NO. 3592 LISSOTHURIA — PAWSON 3 



In an article on the echinoderms of the Panama region, Verrill 

 (1867, p. 322) had diagnosed and described Lissothuria ornata on the 

 basis of one specimen collected from Panama. Verrill's description 

 was inadequate in some respects, and subsequent authors generally 

 regarded Lissothuria as a synonym of Psolus, noting that the species 

 required reexamination. Deichmann (1937, p. 172), in describing 

 the new species Thyonepsolus beebei from Lower California, suggested 

 that "Verrill's imperfectly described Lissothuria ornata (1867) from 

 Panama may quite well be this species," 



I have reexamined the type-specimen of Lissothuria ornata. The 

 deposits of the dorsal surface of the body of this specimen include 

 hourglass-shaped deposits and towers, which are diagnostic characters 

 of Thyonepsolus. In the Zoological Museum, Copenhagen, six other 

 specimens of L. ornata from Panama were found. All of this material 

 is described below. It is evident that Thyonepsolus is a junior 

 synonym of Lissothuria, and it is here proposed that the generic 

 name Lissothuria be resurrected as a senior synonym. 



Lissothuria Verrill 



Lissothuria Verrill, 1867, p. 322. 



Thyonepsolus H. L. Clark, 1901a, p. 167. [Type-species: T. nutriens, original 



designation.] 

 Thionepsolus Delage and Herouard 1903, p. 320. [Error for Thyonepsolus.] 



Diagnosis. — Psolids with tube feet on dorsal surface of body 

 and in midventral interradius. Dorsal scales few or numerous, 

 imbricating, covered by an external layer of deposits that include hour- 

 glass-shaped bodies and towers; one of these types may be absent. 

 Sole deposits are knobbed or smooth plates; in some species shallow 

 or deep cups also present. 



Type-species. — Lissothuria ornata Verrill (original designation, by 

 monotypy) . 



Content of genus. — Verrill (1867) described Lissothuria ornata. 

 In 1901, H. L. Clark described Thyonepsolus nutriens. Deichmann 

 (1930) referred Theel's (1886) species Psolus braziliensis to Thyonep- 

 solus and later (Deichmann, 1937) described a new species, T. beebei, 

 from the Gulf of Cahfornia. Again, Deichmann (1941) described 

 two other new species, T. veleronis from the Galapagos Islands and 

 T. hancocki from Lower California. Thus, at the commencement of 

 this study, six species had been named. In this paper, two of the 

 original six species (Lissothuria ornata and Thyonepsolus beebei) are 

 regarded as synonyms and three species are described as new, so that 

 eight species may now be listed under the genus Lissothuria. 



