Fifty years after: A taxonomic revision of the amphibian species from the Ecuadorian biodiversity hotspot Abra de Zamora, with description of two new Pristimantis species

teeth; (6) males lacking vocal sac and slits; nuptial pads absent; (7) Finger I shorter than Finger II; discs on fingers slightly expanded, truncated; circumferential grooves present; fingers bear- ing lateral fringes; (8) subarticular tubercles prominent, round and rounded in section; super- numerary palmar tubercles prominent, rounded; palmar tubercle completely divided into a larger (inner) and a smaller (outer) tubercles; thenar tubercle ovoid, larger than the inner pal- mar tubercle; (9) ulnar tubercles absent; (10) heel with several small tubercles (trait more visi- ble in life); outer edge of tarsus with a row of small, inconspicuous, tubercles (trait more visible in life); inner edge of tarsus bearing a long fold; (11) inner metatarsal tubercle broadly ovoid, about 3x elongated and rounded outer metatarsal tubercle; supernumerary plantar tubercles prominent, rounded; (12) Toe V much longer than Toe III; discs on toes slightly expanded, truncated, about same size as those on fingers; circumferential grooves present; toes bearing prominent lateral fringes; webbing basal; (13) in life, dorsum various shades of brown or gray with or without middorsal bands, interorbital bars, or dark X-shaped markings on the back; venter light gray or pinkish gray; no markings in axilla, groin or on concealed limb surfaces; iris bronze or reddish bronze with a dark median horizontal streak and fine black reticulations; (14) SVL 20.8–23.3 mm in adult females (22.5 ± 1.12 SD, n = 4) and 19.9–21.2 mm in adult males (20.4 ± 0.68 SD, n = 3).

Comparisons with similar species. Pristimantis matildae is morphologically similar to its closest relatives, the species from the P. orestes group, and especially to the species from the P. colodatylus subgroup (Fig 7), P. colodactylus and P. muranunka. The difference between P. matildae and the species from the other subgroups were presented in the description of P. samaniegoi. Pristimantis matildae is easily distinguished from P. muranunka by the lack of tympanic annulus and tympanic membrane (tympanic annulus and tympanic membrane evi- dent in P. muranunka). Pristimantis matildae best resembles P. colodactylus, but several mor- phological features can be used to distinguish between these two species. The most important feature is the relative size of the fingers and toes (Fig 20). From the three species currently included in this subgroup, P. colodactylus has the shortest fingers and toes (Hand length (length of Finger III) about 22% of SVL; Foot length (length Toe IV) about 36% of SVL), fol- lowed by P. muranunka (Hand length about 23% of SVL; Foot length about 38% of SVL), and finally, P. matildae, has the longest fingers and toes (Hand length about 25% of SVL; Foot length about 40% of SVL) (Fig 20, Table 1). Additionally, P. matildae can be distinguished from P. colodactylus as follows (characters of P. matildae in parenthesis): skin on dorsum and flanks areolate (finely tuberculate), low middorsal fold absent (present), heel with one moder- ate-sized conical tubercle and several small tubercles (without a larger tubercle, only with sev-

eral small ones), ornamentation in cloacal region absent (cloacal region bordered ventrally by two large, oval, tubercles), thenar tubercle the same size or slightly smaller than the inner pal- mar tubercle (thenar tubercle larger than the inner palmar tubercle), inner edge of tarsus lack- ing tubercles (inner edge of tarsus bearing a long fold) and inner metatarsal tubercle about 4 to 5x outer metatarsal tubercle (inner metatarsal tubercle about 3x outer metatarsal tubercle). Also, the iris coloration in P. matildae is more reddish than in the case of P. colodactylus. Description of the holotype. Adult male (MUTPL 731; Figs 16–18), head wider than body, just slightly wider than long, head length 99% of head width, head width 33% of SVL; head length 32% of SVL; snout moderately long (snout to eye distance 14% of SVL), subacuminate in dorsal view and subacuminate and slightly protruding in profile (Fig 18A and 18B); canthus rostralis weakly concave in dorsal view, angular in profile; loreal region slightly concave; eye diameter notably greater than eye-nostril distance; nostrils slightly protuberant, oriented pos- teriorly; lips not flared; cranial crests absent; upper eyelid bearing one prominent tubercle and several small tubercles, width of upper eyelid 77% of IOD; tympanic annulus and tympanic membrane absent (Fig 18B); supratympanic fold absent; one large, rounded postrictal tubercle PLOS ONE Taxonomic revision of the amphibian species from Abra de Zamora PLOS ONE | https://doi.org/10.1371/journal.pone.0238306 September 10, 2020 34 / 59