FOREGUT ANATOMY AND CLASSIFICATION OF CONOIDEA 



155 



ment. Glyphostoma has long slender radular teeth and has 

 been separated in the family Clathurellinae (McLean, 1971). 

 Anarithma has been classified in the Diptychomitrinae (= 

 Mitrolumninae), but Kilburn (1986) could see no significant 

 differences from the Borsoniinae. 



Taxa normally classified in the Borsoniinae (Ophioder- 

 mella, Borsonia, Tomopleura, Micantapex, Tropidoturris and 

 Anarithma) do not form a monophyletic group in any of our 

 analyses. For this reason, in the classification derived form 

 this study we are leaving these taxa, along with Glyphostoma 

 and others in informal groupings within the subfamily 

 Clathurellinae. 



Benthofascis (Conorbinae) and Conus (Coninae) (Node 

 27) share a number of characters. They lack an anterior 

 sphincter to the buccal tube, but have have an intermediate 

 sphincter instead. Both have accessory salivary glands and 

 retain an operculum. Additionally, both genera show resorp- 

 tion of the inner shell whorls. Although Genota (Node 26) is 

 usually classified in the Conorbinae, it lacks an operculum. 



Taxa from Node 28 onwards have tubular salivary glands 

 and most have sculptured protoconchs. The Mangeliinae 

 (Node 30), represented by Eucithara and Mangelia, are a 

 well-defined group with the distinctive buccal tube introvert, 

 and protrusive lips of the buccal tube. Taxa from Node 32 

 have a muscular bulb made up of only one muscle layer and 

 lacking the connective tissue layer, with additionally, an anal 

 sinus located at the suture. Thatcheria (Node 32) has many 

 characters in common with the Daphnellinae and until many 

 more daphnellines have been examined anatomically it can 

 be classified with them. However a great range of foregut 

 anatomy is found in the Daphnellinae and it may be that the 

 group is paraphyletic. At the extreme end of the tree (Node 

 36) are taxa which have lost many foregut characters such as 

 radula, proboscis and glands. Taranis has been classified in a 

 separate subfamily Taraninae (Kantor & Sysoev, 1989), but 

 it has so few characters that its relationships are obscure. It 

 may be a highly derived daphnelline. 



Conclusions 



Our studies have shown that several major autapomorphies 

 associated with the Conoidea have developed independently 

 in separate clades. Also there has been parallel loss of foregut 

 structures. Some of the more important of these are briefly 

 discussed below. 



Hollow, enrolled 'hypodermic style' radular teeth are con- 

 sidered a distinctive feature of the conoidean feeding mecha- 

 nism. Our analysis shows that hollow teeth have been 

 independently derived at least five times in the evolution of 

 the Conoidea. In Imaclava the hollow marginal teeth seem to 

 have developed from the enrolling of the flattened drilliine- 

 type of marginal teeth. In Toxiclionella, the hollow teeth 

 were derived from wishbone teeth similar to those of Clav- 

 atula or maybe from solid teeth like those of Pseudome- 

 latoma. Hollow teeth are found in many Terebridae and are 

 thought to have been derived from solid teeth via semi- 

 enrolled intermediate forms such as found in Hastida bacillus. 

 The enrolled teeth of Pilsbryspira (Zonulispirinae) may have 

 been derived by enrolling of the crassispirine type of wish- 

 bone tooth. The hollow teeth of the higher conoideans such 

 Clathurellinae, Coninae, Mangeliinae and Daphnellinae in 

 all their various forms may represent another separate deriva- 

 tion. The radular caecum found in some Terebridae was 

 derived independently of that found in the higher turrids 



(Clathurellinae, Oenopotinae, Mangeliinae, Daphnellinae) 

 and Coninae. 



The rhynchodeal introvert found in some Daphnellinae, is 

 also found in all Terebridae (including pervicaciines). If our 

 ideas concerning the relationships of the Terebridae are 

 correct, then the structure was evolved independently in the 

 two groups. 



A buccal mass situated at the base of the proboscis is 

 considered to be a diagnostic character of the Conoidea 

 (Ponder, 1973). However, in Turricula nelliae the buccal 

 mass was shown to be located at the distal end of the 

 proboscis (Taylor, 1985; Miller, 1990). We now know that a 

 distally-shifted buccal mass seems to be common feature of 

 the Clavatulinae and is found also in Pilsbryspira 

 (Zonulispirinae) and Strictispira (Strictispirinae) which lacks 

 the venom apparatus. 



One surprising trend seen in at least four clades is the loss 

 of the venom apparatus. In the Daphnellinae, Taraninae and 

 some Terebrinae this is associated with the loss of the 

 proboscis and radular apparatus. Pervicaciinae have a well 

 developed radula apparatus but no proboscis or venom gland. 

 By contrast, Strictispira which also lacks the venom gland, has 

 a proboscis, a distally-located buccal mass and a robust radula 

 apparatus. 



Relationships and status of Terebrinae and 

 Pervicaciinae 



Some controversy concerns the status of the Terebrinae and 

 Pervicaciinae. Rudman (1969) and Taylor (1990) suggested 

 an independent origin for the two groups. However, anatomi- 

 cal studies of more species is revealing some shared apomor- 

 phies which suggest a common origin. 



Although both subfamilies possess elongate multi-whorled 

 shells there are large anatomical differences between the two 

 groups. The family Pervicaciidae was orginally proposed by 

 Rudman (1969) for Pervicacia tristis, a terebriform species 

 with no proboscis and venom apparatus, but with an odonto- 

 phore and a radula with a strong membrane and two sickle- 

 shaped, solid teeth in each row. It is now known, that many 

 more 'terebrids' (Duplicaria species and others) share these 

 characters and should be included in the family (Taylor, 

 1990). Other characters of pervicaciids include a rhynchodeal 

 introvert and a septum in some species. 



Most of the radulate Terebrinae s.s. possess hollow and 

 barbed, radular teeth, similar to those seen in Conus and the 

 Clathurellinae. However, some Hastula species possess an 

 odontophore and Hastula bacillus has partially-solid teeth 

 (Taylor & Miller, 1989). This discovery demonstrates that the 

 Terebridae must be derived from a lower conoidean with an 

 odontophore and radular ribbon, rather than from some 

 group such as the Clathurellinae, which have lost these 

 structures. 



The accessory proboscis structure is an unusual organ 

 found in some Terebrinae, and is known from Hastula 

 bacillus, H. aciculina, H. imitatrix, H. raphanula, Terebra 

 affinis and T. pertusa (Miller 1971, Taylor , 1990; Auffenberg 

 & Lee, 1988; Taylor, unpub.). Some terebrines, for example 

 Terebra subulata, also possess a septum dividing the rhyn- 

 chocoel (Miller, 1971; Taylor 1990). We have found an 

 accessory proboscis structure in the western Australian spe- 

 cies Duplicaria kieneri, and Duplicaria colorata (recently 

 described as a Hastula by Bratcher (1988)), which otherwise 



