Figure27.Proposed interrelationships of the genera of Acipenseridae:Husois defined by two synapomorphies forming the subfamily
Husinae recognized as the sister group to the Acipenserinae.Acipenseris not recognized by any skeletal synapomorphies. Shovelnose
sturgeons ofScaphirhynchusandPseudoscaphirhynchuscompose Scaphirhynchini.
(Figure 27). The family Acipenseridae is supported
by 24 skeletal synapomorphies (Characters 1–24).
The genusHusois defined by two synapomorphies
(Characters 25,26) and is the sister group to a rede-
fined subfamily Acipenserinae defined by 12 syn-
apomorphies (Characters 27–38) comprising all
other genera. Scaphirhynchus and Pseudoscaphi-
rhynchus compose a monophyletic tribe Scaphi-
rhynchini based on 16 synapomorphies (Characters
39–54).Pseudoscaphirhynchusis defined by five
synapomorphies (Characters 55–59) and Scaphi-
rhynchusis defined by 10 synapomorphies (Charac-
ters 60–69). Each node is supported by characters
from different skeletal complexes suggestive of
multiple evolutionary events occurring at one node
rather than a one event affecting multiple charac-
ters.
A remaining phylogenetic problem is the lack of
identified synapomorphies defining the genus Aci-
penser,leaving this largest genus (17 species) as po-