We present a complete POSS II-based refinement of the optical morphologies
for galaxies in the Karatchenseva's Catalog of Isolated Galaxies that forms the
basis of the AMIGA project. Comparison with independent classifications made
for an SDSS overlap sample of more than 200 galaxies confirms the reliability
of the early vs. late-type discrimination and the accuracy of spiral subtypes
within DeltaT = 1-2. CCD images taken at the OSN were also used to solve
ambiguities. 193 galaxies are flagged for the presence of nearby companions or
signs of distortion likely due to interaction. This most isolated sample of
galaxies in the local Universe is dominated by 2 populations: 1) 82% spirals
(Sa-Sd) with the bulk being luminous systems with small bulges (63% between
types Sb-Sc) and 2) a significant population of early-type E-S0 galaxies (14%).
Most of the types later than Sd are low luminosity galaxies concentrated in the
local supercluster where isolation is difficult to evaluate. The late-type
spiral majority of the sample spans a luminosity range M_B-corr = -18 to -22
mag. Few of the E/S0 population are more luminous than -21.0 marking an absence
of, an often sought, super L* merger (eg fossil elliptical) population. The
rarity of high luminosity systems results in a fainter derived M* for this
population compared to the spiral optical luminosity function (OLF). The E-S0
population is from 0.2 to 0.6 mag fainter depending how the sample is defined.
This marks the AMIGA sample as almost unique among samples that compare early
and late-type OLFs separately. In other samples, which always involve galaxies
in higher density environments, M*(E/S0) is almost always 0.3-0.5 mag brighter
than M*(S), presumably reflecting a stronger correlation between M* and
environmental density for early-type galaxies.Comment: A&A accepted, 13 pages, 9 figures, 8 tables. Higher resolution Fig. 1
and full tables are available on the AMIGA (Analysis of the interstellar
Medium of Isolated GAlaxies) website at http://www.iaa.es/AMIGA.htm