INTRODUCTION

The genus Paramphiascella Lang, 1944 belonging to the family Miraciidae Dana, 1846 was composed of 26 species (Wells 2007; Chullasorn et al. 2011). Most species were chiefly recorded from marine habitats except for P. dahmsiChullasorn, 2010 and P. ferrariiChullasorn, 2010 from brackish waters in Thailand, and P. aquaedulcis Dussart, 1984 from freshwaters in Venezuela (Dussart 1984; Chullasorn 2010). This genus is closely related with the genus Amphiascoides Nicholls, 1941, but they represent significant difference in the typical structure of endopod on male P2 (Vervoort 1962; Wells et al. 1982). In the genus Paramphiascella, this structure is characterized by the distal seta on second segment is transformed into a long spine and is also considered as a specific feature for identification (Marcorte 1974; Wells 2007; Chullasorn et al. 2011).

While studying the marine harpacticoids of Korea, the authors met with a Paramphiascella species, P. fulvofasciataRosenfield and Coull, 1974, new to Korean fauna. In the present study, we provide detailed description and illustrations of the species as a first report of the genus Paramphiascella from Korean waters.

MATERIALS AND METHODS

Sandy bottoms were collected by a van Veen grab sampler at a depth of 5 m and were sieved with a pore size of 212 μm using seawaters. The remaining meiofauna on sieve were initially fixed with 99.9% ethyl alcohol. In the laboratory, they were sorted under stereomicroscope (Discovery, V8; Carl Zeiss, Germany) and preserved with 99.9% ethyl alcohol. For the observation and drawing of habitus, we used an aluminum hole slide adhered with a coverslip to prevent the depression of materials. After the dissection of specimens, all appendages were mounted on polyvinyl lactophenol or lactophenol solutions and were observed on light microscope (ECLIPSE 80i; Nikon, Japan). All drawings were performed by the aid of a drawing tube. The examined materials were deposited in the National Institute of Biological Resources (NIBR) and Chosun University in Korea.

The morphological terminology used in the description and figures follows that of Huys et al. (1996). Abbreviations are as follows: ae, aesthetasc; exp, exopod; enp, endopod; P1-P6, first to sixth thoracopod; exp (enp)-1 (2, 3), proximal (middle, distal) segments of a ramus.

SYSTEMATIC ACCOUNTS

Order Harpacticoida Sars, 1903 갈고리노벌레 목

Family Miraciidae Dana, 1846 놀람장수노벌레 과

Genus Paramphiascella Lang, 1944

나도쌍낭장수노벌레 속 (신칭)

Paramphiascella fulvofasciataRosenfield and Coull, 1974 (Figs. 1-7)

노랑나도쌍낭장수노벌레 (신칭)

Synonyms: Paramphiascella fulvofasciataRosenfield and Coull, 1974, p. 296, figs. 1-25; Dahms, 1987, p. 218.

Material examined: 3♀♀, 5♂♂, Dapo-ri, Nambu-myeon, Geoje-si, Gyeongsangnam-do, Korea (34°43ʹ41.26ʺN, 128° 36ʹ2.94ʺE), 23 Mar. 2014, collected by J.G. Kim.

Description: Female. Body (Fig. 1A, B) semicylindrical, fusiform, with inconspicuous boundary between prosome and urosome; total length 834.0 μm (range from 666.5 to 834.0 μm, mean=742.4 μm, n=3), measured from anterior margin of rostrum to posterior margin of caudal ramus; surface ornamented with sensillae and pores. Rostrum (Fig. 3A) elongate, triangular, defined at its base, reaching to end of second antennular segment, and with sensillum on each side subdistally. Cephalothorax tapering anteriorly, longer than 3 prosomites combined. Genital double-somite (fused genital and first abdominal somites; Fig. 2A) 0.8 times as long as wide, and with paired set of spinules on ventrolateral margin of first abdominal somite; lateral surface separated by subcuticular suture. Genital field (Fig. 2B) with separate genital apertures, each covered by vestigial P6 composed of 2 short plumose and 1 long bare setae; copulatory pore obscured by large and elongate, oval-shaped copulatory bulb. Urosomites 4 and 5 (Figs. 1A, B, 2A) with paired set of spinules on ventrolateral margin and row of ventral setules on posterior margin, respectively; posterior somite with pseudoperculum. Anal somite (Fig. 2C) with rows of spinules on lateral surface, and 3 paired rows of delicate spinules and pair of sensillae on dorsolateral surface; median deep cleft with pair of rows of oblique spinules; operculum ornamented with row of delicate spinules along posterior margin; ventral surface with 1 medial and 1 laterally paired rows of delicate spinules, and pair of tube pores; posterior border with pair of spinule rows ventrally. Caudal ramus (Fig. 2C) broader than long, length to width ratio about 1 : 2 in dorsal view, with tube pore on dorsal surface, 2 rows of spinules on median margin, 2 spinules on posterior border ventrally, and 7 setae: seta I small and delicate; seta II bare and slightly longer than 2 times of caudal ramus; seta III slender, bare, situated at ventrolateral margin, and slightly longer than seta II; setae IV and V well-developed (Fig. 1C), seta V about 2 times as long as seta IV; seta VI elongate, bare, and 2 times as long as seta II; seta VII triarticulated basally and slightly shorter than seta II. Table 1.

Antennule (Fig. 3A) 8-segmented; segment 1 longest and with row of spinules on anterior margin; segment 5 shortest; segments 4 and 8 with aesthetasc fused to seta basally, respectively; setal formula as follows: 1-[1], 2-[11], 3-[8], 4-[4+ae], 5-[2], 6-[4], 7-[4], 8-[7+ae].

Antenna (Fig. 3B). Coxa small, with row of setules along lateral margin. Allobasis elongate with 3 rows of spinules and 2 spinules on proximal segment, and 1 abexopodal seta. Exopod 3-segmented; proximal segment longest, with 1 pinnate seta; middle segment smallest, without seta; distal segment with row of spinules distally, and with 1 lateral pinnate, 1 slender plumose and 1 apical pinnate setae. Endopod 1-segmented, elongate, as long as allobasis, and with 2 frills on surface; abexopodal margin armed with 2 rows of stout spinules, 2 stout spines, and 1 slender seta; distal margin armed with frills and with 3 geniculate, 1 spinulose, 1 unipinnate and 1 plumose setae, and 1 pinnate spine; spinulose seta on distal margin fused to unipinnate seta basally.

Mandible (Fig. 3C). Coxal gnathobase well-developed; cutting edge armed with 2 tricuspid and 8 unicuspid teeth, and 1 pinnate seta; inner margin with protrusion. Palp composed of basis, exopod and endopod; basis broad, with set of setules and 3 pinnate setae; endopod 1-segmented, bilobate, inner lobe with 1 apical seta and outer lobe with 2 lateral and 3 apical setae; exopod 2-segmented, proximal and distal segments with 1 and 3 setae, respectively.

Maxillule (Fig. 3D). Praecoxa with 2 rows of spinules on anterior surface; arthrite well-developed, armed with 8 spines, and 1 pinnate and 1 bare setae along distal margin, and 2 parallel setae on anterior surface. Coxal endite with 1 long bare and 1 stout pinnate setae. Basal endite with 2 rows of spinules on anterior surface, 3 setae on lateral margin, and 2 stout pinnate and 2 slender bare setae on distal margin. Both rami 1-segmented; exopod with row of lateral setules and 2 apical plumose setae; endopod with 1 lateral and 2 apical bare setae.

Maxilla (Fig. 3E). Syncoxa large, with 3 rows of spinules along outer margin, 1 row of spinules on surface proximally and 3 endites; proximal endite with 2 plumose setae, middle one with 1 pinnate and 1 spinulose setae, and distal one with 2 slender pinnate and 1 stout spinulose setae. Allobasis drawn out into strong claw armed with 2 rows of spinules, and having 2 slender naked and 1 stout spinulose setae. Exopod absent. Endopod 2-segmented; proximal segment with bare seta; distal segment smaller than preceding one, with 6 setae.

Maxilliped (Fig. 3F). Coxa with row of spinules along inner margin, and bearing 3 spinulose and 1 bare setae at distal corner. Basis elongate, with row of long spinules on surface, row of spinules and 2 setae along palmar margin. Endopod with stout claw armed with row of spinules, and 3 accessory setae.

P1 (Fig. 4A). Intercoxal sclerite small, trapezoidal, and without ornamentation. Preacoxa small, with row of delicate spinules on distal margin. Coxa ornamented with 6 rows of spinules on anterior and posterior surfaces. Basis smaller than preceding one, with outer and inner pinnate spines, each furnished with few spinules at base, and 2 rows of spinules on distal margin. Exopod 3-segmented; outer margin of each segment ornamented with spinules; exp-1 with pinnate outer spine; exp-2 with pinnate outer spine and row of inner setules; exp-3 with 2 pinnate spines, 2 geniculate setae and 1 setule. Endopod 3-segmented; enp-1 elongate, slightly exceeding end of exopod, and armed with rows of spinules along outer margin, and armed with row of setules along margin, and with pinnate seta on inner margin distally; enp- 2 smallest, with few outer spinules and small inner seta; enp-3 slightly longer than preceding one, with few outer spinules, 1 pinnate apical spine, and 1 geniculate apical and 1 small inner setae.

P2-P4 (Figs. 4B, 5A, B). Intercoxal sclerite larger than that of P1, distal margin with 2 pointed process; P2 with 2 rows of spinules on anterior surface distally. Praecoxa (omitted in figure of P2) small and with row of small spinules on distal margin. Coxa large, with 3 rows of spinules and 1 tube pore on anterior margin, and 1 row of spinules on posterior margins. Basis with outer pinnate spine (P2) or seta (P3 and P4), and with 3-4 spinules on anterior surface and distal margin. Both rami 3-segmented; exopod longer than endo- pod; each segment armed with spinules along outer margin; proximal two segments armed with hyaline frills on distal margin; exp-1 without inner seta; exp-3 of P2 without inner seta; exp-1 and exp-2 with pinnate outer spine and row of inner setules; exp-2 of P2 and P3 with several spinules on surface, respectively; each rami with tube pore on second or third segment.

Setal formula of P1-P4 as follows:

P5 (Fig. 2D). Baseoendopod with peduncle bearing bare outer seta; endopodal lobe reaching to 3/5 of exopod, with 5 pinnate setae, and few spinules on outer margin; second innermost seta serrate. Exopod separated from baseoendopod, length to width ratio 1.4 : 1, with few spinules on inner and outer margins, 2 tube pores on anterior surface, and 5 setae, innermost one pinnate, medial one slender.

Male: Sexual dimorphism represented in body size, antennule, P1, P2, P5, P6 and urosome.

Body (Fig. 6A) similar to female, but smaller and slender than female, total length 710 μm (range from 601.4 to 710.0 μm, mean=644.7 μm, n=5). Urosome (Fig. 6B) composed of 6 somites; urosomites 2 and 3 completely separated; urosomites 3 and 4 with row of spinules on ventral surface, respectively.

Antennule (Fig. 6C) 9-segmented, haplocer; segment 4 longest and stout; inner margin of segment 6 concave; segment 7 with 2 spines on inner margin; segment 8 shortest; segments 5 and 9 with aesthetasc fused with setae basally, respectively. Setal formula as follows: 1-[1], 2-[11], 3-[8], 4-[6], 5-[5+ae], 6-[2], 7-[1], 8-[4], 9-[7+ae].

P1 (Fig. 7A). Basis with curved inner spine and stout process. Enp-1 shorter and stouter than that of female.

P2 (Fig. 7B). Endopod modified, 2-segmented; second segment stout spine-like structure, with 2 pinnate setae and 1 stout spine; spine on second segment slightly exceeding end of endopod and bearing bifid tip.

P5 (Fig. 6D). Baseoendopodal lobe with row of delicate spinules on surface, and with 2 rows of stout spinules and 2 modified stout setae on distal margin. Exopod with tube pore on surface, and 2 stout naked, 1 long naked, 1 stout pinnate and 1 stout modified setae on distal margin.

P6 (Fig. 6B). Each leg represented by small plate bearing 1 long and 1 short naked setae, and 1 unipinnate seta.

Distribution: USA, Beaufort Sea, England, German Bight, and South Korea.

Habitat: Association with Laminaria sp. (U.S.A.) and seagrass (Zostera sp.) bed composed of sand (Korea).

Deposition: NIBR No. NIBRIV0000324229.

Identifiers: Jong Guk Kim and Seong Myeong Yoon.

Remarks:Paramphiascella fulvofasciataRosenfield and Coull, 1974 has been reported from worldwide region including U.S.A. (Massachusetts), Beaufort Sea, England (Norfolk), and German Bight, showing an association with macroalgae (Laminaria sp.) (Rosenfield and Coull 1974; Coull 1977; Dahms 1987). In the preset study, however, the materials of this species were collected from a sublittoral seagrass (Zostera sp.) bed composed of sand, without clear relationship of an association with the plant life.

The female of P. fulvofasciata is similar to P. vararensis (Scott, 1903), P. mediterranea Lang, 1948, P. pacificaVervoort, 1962, and P. bodiniMarcotte, 1974, but they can be easily distinguished by the structure of male P2 endopod (Marcotte 1974). Among them, P. fulofasciata is mostly closed with P. pacifica in that the first endopodal segment of male P2 without distal spine, but they represent a certain difference each other in the second endopodal segment of male P2; the former has one spine and two pinnate setae, whereas the latter has tuberculate surface, a spine and a bare seta (Vervoort 1962; Marcotte 1974; Chullasorn 2010). This structure of male P2 in P. fulvofasciata is also very similar to that in P. ferrariiChullasorn, 2010, but they are easily separated by the segmentation of antennary exopod (2-segmented in P. ferrarii).

Paramphiascella fulvofasciata from Korean waters coincides well with the original description of Rosenfield and Coull (1974) from Massachusetts, U.S.A. As Dahms (1987) reported that the morphological differences in antennule and mouth parts are existed between the regional populations in this species, however, Korean specimens showed some differences from the original description in the structures of mouth parts as follows: the mandibular cutting edge is ornamented with eight unicuspid teeth instead of six; the praecoxal arthrite of maxillule has eight spines and one slender seta, whereas U.S.A. specimen has only four spines (seta is absent in the original description); the basal endite of maxillule has seven elements instead of five; the proximal endite on the maxillary syncoxa has two setae instead of one; and the basis of maxilla has an accessory seta, whereas it is absent in the original description. These differences are more or less differentiated from those of the previous report with the materials collected from German Bight by Dahms (1987). The comparison of the morphological differences in mouth parts between the regional populations of P. fulvofasciata is presented in Table 1.

Although these differences between the materials from three regions are existed, we identified Korean materials as P. fulvofasciata because it is possible that the original description of the species (Rosenfield and Coull 1974) has some inaccurate information as in Geehydrosoma intermedia (Chislenko, 1978) noted by Kim et al. (2014). Especially, we thought that the description and illustration of maxillule in the original description (Rosenfield and Coull 1974) of P. fulvofasciata were erroneous because each of three species recently described in detail, P. dahmsiChullasorn, 2010, P. ferrariiChullasorn, 2010, P. choiChullasorn et al. 2011, shows eight spines on the praecoxal arthrite, while itwas described that P. fulvofasciata has only four spines (five spines are appeared in fig. 13) in the original description (Rosenfield and Coull 1974). At this point, it is necessary for clarifying the exact taxonomic status of Korean materials to study with examining the type materials or the materials from type locality.