1988] 
Wolfe — Hydrovatus methlini 
339 
Table 3. continued 
Character No. 
12 3 4 
5 6 7 
8 
9 10 11 12 13 14 15 16 17 18 19 
H. (N)pratus 
112 1 
1 1 1 
2 
1 2 
1 2 
2 
1 1 
10 10 
H. (N) tennetum 
112 1 
1 1 1 
2 
1 2 
1 2 
2 
1 1 
10 10 
H. (Heterosternuta) 
pulcher 
112 1 
1 1 1 
3 
1 2 
1 2 
3 
1 1 
10 10 
Vatellini 
Macrovatellus mexicanus 0 12 1 
1 1 1 
4 
1 2 
1 1 
3 
1 1 
10 10 
The number of equally parsimonious trees can be reduced more 
by eliminating more species. For example, if O. quadrimaculatus 
(Horn) is removed and characters still are scaled, 27 equally parsi- 
monious trees are produced. It is interesting that except for the 
omission of O. quadrimaculatus, the consensus tree of those 27 trees 
remains identical to that shown in Fig. 3A. 
As indicated previously, it is obvious that there are not enough 
characters to resolve the phylogenetic relationship of all taxa listed 
in Table 3. Phylogenetic problems seem particularly acute in 
“higher” hydroporines ( Deronectes , Hydroporus, etc). This is borne 
out by the fact that eliminating taxa from among more apotypic 
groups ( e.g . O. quadrimaculatus) significantly decreases the number 
of equally parsimonious trees (from over 100 to 99 to 27) without 
affecting relationship among plesiotypic clades. Even treating all 
characters as unordered did not perturb relationship among primi- 
tive groups. 
Despite apparent stability of relationship among primitive 
groups, there still are only a few synapotypies to support proposed 
relationships and not all synapotypies are equally important, es- 
pecially after decreasing weight of some characters by scaling. Weak- 
nesses and strengths of various parts of the phylogenetic hypothesis 
in Fig. 3 A overall are reflected by computed branch lengths (length = 
number of character state changes or synapotypies per line segment), 
after Laccornellus is added to the analysis and characters are scaled. 
For example the lengths of the branches connecting node three to 
node four and from node five to node six is only 0.250 for each. The 
length of the branch connecting node six to node seven is 0.833. 
These problems are elaborated further below. 
