Philander Brisson, 1762

Voss, Robert S., Díaz-Nieto, Juan F. & Jansa, Sharon A., 2018, A Revision of Philander (Marsupialia: Didelphidae), Part 1: P. quica, P. canus, and a New Species from Amazonia, American Museum Novitates 2018 (3891), pp. 1-72 : 23-27

Philander Brisson, 1762

TYPE SPECIES: Didelphis opossum Linnaeus, 1758 , by plenary action of the International Commission on Zoological Nomenclature ( ICZN, 1998) .

CONTENTS: Based on evidence summarized in this report, we tentatively recognize the following eight species as valid (synonyms in parentheses): andersoni Osgood, 1913 ; canus Osgood, 1913 (including crucialis Thomas, 1923; mondolfii Lew et al., 2006 ; and olrogi Flores et al., 2008); mcilhennyi Gardner and Patton, 1972 ; melanurus Thomas, 1899 (including fuscogriseus Allen, 1900; grisescens Allen, 1901; and melantho Thomas, 1923); opossum Linnaeus, 1758 (including frenatus Olfers, 1818 ; and superciliaris Olfers, 1818 ); pallidus Allen, 1901 ; pebas , new species (described below); and quica Temminck, 1824 (including azaricus Thomas, 1923).

In the absence of genetic information, we are currently unable to assess the validity of deltae Lew et al., 2006 , and nigratus Thomas, 1923, either or both of which might also be good species.

DESCRIPTION: 7 Combined length of adult head and body ca. 250–350 mm; adult weight ca. 280–700 g. Rhinarium with one ventrolateral groove on each side of median sulcus; dark circumocular mask present, usually continuous with dark coronal fur; pale supraocular spots present; dark midrostral stripe absent; throat gland absent. Dorsal pelage unpatterned-

7 After Voss and Jansa (2009: 121–123), but including corrections and supplementary observations. grayish or -blackish, or with grayish flanks and black middorsal stripe when fresh (foxing to brownish tones in old museum skins); dorsal underfur gray; dorsal guard hairs usually short (but sometimes much longer middorsally than along flanks in P. mcilhennyi ); ventral fur variously pigmented (self-whitish or -buffy, gray-based buffy or cream, or entirely grayish; variable within and among species). Manus mesaxonic (dIII> dIV); manual claws about as long as fleshy apical pads of digits; dermatoglyph-bearing manual plantar pads present; central palmar epithelium smooth or sparsely tuberculate; carpal tubercles absent. Pedal digits unwebbed; dIV longer than other pedal digits; plantar surface of heel naked. Pouch present, opening anteriorly; mammae usually 2–1–2 = 5 or 3–1–3 = 7; cloaca present. Tail longer than combined length of head and body, slender and muscular (not incrassate); furred dorsally and ventrally to about the same extent at base; naked caudal integument blackish proximally and abruptly whitish distally (but a few specimens of some species have all-black tails); caudal scales in spiral series, each scale with 4–6 bristlelike hairs emerging from distal margin; ventral caudal surface modified for prehension distally, with apical pad bearing dermatoglyphs.

Skull in general aspect ( fig. 8 ) smaller and less robust than that of Didelphis (which it otherwise resembles). Premaxillary rostral process absent. Nasals short, usually not extending anteriorly above I1 (exposing nasal orifice in dorsal view), and widened posteriorly near maxillary-frontal suture. Maxillary turbinals elaborately branched. Lacrimal foramina usually two on each side, exposed laterally on orbital margin or on face just anterior to orbit. Interorbital region smoothly rounded, without supraorbital beads or crests; short, blunt postorbital processes usually present in large adult specimens. Left and right frontals coossified (midfrontal suture incomplete or absent), but left and right parietals separated by persistent midparietal suture. Parietal and alisphenoid in contact on lateral braincase (no frontal-squamosal contact). Sagittal crest present, well developed on parietals and extending anteriorly onto frontals. Petrosal not laterally exposed through fenestra in squamosal-parietal suture (fenestra absent). Parietal-mastoid contact absent (interparietal narrowly contacts squamosal).

Maxillopalatine and palatine fenestrae present; maxillary fenestrae absent; posterolateral palatal foramina small, not extending anteriorly between M4 protocones; posterior palate (behind toothrows) with prominent lateral corners, the choanae constricted behind. Maxillary and alisphenoid usually separated by palatine on floor of orbit (but maxillary-alisphenoid contact occurs unilaterally or bilaterally in a few specimens). Transverse canal foramen usually present. Alisphenoid tympanic process small and uninflated, usually with broad lamina enclosing extracranial course of mandibular nerve (secondary foramen ovale present), and not contacting rostral tympanic process of petrosal. Anterior limb of ectotympanic indirectly suspended from basicranium (by malleus). Stapes usually triangular with large obturator foramen. Fenestra cochleae exposed (not concealed by rostral and caudal tympanic processes of petrosal). Paroccipital process large, erect, directed posteroventrally. Dorsal margin of foramen magnum bordered by exoccipitals only (incisura occipitalis absent).

Two mental foramina present on lateral surface of each hemimandible; angular process acute and strongly inflected.

Unworn crowns of I2–I5 with much longer anterior than posterior cutting edges. Upper canine (C1) alveolus in premaxillary-maxillary suture; C1 simple, without accessory cusps. First upper premolar (P1) smaller than posterior premolars but well formed and not vestigial; third upper premolar (P3) taller than P2; P3 with posterior cutting edge only; upper milk premolar (dP3) large and molariform. Molars highly carnassialized (postmetacristae conspicuously longer than postprotocristae; relative widths M1 <M2 <M3 <M4; centrocrista only weakly inflected labially on M1–M3; ectoflexus usually distinct only on M3; anterolabial cingulum and preprotocrista discontinuous (anterior cingulum incomplete) on M3; postprotocrista with carnassial notch. Last upper tooth to erupt is M4.

Lower incisors (i1–i4) without distinct lingual cusps. Lower canine (c1) erect, acutely pointed, and simple (without a posterior accessory cusp). Second lower premolar (p2) much taller than p3; lower milk premolar (dp3) large and molariform with complete (tricuspid) trigonid. Hypoconid labially salient on m3; hypoconulid twinned with entoconid on m1–m3; entoconid much taller than hypoconulid on m1–m3.

Figures

FIG. 8. Dorsal, ventral, and lateral cranial views of Philander opossum (based primarily on AMNH 266387, an adult female from Paracou, French Guiana).