TENTACULARIID TRYPANORHYNCHS FROM THE NHM 



147 



33 



Fig. 31 Heteronybelinia heteromorphi sp. nov.. Scolex from Sphyrna makorran. Scale bar=100 pm. 



Fig. 32 H. heteromorphi sp. nov. from S. makorran. Heteromorphous metabasal armature, bothridial (left hand side) and antibothridial (right hand side) 



surfaces. Scale bar=15 um. 

 Fig. 33 H. heteromorphi sp. nov. from S. makorran. Heteromorphous basal armature, bothridial (left) and antibothridial (right) surfaces. Scale bar=15 um. 



Description (Figs 31-33). With the characters of the genus 

 Heteronybelinia. Measurements: SL=1367, 1300, 1367, 1467; 

 SW=833, 934, 800, 800; pbo=767, 734, 734, 867; pv=534, 500, 567, 

 506; pb=500, 447, 334, 427; ppb=20, 40, 105, 160; vel=333, 340, 

 317, 300; BL=437 (414-454), 404 (387-414), 327 (308-334), 405 

 (368^127); BW=154 (134-163), 181 (174-187), 158 (137-175), 

 176 (173-179); BR=2.8:1, 2.2:1, 2.1:1, 2.3:1; SP=1.5:1.1:1, 

 1.6:1.1:1, 2.2:1.7:1, 2.0:1.2:1. The tentacles are long, robust and 

 increase in diameter towards the tip of the tentacle; TL=540 (27 

 rows of hooks), 480 (23 rows), 560 (25 rows), nm; TW basal=53-60, 

 53-60, 48-50, 52-54; TW apical=75-80, 65-70, 58-61, nm; a basal 

 swelling is absent. The tentacle sheaths are straight; TSW=53-66, 

 45-54, 68-70, 69-74. Prebulbar organs and muscular rings around 

 the basal part of the tentacle sheaths are absent. A thickening, 

 encircling more than half of the tentacle sheath near the entrance to 

 the bulbs, is present. The retractor muscles originate at the basal part 

 of the bulbs. 



The tentacular armature is homeoacanthous, heteromorphous, 

 and a characteristic basal armature is absent. The form of the hooks 

 is rose-thorn shaped becoming more slender towards the tip of the 



tentacle (Fig. 32). Similarly, the form changes from the bothridial to 

 the antibothridial surface. The hook sizes of the metabasal tentacular 

 armature for BMNH 1982.4.26.282-284 and 1968.2.14.30-31 are 

 as follows: above 22th row, L=24-28, B= 19-21; L=25-28, B=15- 

 17 (bothridial) and L=28-32, B=12-15; L=30-32, B=12-15 

 (antibothridial); about 14th row, L=22-25, B=16-17; L=21-23, 

 B=16-17 (bothridial) and L=25-28, B=ll-15; L=30-32, B=12-15 

 (antibothridial); The basal hooks (Fig. 33) ranged between L=16-18 

 and B=10-12; hsr=7-8. 



The strobila of the largest specimen of BMNH 1982.4.26.282- 

 284 consists of about 350 acraspedote proglottids. The proglottids 

 are uniform in measurements, much wider (934-1034) than long 

 (50-134). Proglottids of smaller specimens measured about 600 in 

 width and 100 in length. The genital pores alternate irregularly; 

 cirrus sac 35—40 x 140-160. Small testes (25-4-0 in diameter) and 

 vitellaria (10-15); other internal structures not seen. 



Remarks. The present specimens belong to subgroup IIAa (Palm 

 etal., 1997), with a heteromorphous armature and hooks increasing 

 in size towards the metabasal part of the tentacle. The large hook size 



