phylogenetic relationships and classification of didelphid marsupials ...

174 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 322
Character 115. dp3 trigonid: uni- or bicuspidRtricuspid.
Cryptonanus unduaviensis:
No unambiguous changes.
Gracilinanus aceramarcae:
No unambiguous changes.
Gracilinanus microtarsus:
Character 52. Postorbital process: absentRpresent.
Gracilinanus agilis:
No unambiguous changes.
Gracilinanus emiliae:
Character 34. Caudal scales: annularRintermediate.
Lestodelphys halli:
Character 2. Rhinarium: with 2 groovesRwith 1
groove.
Character 22. Pedal digits III and IV: IV longestRIII
longest.
Character 36. Tail tip: prehensileRnot prehensile.
Character 57. Sagittal crest: absentRsmall.
Character 81. Stapes: bicrurateRcolumelliform.
Character 114. Height p2, p3: subequalRp3 taller.
Character 120. m3 hypoconid position: labially
salientRlingual to protoconid.
Thylamys macrurus:
No unambiguous changes.
Thylamys pusillus:
No unambiguous changes.
Thylamys pallidior:
Character 2. Rhinarium: with 2 groovesRwith 1 groove.
Thylamys venustus:
No unambiguous changes.
Marmosops impavidus:
No unambiguous changes.
Marmosops noctivagus:
No unambiguous changes.
Marmosops incanus:
Character 28. Mammary position: abdominal-inguinalRpectoral.
Character 43. Nasal width: wider posteriorlyR
uniformly narrow.
Character 114. Height p2, p3: p2 tallerRsubequal.
Marmosops parvidens:
Character 105. Preprotocrista: stops at paraconeRmeets
anterolabial cingulum.
Marmosops pinheiroi:
No unambiguous changes.
Marmosa lepida:
Character 94. Upper canine: simpleRposterior accessory
cusp present.
Marmosa murina:
Character 13. Lateral carpal tubercles: present in
adult malesRabsent.
Marmosa demerarae:
No unambiguous changes.
Marmosa paraguayana:
Character 32. Body pelage on tail: noneRsubequal.
Marmosa regina:
No unambiguous changes.
Marmosa mexicana:
Character 65. Palatine fenestrae: absentRpresent.
Marmosa robinsoni:
No unambiguous changes.
Marmosa rubra:
Character 52. Postorbital process: presentRabsent.
Character 76. RTP-CTP contact: absent (gap)Rsutured.
Tlacuatzin canescens:
Character 66. Maxillary fenestrae: absentRpresent.
Character 126. RES {a1+ a5, m1}: metacentricRacrocentric.
Character 128. RES {a3+a10, m3}: metacentricRacrocentric.
Monodelphis brevicaudata:
No unambiguous changes.
Monodelphis theresa:
Character 9. Gular gland: presentRabsent.
Character 73. Secondary foramen ovale: absentR
formed by lamina.
Monodelphis emiliae:
Character 76. RTP-CTP contact: absent (gap)Rsutured.
Character 114. Height p2, p3: subequalRp3 taller.
Monodelphis peruviana:
Character 61. Parietal-mastoid contact: presentRabsent
Hyladelphys kalinowskii:
Character 96. Height P2, P3: subequalRP2 taller.
Character 98. Upper milk premolar: large & molariformRvestigial.
APPENDIX 6
Key to the Didelphid Genera
This key is intended for use on adult
specimens (with completely erupted permanent
dentitions). Juveniles (with dP3/
dp3) and subadults (lacking dP3/dp3, but
with incompletely erupted third premolars
and/or fourth molars) may not key out
accurately if they lack traits seen in
conspecific adults (e.g., large size, postorbital
processes, secondary foramina ovales,
contact between left and right exoccipitals;
Abdala et al., 2001). Although the following
couplets are based, insofar as possible,
on characters with unambiguously distinguishable
alternative states, key results
should always be checked by comparing
specimens character-by-character against
generic descriptions and cranial illustrations
(figs. 37–54). Couplet 10, the only
step in our key based on a single character,
is obviously problematic if an atypical
specimen is in hand. Users would be well
advised, if an unsatisfactory result is
obtained at any subsequent step, to follow
the alternative sequence on the hypothesis
that the species in question is polymorphic.
External and craniodental measurements
used to index size in this key are defined
and abbreviated as follows: Head-and-