Rhabdias kafunata, Sata & Takeuchi & Nakano, 2020

Sata, Naoya, Takeuchi, Hirohiko & Nakano, Takafumi, 2020, A New Species of Rhabdias (Nematoda: Rhabditida: Rhabdiasidae) from Miyakojima Island, Okinawa, Japan, Species Diversity 25 (2), pp. 117-121 : 118-120

Rhabdias kafunata sp. nov.

( Fig. 1 )

Rhabdias incerta non Wilkie, 1930: Hasegawa 1984: 16, figs 11–13; Kuzmin 2013: 41 , 44 (in part), fig. 21, table 9.

Diagnosis. The East Asian Rhabdias , with long and slender body. Buccal capsule small and cup-like. Esophagus 694–878 long, anterior muscular region thickened. Cuticular inflation less prominent in region posterior to small cephalic cuticular inflation, middle part of body and tail tip. Tail long and tapering sensu Wilkie (1930) and Yuen (1965).

Material examined. Holotype: KUZ Z2572 , whole specimen, adult female, obtained from the lung of a specimen of Bufo gargarizans miyakonis ( KUZ R 77141), collected from Hirara-Nishinakasone (24°48′48.0″N, 125°18′44.0″E), Miyakojima island, Okinawa Prefecture, Japan on 14 November 2016 . Paratypes: KUZ Z2573 – Z2579 , whole specimens obtained from the lung of the same specimen of holotype’s host and other B . g. miyakonis specimens ( KUZ R77142, R77143, R77147, R77149), collected from the same locality and data as the holotype’s host-specimen; KUZ Z2581 , one prepared slide of a section of anterior end of a female; and KUZ Z2580 , remaining body specimen of KUZ Z2581 . KUZ Z2581 and Z2580 were obtained from the lung of a B . g. miyakonis specimen ( KUZ R 77148), collected from the same locality and data as the holotype’s host-specimen .

Additional materials: in total, 164 adult and young females were obtained from the lung of B. g. miyakonis; KUZ Z2702 and Z2703, 57 whole specimens, and six non-deposited specimens for the present and future molecular studies, obtained from KUZ R 77149; KUZ Z2704 and Z2705, eight whole specimens, and one non-deposited specimen for a future molecular study, from KUZ R 77147; KUZ Z2706 , five whole specimens, and three non-deposited specimens for a future molecular study, from KUZ R 77143; KUZ Z2707 and Z2708, 33 whole specimens from KUZ R 77142; KUZ Z2709 and Z2710, 44 whole specimens, and five non-deposited specimens for the present and future molecular studies, from KUZ R 77141; and KUZ Z2711 , two whole specimens, from KUZ R 77148 .

Type locality. Hirara-Nishinakasone (24°48′48.0″N, 125°18′44.0″E), Miyakojima island , Okinawa Prefecture, Japan .

Type host. Bufo gargarizans miyakonis Okada, 1931 ( Amphibia: Bufonidae ); site of infection: lung. A total of 173 individuals were obtained from six specimens of B. g. miyakonis; mean intensity (mean±standard error, followed by ranges): 28.8±10.5, 3–66.

Description. General. Body long and slender with tapered extremities, body becoming wider at region between anterior end of genital system and vulva. Cephalic end with six lips, each lip with a minute papilla. Amphids situated on posterior surface of lateral lips. Oral opening rounded-hexagonal. Small cuticular inflation present on cephalic region. Cuticular inflation less prominent in region posterior to small cephalic cuticular inflation, middle part of body and tail tip.

Body length 11.06 (10.99–16.77) mm, and maximum width 236 (204–355). Body length/maximum body width=46.9 (44.8–53.9). Body width at junction of esophagus and intestine 157 (141–239), at vagina 181 (181–340), and at anus 98 (91–144). Vestibulum short, 4.3 (2.5–6) (n =7). Buccal capsule small, cup-like in lateral view, 16 (15– 19) deep (n =7), 26 (21–30) wide (n =7). Anterior muscular region of esophagus thickened. Length of esophagus 758 (694–878) long [6.9% (4.2–7.3) of body length] with width of 43 (33–46) at anterior end, 56 (47–59) at thickened muscular part, 39 (39–56) at nerve ring, 80 (80–101) at bulbar part. Nerve ring and excretory pore 227 (193–231) [2.1% (1.2–2.1%) of body length] and 262 (228–277) [2.4% (1.5– 2.5%) of body length], respectively, from cephalic end, and 208 (166–208) [27.4% (20.8–27.4%) of esophagus length] and 247 (195–259) [32.6% (26.2–32.6%) of body length], respectively, from anterior end of esophagus. Intestine thick walled. Rectum short, with thin wall. Vulva 6.18 (5.97–8.32) mm from cephalic end, and located at middle to posterior of body [55.9% (49.6–55.9%) of body length], having slightly salient lips. Genital system amphidelphic, anterior limb turned posteriorly at 2.18 (2.18–3.28) mm from cephalic end, and posterior limb turned anteriorly at 2.48 (1.45–3.25) mm from tail end. Uteri long, tubular, filled with numerous eggs. Tail long, gradually tapering from anus, and 477 (376– 493) long [4.3% (2.8–4.3%) of body length]. Most specimens possessing few numbers of lateral pores. Phasmids located both lateroventral sides, 166 (144–200) from tail end (n =4). Eggs elliptical, 101 (89–107) by 47 (42–55) (n =10), thin shelled, most eggs containing first stage larva.

Etymology. The specific name kafunata is a noun from the word locally used in the Miyako Islands for B. g. miyakonis, the host toad of the new species ( Okinawa Center of Language Study 1999 –2003); thus not a Latin or Latinized word.

DNA Sequences. In total, 4 sequences were determined: one specimen obtained from a same host toad as holotype ( KUZ R 77141), 2 sequences—COI ( LC 496790 ; 655 bp), and 12S ( LC 496792 ; 475 bp); one specimen obtained from a same host toad as paratypes ( KUZ R 77148), 2 sequences— COI ( LC 496791 ; 655 bp), and 12S ( LC 496793 ; 475 bp) .

Remarks. Rhabdias kafunata sp. nov. can be discriminated from the other nine congeners recorded from East Asia and the Russian Far East as follows. The new species, of which body length ranges from 10.99 to 16.77 mm, can be distinguished from the following four Rhabdias species: R. globocephala Kung and Wu, 1945 [3.18–6.88 mm in Kuzmin (2005)], R. montana Yamaguti, 1954 (6.0– 7.8 mm; Yamaguti 1954), R. nipponica Yamaguti, 1935 (4.18–5.04 mm; Yamaguti 1935), and R. polypedatis Yamaguti, 1941 (4.2–5.2 mm; Yamaguti 1941). Rhabdias kafunata sp. nov. can be discriminated from R. bermani Rausch, Rausch, and Atrashkevich, 1984 and R. rhacophori Yamaguti, 1941 by their esophagus lengths, because latter two species possess much shorter esophagus than that of the new species ( Yamaguti 1941; Rausch et al. 1984). Rhabdias kafunata sp. nov. also differs from R. bermani in its possession of the thickened anterior muscular part in esophagus. Rhabdias kafunata sp. nov. is distinguishable from R. japalurae Kuzmin, 2003 , and R. tokyoensis Wilkie, 1930 by having a long and tapering tail. Unlike the new species, R. japalurae and R. tokyoensis have short and conical tails. Rhabdias kafunata sp. nov. also differs from R. japalurae in the absence of a cuticular inflation at the region middle of esophagus. The new species possesses a cup-like buccal capsule; this characteristic can discriminate R. kafunata sp. nov. from R. bicornis Lu, 1934 , which has a funnel-like buccal capsule ( Lu 1934).

Figures

Fig. 1. Rhabdias kafunata sp. nov., holotype (KUZ Z2572: A, C, D, H), paratypes (KUZ Z2581: B; KUZ Z2578: E–G). A, anterior region, lateral view; B, cephalic region, apical view; C, cephalic region, lateral view; D, vulvar region, lateral view; E, cuticular inflation in anterior region, lateral view; F, cuticular inflation in caudal region; G, caudal region, lateral view; H, phasmids, ventral view. Scale bars: 200µm (A), 40µm (B, C), 180µm (D), 400µm (E), 450µm (F, G), and 150µm (H).