Monodelphis arlindoi, Pavan & Rossi & Schneider, 2012

Pavan, Silvia Eliza, Rossi, Rogerio Vieira & Schneider, Horacio, 2012, Species diversity in the Monodelphis brevicaudata complex (Didelphimorphia: Didelphidae) inferred from molecular and morphological data, with the description of a new species, Zoological Journal of the Linnean Society 165 (1), pp. 190-223 : 204-207

MONODELPHIS ARLINDOI SP. NOV. ( FIG. 7 )

Holotype

MPEG 38052 , an adult male collected on 17.v.2006 by B. A. Costa (field number BAC 204 ), at Platô Greig, 43 km south-west of Porto Trombetas, Oriximiná, Paratypes

MPEG 38054 , 38095 , 38056 , 38074 , two adult males and two adult females collected v.2006 (field numbers BAC 164, 202, 166, 169); UFMG 3184 , 3185 , 3189 , 3190 , two juvenile males and two adult males collected viii.2006 (field numbers, BAC 228, 229, 236, 237); all of them collected by B. A. Costa at the type locality, consisting of skin, skull, and liver tissue fixed in ethanol, except for MPEG 38095 and 38074, which consist of ethanol preserved specimens. MPEG 38063 , an adult male collected v.2006 (field number BAC 177 ) ; UFMG 3187 , 3188 , an adult male and a subadult female collected viii.2006 (field numbers BAC 231 , 233 ); all of them collected by B. A. Costa, at Platô Teófilo , Porto Trombetas , Oriximiná, Pará, Brazil, 1°45′60′′S, 56°34′16′′W, elevation 176 m, consisting of skin, skull, and liver tissue fixed in ethanol . MPEG 38093 , an adult male collected in v.2006 (field number BAC 201 ) ; UFMG 3186 , a juvenile female collected viii.2006 (field number BAC 230 ); both collected by B. A. Costa at Platô Bela Cruz, 40 km south-west of Porto Trombetas , Oriximiná, Pará, Brazil, 1°48′09′′S, 56°30′30′′W, elevation 176 m, the first one consisting of an ethanol conserved specimen, and the last one consisting of skin, skull, and liver tissue fixed in ethanol . MPEG 39810 , a juvenile female collected v.2007 by L. G. Vieira (field number LGV 146 ), at Platô Cipó , 60 km south of Porto Trombetas , Oriximiná, Pará, Brazil, 1°44′03′′S, 56°36′42′′W, elevation 160 m, consisting of skin and liver tissue fixed in ethanol . MPEG 39811 , 39812 , an adult male and a juvenile male collected v.2007 by L. G. Vieira (field numbers LGV 148 , 149 ) at Igarapé Greig , c. 60 km south-west of Porto Trombetas , Oriximiná, Pará, Brazil, 1°50′26′′S, 56°31′31′′W, elevation 160 m, consisting of skin and liver tissue fixed in ethanol . MPEG 42371 , 42399 , a juvenile female and a juvenile male collected v.2007 (field numbers SLF 216 , 244 ) ; MPEG 42428 , 42438 , 42440 , two adult males and a juvenile female collected xi.2007 (field numbers SLF 325 , 335 , 337 ); all of them collected by S. L. Freitas, at Platô Bacaba , Porto Trombetas , Oriximiná, Pará, Brazil, 1°46′11′′S, 56°22′09′′W, elevation 160 m, consisting of skin, skull, and liver tissue fixed in ethanol .

Morphological diagnosis

Same as for the M. brevicaudata complex with the following additions: HBL averages 133 mm in adult females and 149 mm in adult males (Supporting Information Table S2). Dorsal pelage with grizzled, grey coloured stripe at mid-dorsum, contrasting with reddish sides ( Fig. 4 ); head pelage reddish laterally, with narrow mid-dorsal stripe, commonly illdefined and sometimes almost indistinct, confined mid-dorsally by a band of red hairs above each eye; underparts greyish cream to yellowish, sharply differentiated from the reddish sides ( Fig. 4 ); throat and chin distinctly reddish; tail covered dorsally with body fur to about one third of the caudal length; ventrally, the body fur coverage is limited to the tail’s connection with the body. CBL averages 35.0 mm in adult females and 38.5 mm in adult males (Supporting Information Table S2); interorbital region relatively narrow ( Fig. 5 ); zygomatic arches slightly convergent anteriorly; maxillopalatine foramina relatively short ( Fig. 5 ); UMS averages 7.7 mm in adult females and 7.9 mm in adult males (Supporting Information Table S2).

Description

Dorsal and lateral pelage: Dorsal body pelage grizzled, with grey mid-dorsum contrasting with reddish flanks, therefore forming a well-defined stripe from the ears to the base of the tail ( Fig. 4 ), becoming red-washed on the rump, mainly in older specimens. Cover hairs of mid-dorsal fur c. 8 mm long at shoulders, grey basally (light brown at the base, darker toward the middle) and whitish distally (white band c. 1 mm), turning dark brown or black at the tip. Guard hairs sparser, longer (c. 10 mm), slightly coarser than cover hairs, entirely dark brown or black. At head, mid-dorsal stripe narrow and light coloured, commonly light grey to whitish buff, illdefined, confined mid-dorsally by a band of red hairs above each eye, giving a general reddish aspect to the head. Some specimens show the band of red fur above each eye wider, and the stripe is reduced to a line. Lateral fur bright red coloured, with hairs greyish brown basally, gradually turning darker to the middle and reddish distally. Next to the ears the red portion of the hairs becomes proportionally longer, resulting in a fur almost entirely or entirely reddish.

Ventral pelage: Ventral fur greyish basally and yellowish cream distally, clearly distinct from the lateral fur in colour ( Fig. 4 ). Ventral hairs c. 4 mm long, whitish at the base, becoming brownish toward the middle, and yellowish cream distally. Some hairs entirely cream or entirely grey are also present. Hairs become gradually shorter and red-washed from the chest toward the chin. Some specimens exhibit reddish tipped hairs next to the base of the tail, showing the inguinal region reddish coloured.

Vibrissae: Mystacial and genal vibrissae blackish, except for a few shorter ones that are light coloured in the two series. The longest mystacial vibrissae generally extend beyond eyes when laid flat against cheek, but do not reach the base of pinnae. The genal vibrissae generally reach pinnae and frequently do not extend beyond its posterior border. There is one pair of supraorbital vibrissae, blackish and unequal in size. There are few (up to five) submental and inter-ramal vibrissae, which vary from whitish to light brown coloured. Vibrissae are also present on the dorsal surface of forearm close to the elbow (one or two sparse hairs), and on the ventral surface of forearm close to the manus (one to three hairs); both vibrissae arrays have hairs turned to the sides, unequal in size, varying from whitish to brownish, frequently darker basally and lighter toward the tips. Limbs: Dorsal pelage of legs and arms coloured as the lateral body pelage; ventral pelage of legs and arms coloured as the ventral body pelage. Hands and feet brownish grey in general aspect. Hairs on metacarpals and metatarsal generally brown basally and yellowish to orange distally, but some are entirely brown, yellowish or orange. Digits dorsally covered with short brownish hairs. Ungual tufts brownish to goldenbrown, sparse and short, reaching approximately the middle of the claws on hands and almost the tips of the claws on feet. Hands and feet with digit III slightly longer than digits II and IV, the latter two subequal in size. Digits I and V shorter than digits II- IV. On feet, digit V reaches about two thirds of digit IV’s length, and the hallux reaches about the base of digit II. Plantar surface hairless, covered with five enlarged convex tubercles: the thenar pad and four interdigital pads; the former is the longest, and the latter are proportionally wider, of which the fourth interdigital pad is commonly the longest.

Tail: Tail short, a little longer than one half of the head and body’s length. Body fur covers the dorsal surface of the tail to about one third of caudal length. This coverage fur is reddish coloured, and gradually becomes sparser and shorter toward the tail tip. The uncovered part of the tail is weakly bicoloured (brownish dorsally and lighter brown ventrally). Tail scales are small, brownish, and rectangular in shape, each one bearing three hairs, the central one generally darker and slighter thicker.

Other external features: Ears small, uniformly brownish, hairless with no magnification, but covered internally and externally with very short and thin hairs, brownish or golden coloured. Scrotal skin brownish, covered with yellowish cream hairs.

General skull features: Skull relatively large for the genus (Supporting Information Table S2), with braincase shorter than rostrum ( Fig. 5 ).

Rostrum: Rostrum gently concave in dorsal view at premolars line, especially at P2. Infraorbital foramen enlarged. Nasals narrow and parallel anteriorly, becoming gradually wider posteriorly until reaches the greatest width at the frontal/maxillary suture, and then gradually narrowing toward the posterior end; the shape of the posterior end is generally round. Premaxillary extends anteriorly slightly beyond the first upper incisor (I1), not forming a distinct rostral process.

Orbital region: Lacrimal foramen consists of two openings located at the anterior edge of orbits, externally to the orbital cavity. A third smaller, anteriorly directed foramen is located in the orbital process of the lacrimal. This latter opening may be absent on one or both sides. Interorbital region moderately constricted, hourglass shaped. Supraorbital crests absent, with crown elements and orbital elements connected in a smooth curvature. Zygomatic arches robust, slightly convergent anteriorly, more expanded to laterals on males than in females, and commonly more expanded in older specimens.

Braincase: Sagittal crest evident in males and weak in female. Temporal lines weak in males and indistinguishable in females. Interparietals almost reaching the squamosal laterally (reach in specimen UFMG 3190, left side), hat-shaped, with the medial portion larger, becoming gradually narrower toward laterals. Nuchal crests well defined and developed, with the lateral expansions merging with the enlarged posttympanic processes of the squamosal. Exoccipitals not joined, and dorsal margin of foramen magnum formed by exoccipitals and supra-occipital.

Palate: Incisive foramen short, extending anteriorly until the fourth upper incisor or the posterior line of the third upper incisor, and posteriorly until the upper canine ( Fig. 5 ). Maxillopalatine fenestra approximately twice as long as the incisive foramen, extending from the first upper molars to the third upper molars. Posterolateral palatal foramen relatively large, as long as one half of the incisive foramen length, oval shaped, located immediately behind the fourth molar, with anterior border reaching about the posterior line of M 4 in adult specimens. Maxillary and palatine fenestra absent, but some diminutive perforations are present on the palatine. Palatine inflected ventrally, with approximately straight posterior edge.

Basicranium: Roof of the nasopharyngeal passage not perforated by vacuities. Alisphenoid bone with a distinct infratemporal longitudinal crest, which marks the ventral limit of the attachment of the temporalis muscle (see Wible, 2003). Bulla usually extending ventrally beyond the occipital condyle. Occipital condyle extending ventrally beyond the small and rounded paroccipital process. Alisphenoid tympanic process moderately inflated, rounded, slighter wider than longer. Ectotympanic about twice as long as wider. Anteromedial surface of the tympanic process of the alisphenoid pointed or rounded, with no bony strut or lamina connecting it with the transverse canal foramen. Promontorium well developed, with an elongated rostral tympanic process of the petrosal.

Mandibles: Mandibular rami shallow and bowed, but robust. Mandible with two mental foramina, the anterior between first lower premolar (p1) and second lower premolar (p2) or below p2, and the posterior below m1 or between m1 and second lower molar (m2). Coronoid process high and wide, three times higher than the ramus. Mandibular condyle rounded laterally, extending posteriorly beyond the broader coronoid process. Angular process acute and inflected medially. Posterior shelf of masseteric fossa robust.

Teeth: First upper incisor styliform, hypsodont, separated from I2–I5 by a short diastema. I2-I5 subequal in size, but with crowns showing a tendency to become wider from I2 to I5. Upper canines large and robust, at least twice as high as first upper premolar (P1) in females and young adult males, and at least three times higher than P1 (commonly more) in adult male specimens. P1 about one half the size of P2, separated from the latter by a very small gap, absent in the specimen MPEG 38054. P2 and P3 subequal in size, but P3 slightly higher than P2, and P2 proportionally wider, with posterior cutting edges more developed than in P3. Upper molars large, increasing in breadth from M1 to M4, all of them with well-developed anterior cingulum. Lower incisors similar in size, spoonshaped, with lingual cusp present. Commonly, there is a small gap between p1 and p2. Second and third lower premolars subequal in height, with p2 commonly slightly taller (specimen UFMG 3190, however, show p3 clearly taller than p2), but p2 wider and with posterior cutting edges more developed than p3.

Etymology

The name is given in honour of Arlindo Pinto de Souza Júnior (1958–2009), in recognition of his whole life dedication to preparing mammals for the mammal collection of Museu Paraense Emílio Goeldi, including several specimens examined in this study.

Geographical distribution

Central-south Guyana and Brazil in south-eastern Roraima, eastern Amazonas (north of the Amazon river) and northern Pará (north of the Amazon river) ( Fig. 6 ). No other species of the M. brevicaudata complex were found in sympatry with M. arlindoi sp. nov.

Geographical variation

Monodelphis arlindoi sp. nov. shows the extension of the body fur onto the tail and the tonality of the body fur variable. Specimens from Cachoeira Porteira, Oriximiná (Pará, Brazil) have a longer proportion of the tail covered by body hairs (one third or slightly more) than specimens from Porto Trombetas (also in Oriximiná), Faro (Pará, Brazil), and Alenquer (Pará, Brazil) (one third). Specimens from the latter three localities show the greyish base of the venter more evident than specimens from Cachoeira Porteira. Specimens from Potaro-Siparuni ( Guyana) have about one half of the tail length covered by body fur, and the venter more greyish than all other specimens examined. Specimens from Manaus and Itacoatiara (Amazonas, Brazil) appear smaller than specimens from all other localities and exhibit underparts more yellowish, more extensive coverage of the tail by body fur (at least one half of the tail length, commonly more), and mid-dorsal fur with greyish tonality lighter than average in this species, whitish or yellowish at head’s crown. Specimens from these two municipalities also exhibit smaller skull, and zygomatic arches less expanded to laterals than average for this species.

Remarks

The central clade constitutes a genetic lineage clearly independent from any other found in the M. brevicaudata complex. As there is no available name for this lineage, we describe it here as a new species. Morphologically, specimens included in this taxon are distinguishable from all other species of the M. brevicaudata complex, except for some specimens of M. touan (see the Morphological comparisons section below).

Figures

Figure 4. Dorsal (left) and ventral (right) views of the skins of adult specimens of (top to bottom): Monodelphis glirina (USNM 521429), Monodelphis palliolata (USNM 406904), Monodelphis brevicaudata (USNM 385005), Monodelphis arlindoi sp. nov. (UFMG 3190, paratype), Monodelphis touan (IEPA 1154). Scale bar = 50 mm.

Figure 5. Dorsal (top) and ventral (bottom) views of the skulls of old adult specimens of: A, Monodelphis glirina (USNM 521431, female); B, Monodelphis palliolata (USNM 371285, female); C, Monodelphis brevicaudata (USNM 385005, female); D, Monodelphis arlindoi sp. nov. (MPEG 38052, holotype, male); E, Monodelphis touan (ISEM V-1563, male). Scale bar = 10 mm.

Figure 6. Distribution of species of the Monodelphis brevicaudata complex recognized in this study. Species boundaries (shades) are based on our data and Pine & Handley (2008). Points indicate collecting localities of specimens examined by us (except for species B, not analysed). Monodelphis palliolata also occurs in Colombia, but distribution in that country cannot be correctly drawn because of the absence of known precise localities (Pine & Handley, 2008).

Figure 7. Adult male of Monodelphis arlindoi sp. nov. (MPEG 42428, paratype) from Porto Trombetas, Oriximiná, Pará, Brazil.