The phylogenetic position of the enigmatic Atlantic forest-endemic spiny mouse Abrawayaomys (Rodentia: Sigmodontinae)

Ventura, Karen; Silva, Maria José J; Geise, Lena; Leite, Yuri LR; Pardiñas, Ulyses FJ; Yonenaga-Yassuda, Yatiyo; D'Elía, Guillermo

doi:10.1186/1810-522X-52-55

Zoological Studies

Table 2 Morphological comparisons among Abrawayaomys and other members of the Sigmodontinae

From: The phylogenetic position of the enigmatic Atlantic forest-endemic spiny mouse Abrawayaomys (Rodentia: Sigmodontinae)

Character	*Abrawayaomys*	*Rhagomys* ^b	*Phaenomys* ^d	*Thomasomys* ^f	*Aepeomys* ^g	*Akodon*	*Reithrodon*
Plantar pads	6	6	6	6	6	6	4
Hindfoot surface	Smooth?	Smooth	Squamated	Smooth	Smooth	Squamated	Squamated
Mammae	6a	6	8	6	6	8	8
Spines	Present	Present^c	Absent	Absent	Absent	Absent	Absent
Relation of tail length (LT) to head-body length (HB)	LT < = > HB	LT ≤ HB	LT > > HB	LT < = > HB	LT > HB	LT ≤ HB	LT < < HB
Rostrum	Short	Short	Long	Long	Long, rostral tube developed	Moderate	Moderate
Interorbit	Hourglass-shaped or slightly convergent, with rounded margins	Convergent, with beaded margins	Hourglass-shaped^e, with beaded margins	Hourglass-shaped, with rounded margins	Hourglass-shaped, with rounded margins	Hourglass-shaped, with rounded margins	Symmetrically constricted, with parallel margins
Palate	Typically short	Long	Short	Short	Short	Short	Long
Mesopterygoid fossa	Not fenestrated	Not fenestrated	Not fenestrated	Not fenestrated	Not fenestrated	Fenestrated	Fenestrated
Alisphenoid strut	Typically present	Present	Absent	Present	?	Typically present	Present
Tegmen tympani	Overlaps squamosal	Overlaps squamosal	Overlaps squamosal	Overlaps squamosal	Overlaps squamosal	Overlaps squamosal	Does not overlap squamosal
Carotid circulation	Pattern 1	Pattern 3	Pattern 1	Pattern 1	Pattern 1	Pattern 1	Pattern 3
Capsular process	Present	Present	Absent	Absent	Absent	Typically present	Present
Retromolar fossa	Enlarged	Enlarged	Not enlarged	Not enlarged	Not enlarged	Not enlarged	Not enlarged
Molar design	Intermediate to alternate, crested	Opposite, crested	Opposite, crested	Opposite, crested	Opposite, crested	Intermediate, crested to terraced	Alternate, plane
Anteromedian flexus	Patent	Patent	Patent	Patent	Patent	Patent	Not patent
Mesoloph on M1	Present, small	Present, large	Present, large	Present, large	Present, large	Present, small	Absent
M3 reduction to M2	Much reduced	Moderately	Weakly	Moderately	Moderately to reduced	Much reduced	Weakly
Incisors	Orthodont to proodont	Orthodont	Opisthodont	Opisthodont	Opisthodont	Typically opisthodont	Opisthodont
Incisive foramina	Reaching anterior face M1	Very short	Reaching anterior face M1	Reaching anterior face M1	Reaching anterior face M1	Reaching protocone M1	Reaching protocone M1
Subsquamosal foramen	Present	Present	Absent	Present	Present	Present	Present
Number of ribs	12	13	12	13	13	13	12
Gall bladder	Absent	Absent	Present	Present	Present	Typically present^h	Present

^aInguinal, abdominal, and postaxial pairs (Pardiñas, unpublished data). ^bBased on Rhagomys longilingua, after Luna and Patterson (2003). ^c Rhagomys rufescens lacks spines (cf. Luna and Patterson 2003). ^dData from Voss et al. (2002) and Pardiñas (unpublished data). ^eScored as ‘convergent’ by Pacheco (2003, p. 43). ^fVariation in this genus is remarkable (cf. Pacheco 2003); herein, we follow Voss (1993). ^gBased on Aepeomys lugens, after Voss et al. (2002). ^h Akodon montensis lacks gall bladder (cf. Geise et al. 2004).

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