Apotrachelocerca orientalis, Ma & Xu & Yan & Li & Warren & Song, 2021

Ma, Mingzhen, Xu, Yuan, Yan, Ying, Li, Yuqing, Warren, Alan & Song, Weibo, 2021, Taxonomy and molecular phylogeny of four karyorelictid species belonging to the genera Apotrachelocerca and Tracheloraphis (Protozoa: Ciliophora), with descriptions of two new species, Zoological Journal of the Linnean Society 192 : -

APOTRACHELOCERCA ORIENTALIS SP. NOV.

( Figs 3, 4; Table 3)

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. o r g: a c t: A 8 2 B 3 8 9 9 - B E D 2 - 4 1 6 0 - 8 0 D 4 - 3718F962CE8B

Diagnosis: Body length in vivo 200–500 Μm; single nuclear group composed of two or three macronuclei and one micronucleus; six to seven somatic kineties on right side, left side unciliated except for bristle kinety; spine-like cilia on border of glabrous stripe; width of glabrous stripe same as trunk; no cortical granules.

Type locality: The intertidal zone of a swimming beach near the Zhanqiao Pier in Qingdao (36°03′50″N, 120°19′47″E), China .

Type specimens: A protargol slide containing the holotype specimen marked with an ink circle is deposited in the Laboratory of Protozoology, OUC (No. MMZ2018122201).

Etymology: The species-group name orientalis – from Latin oriens, east – reflects that this organism was first discovered in east China.

Description: Fully extended cells about 400 × 15 Μm in vivo; body flexible and dorsoventrally flattened, i.e. ribbon-like ( Figs 3A, 4A, B). Body width almost constant in anterior three-quarters of cell, with no distinguishable neck region; posterior quarter progressively narrowed forming a curved tail. Cytoplasm colourless and transparent under high magnification, but appears to be yellow-greenish or brownish at lower magnifications, possibly due to food

All data are based on protargol-stained specimens. Measurements in Μm. Abbreviations: CV, coefficient of variation in %; Max, maximum; Mean, median; Min, minimum; N, number of specimens investigated; SD, standard deviation of the mean.

contents and/or colourless to dark brownish inclusions (mitochondria?), about 2–3 Μm in size, ellipsoid in shape and located beneath pellicle ( Figs 3E, 4D, E, F, G). Pellicle thin and characteristically forming a nipple-like rugged edge in contracted cells ( Fig. 4E). Cortical granules not recognized. Single nuclear group located in centre of trunk, containing two or three (usually two) macronuclei, 4–6 Μm in diameter and, invariably, one micronucleus located between macronuclei ( Figs 3D, G, 4J, K, M). Somatic cilia about 10 Μm long; bristle cilia rigid, spine-like and readily observable in vivo ( Fig. 4E). Locomotion by gliding between sand grains and organic debris.

Infraciliature consisting of dikinetids on right side. Glabrous stripe occuping entire left side; right side with six to seven somatic kineties, cilia c. 10 Μm long ( Figs 3F–I, 4L–O). No anterior or posterior secant system ( Figs 3G, I, 4M, O). Glabrous stripe bordered by one bristle kinety composed of dikinetids; only one basal body of each dikinetid bearing a cilium ( Fig. 3E). Circumoral kineties composed of two uninterrupted rows of dikinetids; upper row winding anticlockwise, lower row winding clockwise ( Figs 3H, I, 4N, O).