The genus Parathyone Deichmann, 1957 encloses two species, Parathyone surinamensis and Parathyone suspecta, and is close to the genus Ocnus Forbes, 1841. Ekmanothyone nomen novum is erected to replace the pre-occupied Parathyone Cherbonnier, 1988 (non Parathyone Deichmann, 1957)

Massin, C.

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BULLETIN DE L'INSTITUT ROYAL DES SCIENCES NATURELLES DE BELGIQUE, BIOLOGIE, 63: 257-258, 1993 
BIOLOGIE, 63 257-258, 1993 BULLETIN VAN HET KONINKLIJK BELGISCH INSTITUUT VOOR NATUURWETENSCHAPPEN, 
Short note. 
On the taxonomic status of the genus P arathyone 
(Echinodermata, Holothurioidea, Dendrochirotida) 
by Cl. MASSIN 
Abstract 
The genus Parathyone DEICHMANN, 1957 encloses two species, Para-
thyone surinamensis and Parathyone suspecta, and is close to the 
genus Ocnus FORBES, 1841. Ekmanothyone nomen novum is erected 
to replace the pre-occupied Parathyone CHERBONNIER, 1988 (non 
Parathyone DEICHMANN, 1957). 
Key words: Taxonomy, holothurians, Ekmanothyone nom. nov . 
Resume 
Le genre Parathyone DEICHMANN, 1957 comprend deux especes, 
Parathyone surinamensis et Parathyone suspecta, et est proche du 
genre Ocnus FORBES, 1841. Ekmanothyone nomen novum est cree en 
remplacement de Parathyone CHERBONN!ER, 1988 (non Parathyone 
DE!CHMANN, 1957). 
Mots-des: Taxonomie, holothuries, Ekmanothyone nom. nov. 
DEICHMANN (1957, p. 16) erected a new genus, Para-
thyone DEICHMANN, 1957 with Thyone surinamensis 
SEMPER, 1868 as type species. The new genus belongs 
to the family Cucumariidae and is defined as follow-
ing : medium size dendrochirotes; tentacles 10, equal 
size; tube feet stout all over body wall; calcareous ring 
simple, without posterior processes; deposits, outer 
layer of baskets and innner layer of regular strongly 
knobbed buttons; tube feet with end plates and large 
rods. 
DEICHMANN justified her new genus mainly because T. 
surinamensis has a simple calcareous ring without pos-
terior processes whereas species belonging to the genus 
Thyone JAEGER, 1833 have a fragmented calcareous 
ring with long posterior processes. PANNING (1949, 
p. 437) had already transferred T. surinamensis from 
the genus Thyone to the genus Genus FoRBES, 1841. 
PAWSON & MILLER (1981 , p. 393) accepted PANNING 's 
point of view. According to me, however, Ocnus and 
Parathyone are closely related but distinct genera. The 
genus Parathyone differs from Ocn.us by the presence 
of ten equal tentacles and by the tube feet being spread 
all over the whole body wall rather than being re-
stricted to the radii as they are in Ocnus. 
DEICHMANN (1957, p. 16) included in her new genus 
Thyone suspecta LUDWIG, 1875 and Thyone so/ida 
DEICHMANN, 1930. It was rather strange for her to 
include T. salida in the genus Parathyon.e because she 
had already erected (DEICHMANN 1954, p. 399) a new 
genus, Euthyonacta DEICHMANN, 1954 having as its 
type species Thyone salida ! T. so/ida certainly should 
not be included in the genus Parathyone because it has 
8 large and 2 very small tentacles (10 tentacles of equal 
size in Parathyone). As PAWSON & MILLER (1981, 
p. 393), I agree with the combination Euthyonacta sali-
da. T. suspecta LUDWIG, 1875 is referred by PAWSON & 
MILLER (1981, p. 393) to the genus Ocnus without any 
comment. However, LUDWIG (1875, p. 92) stated that 
the tube feet of T. suspecta are numerous and spread all 
over the body wall ("Die Fi.isschen sind in grosser 
Anzahl tiber die ganze KorperoberfHiche zerstreut"). 
Because of the tube feet distribution, I consider, as 
DEICHMANN (1957, p. 16), that T. suspecta must be 
referred to the genus Parathyone. The genus Para-
thyone, as defined by DEICHMANN (1957), thus includes 
two species : P. surinamensis and P. suspecta, both 
from the East Atlantic Ocean. 
In his study of the sea cucumbers of Madagascar, 
CHERBONNIER (1988 p. 206) erected a new genus, Para-
thyone CHERBONNIER, 1988 with the type species Para-
thyone incurvata CHERBONNIER, 1988. This species has 
a fragmented calcareous ring with long posterior pro-
cesses. This new genus was placed close to the genus 
Thyone in the family Phyllophoridae (subfamily Thyo-
ninae). However, Parathyone is a pre-occupied name 
(see above). It is therefore necessary to create a new 
genus name for the species incurvata. I propose the 
name Ekmanothyone nomen novum, replacing Para-
thyone C!-IERBONNIER, 1988 (non Parathyone DEICI-1-
MANN, 1957) with the new combination Ekmanothyone 
incurvata (CHERBONNIER, 1988). The new genus dia-
gnosis is as in CHERBONNIER ( 1988 p. 206) : tentacles 
10, 2 ventral smaller; ventral and dorsal tube feet on 
two rows along radii; no interradial tube feet. Small V-
shaped or U-shaped sea cucumbers; skin thick, rigid; 
calcareous ring fragmented, radials with very long 
• 
258 Cl. MASSIN 
posterior processes; deposits of body wall pseudo-
baskets, 4-holed knobbed buttons, large knobbed 
plates; deposits of tube feet rods with central 2-pillared 
spire; deposits of introvert small perforated plates and 
rods; deposits of tentacles elongated knobbed plates 
and large rods. 
The name Ekmanothyone nomen novum is dedicated to 
the Swedish holothurian specialist, Sven EKMAN. 
Literature 
CHERBONNIER, G. , 1988. Echinodermes: Holothuries. Faune 
de Madagascar, 70 : 1-292. 
DEICHMANN, E ., 1954. The holothurians of the Gulf of Mexi-
co. Fishery Bulletin of the Fish and Wildlife Service, 55 : 38 1-
410. 
DEICHMANN, E., 1957. The Littoral Holothurians of the Baha-
mas Islands. American Museum Novitates, 182 1 : 1-20. 
LUDWIG, H., 1875. Beitrage zur Kenntniss der Holothurien. 
Arbeiten aus dem Zoologisch-zootomischen Institut in Wiirz-
burg, 2(2): 77- 118 + 2 pis. 
PANNING, A. 1949. Versuch einer Neuordnung der Familie 
Cucumariidae (Holothurioidea, Dendrochirota). Zoologische 
Jahrbiicher, Abteilung fiir Systematik, Okologie und Geogra-
phie der Tiere, 78(4) : 404-470. 
PAWSON, D.L. & MILLER, J.E., 1981. Western Atlantic sea 
cucumbers of the genus Thyone, with description of two new 
species (Echinodermata : Holothuroidea). Proceedings of the 
Biological Society of Washington , 94(2): 39 1-403. 
Claude MASSIN 
Section Malacologie 
Institut Royal des Sciences 
Nature lles de Belgique 
29 rue Vautier 
B-1 040 Bruxelles 
Belgique 
II 


On the taxonomic status of the genus <i>Parathyone</i> (Echinodermata, Holothurioidea, Dendrochirotida)

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