Fig. 2: Palmar views of hands of two species of the western complex of Syrrhophus. pipilans (left, KU 58908, ×6) and teretistes (center, KU 75269, and right, KU 75263, respectively, ×9).
In S. cystignathoides and leprus, the first finger is longer than the second, and the first two fingers are equal in length in guttilatus and marnockii. In the other species the first finger is shorter than the second.
Supernumerary tubercles are well developed on the plantar surfaces in all species, except S. guttilatus, in which they are poorly defined ([Fig. 3]). The relative sizes of the metatarsal tubercles has been used in the classification of the species and species groups of Syrrhophus. The metatarsal tubercles are similar in all species of the eastern complex (including rubrimaculatus); the outer tubercle is always about one-half the size of the ovoid inner metatarsal tubercle. In the leprus group the outer tubercle is conical and compressed. The metatarsal tubercles of pipilans are about the same size, or the outer is slightly smaller than the inner. In the modestus group the outer metatarsal tubercle is about one-third the size of the inner.
All species, except guttilatus, have well-defined to poorly defined lateral fringes on the toes. All species have expanded toe pads. The fifth toe is usually shorter than the third, but the second is equal in length to the fifth in some specimens of S. cystignathoides and S. marnockii. Syrrhophus nivocolimae is the only species with tubercles along the outer edge of the tarsus; this is merely a reflection of the highly tuberculate nature of the skin in this species.
Skin texture.—The skin of the dorsum is smooth or very weakly pustular in all species of the genus except nivocolimae and verrucipes. The dorsal surfaces of nivocolimae are warty; in verrucipes the skin is pustular. The skin of the venter is areolate in cystignathoides cystignathoides, dennisi and verrucipes but is smooth in all other species of the genus.
Fig. 3: Plantar views of feet of four species of the eastern complex of Syrrhophus. (A) guttilatus (UIMNH 55519, ×6), (B) leprus (UIMNH 42726, ×6), (C) verrucipes (UIMNH 15995, ×6), and (D) longipes (TCWC 12179, ×4.6).