phylogenetic relationships and classification of didelphid marsupials ...

2009 VOSS AND JANSA: DIDELPHID MARSUPIALS 163
distribution of these traits among didelphid terminal
taxa were provided by Voss and Jansa (2003:
character 16). See text for comments about traits
expressed by outgroup taxa.
Character 26: Pouch absent (0); or present (1).
Scoring criteria and information about the distribution
of these traits among didelphid terminal
taxa were provided by Voss and Jansa (2003:
character 17). See text for comments about traits
expressed by outgroup taxa.
Character 27: Pouch consists of separate lateral
skin folds opening medially (0); or lateral folds
connected posteriorly, pouch opening anteriorly (1);
or lateral folds connected anteriorly, pouch opening
posteriorly (2); or folds connected anteriorly and
posteriorly, pouch opening by a central orifice (3).
Scoring criteria and information about the
distribution of states 0–2 among didelphid terminal
taxa were provided by Voss and Jansa
(2003: character 18). See text for comments
about traits expressed by outgroup taxa. In
the absence of any compelling evidence for
intermediacy among these alternative conditions,
we treated this character as unordered in all of our
analyses.
Character 28: Mammae all abdominal/inguinal, more
or less confined to pouch region (0); or extending
anteriorly beyond pouch region to thoracic region
(1). Scoring criteria and information about the
distribution of these traits among didelphid terminal
taxa were provided by Voss and Jansa (2003:
character 19). See text for comments about traits
expressed by outgroup taxa.
Character 29: Unpaired median teat absent (0); or
present (1). See text for a discussion of this
character and its taxonomic distribution. Our
scoring of Rhyncholestes was based on literature
cited in the text. In the absence of suitably
preserved parous female specimens or relevant
published descriptions of mammary counts, we
scored 11 didelphid terminals as missing (‘‘?’’) for
this character.
Character 30: Urogenital and rectal openings are
inguinal (0); or basicaudal (1). See text for a
discussion of this character and its taxonomic
distribution.
Character 31: Urogenital and rectal openings closely
juxtaposed, and sharing a common mucosa (0); or
urogenital and rectal openings widely separated
by furred skin (1). Scoring criteria and information
about the distribution of these traits
among didelphid terminal taxa were provided
by Voss and Jansa (2003: character 20). See text
for comments about traits expressed by outgroup
taxa.
Character 32: Body pelage extends onto tail conspicuously
farther dorsally than ventrally (0); or body
pelage extends onto dorsal and ventral surfaces of
tail to about the same extent (1); or body pelage
does not extend appreciably onto tail (2). Scoring
criteria and information about the distribution of
these traits among didelphid terminal taxa were
provided by Voss and Jansa (2003: character 21).
See text for comments about traits expressed by
outgroup taxa. In the absence of any compelling
evidence for intermediacy among these alternative
conditions, this character was treated as unordered
in all of our analyses.
Character 33: Caudal integument uniformly pigmented
or indistinctly or irregularly marked (0);
or blackish basally and abruptly whitish distally (1).
Scoring criteria and information about the distribution
of these traits among didelphid terminal
taxa were provided by Voss and Jansa (2003:
character 22). No examined outgroup taxon
exhibits state 1.
Character 34: Tail scales in predominantly annular
series (0); or in annular and spiral series (1); or in
predominantly spiral series (2). Scoring criteria and
information about the distribution and ordering
(0 « 1 « 2) of these traits among didelphid
terminal taxa were provided by Voss and Jansa
(2003: character 23). All examined outgroup taxa
have annular caudal scale rows.
Character 35: Unfurred ventral surface of tail base
covered with smooth scales (0); or provided with
raised tubercles (1). Scoring criteria and information
about the distribution of these traits among
didelphid terminal taxa were provided by Voss and
Jansa (2003: character 24). No examined outgroup
taxon has raised tubercles on the ventral surface of
the tail base.
Character 36: Ventral surface of tail tip covered by
unmodified hair-bearing scales (0); or ventral
surface of tail tip modified for prehension (1).
Scoring criteria and information about the distribution
of these traits among didelphid terminal
taxa were provided by Voss and Jansa (2003:
character 25). See text for comments about traits
expressed by outgroup taxa.
Character 37: Caudal scales bearing three hairs
each (0); or more than three hairs each (1). Scoring
criteria and information about the distribution of
these traits among didelphid terminal taxa were
provided by Voss and Jansa (2003: character
26). Despite the fact that annular scale rows
could be distinguished in all examined outgroup
taxa, individual scales were seldom clearly
distinguishable within rows, so the number of
hairs per scale could not be counted. The
exceptions were Caenolestes (which usually has
three hairs per scale; state 0) and Dromiciops
(which usually has four or more hairs per scale;
state 1).
Character 38: Tail hairs emerging from each scale not
grossly differentiated, varying in length but subequal
in thickness (0); or central hair much thicker than
lateral hairs (1). Scoring criteria and information
about the distribution of these traits among
didelphid terminal taxa were provided by Voss
and Jansa (2003: character 27). Adjacent caudal
hairs were similar in gross morphology (state 0) in
all examined outgroups.
Character 39: Tail not incrassate (0); or incrassate
(1). Scoring criteria and information about the
distribution of these traits among didelphid terminal
taxa were provided by Voss and Jansa (2003:
character 28). See text for comments about traits
expressed by outgroup taxa.