Homeokotorella anterioporus, Palm & Haseli, 2023

Palm, Harry Wilhelm & Haseli, Mohammad, 2023, Tentaculariids (Cestoda, Trypanorhyncha) of elasmobranchs from Malaysian Borneo, Zoosystema 45 (18), pp. 513-529 : 516-518

Homeokotorella anterioporus n. sp.

( Fig. 1 A-F)

urn:lsid:zoobank.org:act:39F66909-0486-458E-BB5A-E8AC05510A9A

TYPE MATERIAL. — Holotype. Malaysia • 1 specimen; Malaysian Borneo, Sabah, off Semporna (fish market); 04°28’44.09”N, 118°37’00.57”E; from stomach of Taeniura lymma 1 (sensu Naylor et al. 2012) ( Myliobatiformes , Dasyatidae ) (BO-86); LRP 10983 . Paratypes. Malaysia • 1 specimen; same data as for holotype; LRP 4379 • 6 specimens in 5 slides; Malaysian Borneo, Sabah, off Pulau Mabul ; 04°14’44.02”N, 118°37’53.32”E; same host as for holotype; LRP 4380 , 10984; ZMB E.7744-46 .

ETYMOLOGY. — The specific name refers to the anterior position of the cirrus sac in this species.

DESCRIPTION

[Based on whole mounts of 4 specimens.]

Worms 7800-7875 (7837, N =2) long, with 37-40 (N= 2) proglottids; scolex slender, craspedote ( Fig. 1A, B ), 724-781 (739, N= 4) long. Scolex width 290-419 (340, N= 4) at level of pars bothrialis, 282-378 (320, N= 4) at level of pars vaginalis, 314-338 (324, N =4) at level of pars bulbosa. Bothria 4 in number, elongate, with free lateral and posterior margins ( Fig. 1B ). Hamulate spinitriches present along bothrial borders. Pars bothrialis 451-523 (497, N =4) long, slightly overlapping pars bulbosa; pars vaginalis shorter than pars bothrialis, 402- 499 (441, N =4) long; tentacle sheaths straight, 20-30 (26, N =2, n=4) in diameter; muscular ring around basal part of tentacle sheath present. Pars bulbosa 160-192 (179, N = 4) long; prebulbar organs and gland cells inside bulbs absent; bulbs 152-188 (172, N=3, n= 11) long, 64-80 (72, N= 3, n=11) wide, bulb width: length ratio 1.0: 2.1-2.7 (2.4, N=3, n = 11); retractor muscles originate at posterior extremity of bulbs; pars post-bulbosa absent. Velum long, 104-160 (130, N =4). Scolex ratio (pars bulbosa: pars bothrialis: pars vaginalis) 1.0: 2.4-3.3: 2.1-2.8 (1.0: 2.8: 2.5, N =4).

TYMOLOGY

Tentacles elongate and slender, 480-500 (490, N=1, n=2) long; basal swelling absent; tentacle width 20 (N = 2, n =2) at level of basal region, 24 (N=2, n=2) at level of metabasal region, and 20 (N=1, n =1) at level of distal region of tentacle. Hooks solid, tentacles with 27-31 (29, N =1, n= 2) rows of hooks.Tentacular armature homeoacanthous, homeomorphous ( Fig. 1C, D ). First four to five rows of basal hooks increasing in size ( Fig. 1D ), hooks falcate, 4.5-10 (7.0, N=3, n=3) long, base 3-4 (4, N =2, n= 3) long, a single slender uncinate hook with anterior extension of base seen. Metabasal armature with falcate hooks ( Fig. 1C ), 12-14 (13, N = 3, n =7) long, base 4-5 (5, N=2, n=3) long; distal region of tentacle with falcate hooks, 12 (N =1, n=5) long, base 4-5 (5, N=1, n= 5) long. Number of hooks per half spiral row in basal and metabasal region of tentacle 5-6 (N=1, n =2), 6 (N=1, n =1) respectively.

Proglottids acraspedote ( Fig. 1E, F ), euapolytic; immature and mature proglottids wider than long. Mature proglottids 1-5 (3, N= 2) in number, 375-445 (410, N=2, n= 6) long, with maximum width of 525-650 (572, N= 2, n=6); gravid proglottids not observed. Genital pore submarginal in mature proglottids, close to anterior end of proglottids. Cirrus sac elongate, running along anterior end of each proglottid, 44-52 (47, N =1, n =4) long, 160-192 (179, N=1, n =4) wide; cirrus sac length: width ratio 1.0: 3.5-4.4 (3.8, N =1, n= 4). Cirrus unarmed, coiled. Seminal vesicles absent. Vas deferens tightly coiled, running anterior medially and posteriorly towards ovarian isthmus. Vagina runs sinuously from ovary towards cirrus sac, then turning laterally along cirrus sac, opening to genital atrium posterior to cirrus sac ( Fig. 1F ). Testes round to oval, in a single layer, not reaching anterior to cirrus sac, 40-52 (44, N = 2, n= 6) long in diameter, 48 (n =1) in number ( Fig. 1E ). Ovary bilobed, located in centre of proglottid, ovarian lobes 160-200 (178, N=1, n =4) long, 72-92 (83, N=1, n=4) wide. Mehlis’ gland posterior to ovarian isthmus, 40-52 (46, N =1, n= 2) in diameter. Vitelline follicles circumcortical ( Fig. 1F ), round to oval shaped, 20-40 (30, N =1, n=5) in diameter.

REMARKS

The specimens from the host described as Taeniura lymma 1 are very similar to one another and show only little variability in scolex size, hook sizes and proglottid features. The closely related species K. pronosoma and Ko. jonesi differ from H. anterioporus n. gen., n. sp. in their scolex proportions and bulb ratios (see Palm & Beveridge 2002; Palm 2004). The tentacular armature of these two species, K. pronosoma and Ko. jonesi , is homeoacanthous, heteromorphous in the metabasal and/ or basal armature. While K. pronosoma always shows stout, tightly packed hooks with typical, broad diamond-shaped bases on the bothrial tentacle surface, Ko. jonesi has uncinate hooks with an anterior extension of the base on the bothrial and slender spiniform hooks on the antibothrial surface. Homeokotorella anterioporus n. gen., n. sp. displays slender falcate hooks without an anterior extension of the base, which are of similar shape on all tentacle surfaces.

Figures

FIG. 1. — Homeokotorella anterioporus n. gen., n. sp. ex Taeniura lymma 1: A, B, scolex; C, metabasal armature, bothrial surface; D, basal towards metabasal armature, bothrial surface (BH and MH indicate basal and metabasal hooks, respectively); E, F, mature proglottid, in F, open circles are vitelline follicles. Scale bars: A, B, E, F, 125 µm; C, D, 20 µm.