Bradyscela hoonsooi, Song, Min Ok & Min, Gi-Sik, 2015

Song, Min Ok & Min, Gi-Sik, 2015, A new species and ten new records of bdelloid rotifers from Korea, Zootaxa 3964 (2), pp. 211-227 : 213-215

Bradyscela hoonsooi new species

Figures 1 and 2

Holotype and paratypes. In permanent slides, deposited in the collection of the National Institute of Biological Resources, Incheon, Korea (holotype: KOSPIV0000192577; two paratypes: KOSPIV0000192578, and KOSPIV0000192579). Specimens isolated from mosses growing on a tree trunk at Wanggok-ri, collected by Min Ok Song. Type material is further fixed with 4 % formalin after boiling water fixation ( Pennak 1978), and preserved in 100 % glycerin ( Stemberger 1979).

Type locality. Wanggok-ri, Goseong-gun, Gangwon-do, Korea. GPS 38° 22’ 48.46” N / 128° 28’ 2.78” E

Material. Five specimens found in mosses growing on a tree trunk at Wanggok-ri, Goseong-gun, Gangwondo.

Differential diagnosis. In the genus Bradyscela , only two species, B. clauda (Bryce, 1893) and B. granulosa De Koning, 1947 , have previously been described. B. hoonsooi n. sp. seems to be more morphologically similar to B. clauda than to B. granulosa . B. clauda and B. hoonsooi n. sp. have numerous papillae surrounding the posterior margin of the second foot pseudosegment, whereas B. granulosa has two very small spurs, which are usually hidden inside the U-shaped swollen part of the second foot pseudosegment. B. hoonsooi n. sp. can be distinguished from B. clauda by the following morphological characteristics: (1) the number of teeth on the outer margin of the rake apparatus; and (2) the number and shape of papillae around the posterior margin of the second foot pseudosegment. B. hoonsooi n. sp. has four teeth on the outer margin of the rake apparatus, whereas B. clauda has six; B. hoonsooi n. sp. has approximately 42 thin papillae, two thin and knobby papillae, and two thick paddleshaped papillae, whereas B. clauda has approximately 21 short and round-ended papillae and two inverted triangleshaped papillae; and the majority of papillae in B. hoonsooi n. sp. are thinner and much longer than those of B. clauda .

Description. Body reddish, highly granulated, and vermiform. Rostral lamella trilobed with auricle-like lateral lobes; each lateral lobe very thin and hexagonal in frontal view; median lobe with variable shapes depending on head movement (flat, arched, or slightly bilobed). Head wider than its length when rake apparatus fully opened, and slightly narrower than maximum body width in creeping. Rake apparatus with four teeth on outer margin and one tooth inside; each corner of outer margin of rake apparatus triangular, variable in shape, from a dull angle to a sharp process depending on the degree of retraction or expansion of the rake apparatus during its grasping action ( Fig. 1 b). Dental formula 2/2. Pharyngeal tube as long as trophi length. Foot very short, barely extended fully, and with three pseudosegments; posterior margin of second pseudosegment surrounded by approximately 42 thin papillae, and with two thin and round-ended papillae on each ventrolateral corner, and two large paddle-shaped papillae on each dorsolateral corner. Three toes very short, thick, and blunt.

Measurements. Total length 200–210 µm. Greatest trunk width 45–50 µm. Rostral lamellae width 21–22 µm.

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

Etymology. The species is named after the late Dr. Hoon Soo Kim, Professor Emeritus of the Department of Zoology at Seoul National University, in recognition of his outstanding contribution to invertebrate taxonomy in Korea, as well as his excellent mentoring during the authors’ graduate studies.

Figures

FIGURE 1. Bradyscela hoonsooi n. sp. (a) creeping, ventral view; (b) feeding head, ventral view; (c) toes and papillae, ventral view (scale bars: a = 50 µm; b – c = 10 µm)

FIGURE 2. Light microscopy photographs of Bradyscela hoonsooi n. sp. (a – b) feeding head, ventral view; (c) toes and papillae, ventral view (scale bars: a – b = 20 µm; c = 10 µm).