Heteronybelinia nipponica (Yamaguti, 1952)

Palm, Harry W. & Walter, Thorsten, 2000, Tentaculariid cestodes (Trypanorhyncha) from the Muséum national d’Histoire naturelle, Paris, Zoosystema 22 (4), pp. 641-666 : 656-658

Heteronybelinia nipponica (Yamaguti, 1952)

Nybelinia nipponica Yamaguti, 1952 .

Nybelinia rougetcampanae Dollfus, 1960 . New synonym.

MATERIAL EXAMINED.— Described by Dollfus (1960), holotype of H. rougetcampanae (Dollfus, 1960) from Sphoeroides pachygaster (Müller & Troschel, 1848) (junior synonym Liosaccus cutaneus [Günther, 1870]) ( MNHN 716 HF).

REMARKS

The holotype of H. rougetcampanae (Dollfus, 1960) closely resembles H. nipponica (Yamaguti, 1952) . Both species can be characterised by the presence of bill hooks in the basal armature and the general arrangement of claw-like metabasal hooks. The only real difference between the two species is the metabasal hook size (27 mm in H. rougetcampanae and 35-38 mm in H. nipponica ). However, in its original description, H. nipponica also had a larger scolex size (1350-2900 vs 1220), which might explain the larger hook size. Dollfus (1960) commented that N. rougetcampanae was the only Nybelinia species with bill hooks in the basal armature. However, he overlooked the description of N. nipponica by Yamaguti (1952). Thus, we conclude that H. rougetcampanae is a junior synonym of H. nipponica , and that the latter species has a variable scolex and hook size, as has been described for a species with similar scolex and hook morphology and a wide geographic distribution, Heteronybelinia yamagutii (Dollfus, 1960) .

Interestingly, H. rougetcampanae obtained from the hammerhead shark Sphyrna lewini from the Brazilian coast had a small scolex size (510-690) but metabasal hooks (26-29) similar in size to those described by Dollfus (Sao Clemente & Gomes 1992). The size of the scolex of the larvae can be distinctly greater than observed for adult specimens (Sao Clemente & Gomes 1992). This might be explained by a different scolex size which the postlarvae can reach in the second intermediate hosts (see Discussion).

Heteronybelinia robusta (Linton, 1890) (Fig.8)

Tetrarhynchus robustum Linton, 1890 .

MATERIAL EXAMINED. — III.1923, leg. T. Monod, 1 adult and 1 postlarva from the intestine of Mustelus asterias Cloquet, 1821 ( MNHN 808-809 HF).

DESCRIPTION

Measurements for the adult and postlarva (Fig.

8A): sl = 1166, 1469; sw = 585, 871; pbo = 540, 533; pv = 278, 223; pb = 310, 360; app = not present, 962; vel = 530, 806; bl = 297 (292-302), 331 (318-345); bw = 80 (74-85), 85 (80-90);

br = 3.7;1, 3.9:1; sp = 1.7:0.9:1, 1.5:0.7:1. The tentacle sheaths are coiled. tsw = 33-36, 29-33; tw basal 28-29, 26-27, tw metabasal 28, 26, a basal tentacular swelling is absent. Prebulbar organs are absent, muscular rings around the basal part of the tentacle sheaths not visible. The retractor muscles originate at the base of the bulbs.

The tentacular armature is homeoacanthous, heteromorphous and a characteristic basal armature is absent. The form of the hooks changes slightly from compact and rose-thorn-shaped (bothridial) to more slender hooks with a stout base (antibothridial) (Fig.8B). The hook size in the metabasal armature ranged between l = 9-13, 10-14; b = 7-9, 7-9, (bothridial) and l = 12-14, 12-15; b = 6-8, 6-8 (antibothridial), and hooks of the basal part of the tentacle were minute, between l = 5-6, 4-6; b = 5-6, 5-6 (bothridial) and

l = 4-5, 4-5; b = 5-6, 5-6 (antibothridial), increasing gradually towards the tip; hsr = 6-7.

The incomplete strobila of the adult worm consists of about 65 acraspedote proglottids behind the velum (Fig.8C). The first 15 proglottids behind the velum are short (40-70 long × 420-440 wide), the following enlarge in size (100-600 × 530-970). In mature proglottids, genital atrium ventro-submarginal, in anterior third of segment; genital pores alternate irregularly. Cirrus sac short, 300 × 65, directed anterio-medially and extending halfway to the centre of the proglottis, sac thinwalled; cirrus unarmed and coiled within sac, internal and external seminal vesicle absent; testes of different shape, often ovoid, 60-100 in diameter, arranged in more than a single layer; testis number 60-75 per proglottid, encircle female genital complex and occupy entire medulla except for region of female genital complex and anterior of it. Ovary central, follicular. Vitelline follicles 15-25 in diameter. Other internal structures not visible in the present specimen.

REMARKS

The present specimens correspond directly with the description of H. robusta by Palm (1999), with respect to scolex size as well as size and arrangement of the tentacular hooks. However, the bulb ratio is 3.7-3.9: 1 in the present specimens compared with 3.0: 1 in the specimen from Carcharhinus limbatus described by Palm (1999). It was obvious that within the same final host species, the postlarva had a larger scolex size than that of the adult worm. However, scolex length measured to the beginning of the velum was the same size in both specimens. H. robusta has been recorded from Carcharhinus limbatus (Müller & Henle, 1839) , Dasyatis centroura (Mitchill, 1815) , and Mustelus asterias Cloquet, 1821 as final hosts, the latter finding represents a new host record.