Habrotrocha minima De Koning 1947

1. Habrotrocha minima De Koning, 1947 꼬ŔḏĒḆệ (ṵÿ) Habrotrocha minima De Koning, 1947, p. 191, pl. 3, figs. 12a- d. Material examined. One specimen found from mushrooms, mosses and tree barks at Daegwallyeong Guksaseonghwangdang, Hoenggye-ri, Daegwallyeong-myeon, Pyeongchang-gun, Gangwon-do, 37°41 ʹ 41.12 ʺ N, 128°45 ʹ 15.27 ʺ E, 20 May, 2023. Diagnosis. Rostrum round. Corona much narrower than cingulum; the ratio of corona width to cingulum width about 1: 1.43. Upper lip slightly concave and with low arch medially; lower than sulcus base. Sulcus very narrow; narrower than 1/5 of pedicel width. Disc retractor shallow U-shaped, narrow and much higher than upper lip. Pedicel short. Cingulum pad rather long, round anterolaterally and cylindrical posteriorly. Foot very short and about 1/10 of total length in creeping. Spurs short and with narrow interspace; interspace much narrower than spur base width. Measurements. Total length in feeding 142-148 μm. Total length in creeping 202 μm. Rostrum width in creeping 14 μm. Corona width 15-16 μm. Cingulum width 20-22 μm. Cingulum pad width 21-23 μm. Greatest trunk width in creeping 36 μm. Spur length 3 μm. Remarks. Habrotrocha minima can be distinguished from the other Habrotrocha species by the narrow corona, lowly arched median lobe of upper lip and narrow sulcus. The characteristics of the Korean specimen agree well with the original description except the morphology of upper lip and the ratio of cingulum to cingulum pad. The upper lip is slightly arched in the original description, while that of the Korean specimen was rather concave and with low and arched median lobe. The cingulum of the type specimens was much wider than cingulum pad, while that of the Korean specimen was slightly narrower than cingulum pad. The shape of the feeding head of the Korean specimen was more close to that of the Austrian specimens reported by Donner (1962). *New to Asia. a 1=Daegwallyeong Guksaseonghwangdang, Hoenggye-ri, Daegwallyeong-myeon, Pyeongchang-gun, Gangwon-do, 37°41 ʹ 41.12 ʺ N/128°45 ʹ 15.27 ʺ E, 20 May, 2023; 2=Daegwallyeong Guksaseonghwangdang (near parking area), Hoenggye-ri, Daegwallyeong-myeon, Pyeongchang-gun, Gangwon-do, 37°41 ʹ 46.9 ʺ N/128° 45 ʹ 13.5 ʺ E, 11 May, 2024. This species is rather rare and has been reported only from Austria (Donner, 1962) and Czech Republic (Devetter et al., 2020) since the description from the Netherlands by De Koning (1947). Devetter et al. (2020) reported this species only in the species list. New to Asia. World distribution. Austria, Czech Republic, the Netherlands and Korea. Deposition. Deposited in the collection of the National Institute of Biological Resources, Incheon, Korea (NIBR IV0000910356).