On the Identity of Spongocladia and Cladophoropsis 1 
George F. Papenfuss 2 
In their treatments of the green algae 
in Engler and Prantl’s "Die Natiirlichen 
Pflanzenfamilien,” Wille (1911: 119) and 
Printz (1927: 282) consider Spongocladia 
Areschoug (1853) as a genus of question- 
able merit. This belief was founded upon the 
observation of Weber- van Bosse (1890) that 
examples of Struvea delicatula which lived 
in association with the sponge Halichondria 
bore a great resemblance to Spongocladia 
vauch eriaeformis, the type species of the 
genus Spongocladia. 
However, in a later work, Weber- van Bosse 
(1913: 86) not only maintained Spongo- 
cladia but emphasized that she had not dem- 
onstrated that S. vauch eriaeformis actually 
was a form of Struvea delicatula living in 
association with a sponge, and that there con- 
sequently was no justification for the state- 
ment of Wille (loc. cit.): "Nachdem es von 
A. Weber v. Bosse nachgewiesen worden ist, 
dass die typische Art: S. vauch eriaeformis 
Aresch. nur eine durch Symbiose mit einer 
Spongie {Halichondria) umgebildete Struvea- 
Art darstelle, muss auch die Stellung der 2 
iibrigen Arten: Spongocladia dichotoma 
( Zanard. ) Murr. et Boodle, sowie S. neocale- 
donica Grun. als sehr zweifelhaft angesehen 
werden.” 
Even though there probably is no partic- 
ularly close relationship between Spongocla- 
dia and Struvea Sonder (1845), both of which 
belong to the order Siphonocladales, but to 
the families Siphonocladaceae and Boodlea- 
ceae, respectively, I have on a number of oc- 
’This study was made during the tenure of a 
Guggenheim Fellowship. 
2 Department of Botany, University of Califor- 
nia, Berkeley, California. Manuscript received 
February 1, 1950. 
casions been struck by the agreement in the 
published descriptions and illustrations of 
Spongocladia and Cladophoropsis Bprgesen 
(1905), both members of the family Sipho- 
nocladaceae. The purpose of the present arti- 
cle is to assemble the published facts and to 
record my own observations in support of the 
contention that these two genera of essen- 
tially tropical and subtropical marine algae 
actually are identical, a conclusion which 
Bprgesen (1948) has also reached. Finally, 
Cladophoropsis, which is the better known 
genus, is proposed for conservation against 
Spongocladia. 
The genus Spongocladia was erected by J. 
E. Areschoug in 1853 upon a new species, 
S. vaucheriaeformis, which he received from 
Mauritius. The plants grew upon encrusting 
corallines, forming a horizontal spongiose 
mass, from which issued erect, more or less 
dichotomously divided, spongiose growths. 
Both the horizontal and the erect portions of 
the thallus were composed of irregularly 
branched, septate, uniseriate filaments and, as 
shown in Areschoug’s figure 3, the branches 
of the filaments lacked a cross wall at the 
base. Reproduction appeared to be by swarm- 
ers, many of which germinated within the 
cells in which they were produced. The thal- 
lus contained an abundance of sponge spic- 
ules, especially at the terminal ends of the 
erect portions. 
Thirty years later the known geographic 
distribution of Spongocladia vaucheriaeformis 
was extended to Singapore by Hauck (1884). 
His study of the plant led him to the signif- 
icant conclusion that systematically it be- 
longed in the immediate vicinity of Siphono- 
cladus, a genus which had been founded a 
few years previously by Schmitz (1879) to 
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