Corresponding author: Gi-Sik Min (
Academic editor: S. Brix
Two new species of cymothoid isopods,
Song J-H, Min G-S (2018) First records of
The isopod crustacean family
The family
Herein, we report two new species collected from South Korea,
Specimens of
The specimens were transferred to glycerine for dissection, and then examined and dissected under a dissection microscope (Olympus, model SZX-7). Figures of dissected appendages were drawn under a light microscope with an attached drawing tube (Leica, model DM 2500). Figures of the whole body were drawn using a drawing tube attached to a stereomicroscope (Olympus, model SZX-12). The lengths of all appendages and the whole body were measured with a stage micrometre (Leica, model no. 11513106) and an ocular micrometre. The photograph of the whole body of
Morphological terminology and the orientation of each appendage largely follows
This key is based on males.
1 | Dorsal surface of pereon without tubercles |
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– | Dorsal surface of pereon with tubercles, especially anteriorly |
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2 | Paraocular ornamentation absent; mandible without incisor |
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– | Paraocular ornamentation present; mandible with incisor |
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3 | Dorsal surface of cephalon with tubercles; pylopod with three articles |
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– | Dorsal surface of cephalon without tubercles; pylopod with two articles |
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4 | Body very setose; inferior margins of pereopods without tubercles |
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– | Body smooth or sparsely setose; inferior margins of pereopods with tubercles |
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5 | Mediofrontal process bifid |
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– | Mediofrontal process a single projection |
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6 | Mediofrontal process broad, not elongated; superior frontolateral process triangular; mandible mediocre |
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– | Mediofrontal process narrow anteriorly, elongated; superior frontolateral process rounded; mandible stout |
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7 | Mediofrontal process acute; mandibular setae absent |
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– | Mediofrontal process rounded; mandibular setae present |
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8 | Mediofrontal process absent |
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– | Mediofrontal process present |
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9 | Mediofrontal process dividing into two apices; internal lobe of mandible absent |
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– | Mediofrontal process not divided, a single projection; internal lobe of mandible present |
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10 | Lateral margins of pereonites 2 and 3 with serrations; mediofrontal process broad, with remarkably concave apex |
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– | Lateral margins of pereonites 2 and 3 without serrations; mediofrontal process narrow, with bifid apex |
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11 | Paraocular ornamentation forming a ridge; superior frontolateral process rounded, serrated |
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– | Paraocular ornamentation not forming a ridge, with three indistinct tubercles; superior frontolateral process acute, not serrated |
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12 | Cephalon without tubercles; paraocular ornamentation forming a ridge; mediofrontal process conical, longer than superior frontolateral process |
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– | Cephalon with tubercles; paraocular ornamentation not forming a ridge, with several tubercles; mediofrontal process rounded, shorter than superior frontolateral process |
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13 | Mandible as long as or shorter than half-length of cephalon, with smooth blade |
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– | Mandible longer than half-length of cephalon, with dentate blade |
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14 | Cephalon with distinct serrations on lateral margins; mandible as long as half-length of cephalon |
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– | Cephalon serrated, but without distinct serrations on lateral margins; mandible shorter than half-length of cephalon |
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15 | Epimera linguiform, visible dorsally on pleonites 1–5, directed to the sideward |
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– | Epimera acute, visible dorsally on pleonites 4 and 5, directed downward |
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16 | Body sparsely setose; pylopod with two articles |
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– | Body very setose, covered with long setae; pylopod with three articles |
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17 | Mediofrontal process broad, not elongated; epimera not visible dorsally on all pleonites |
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– | Mediofrontal process narrow anteriorly, elongated; epimera visible dorsally on pleonites 3–5 |
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18 | Mediofrontal process dividing into two apices; supraocular lobe with blunt apex |
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– | Mediofrontal process not divided, rounded; supraocular lobe with dentate apex |
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19 | Dorsal surface of pereonite 4 without tubercles; superior frontolateral process with four setae |
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– | Dorsal surface of pereonite 4 with tubercles; superior frontolateral process with several setae and tubercles |
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20 | Dorsolateral surface of pereonites 5 and 6 with tubercles; pleotelson with acute apex |
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– | Dorsolateral surface of pereonites 5 and 6 without tubercles; pleotelson with rounded apex |
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Holotype: adult male (4.6 mm, NIBRIV0000554213); Yeogaekseon terminal, Geomundo Island, Yeosu-si, Jeollanam-do, South Korea;
The specific name ‘
Pereon dorsal surface smooth, sparsely setose, without tubercles. Cephalon dorsal surface sparsely setose with several granules medially. Paraocular ornamentation strongly developed, forming a ridge, without tubercles. Mediofrontal process strong and bifid. Superior frontolateral process shorter than mediofrontal process, rounded, and serrated. Mandible without pseudoblade and internal lobe.
This species was collected at approximately 10 m depth corresponding to a sedimentary bottom of muddy sand.
Only known from the type locality.
Six species are distributed in Asia:
This key is based on females. Therefore, we excluded
1 | Propodus of pereopod 1 expanded on inferior margin |
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– | Propodus of pereopod 1 not expanded on inferior margin |
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2 | Maxillipedal palp with three articles; endopod of uropod surpassing pleotelson |
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– | Maxillipedal palp with four articles; endopod of uropod not surpassing pleotelson |
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3 | Pereonite 1 as long as pereonite 2; incisor of mandible with two cusps; apical lobe of maxilla without seta; pleotelson with eight robust setae on posterior margin |
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– | Pereonite 1 1.7 times longer than pereonite 2; incisor of mandible with one cusp; apical lobe of maxilla with one seta; pleotelson with ten robust setae on posterior margin |
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4 | Incisor of mandible with three cusps; maxillipedal palp with five articles |
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– | Incisor of mandible with one or two cusps; maxillipedal palp with three or four articles |
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5 | Pereonite 1 longer than other pereonites, 2.0 times longer than pereonite 5; apex of pleotelson with truncated margin |
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– | Pereonite 1 marginally longer or shorter than pereonite 5; apex of pleotelson with rounded margin |
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6 | Pereonite 1 longer than pereonite 5; maxillipedal palp with three articles |
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– | Pereonite 1 shorter than pereonite 5; maxillipedal palp with four articles |
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Holotype: non-ovigerous female (4.8 mm, NIBRIV0000554215); Buheungji reservoir, Yeongcheon-si, Gyeongsangbuk-do, South Korea;
The specific name ‘
Pereopods 1–3 propodus expanded with serrations on inferior margins. Pereopods 4–7 propodus with serrations on inferodistal margins. Mandible incisor with one cusp. Maxilla apical lobe with one seta. Maxillipedal palp with four articles. Pleotelson with ten robust setae on posterior margin.
Jeollanam-do and Gyeongsangbuk-do (South Korea).
This work was supported by grants from Inha University. We thank ‘Kwang-Sub Sim’ (Natural Environmental Restoration Institute Co., LTD, Korea) for providing specimens of