fauna list of Korea in the last two decades.
During the course of a zooplankton survey in the southern waters of Korea, a male Stylocheiron abbreviatum was collected. This species has not previously been reported in the Korean fauna.
Materials and Methods
Zooplankton samples, from which a male specimen of Stylocheiron abbreviatum was identified, were collected from the southern waters of Jeju Island, Korea (33°N, 126°15´E) on the morning of August 29, 1997. Samples were obtained by a MOCNESS net with a mesh size of 300 μm towed obliquely through a layer between 80 and 60 m depth. The collected samples were preserved in 5% neutralized formalin/seawater solution. Body length was measured from the anterior margin of the carapace to the posterior margin of the telson. Drawings were made with the aid of a drawing tube equipped on a microscope.
- Descriptions
- Stylocheiron abbreviatum G. O. Sars, 1883 (Fig. 1)
S. abbreviatum G. O. Sars, 1883: 33; 1885: 147-149, pl. 27, figs. 11-13; Hansen, 1910: 121-123; 1912: 280-283, pl. 11, fig. 5a-f; Boden et al., 1955: 390-391, fig. 54; Brinton, 1975:
PPT Slide
Lager Image
Stylocheiron abbreviatum, male: (A) habitus, lateral view; (B) enlargement of chela; (C) petasma. Scale bars: A = 2 mm, B = 0.5 mm, C = 0.1 mm.
220-221, figs. 118, 124f.
Male : Body length 13 mm. Eye with upper lobe somewhat pyriform in appearance, much smaller than lower lobe; facets of upper lobe larger than those of lower, but crystalline cones not conspicuously enlarged. Frontal plate produced as slender rostrum reaching barely beyond the anterior limit of eyes. Gastric region of carapace domed, with a small median keel ( Fig. 1 A). Third thoracic leg elongated with a true chela. The distal 1/3 of dactylus modified into three teeth or pectinate indentations ( Fig. 1 B). Third to fifth segments of the abdomen with low mid-dorsal keels. Sixth segment length/depth ratio 1.9. Petasma with strong terminal process, somewhat hollowed distally; proximal process shorter, more slender and tapering throughout its length; lateral process curved, slender, nearly equal in length to proximal process ( Fig. 1 C).
Female : Not found in this study.
- Remarks
This species is an offshore warm-water species, and is usually found at latitudes between 40°N and 40°S in the Pacific Ocean (Brinton 1962). This species also occurs in the tropical and subtropical waters of the Indian Ocean and the Atlantic (Boden et al. 1955). In the Korean waters, Hong (1969) recorded two species of Stylocheiron : S. affine and S. carinatum. S. abbreviatum is clearly distinguished from both species by the presence of a true chela at the penultimate segment of the elongated third pair of thoracic legs. In the genus Stylocheiron , moreover, there are only three species with a true chela at the penultimate segment of the third thoracic legs: S. maximum, S. robustum , and S. abbreviatum . The narrow pyriform shape of the upper lobe of the eye and the presence of keels on the third to fifth abdominal segments distinguish S. abbreviatum from the others.
- Key to Euphausiidae species from Korean waters
1. Thoracic legs nearly uniform in structure. ·····················2
Thoracic legs unequally developed, one or two of the anterior pairs of legs being greatly elongated. ······················ 9
2. Distal three segments of sixth thoracic legs greatly reduced. ······························································ 3 ( Pseudeuphausia )
Sixth thoracic leg similar in appearance to fifth. ··············· ······································································ 4 ( Euphausia )
3. Mandibular palp present. ···························· P. latifrons
Mandibular palp absent. ········································ P. sinica
4. Species with two pairs of lateral denticles on the carapace. ·· 5
Species with one pair (rarely none) of lateral denticles on the carapace. ··································································· 6
5. No process on second antennular segment. ·········· E. mutica
Second antennular segment with a spine and tubercles. ······· ············································································· E. recurva
6. Hind margins of first and second abdominal segments straight dorsally. ··························································· 7
Hind margins of first and second abdominal segments dorsally with a produced rounded part. ·················· E. similis
7. Antennular lappet developed in both male and female. ···· 8
Antennular lappet absent in male, present as a very small triangular process in female. ····························· E. tenera
8. Body length 7 to 8 mm. Primary setal distance on ischium of fifth thoracic leg 29 μm. ·································· E. nana
Body length 13 to 24 mm. Primary setal distance on ischium of fifth thoracic leg 20 μm. ······················· E. pacifica
9. Second pair of thoracic legs greatly elongated. ················· ··························································· Thysanoessa longipes
Third pair of thoracic legs greatly elongated. ······················· ·································································· 10 ( Stylocheiron )
10. Penultimate segment of the elongated third pair of thoracic legs with lateral setae only. ··················· S. carinatum
Penultimate segment of the elongated third pair of thoracic legs terminates in a false chela. ···················· S. affine
Penultimate segment of the elongated third pair of thoracic legs terminates in a true chela. ················· S. abbreviatum
Thanks are due to the captain and crew of the R/VTamyangfor their cooperation in sampling at sea and in sharinglog data. Thanks are also due to Prof. Park C, Chungnam NationalUniversity, who generously provided the zooplanktonsamples, and Mr. Im DH for his help in preparing the artwork.This study was financially supported by Chonnam NationalUniversity, 2008.
Boden BP , Johnson MW , Brinton E 1955 The Euphausiacea (Crustacea) of the North Pacific. Bull Scripps Inst Oceanogr 6 287 - 400
Brinton E 1962 The distribution of Pacific euphausiids. Bull Scripps Inst Oceanogr 8 51 - 270
Brinton E 1975 Euphausiids of Southeast Asian waters. Naga Rep 4 1 - 287
Hansen HJ 1910 The Schizopoda of the Siboga expedition. Siboga Exped 37 1 - 123
Hansen HJ 1912 Reports on the scientific results of the expedition tothe eastern tropical Pacific, in charge of Alexander Agassiz, by theU.S. Fish Commission Steamer Albatross, from October 1904 toMarch 1905, Lieut. Commander L.M. Garett U.S.N., commanding.The Schizopoda. Mem Mus Comp Zool Harvard 35 175 - 296
Hong SY , Marr JC 1969 The euphausiid crustaceans of Korean waters. In: TheKuroshio. University of Hawaii Press Honolulu, HI, US 291 - 300
Mauchline J 1980 The biology of mysids and euphausiids. Adv Mar Biol 18 1 - 681
Sars GO 1883 Preliminary notices on the Schizopoda of H.M.S. ChallengerExpedition. Forh Videnskpsselsk Kristiania 7 1 - 43
Sars GO 1885 Report on the Schizopoda collected by H.M.S. Challengerduring the years 1873-76. Rep Sci Results Voyag H.M.S.Chall 1873-1876 Zool 13 1 - 228
Siegel V 2011 “Euphausiidae Dana, 1852”. In: World Register of MarineSpecies, World Euphausiacea database. Siegel V, ed. [Internet]. World Register of Marine Species
Suh HL 1990 Pseudeuphausia sinica (Euphausiacea, Crustacea): a new record from the Korean waters. Bull Korean Fish Soc 23 65 - 67