Research Article |
Corresponding author: Ivana Karanovic ( ivana.karanovic@utas.edu.au ) Academic editor: Saskia Brix
© 2017 Jeongho Kim, Wonchoel Lee, Ivana Karanovic.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Kim J, Lee W, Karanovic I (2017) A new species of Microcharon from marine interstitial waters, Shizuoka, Japan (Isopoda, Lepidocharontidae). ZooKeys 680: 13-31. https://doi.org/10.3897/zookeys.680.12048
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A new species of Microcharon Karaman, 1934 (Asellota: Lepidocharontidae) is described from Miho-Uchihama beach, Shizuoka, Japan. Microcharon tanakai sp. n. differs from its congeners by having nine simple, five penicillate setae on antennal article 6; one simple distal seta on article 1 of the mandibular palp and having the apical lobe of male pleopod 1 convex, rounded, armed with seven setae. A key to Asian species of the genus and 16S rRNA of the new species are provided.
interstitial, isopoda , Japan, morphology, taxonomy
Members of the genus Microcharon Karaman, 1934, are free-living interstitial isopods. Being highly adapted to the narrow spaces of the interstitial environment, the species possesses an elongated body without visual organs or pigmentation (
The genus Microcharon is one of the best studied groups of the family Lepidocharontidae and 69 species have been described from all over the world (
During a survey of the interstitial fauna of Miho-Uchihama beach (Shizuoka, Japan), a small number of psammolittoral isopods were collected together with other marine interstitial fauna such as, harpacticoid copepods, nematodes and ostracods. The isopod specimens had a typical Microcharon body plan, but a unique combination of morphological characters which lends support to the establishment of the new species described herein. Beside its description an identification key to the four Asian species of this genus currently recorded. In addition, a partial sequence of 16S rRNA gene was obtained and this may be useful for the future phylogenetic study studies of Microcharon and the family Lepidocharontidae.
Seven female and two male specimens were collected from coarse sand from Miho- Uchihama beach, Shizuoka City, Shizuoka Prefecture, Japan on 7 February 2015 (Fig.
Two females from the type locality sample were identified without dissection under an Olympus SZX 12 dissecting microscope. Before amplification, specimens were transferred into distilled water for 20 minutes to remove ethanol and then macerated with a small glass rod. Whole specimens were used to isolate genomic DNA with the aid of the LaboPassTM Kit (COSMO Co. Ltd., Korea) following the manufacturer’s protocols. 16S rRNA was amplified with polymerase chain reaction (PCR) using PCR premix (BIONEER.Co) in TaKaRa PCR thermal cycler (TaKaRa Bio Inc., Otsu, Shiga, Japan). The primers used were 16sar-L (5`-CWAAYCATAAAGAYATTGGNAC-3`) and 16sar-H (5`-ACTTCAGERTGNCCAAARAAYCA-3`) (
Microcharon stygius (Karaman, 1933)
(modified from
Interstitial water of coarse sand, Miho-Uchihama beach, Shizuoka city, Shizuoka Prefecture, Japan, 35°01'83"N, 138°51'71"E (Fig.
Holotype: adult female, (NIBRIV0000787789) completely dissected and mounted in lactophenol on four slides; paratype 1 female (NIBRIV0000787790) dissected on three slides, paratype 2 female (NIBRIV0000787791) dissected on one slide; adult male pleotelson dissected on three slides; 2 females and 1 male used for SEM.
Antennular article 6 smallest, with one aesthetasc, one penicillate, three simple setae distally; article 1 of mandibular palp with one distal simple seta; lateral lobe of maxillula with eleven robust setae; distal apex of male pleopod 1 convex, round, with three apical, four subapical setae; protopod of male pleopod 2.9 times longer than wide; protopod of uropod 3.1 times longer than wide, with fifteen setae.
Body (Fig.
Cephalon (Fig.
Pereon (Fig.
Pleonite 1 (Fig.
Pleotelson (Fig.
Antennula (Fig.
Antenna (Fig.
Mandible (Figs
Paragnaths (Fig.
Maxillula (Fig.
Maxilla (Fig.
Maxilliped (Fig.
Pereopods 1–4 (Figs
Pereopods 5–7 (Figs
Female operculum (Fig.
Uropods (Fig.
Scanning electron microscope images of Microcharon tanakai sp. n., A female antennal scale, lateral, B female mandibular palp, lateral C female pereopod 1-3, lateral, D female coxal plate of perepod 2, ventral E female bifurcate seta of pereopod 4, lateral, F female articular plate of pereopod 5, lateral. Scale bar unit µm.
Penial papillae (Fig.
Pleopod 1 (Figs
Scanning electron microscope images of Microcharon tanakai sp. n., G pereonite 7 and free pleonite, ventral, paratype male H penial papillae, ventral, I pleopod 1, dorsal, J distal part of male pleopod 1, dorsal K proximal part of male pleopod 1, dorsal L distolateral view of male pleopod 1. Scale bar unit µm.
Pleopod 2 (Figs
Pleopod 3 (Figs
Pleopod 4 (Fig.
The species is named in honor of the collector, Dr. Hayato Tanaka, to express our appreciation for his support in this study.
1 | Endopod of pleopod 3 with three plumose setae; article 1 of mandibular palp with one single seta distally | M. tanakai sp. n. |
– | Endopod of pleopod 3 naked; article 1 of mandibular palp naked | 2 |
2 | Antennula consist of 6 articles | M. halophilus |
– | Antennula consist of 5 articles | 3 |
3 | Female operculum with 4 distal simple setae; distal part of male pleopod 1, rounded | M. raffaellae |
– | Female operculum with 2 distal simple setae; distal part of male pleopod 1, straight | M. kirghisicus |
Partial 16S rRNA sequence was obtained only from a single female. The final length of trimmed sequence was 493 base pairs (GenBank accession number KY498031) and BLAST (
Microcharon tanakai sp. n. is identified as a member of the genus Microcharon based on the combination of the following characters: 1) body slender, elongate and all somites subequal in width, 2) pereopods 1-4 inserted anterolaterally, pereopods 5-7 inserted posterolaterally 3) coxal plates indiscernible in dorsal view, 4) pleotelson longer than wide, longer than any pereonite, 5) antennal article three with scale laterally 6) antennal flagellum longer than podomeres 7) maxillipedal palps composed of five articles, which are broader than the endite, 8) pereopod 1 leg-like, 9) uropods with long, broad protopod, both endopod and expod shorter than protopod in all other marine species of Microcharon and exopod inserted subapically (
We were able to amplify 16S rRNA partial sequence of M. tanakai. To date, 228 16S rRNA sequences of the suborder Janiroidea G.O. Sars, 1897 have been deposited on GenBank belonging to the following 7 families: Desmosomatidae G.O. Sars, 1897, Macrostylidae Hansen, 1916, Joeropsididae Nordenstam, 1933, Janiridae G.O. Sars, 1897, Munnopsidae Lilljeborg, 1864, Haploniscidae Hansen, 1916 and Acanthaspidiidae Menzies, 1962. Although this molecular marker has not been commonly used for barcoding (
This study was supported by the BK21 Plus Program (Future-oriented innovative brain raising type, 22A20130012806) funded by the Ministry of Education (MOE, Korea). This study was also supported by a grant (NIBR201601201) of National Research Foundation of Korea (NRF) and National Institute of Biological Resource (