Monodelphis (Pyrodelphys), Pavan & Voss, 2016

Pavan, Silvia E. & Voss, Robert S., 2016, A Revised Subgeneric Classification of Short-tailed Opossums (Didelphidae: Monodelphis), American Museum Novitates 2016 (3868), pp. 1-44 : 22-24

Pyrodelphys , new subgenus

TYPE SPECIES: Monodelphis emiliae ( Thomas, 1912) .

CONTENTS: emiliae Thomas, 1912 .

DIAGNOSIS: Dorsal body pelage with grayish midbody contrasting with reddish head and rump ( fig. 14A ); ventral pelage uniformly colored (without self-whitish median markings), yellowish or orangish on museum skins, but much brighter in life ( fig. 14B ). Mammae 2–1–2 = 5 (MZUSP 35064), 3–1–3 = 7 (MPEG JUR 79), or 4–1–4 = 9 (MPEG 39106, 39182, 42955), all abdominal-inguinal. Thenar and first interdigital pad of pes usually fused or in contact; hypothenar pad of pes usually present. 8 Body pelage extends onto tail farther dorsally than ventrally, or to about the same extent dorsally and ventrally; tail scales arranged in annular series. Infraorbital foramen dorsal to M1; frontal process of jugal present but rounded, not distinctly angular; parietal usually (ca. 80% of examined specimens) in contact with mastoid; incisive foramina usually short; maxillopalatine fenestrae short; sphenorbital fissure large, exposing basisphenoid in lateral view; infratemporal crest of alisphenoid distinct; secondary foramen ovale present or absent; tympanic wing of alisphenoid large; tip of anterior process of malleus not exposed on external bullar surface; rostral tympanic process of petrosal broad and rounded, concealing fenestra cochleae in ventral view; stapes columelliform, imperforate or microperforate; subsquamosal foramen small. Anterior cingulids of m2 and m3 broad; entoconids of m1–m3 distinct; dp3 small, with incomplete trigonid and indistinct anterior cingulid.

COMPARISONS: Pyrodelphys is uniquely distinguished from other subgenera of Monodelphis by fusion or contact between the thenar and first interdigital pads of the hind foot (the thenar and first interdigital are separate in members of other subgenera) and by having a small subsquamosal foramen (the subsquamosal foramen is distinctly larger in members of other subgenera.

Among other diagnostic comparisons ( table 2 ), Pyrodelphys is additionally distinguished from the subgenus Monodelphis by having a reddish head and rump separated by a grayish midbody, an infraorbital foramen dorsal to M1, large alisphenoid tympanic wing, unexposed tip of the anterior process of the malleus, broadly rounded rostral tympanic process of the petrosal, columelliform stapes, and smaller dp3. Pyrodelphys is additionally distinguished from Microdelphys by lacking dorsal stripes in all age-sex classes, by lacking a distinctly angular frontal process of the jugal, and by having a distinct infratemporal crest of the alisphenoid. Pyrodelphys is also distinguished from Monodelphiops by its dorsal pelage pattern, by lacking pectoral mammae, and by having tail scales in annular series, a large alisphenoid tympanic wing, and a broadly rounded rostral tympanic process of the petrosal. Diagnostic comparisons between Pyrodelphys and Mygalodelphys have already been provided (see above).

ETYMOLOGY: From pyr, ancient Greek for “fire,” in reference to the flame-colored underparts of living and freshly dead specimens of this clade ( fig. 14B ).

REMARKS: This taxon is widely divergent from other clades in the genus Monodelphis and appears to represent an ancient lineage with no close extant relatives ( Pavan et al., 2014; Pavan et al., 2016).

NOTES ON DISTRIBUTION AND SYMPATRY: Monodelphis (Pyrodelphys) emiliae is known from southwestern and southeastern Amazonia ( table 3 ), where it ranges from near the base of the Andes in Peru and Bolivia to eastern Pará, Brazil. Based on geographic range overlap and published reports of cooccurring species (e.g., in the lower Urubamba region of eastern Peru; Solari et al., 2001), Pyrodelphys may occur sympatrically with species of the subgenera Mygalodelphys and/or Monodelphis throughout its geographic range.

Figures

FIG. 14. Dorsal (A) and ventral (B) views of a freshly killed specimen of Monodelphis (Pyrodelphys) emil- iae, illustrating the diagnostically flame-colored ventral pelage (photo courtesy of M. Hoogmoed). Whereas the dorsal coloration of this species is faithfully preserved even in decades-old museum skins, the ventral coloration quickly fades aπer death.

Tables

TABLE 2. Diagnostic Characters of Subgenera of Monodelphis Recognized in this Study.

	Mygalodelphys	Pyrodelphys	Monodelphis	Microdelphys	Monodelphiops
Dorsal body pelage	unpatterned	reddish head & rump	reddish sides or unpatterned	stripes, reddish head & rump, or unpatterned	reddish sides with or without mid- dorsal stripe
Self-whitish ventral marking	variablea,b	absent	absent	absent	absent
Pectoral mammae	absent	absent	absent	present or absenta, b	present
Thenar & 1st interdigital pads of hind foot	separate	fused or in con- tact	separate	separate	separate
Hypothenar pad of hind foot	present	usually present	usually absent	variablea	absent
Extension of body pelage onto tail	farther ventrally than dorsally	farther dorsally or to about the same extent	farther dorsally or to about the same extent	to about the same extent dorsally and ventrally	to about the same extent dorsally and ventrally
Tail scale arrangement	variablea,b	annular	annular	annular	spiral
Infraorbital foramen	dorsal to M1	dorsal to M1	dorsal to P3 or P3/M1	usually dorsal to M1	dorsal to P3 or M1
Frontal process of the jugal	absent/ indistinct	rounded	rounded	distinctly angular	rounded
Parietal/mastoid contact	absent	present	present	present	present
Incisive foramina	variablea	usually short	long	long	short
Maxillopalatine fenestra	variablea	short	usually long	long	short
Sphenorbital fissure	narrow	broad	broad	broad	broad
Infratemporal crest of alisphenoid	variablea	distinct	distinct	indistinct	distinct
Secondary foramen ovale	absent	variableb	absent	variablea	absent
Alisphenoid tympanic wing	small	large	small	large	variableb
Anterior process of malleus	exposed	concealed	exposed	concealed	variableb
Rostral tympanic process of petrosal	triangular	broad and rounded	triangular	broad and rounded	roughly triangular
Stapes	columelliform	columelliform	triangular	columelliform	columelliform
Subsquamosal foramen	large	small	large	large	large
Anterior cingulids	narrow	broad	broad	broad	broad
Entoconids of m1-m3	indistinct	distinct	usually distinct	distinct	distinct
Dp3	variablea	small & incom- pletely molari- form	large & molari- form	small & incom- pletely molariform	small & incompletely molari- form

a Differs among member species.

b Intraspecific variation.