INTRODUCTION

In the genera Macrotrachela Milne, 1886 and Habrotrocha Bryce, 1910, about 106 and 128 taxa, respectively, have been known to the world (Segers 2007, updated in 2012). In Korea, 17 Macrotrachela and 18 Habrotrocha taxa have been reported until recently (Song 2015; Song and Min 2015). The result of the present study added three Macrotrachela and two Habrotrocha species to the Korean record, which led to 20 taxa in Macrotrachela and 20 in Habrotrocha.

These Korean new records included four rare species with very limited distributions such as M. magna, M. oblita, M. inermis and H. schultei. Most remarkably, M. magna and H. schultei are recorded outside their type localities for the first time after 60 and 49 years after their descriptions, respectively. M. oblita has been reported only from five European countries, and M. inermis has been known from three European countries and Eastern Turkey before the present study. While H. eremita is a presumably cosmopolitan species because of its wide distribution, it is new to Asian fauna.

Here diagnostic characteristics, illustrations and discussions on the taxonomy and distribution of each Korean new record are provided.

MATERIALS AND METHODS

For the present taxonomic study on Korean rotifers, specimens collected from various terrestrial habitats such as mosses, lichens, mushrooms on tree trunks, leaf litter and soil were investigated. Samples were collected from four locations in Korea from July 4, 2014 to May 24, 2015. The detailed habitat information and sampling date of each locality are listed in Table 1. The bdelloids were extracted, examined and identified according to a previously described method (Song 2014). The photography and motion records of living specimens were performed using an Infinity 2 digital camera (Lumenera Corporation, ON, Canada). The photographs and computer-grabbed images of motion records were used for illustrations. Measurements were made by using Photoshop CS3. The specimens were killed with head, foot, and toes extended, by using the boiling water fixation method (Pennak 1978) instead of narcotization. The method of Stemberger (1979) was used for the preparation of permanent mounts.

The classification scheme is based on Melone and Ricci (1995).

RESULTS AND DISCUSSION

Phylum Rotifera Cuvier, 1817 윤형동물문

Class Eurotatoria De Ridder, 1957 진윤충강

Subclass Bdelloidea Hudson, 1884 질형아강

Order Philodinida Melone & Ricci, 1995 선윤충목

Family Philodinidae Bryce, 1910 선윤충과

Genus Macrotrachela Milne, 1886 큰관윤충속

1M acrotrachela inermisDonner, 1965 (Fig. 1) 연약큰관윤충 (신칭)

Synonyms: Macrotrachela inermisDonner, 1965, pp. 139- 140, Fig. 103; Donner, 1970, p. 242, Abb. 21d, g, h.(Fig. 1)

Material examined: 2 specimens, Saryeoni forest, Jocheoneup, Jeju-si, July 4, 2014.

Diagnosis: Upper lip arched and with rounded triangle-shaped median lobe; upper lip slightly lower than trochal discs. Corona much narrower than cingulum pad. Pharyngeal tube slightly longer than trophi length. Teeth 4/4. Spurs conical with pointed ends; interspace narrower than spur base width.

Measurements: Total body length (in feeding) 203~210 μm. Total body length (in creeping) 270 μm. Greatest trunk width (in feeding) 58 ~59 μm. Greatest trunk width (in creeping) 44 μm. Corona width 22 μm. Cingulum width 23~ 25 μm. Cingulum pad width 28~ 29 μm. Trophi length 11~ 12 μm. Spur length 6 μm.

Remarks: This species is distinguished from its congeners by wide rostrum, short rostral lamella, 4/4 teeth and corona as wide as or narrower than cingulum pad. The general morphology of the Korean specimens conforms to the original description well except that the upper lips of some Austrian specimens were much lower than trochal discs and with a slight median notch (Fig. 103d-e in Donner 1965).

While the Austrian and Turkish specimens were collected from mosses (Donner 1970; Kaya 2013), the Korean specimens were isolated from mushrooms on a tree trunk. Kaya (2013) reported this species from the eastern part of Turkey (Erzurum), which was the first Asian record of it.

Habitat: The specimens were isolated from mushrooms on a tree trunk at Saryeoni forest.

World Distribution: Austria, Italy, Turkey, Belarus, Korea.

Deposition: NIBR (KOSPGR0000270525, KOSPIV 0000206148, KOSPIV0000206149).

Identifier: Min Ok Song.

2M acrotrachela magnaSchulte, 1954 (Fig. 2) 거대큰관윤충 (신칭)

Synonyms: Macrotrachela magnaSchulte, 1954, pp. 603- 604, Abb. 29a-d; Donner, 1965, p. 140, Fig. 94j.(Fig. 2)

Material examined: 3 specimens, Gangneung-Wonju National University campus, June 22, 2014.

Diagnosis: Upper lip bilobed medially and with slightly bilobed depression between 2 lobes. Corona wider than cingulum. Body reddish and granulated. Spurs conical, pointed, not granulated and with narrow interspace. First foot pseudosegment with one hump dorsally. Teeth 2+1/1+2.

Three toes very short.

Measurements: Total body length (in feeding) 380 μm. Greatest trunk width (in creeping) 74 μm. Greatest trunk width (in feeding) 102~ 116 μm. Corona width 83 μm. Cingulum width 70~ 71 μm. Cingulum pad width 65~ 68 μm. Trophi length 29~ 30 μm. Spur length 14 μm.

Remarks: This species is rather bigger than other Macrotrachela species and its total body length is up to 500 μm (Donner 1965). The general morphology of the Korean specimens is in good agreement with the original description. The present study is the first record after the original description of this species from Germany by Schulte (1954).

Habitat: The specimens were isolated from mushrooms on a tree trunk at Gangneung-Wonju National University campus.

World Distribution: Germany and Korea.

Deposition: NIBR (KOSPGR0000270524, KOSPIV 0000206146, KOSPIV0000206147).

Identifier: Min Ok Song.

3M acrotrachela oblitaDonner, 1949 (Fig. 3) 삼엽무늬큰관윤충 (신칭)

Synonyms: Macrotrachela oblitaDonner, 1949, pp. 148- 149, Abb. 26a-g; Donner, 1965, pp. 164-166, Figs. 121ae.(Fig. 3)

Material examined: 5 specimens, Jeongan-myeon, Gongju- si, Chungcheongnam-do, Sep. 20, 2014.

Diagnosis: Corona wider than cingulum and higer than upper lip. Upper lip arched and trilobed medially; upper lip with trilobed and crusted area dorsally. Sulcus with 2 small projections medially. Teeth 2/2. Spurs conical, narrow, with straight margins and with pointed ends; interspace wider than spur base width.

Measurements: Total body length (in creeping) 385 μm. Greatest trunk width (in feeding) 89~ 90 μm. Greatest trunk width (in creeping) 70 μm. Corona width 75 μm. Cingulum width 61 ~63 μm. Cingulum pad width 55 μm. Smallest neck width 34 μm. Trophi length 22 μm. Spur length 10~13 μm.

Remarks: This species is characterized by two small processes on sulcus and thick patched area on upper lip, which is granulated and trilobed anteriorly. The morphology of the Korean specimens conforms well with that of the original description except that the spurs are narrower and the interspace is a little bit wider than those of the type specimens. This species has been reported only four European countries after its description from Austria by Donner (1949). The present report is the first one outside Europe.

Habitat: The specimens were isolated from lichens and mosses collected from a mountain at Jeongan-myeon, Gong ju-si.

World Distribution: Austria, Belgium, Czech Republic, Hungary, Belarus and Korea.

Deposition: NIBR (KOSPGR0000276141, KOSPIV 0000219237, KOSPIV0000219238).

Identifier: Min Ok Song.

Family Habrotrochidae Bryce, 1910 협관윤충과

Genus Habrotrocha Hudson and Gosse, 1886 협관윤충속

4Habrotrocha eremita (Bryce, 1894) (Fig. 4) 은둔협관윤충 (신칭)

Synonyms: Callidina eremitaBryce, 1894, pp. 452-454, pl. 23, fig. 3.(Fig. 4)

Habrotrocha eremita: Donner, 1949, p. 140, fig. 17; Donner, 1950, p. 292, fig. 2; Donner, 1962, p. 316, figs. 12b, c.

Material examined: 1 specimen, Mongsanpo, Nam-myun, Taean-gun, Chungcheongnam-do, May 24, 2015.(Fig. 5)

Diagnosis: Nest composed of gelatinous material and debris. Corona much wider than cingulum pad. Sulcus V-shaped and slightly narrower than pedicel width; one small and triangular projection in the middle of sulcus. Pedicel long and divergent. Upper lip much lower than sulcus base; arched, rimmed and with auricel-like swollen lateral margin. Head and neck cylindrical. Trunk round.

Measurements: Total body length (in creeping) 180 μm. Corona width 38 μm. Cingulum width 34 μm. Cingulum pad width 28 μm. Dorsal antenna length 12 μm. Trophi length 20 μm. Smallest neck width 25 μm.

Remarks: This species closely resembles H. solitariaDonner, 1949 and H. visa Donner, 1954. Donner (1962) placed these three species in a “solitaria-visa-eremita” group, and examined the variations in body size, trophi length, feeding head length, dental formula, corona width, cingulum pad width, sulcus width, upper lip morphology, presence or absence of a projection on the sulcus, and egg size. One of the most distinguishable characteristic may be the ratio of the corona width to the cingulum pad width, which is 0.75~ 0.93 for H. solitaria, 0.92~ 1.11 for H. visa, and about 1.38 for H. eremita (Song and Min 2015). The ratio of the corona width to the cingulum pad width is 1.36 for the Korean specimen.

Even though this species has a very wide distribution as shown below, the present study is the first Asian record of it.

Habitat: The specimen was isolated from leaf litter, mosses and soil collected from Mongsanpo beach area.

World distribution: Europe, Africa, North and South America, New Zealand and Korea.

Deposition: NIBR (KOSPIV0000228917).

Identifier: Min Ok Song.

5H abrotrocha schulteiDonner, 1965 (Fig. 5) 슐트협관윤충 (신칭)

Synonyms: Habrotrocha spec. A, Schulte, 1954, p. 599, Abb. 17a-d.

Habrotrocha schulteiDonner, 1965, p. 79, Fig. 58h-k.

Material examined: 2 specimens, Saryeoni Forest, Jocheon- eup, Jeju-si (mushrooms on tree trunk), July 4, 2014.

Diagnosis: Upper lip wavy and rounded triangle-shaped; upper lip much lower than trochal discs. Corona much narrower than cingulum pad; corona width about 3/5 of cingulum width. Sulcus very narrow. Pharyngeal tube as long as trophi. Teeth 5/5. Spurs conical with pointed ends; interspace much narrower than spur base width.

Measurements: Total body length (in feeding) 164 μm. Greatest trunk width (in feeding) 57~ 58 μm. Corona width 16 μm. Cingulum width 25 μm. Cingulum pad width 24 μm. Smallest neck width 22 μm. Trophi length 12 μm. Spur length 4 μm.

Remarks: This species is easily recognized by its very narrow sulcus, rounded triangle-shaped upper lip, plump trunk during feeding and very narrow corona, which is only about 3/5 of cingulum width.

This is very rare species and the present study is the first report of it after the original description. Schulte (1954) described the present species as Habrotrocha spec. A from pinewoods at Erlangen, Germany. Donner (1965) made a new specific epithet “schultei” for this species.

Habitat: The specimens were isolated from mushrooms on a tree trunk at Saryeoni forest.

World Distribution: Germany and Korea.

Deposition: NIBR (KOSPGR0000270526, KOSPIV000 0206151).

Identifier: Min Ok Song.