How can I plot colored tip labels in ggtree without including it as part of the legend?

I have been trying to plot a tree with color-coded branches and tips using the ggtree package in R. Here is an example code using a tree of Anolis lizards.

library(ggtree);library(tidyverse);library(ape)
anole.tree<-read.tree("http://www.phytools.org/eqg2015/data/anole.tre")
svl <- read.csv("http://www.phytools.org/eqg2015/data/svl.csv",row.names=1)
cls<-list(clade1=c("baleatus","barahonae","ricordii","eugenegrahami","christophei","cuvieri"),
          clade2=subset(anole.tree$tip.label,!(anole.tree$tip.label %in% c("baleatus","barahonae","ricordii","eugenegrahami","christophei","cuveri"))))
anole.tree_new<-groupOTU(anole.tree,.node=cls)
ggtree(anole.tree_new,layout="circular",ladderize=TRUE)+
  geom_tree(aes(color=group))+
  scale_color_manual(values=c("blue","red"))+
  geom_tiplab(size=0.8,aes(color=group))+
  theme(legend.position = c(0.9, 1),
        legend.justification = c(0,1),
    legend.title=element_text(size=7),legend.text=element_text(size=7))

The issue I am having with this is that the resulting plot includes a text element (a small "a") as part of the legend. I have been unable to figure out how to omit this text element from the legend. I want to keep the legend itself but I don't want the red and blue "a" that are plotted alongside the red and blue lines in the above example.

Normally it would be as simple as not setting the color argument to be an aes within the element labels (geom_tiplab). However, if I do not call group color under aes...

ggtree(anole.tree_new,layout="circular",ladderize=TRUE)+
  geom_tree(aes(color=group))+
  scale_color_manual(values=c("blue","red"))+
  geom_tiplab(size=0.8,color=group)+
  theme(legend.position = c(0.9, 1),
        legend.justification = c(0,1),
        legend.title=element_text(size=7),legend.text=element_text(size=7))

I get an error saying object "group" not found. So it doesn't seem to be as straightforward as in a normal ggplot.

You can remove the addition of the aesthetics to the legend from any geom (at least, I think any geom) by setting the boolean show.legend within that geom call. So, show.legend = FALSE seems to do the trick for me:

ggtree(anole.tree_new,layout="circular",ladderize=TRUE)+
  geom_tree(aes(color=group))+
  scale_color_manual(values=c("blue","red"))+
  geom_tiplab(size=0.8,aes(color=group), show.legend=FALSE)+
  theme(legend.position = c(0.9, 1),
        legend.justification = c(0,1),
        legend.title=element_text(size=7),legend.text=element_text(size=7))

Alternatively, you can do this without using show.legend if you want by overriding the aesthetics of the legend. In this case, you would want to turn all the labels into an empty string, so the label shown on the legend is just "". You can do this through guides():

# add the following to your plot code
guides(color=guide_legend(override.aes = list(label="")))