INTRODUCTION

The opheliid polychaetes can be found in the sand or mud flats as well as hard bottoms from the intertidal to abyssal depth (Rouse and Pleijel 2001; Neave and Glasby 2013). They can be largely divided into three groups based on the body shape as follows: short and thick grub-shaped (e. g. Travisia Johnston, 1840), slender and smooth torpedoshaped (e.g. Armandia Filippi, 1861), and anteriorly inflated and posteriorly cylindrical or narrow (e.g. Euzonus Grube, 1866) (Fauchald 1977; Rouse and Pleijel 2001). To date, 11 genera of the family Opheliidae have been classified (Silva 2007).

Among them, the genus Armandia includes the species bearing the ventral groove, the lateral eyespots, the parapodial branchiae, the long unpaired cirrus on anal funnel, and the simply capillary setae (Fauchad 1977; Blake 2000). This genus comprises currently 22 valid species described worldwide (Saito et al. 2000). It has been relatively well studied in East Asia, including total seven reported species; three species, A. exiguaKükenthal, 1887, A. intermedia Fauvel, 1902, and A. leptocirris (Grube, 1878), have been recorded from Chinese waters, and four species, A. amakusaensis Saito, Tamaki and Imajima, 2000, A. brevis (Moore, 1906), A. lanceolataWilley, 1905, and A. simodaensisTakahashi, 1938, from Japanese waters (Kükenthal 1887; Annenkova 1938; Okuda 1938; Takahashi 1938; Imajima and Hartman 1964; Yang and Sun 1988; Paxton and Chou 2000; Saito et al. 2000). Among these, two species, A. lanceolata and A. simodaensis, are also known from Korean waters (Paik 1975, 1982, 1989).

The diagnostic features of genus Polyophthalmus are most similar to those of Armandia, but Polyophthalmus doesn’t have the parapodial branchiae and the long unpaired cirrus on anal funnel (Fauchad 1977; Blake 2000). Until now, 15 species of Polyophthalmus have been described but only four species of them are regarded to be valid (Purschke et al. 1995). In East Asia, two Polyophthalmus species are recorded. P. pictus (Dujardin, 1839), which is known as cosmopolitan species, has been widely reported in this region (Okuda 1938; Imajima and Hartman 1964; Imajima and Gamo 1970; Paik 1982, 1989; Paxton and Chou 2000), and P. qingdaoensis Purschke, Ding and Müller, 1995 was additionally recorded from Chinese waters (Purschke et al. 1995).

The purpose of this study is to describe the two new records of Armandia and Polyophthalmus species from Korean waters along with the descriptions and illustrations. We also provide the keys to Armandia and Polyophthalmus species from Korean waters.

MATERIALS AND METHODS

Samples were collected from the soft and rocky bottoms of intertidal zone in Korean waters. The specimens were sorted by using sieves with a pore size of 0.5 mm, fixed initially with 5% formaldehyde-seawater solution, and transferred to 85% ethyl alcohol after sorting in the laboratory. The characteristics of the whole body were observed and the appendages were dissected in a petri dish by using dissection forceps or surgical knives and needles under stereomicroscope (SMZ1500; Olympus, Tokyo, Japan). Dissected specimens were mounted on temporary slides using glycerol or permanent slides using polyvinyl lactophenol solution. Drawings were made by the stereomicroscope and light microscope (LABOPHOT-2; Nikon, Tokyo, Japan) with the aids of drawing tubes. The examined materials are deposited in Chosun University and the National Institute of Biological Resources (NIBR) in Korea.

RESULTS AND DISCUSSION

Class Polychaeta Grube, 1850 다모 강

Order Opheliida Malmgren, 1867 요정갯지렁이 목

Family Opheliidae Malmgren, 1867 요정갯지렁이 과

Genus Armandia Filippi, 1861 보석요정갯지렁이 속

1.A rmandia amakusaensis Saito, Tamaki and Imajima, 2000 아가미보석요정갯지렁이 (신칭) (Fig. 1)

Synonyms: Armandia amakusaensis Saito et al., 2000: 2032, Figs. 2, 3.Fig. 1

Material examined: Korea, 8 specimens, Chungcheongnam- do, Taean-gun, Iwon-myeon, Gwan-ri (36°53′05″N, 126°14′19″E), 23 May 2012, Choi HK; 11 specimens, Jeollabuk- do, Buan-gun, Byeonsan-myeon, Docheong-ri (35° 35′24″N, 126°28′51″E), 14 Aug 2014, Choi HK; 10 specimens, Jeollanam-do, Jindo-gun, Imhoe-myeon, Ganggye-ri (34°23′30″N, 126°15′16″E), 09 Apr 2013, Choi HK.

Description: Body about 6.0 to 7.0 mm long with about 29 segments, slender and convex dorsally, and tapering anterior and posterior end; width 0.8 to 1.0 mm; surface smooth and faintly annulated; ventral groove from setiger 2 to last segment.

Prostomium conical shaped, with ball-shaped palpode distally; 2 or 3 subepidermal eyespots on dorsal side; nuchal organs visible on base of prostomium (Fig. 2A, C).

Branchiae filament-shaped, present on setigers from setiger 2 to second or third from last setiger (Fig. 2A, B).

Lateral eyespots beginning from setiger 7, composed of 11 pairs; anterior eyespots slightly larger than posterior ones (Fig. 2A).

Anal funnel with V-shaped incision on both dorsal and ventral sides, fringed with 8 to 10 short cirri and long unpaired cirrus originated mid-ventrally from inside of anal funnel; ventral length slightly shorter than dorsal length (Fig. 2D).

Parapodia biramous, with presetal lobes and ventral cirrus; presetal lobes semi-circular shaped, with minute projection (Fig. 2E).

Notosetae and neurosetae simple capillary in bundles; notosetae longer than neurosetae (Fig. 2E).

Remarks: Armandia amakusaensis was originally described from western Kyushu in Japan by Saito et al. (2000). They indicated that A. amakusaensis resembled A. leptocirris and A. intermedia in the total number of setigers, the number of branchiae on the setigers, the distribution of lateral eyespots, and the number of anal funnel papaillae (Saito et al. 2000). However, A. amakusaensis is distinguished from these species by the following characteristics: A. amakusaensis and A. intermedia possess the lateral eyespots beginning from the setiger 7, while A. leptocirris has the lateral eyespots beginning from the setiger 5; the branchiae are present on the setigers from the setiger 2 to the second or third from the last setiger in A. amakusaensis, while those of A. leptocirris are present on the setigers from the setiger 2 to the last setiger and those of A. intermedia are present on the setigers from the setiger 2 to the fourth from the last setiger (Saito et al.2000).

Korean materials of the present study show several characteristics which are generally agreed well with the original description of A. amakusaensis as follows: the prostomium has two or three subdermal eyespots; total number of setigers are 29 (27~34 in the original description of A. amakusaensis); the branchiae are present on the setigers from the setiger 2 to the second or third from the last setiger; the lateral eyespots beginning from the setiger 7 are composed of 11 pairs; the anal funnel has 8~11 short cirri and a long cirrus. However, A. amakusaensis of the present study has a minor difference such that its long cirrus on anal funnel is smooth, while that of Japanese materials has constrictions at intervals (Saito et al. 2000).

Armandia amakusaensis resembles A. lenceolata previously reported by Paik (1989) from Korean waters in which the anal funnel is fringed, the lateral eyespots are composed of 11 pairs, and the body has about 29 setigers. However, these species are clearly distinguishable from each other by the following characteristics: A. amakusaensis has two or three subepidermal eyespots on the prostomium, while A. lenceolata has the prostomium without eyespots; A. amakusaensis possesses one or two abranchiate setigers posteriorly, while A. lenceolata has more than two; the anal funnel bears 8~11 short cirri in A. amakusaensis, while that of A. lenceolata has 14~18 short cirri (Willey 1905; Imajima and Hartman 1964; Paik 1989).

Habitat: This species collected from the soft bottoms of intertidal zone in the Yellow Sea of Korean waters.

World distribution: Korea, Japan.

Deposition: NIBRIV0000307837.

Identifiers: Hyun Ki Choi, Seong Myeong Yoon.

2.A rmandia lenceolata Willey, 1905 침보석요정갯지렁이

Synonyms: Armandia lanceolata Willey, 1905: 288, pl. 5, fig. 120; Imajima and Hartman, 1964: 306; Tampi and Rangarajan, 1964: 115; Paik, 1975: 422; 1982: 815; 1989: 502-503, Fig. 199.

3.A rmandia simodaensisTakahashi, 1938 둥근보석요정갯지렁이

Synonyms: Armandia simodaensis Takahashi, 1938: 152, 3 textfigs; Imajima and Hartman, 1964: 306; Paik, 1982: 815; 1989: 503.

Key to the species of the Genus Armandia from Korea

1. Anal funnel fringed ............................................................2

- Anal funnel not fringed........................................................ .......................................... A. simodaensisTakahashi, 1938

2. Abranchiaete setigers on posterior region 1 or 2; anal funnel bearing 8~11 papillae.................................................... ............ A. amakusaensis Saito, Tamaki and Imajima, 2000

- Abranchiaete setigers on posterior region more than 2; anal funnel bearing 14~18 papillae .................................... ................................................... A. lenceolataWilley, 1905

Genus Polyophthalmus Quatrefages, 1850 무늬요정갯지렁이 속

4.P olyophthalmus pictus (Dujardin, 1839) 무늬요정갯지렁이

Synonyms: Polyophthalmus pictusSouthern, 1914: 133; Fauvel, 1927: 137, Fig. 48l-n; Imajima and Hartman, 1964: 309; Day, 1967: 579, Fig. 25.2k-m; Imajima and Gamo, 1970: 16, Figs. 66, 67; Paik, 1982: 815; 1989: 500, Fig. 198.

5Polyophthalmus qingdaoensisPurschke, Ding and Müller, 1995 안점무늬요정갯지렁이 (신칭) (Fig. 3)

Synonyms: Polyophthalmus qingdaoensisPurschke et al., 1995: 239, Fig. 7.

Material examined: Korea, 6 specimens, Jeju-do, Jeju-si, Udo-myeon, Yeonpyeong-ri (33°30′08″N, 126°56′34″E), 24 Jun 2014, Choi HK; 2 specimens, Gangwon-do, Gangneungsi, Jumunjin-eup, Hyangho-ri (33°12′19″N, 126°21′58″E), 15 Sep 2014, Choi HK.

Description: Body slender, about 12.0 to 17.0 mm long with 27 setigerous segments and width 0.8 to 1.2 mm; body color brightly white in alcohol; separations of segments indistinct; ventral groove from setiger 2 to last segment.

Prostomium rounded, with 2 or 3 subepidermal eyespots; 4 or 5 dark pigment-spots on prostomial brain; pair of nuchal organ distinct, formed cylindrical projection, and positioned between prostomium and setrger 1 (Fig. 3A).

Lateral groove present on both sides, from setiger 3 to 24; reduced parapodia and lateral eyespots within lateral groove (Fig. 3B).

Dorsum convex, with short and dark pigment-streaks composed of numerous spots appeared on surface in most segments (Fig. 3C).

Lateral eyespots distinct, circular and with heavily dark pigmentation, beginning from setiger 7, and composed of 12 pairs; median eyespots larger than anterior and posterior ones (Fig. 3B).

Anal funnel with single median notch on dorsal side and 8~10 small cirri on posterior margin; dorsal papillae smaller than ventral (Fig. 3D).

Parapodia without dorsal and ventral cirri, with only subglobular parapodial lobe and 2~5 capillary setae per bundle; setae from parapodial lobe, and grouped into notopodial and neuropodial setae. Branchiae absent (Fig. 3E).

Remarks. Polyophthalmus qingdaoensis, which was first described by Purschke et al. (1995) from Qingdao in China, has a unique feature such as the prostomial brain bearing dark pigment-spots. The authors could find out the presence of this feature from the Korean materials of Polyophthalmus species in the present study. They generally agree well with the original description of P. qingdaoensis as the following characteristics: the body is slightly translucent and poorly pigmented, and has only short and dark pigment-streaks on the dorsal side; the lateral eyespots beginning from the setiger 7 are composed of 12 pairs (Purschke et al. 1995). However, there are some minor differences between Korean materials and Chinese materials of the original description: Korean materials possess the prostomial brain with 4 or 5 pigment-spots, while Chinese materials has the brain with 10 pigment-spots; the anal funnel bears 8~10 small cirri in Korean materials, but that in Chinese materials has only 6 small cirri (Purschke et al. 1995).

Polyophthalmus qingdaoensis is distinguished from P. pictus, which is widely known from East Asia, by the following characteristics: P. qingdaoensis has distinct prostomial brain bearing the dark pigment-spots, while P. pictus possesses indistinct prostomial brain; P. qingdaoensis bears the distinct lateral eyespots, but P. pictus has faintly small lateral eyespots; the body possesses only dark pigment-streaks on the dorsal side in P. qingdaoensis, whereas that of P. pictus bears brown streaks and variable spots (Fauvel 1927; Imajima and Hartman 1964; Day 1967; Imajima and Gamo 1970; Paik 1982, 1989; Purschke et al. 1995).

Habitat: This species collected from algae on the rocky bottoms of intertidal zone in Jeju Is. and the East Sea of Korea.

World distribution: Korea, China.

Deposition: NIBRIV0000307838.

Identifiers: Hyun Ki Choi, Seong Myeong Yoon.

Key to the species of the Genus Polyophthalmus from Korea