Philodina hongcheonensis, Song & Lee, 2022

Song, Min Ok & Lee, Chang-Ho, 2022, Descriptions of Philodinavus koreanus n. sp. and two new species of Philodina (Rotifera, Bdelloidea) from Korea, Zootaxa 5129 (3), pp. 399-411 : 406-408

Philodina hongcheonensis n. sp.

Figures 5 and 6

urn:lsid:zoobank.org:act:1CA0536D-50F3-4FF6-8D6E-26A2AB70BA47

Holotype and paratypes. On permanent slides, deposited in the collection of the National Institute of Biological Resources, Incheon, Korea (holotype: NIBRIV0000862814; two paratypes: NIBRIV0000862815 and NIBRIV0000862816) .

Type locality. Bangnae-ri , Nae-myeon , Hongcheon-gun, Gangwon-do, Korea. GPS coordinates based on WGS84 datum 37°48’21”N / 128°16’02”E .

Material. Four specimens sorted out from tree barks and mosses, collected by Min Ok Song and Chang-Ho Lee on 6 May, 2019.

Differential diagnosis. Philodina hongcheonensis n. sp. appears to be most similar to P. rugosa coriacea due to the morphology of granulated trunk and spurs with wide interspace; however, this new species is different from P. rugosa coriacea by the following characteristics: (1) Philodina hongcheonensis n. sp. doesn’t have eyespots, while P. rugosa coriacea has two orange cerebral eyespots; (2) the corona of P. hongcheonensis n. sp. is slightly narrower than cingulum width, while that of P. rugosa coriacea is wider than cingulum; (3) the upper lip of P. hongcheonensis n. sp. is arched and without a median depression, whereas that of P. rugosa coriacea is with two bulges flanking a wide median depression; (4) the anal pseudosegment of P. hongcheonensis n. sp. has four round processes dorsally, while that of P. rugosa coriacea doesn’t have any processes dorsally; (5) the spurs of P. hongcheonensis n. sp. are thinner and shorter than those of P. rugosa coriacea , and (6) the interspace between spurs is four times as wide as spur base width in P. hongcheonensis n. sp., while it is slightly wider than spur base width in P. rugosa coriacea ( Bryce 1903; Song & Kim 2000).

The most prominent characteristic that distinguishes this new species from its congeners is the four dorsal hemispherical processes on anal pseudosegment ( Fig. 5a ).

Description. Body yellowish. No eyespots. Rostrum round, short and as long as it is wide. Rostral lamella bilobed and with narrow interspace; each lobe very short. Corona very slightly narrower, as wide as, or very slightly wider than cingulum depending on the extension of feeding head. Pedicel short. Sulcus slightly narrower than pedicel width; sulcus base slightly bilobed medially ( Fig. 6c ). Disc retractor U-shaped and with convex sides. Upper lip arched, rimmed and without median notch; slightly higher than sulcus base; much lower than trochal discs. Cingulum pad as wide as cingulum; lateral margins rather parallel medially and round posterolaterally. Pharyngeal tube slightly shorter than trophi length in creeping and much shorter than trophi length in feeding. Teeth 4/4. Trunk highly granulated and with coarsely granulated longitudinal ridges; granulated longitudinal ridges continue to preanal pseudosegment; spindle-shaped in creeping. Anal pseudosegment with four hemispherical processes; two processes dorsally and the other two dorsolaterally; four V-shaped folds under the hemispherical processes. Foot narrower than rump and tapering gradually to pseudosegment bearing toes; with four pseudosegments; foot very short and about 1/13 of total body length in creeping. Toes short and plump. Spurs conical, very thin, short and with pointy ends; with wide interspace; interspace about 4 times as wide as spur base width. Egg oval and with smooth surface.

Measurements. Total length in creeping 246–248 μm. Total length in feeding 181 μm. Rostrum length 13 μm. Corona width 44–47 μm. Cingulum width 43–45 μm. Cingulum pad width 43–45 μm. Antenna length 16 μm. Greatest neck width in creeping 44–45 μm. Greatest trunk width in creeping 60–68 μm. Trophi length 16 μm. Spur length 4.2 μm.

Distribution. This new species is known only from its type locality.

Etymology. The specific name hongcheonensis is derived from the name of its type locality, Hongcheon-gun, Korea.

Figures

FIGURE 5. Philodina hongcheonensis n. sp. (a) creeping, dorsal view; (b) feeding, dorsal view; (c) foot, spurs and toes, dorsal view (scale bars: a–b = 50 μm; c = 10 μm).

FIGURE 6. Light microscopy photographs of Philodina hongcheonensis n. sp. (a) creeping, dorsal view; (b) feeding head and neck, dorsal view; (c) feeding head and neck (an arrow pointing at sulcus base); (d) foot and spurs, dorsal view (scale bars: a = 50 μm; b–c = 25 μm; d = 10 μm).