Dongsung Kim

Occurrence of the newly described kinorhynch genus Meristoderes (Cyclorhagida: Echinoderidae) in Korea, with the description of four new species

Meristoderes is the most recently described kinorhynch genus and has until now only accommodated its type species M. macracanthus from the Mediterranean and M. galatheae from the Solomon Islands in Southeast Asia. The present contribution is an account on the genus based on samples from the ongoing exploration of the kinorhynch fauna in coastal and subtidal waters around in the Korean Peninsula. The samples yielded no less than five new species of Meristoderes, of which four are formally described herein, whereas only diagnostic notes are provided for the fifth. The descriptions are supplemented with a key to species of the genus, and morphological notes on the organization of cephalic structures and cuticular trunk structures. New morphological findings include intrageneric variation in the composition of the terminal segment, which may have either one unpaired or two paired tergal plates. The data also show that the differentiation of a tergal and sternal plate in segment 2 varies greatly between the species. Results of the present study indicate that the genus probably holds a significant, unrecovered biodiversity, but the data also shed light on potential future taxonomic problems among genera of Echinoderidae and stress the importance of identifying additional diagnostic traits to define Meristoderes.

A New Species of Condyloderes (Cyclorhagida, Kinorhyncha) from Korea

A new kinorhynch species, Condyloderes megastigma sp. nov., is described from the Korea Strait. The new species is characterized by the presence of 16 placids with either eight, four, or two knobby projections, middorsal and lateroventral acicular spines on segments 1 to 9, lateroventral cuspidate spines on segment 2 in females only, but otherwise lateroventral cuspidate spines on segments 4 and 5, and 8 and 9 in both sexes. Unique for the new species is furthermore the presence of paired ventromedial appendages on segments 7 and 8, giant ventromedial sensory spots on segment 9, and a terminal segment consisting of one tergal and one sternal plate. The mouth cone and introvert armature are described in detail for the first time for the genus Condyloderes Higgins, 1969. This study reveals similarities in several morphological characters between this genus and species of Campyloderes Zelinka, 1913.

A new species of the rare genus Sphenoderes (Cyclorhagida, Kinorhyncha), with differential notes on S. indicus Higgins, 1969

Abstract A new species of the rarely recorded kinorhynch genus Sphenoderes was collected in the Korea Strait and East China Sea. The new species, Sphenoderes poseidon sp. nov., is distinguished by the presence of lateroventral cuspidate spines on segments 5 and 9 only, opposed to cuspidate spines on segments 5, 8 and 9 as found in S. indicus. The new species is furthermore characterized by having the special head aperture that is diagnostic for species of Sphenoderes, but yet possessing a segment 1 composed of a single, closed cuticular ring, rather than a dorsal, a ventral and two lateral plates as found in S. indicus. The description of Sphenoderes poseidon sp. nov. includes the first scanning electron microscopical examinations of cuticular details in a species of Sphenoderes. The new information is discussed and a comparison is made with the putative closely-related species S. indicus, as well as with other species more generally across the Kinorhyncha.

New Report of Majoid Crab, Pugettia intermedia (Crustacea: Decapoda: Majoidea) from Korea

As a result of continuous taxonomic investigations of Korean crabs, Pugettia intermedia Sakai, 1938 is newly reported from Korean waters. Pugettia intermedia had previously been reported in Korean fauna, but the previous reports of P. intermedia were resulted in misidentification of P. quadridens (De Haan, 1839). Pugettia intermedia differs from P. quadridens in having two subequal medial lobes of the first pleopod in male. In P. quadridens, one of the two medial lobes is about half-length of the other. Pugettia intermedia occurs on the southern coast of the Korean peninsula. The descriptions and illustrations of this species are provided herein.

Two new species of the genus Monstrillopsis Sars, 1921 (Copepoda: Monstrilloida: Monstrillidae) from South Korea

Monstrilloid copepods of the genus Monstrillopsis Sars, 1921 are recorded from Korea, as well as from the northwestern Pacific, for the first time. Specimens were obtained using a light trap set overnight at piers or seawalls in small harbors. Males of two new species were found and are described herein with remarks on their affinities and detailed drawings and SEM photographs of their morphological features. Monstrillopsis longilobata sp. nov. is allied to M. chathamensis Suárez-Morales & Morales-Ramírez, 2009 and M. sarsi Isaac, 1974 in having the character combination of a long, claw-like apical spinous process on the male antennule and elongate genital lappets. It differs from them in having conspicuous transverse striations on the dorsal surface of the cephalothorax and extremely long male genital lappets, which extend far beyond the anterior margins of the caudal rami. Monstrillopsis coreensis sp. nov. also has a claw-like apical spinous process of the male antennule and conspicuous transverse striations on the dorsal surface of the cephalothorax, but it differs from M. longilobata in having a much longer and stronger apical spine of the antennule and a relatively shorter and undulating genital apparatus.

Dendrodasys duplus, a New Gastrotrich Species (Macrodasyida: Dactylopodolidae) from South Korea

A new gastrotrich species of the genus Dendrodasys (Dactylopodolidae) is described on the basis of specimens collected from sublittoral fine sandy bottoms at Uljin, East Sea and at Gujwa, the northeastern coast of Jeju Island, South Korea. Dendrodasys duplus is characterized by a triangular head with lateral lobes extending outward, two pairs of pestle organs posterior to the lateral cephalic lobes, a pair of anterior adhesive tubes, the absence of dorsal, lateral and ventral adhesive tubes, large posterior adhesive tubes arising from the anterior third of the caudal peduncle, and paired testes of different lengths. The genus Dendrodasys is recorded for the first time in East Asia.

Responses of meiofauna and nematode communities to crude oil contamination in a laboratory microcosm experiment

We examined the effects of crude oil contamination on community assemblages of meiofauna and nematodes after exposure to total petroleum hydrocarbons in the laboratory. We administered a seawater solution that had been contaminated with total petroleum hydrocarbons to seven treatment groups at different concentrations, while the control group received uncontaminated filtered seawater. The average density of total meiofauna in the experimental microcosms diluted with 0.5%, 1%, 2%, and 4% contaminated seawater was higher than the density in the control. The average density of total meiofauna in the 8%, 15%, and 20% microcosms was lower than the density in the control. The density of nematodes was similar to that of the total meiofauna. Cluster analysis divided the microcosms into group 1 (control, 0.5%, 1%, 2%, and 4% microcosms) and group 2 (8%, 15%, and 20% microcosms). However, SIMPROF analysis showed no significant difference between the two groups (p > 0.05). Bolbolaimus spp. (37.1%) were dominant among the nematodes. Cluster analysis showed similar results for nematode and meiofaunal communities. The total meiofaunal density, nematode density, and number of Bolbolaimus spp. individuals were significantly negatively associated with the concentration of total petroleum hydrocarbons (Spearman correlation coefficients, p < 0.05). Within the nematodes, epistrate feeders (group 2A: 46%) were the most abundant trophic group. Among the treatment groups, the abundance of group 2A increased in low-concentration microcosms and decreased in high-concentration microcosms. Thus, our findings provide information on the effects of oil pollution on meiofauna in the intertidal zones of sandy beaches.

Characteristics of Meiobenthic Community Inhabiting Sandy Sediment in the Yellow Sea, Korea

The community structure of meiobenthos was studied at 16 stations within sandy tidal and subtidal zones in Jangbongdo in the Yellow Sea, Korea from Aug. 2006 to Jan. 2007. Meiobenthic organisms were collected by three core samples, with a 3.6 ㎝ diameter, from each sediment sample taken with a Smith-McIntyre Grab. Mean grain size of study stations ranged from 1.49φ to 3.55φ. Composition of sand ranged from 80.38% to 99.89%. There was reduction in total abundance and biomass of meiobenthos from summer to winter. Total densities of meiofauna ranged between 17 inds./10 ㎠ and 853 inds./10 ㎠. Nematodes, gastrotricha, nauplius and harpacticoids appeared as major taxa in decreasing order. This study shows that major taxa comprised 90 percent of total abundance. Most meiofaunal organisms are concentrated in the upper sediment layers and the total abundance and biomass of organisms in the tidal zone is higher than the subtidal zone.

Redescription of free-living marine nematode, dracograllus filipjevi allen and noffsinger, 1978 (nematoda: draconematidae) from korea

A draconematid nematode species,Dracograllus filipjevi Allen and Noffsinger, 1978, is described from the washings of shallow littoral coralline algae at Guryongpo in the eastern coast of Korea. This species is recognized by the following characteristics: larger body size, number of posterior sublateral adhesion tubes (9 in male and 12-13 in female) and subventral adhesion tubes (8-9 in male and 9-10 in female), the absence of cephalic acanthiform setae on rostrum, the presence of longitudinally areolated body cuticle with dot-like punctations, the presence of some cuticular collar in swollen pharyngeal region, the shape of amphidial fovea (large, elongate, and loop-shaped in both sexes), the absence of preanal corniform setae, and the absence of lateral differentiation on narrow body region. Morphological features of the species using differential interference contrast photomicrographs are described in detail in the present work. This is the first report ofD. filipjevi in Korea.

Distribution and Variability of the Meiobenthic Assemblages near the Korean Polymetallic Nodule Claim Area of the Clarion-Clipperton Fracture Zone (Subequatorial NE Pacific)

This study was carried out as part of a baseline long-term environmental project in the proposed mining areas for an environmental impact assessment of future mining in the Clarion-Clipperton Fracture Zone (CCFZ). The community structure and distributional pattern of meiobenthos were investigated in the deep-sea bottom of the Clarion-Clipperton Fracture Zone of the northeastern Pacific in July 1998, 1999, 2001, 2003 and August 2004, 2005. Twenty one meiobenthic groups were found at the stations in the study area. The most abundant meiobenthos comprised nematodes followed by benthic foraminiferans and harpacticoid copepods. The maximum density of meiobenthos was 306 ind/10 cm2 at the station located at 11°N (water depth, 4833 m), and the minimum density was 6 ind/10 cm2 at the station located at 14°N (water depth, 5037 m). Oligotrophic conditions in the CCFZ seem to directly reflect the lower standing stocks of meiobenthos in the CCFZ compared to other deep-sea plains of similar depth. The latitudinal distribution pattern of meiobenthos in the study area seemed to be related with surface water primary productivity, which was connected to the water circulation pattern of the Pacific Ocean near the Equator, diverging at 8ºN latitude and converging at 5°N. The horizontal distribution of meiobenthic organisms in the study area showed high densities at the stations within 135–136°W. The densities of meiobenthic organismas within the CCFZ were high at stations with few manganese nodules on the sediment surface at low-latitude sites. In 1998, the observed relative high values of meiobenthic abundance were at stations from 5° to 6°N. Other stations from 7° to 10°N showed no significant fluctuations during the interannual sampling periods. It is considered that the inter-annual fluctuation of meiobenthos abundance is intimately related with a regime shift that may have occurred in the north Pacific between 1998 and 1999, the El Niño period. Vertical distribution of meiobenthic organisms showed the highest individual numbers in the surface sediment layers of 0∼2 cm depth and a steep decreasing trend as sediment becomes deeper at the stations of high latitude located in 16∼17°N. Size distribution analyses showed that organisms that fit into the sieve mesh size of 0.063 mm were abundant.