February, 2000 
SCAMIT Newsletter 
Vol. 18, No. 10 
testing of the significance of the monophyly 
results showed that several were not 
statistically more likely than non-monophyly 
results. 
As to the age of the origin of the Neomphalina, 
results were somewhat equivocal and further 
investigations using both a broader sampling of 
taxa and longer sequences of the 28S rDNA 
molecule or other molecular data appear to be 
necessary. The Neomphalina, as a vent 
endemic taxon containing a number of the 
species restricted to vents, was used as a 
surrogate for the entire community in this 
analysis. While it did seem very likely that the 
group originated in the Mesozoic, other 
hypotheses could not be rejected. Other 
approaches based on the fossil record were also 
tried, but the record for non-mollusk endemic 
groups of interest (such as barnacles) is too 
incomplete to yield a reliable estimate of the 
evolutionary age of the vent biota (but also 
seems to point to a Mesozoic or earlier origin). 
A much longer sequence was used by 
Wollscheid & Wagele (1999) in their 
examination of the phylogeny of the 
nudibranchs. They used complete sequences of 
the 18S rDNA molecule, including between 
1850 and 2100 bp. Even so, only about 600 of 
the sites were phylogenetically informative. 
Over 50 mollusk taxa were included, of which 
19 were nudibranchs. Representatives from 
other groups were included (such as 
cephalaspids, sacoglossans, anaspids, 
gymnomorphs, and pulmonates) and the trees 
were rooted in either the Neritopsina or 
Littorinidae (depending on the nature of the 
analysis - all taxa, or opisthobranchs only). 
While this analysis, along with all others, 
might have benefitted from a broader sampling 
of nudibranch taxa, these initial results are 
most encouraging. Bootstrap values were for 
the most part quite high and the analysis 
yielded independent molecular support for 
most of the morphologically based conclusions 
regarding major group monophyly. 
Within the Doridoidea separation of the 
phanerobranch and cryptobranch groups were 
not supported based on the 15 dorids included. 
This tends to echo the problems mentioned last 
NL in a cladistic analysis of the dorids by 
themselves. A similar problem was found in the 
gymnomorphs, where the two taxa analyzed 
did not form a monophyletic group. I do 
question one of the nudibranch 
synapomorphies listed by the authors, that of 
loss of shell. This is a clearly homoplaseous 
character which has occurred numerous times 
in the Opisthobranchia and in other distantly 
related mollusk groups as well. 
Anyone who often watches marine 
invertebrates live will observe reproductive 
activity. Let’s face it, it is one of the essential 
activities of any species. Such observations are 
not always written down, leaving gaps in the 
knowledge of the natural history of many 
groups. Jensen (1999) provides first records of 
reproductive activity in two families of shelled 
sacoglossan gastropods. Combined with 
published information on reproduction in other 
sacoglossan groups (and other observations by 
the author) these new observations allow a 
survey of reproductive behavior in the 
Sacoglossa. The range of behavior in the group 
is fairly broad, although all are simultaneous 
hermaphrodites. While reciprocal copulation is 
the norm, in some cases it is refused, and in 
others the hypodermic “quickie” allows male 
function without reciprocation. Injection of 
sperm through the body wall and into the 
coelom of the recipient through a hollow penial 
stylet makes sex considerably more casual (no 
particular position is necessary, there is no 
need for obligate reciprocation, and no 
behavioral preliminaries). This non-reciprocal 
sexual mode may be preferred in some cases as 
it allows the animal to escape the energetic 
burden of female function while allowing 
production of progeny. This has been seen 
elsewhere among invertebrates, particularly in 
flatworms, where two hermaphroditic 
individuals have been observed to duel with 
their penes, each seeking to hypodermically 
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