146 



27 



H.W. PALM 



28 



30 



^ 



* 



m 

 ^ 





Fig. 27 H. estigmena from C. limbatus. Heteromorphous basal armature, 



bothridial surface. Scale bar=10 urn. 

 Fig. 28 H. estigmena from C. limbatus. Heteromorphous metabasal 



armature, antibothridial surface. Scale bar=10 urn. 



depending on contraction (anterior segments: 80 x 330-20 x 520), 

 final segments 300-370 x 860-880; testes 33-55 in diameter. 



Remarks. The present specimens are most similar to H. alloiotica, 

 H. punctatissima and H. estigmena, which were considered as 

 belonging to subgroup IIAa by Palm et al. (1997), comprising 

 species having a heteromorphous tentacular armature with hooks 

 diminishing in size towards the basal part of the tentacle, and no 

 characteristic basal armature. Dollfus (1960) described 6 species, H. 

 dakari, H. estigmena, H. punctatissima, H. senegalensis, H. alloiotica 

 and H. cadenati, with a heteromorphous tentacular armature and 

 small hooks of about 10-1 1 urn (bothridial) and 8 um (antibothridial). 

 All these species have a very similar scolex and hook morphology, 

 mainly differing from each other by a different bulb ratio and 

 different scolex proportions. Palm & Walter (1999) proposed the 

 synonymy of Nybelinia dakari Dollfus, 1960 with H. perideraeus, 

 differing from the other species in having a basal armature of similar 

 size to the metabasal armature. Though Dollfus (1960) stated that 

 the bulb ratio of H. dakari was small (about 2.5:1), his drawing 

 (figure 43) indicates a ratio of about 4. His bulb measurements of 

 0.380-0.386 x 0.96-0.100 mm are faulty (0.96 might stand for 

 0.096), which would also indicate a bulb ratio of about 3.9, thus, 

 corresponding to the ratio of H. perideraeus (see Palm & Walter, 

 1999). H. senegalensis, H. alloiotica and H. cadenati also have a 

 bulb ratio of about 4, and H. punctatissima differs from H. estigmena 

 by having a slightly different bulb ratio and different scolex dimen- 

 sions (2. 1 : 1 .6: 1 vs 1 .5 : 1 : 1 ). However, these two species appear to be 

 very similar, and the tentacular armature of H. alloiotica (Figs 29- 

 30), which was re-described by Palm (1995) from Carcharhinus 

 limbatus from the Gulf of Mexico, also corresponds with that of the 

 present material. The present finding represent 3 new host and 

 locality records for H. estigmena. 



This and a previous study (Palm & Walter, 1999) demonstrate 

 wide intraspecific variability in scolex morphology within several 

 species of Nybelina (see also H. africana) and Heteronybelinia, 

 similar to that described earlier for other tentaculariid genera 

 Tentacularia and Hepatoxylon (Palm, 1995). Additionally, Palm et 

 al. (1997) pointed out the dubious value of the 2 characters tentacle 

 width and bulb ratio, which Dollfus used to distinguish the above 6 



29 



Fig. 29 Heteronybelinia alloiotica from Carcharhinus limbatus. 



Heteromorphous basal armature, bothridial surface. Scale bar=10 um. 

 Fig. 30 H. alloiotica. Heteromorphous metabasal armature, antibothridial 



surface. Scale bar=10 urn. 



species. The identification of the present specimens as 

 Heteronybelinia estigmena needs to be confirmed by re-examining 

 the type material of the above mentioned species. The possibly 

 synonymy of all these species has to be kept in mind. 



Heteronybelinia cf. estigmena (Dollfus, 1960) comb. nov. 



Material examined. BMNH 1989.1.18.2, R. Bray leg., 

 14.01 . 197 1 , Cirolana, Atlantic Ocean off Morocco, 33°43'N, 8°38'W, 

 222-236 m. 1 postlarva from Scomber scolias. 



Remarks . Due to its scolex morphology and the homeoacanthous, 

 heteromorphous tentacular armature with a basal hook size of 

 L=8.8-10.4, B=8.8-10.4 (bothridial) and L=5.6-7.2, B=5.6-7.2 

 (antibothridial), the present specimen was tentatively identified as 

 H. estigmena. However, the partly invaginated metabasal armature 

 and the unusual form due to fixation prevent precise identification. 

 The presence of a muscular ring around the tentacle sheaths could 

 not be demonstrated to be of any taxonomic significance. 



12. Heteronybelinia heteromorphi sp. nov. (Figs 31-33) 



Material examined. Holotype and paratype, BMNH 

 1982.4.26.282-284, R. van der Elst leg., 16.5.78, 2 adults from the 

 stomach of Sphyrna mokarran. South Africa; Additional material: 

 BMNH 1968.2.14.30-31, Gooding leg., 2 adults from Sphyrna 

 blochii, Singapore. 



