Thursday, September 13, 2018

[Herpetology • 2018] Pristimantis tiktik • A New Minute Pristimantis (Anura: Strabomantidae) from the Andes of southern Ecuador

Pristimantis tiktik 
 Székely, Eguiguren, Székely, Ordóñez-Delgado, Armijos-Ojeda, Riofrío-Guamán & Cogălniceanu, 2018

in Székely, Eguiguren, Székely, et al., 2018. 

We describe a new rainfrog species (Pristimantis), from the wetland complex Oña, Nabón, Saraguro and Yacuambi, in the Andes of southern Ecuador, at altitudes ranging between 3000–3400 m a.s.l. Pristimantis tiktik sp. nov. is a small frog, displaying sexual dimorphism (the males with dorsum of various shades of gray, brown, orange or green and a whitish or pinkish yellow venter; females with brownish gray or gray dorsum and a reticulated white and black venter), with SVL ranging between 19.7–20.4 mm in females (n = 3) and 16.1–18.4 mm in males (n = 6). The skin on dorsum is tuberculated, that on venter is coarsely areolate, dorsolateral folds are absent, tympanic membrane is absent but the tympanic annulus is evident, cranial crests are absent, discs on fingers just slightly expanded, heel is lacking enlarged tubercles, inner edge of tarsus is bearing a long fold, Toe V is slightly longer than Toe III and the iris coloration is bronze with fine black reticulations. The males have a large subgular vocal sac that extends onto the chest and vocal slits but lack nuptial pads. The unique advertisement call consists of long duration series of periodically repeated clicks: “tik”. Molecular analyses place the new species in the recently resurrected P. orestes group, as the sister species of the assemblage that contains P. bambu, P. mazar, P. simonbolivari and an undescribed species.

Fig 2. Holotype of Pristimantis tiktik sp. nov. (MUTPL 239, adult male), SVL 16.7 mm, in life.
 A. Dorsolateral view; B. Ventral view; C. Dorsal view.

Class Amphibia Linnaeus, 1758
Order Anura Fischer von Waldheim, 1813

Superfamily Brachycephaloidea Günther, 1858
Family Strabomantidae Hedges, Duellman, and Heinicke, 2008
Subfamily Pristimantinae Pyron and Wiens, 2011

Genus Pristimantis Jiménez de la Espada, 1870

Pristimantis tiktik sp. nov. 
Székely, Eguiguren, Székely, Ordóñez-Delgado, Armijos-Ojeda, Riofrío-Guamán, and Cogălniceanu.

Fig 6. Color variation in males of Pristimantis tiktik sp. nov. in life.
 Paratype (MUTPL 240), SVL 18.4 mm: A. dorsolateral view; B. ventral view. Paratype (MUTPL 251), SVL 16.1 mm: C. dorsolateral view; D. ventral view. Paratype (MUTPL 277), SVL 17.0 mm: E. dorsolateral view; F. ventral view. 

Fig 7. Color variation in females of Pristimantis tiktik sp. nov. in life.
 Paratype (MUTPL 247), SVL 20.2 mm: A. dorsolateral view; B. ventral view. Paratype (MUTPL 252), SVL 19.7 mm: C. dorsolateral view; D. ventral view. Paratype (MUTPL 276), SVL 20.4 mm: E. dorsolateral view; F. ventral view.

Common English name. Tiktik Rain Frog
Common Spanish name. Cutín tiktik

Etymology. The specific name is the onomatopoeic representation of the frog’s particular call.

Holotype. MUTPL 239, an adult male (Figs 2, 3 and 5A) from Ecuador, Loja province, Saraguro canton, 21 km (by road) E of Urdaneta (3.58612° S, 79.07516° W; datum WGS84), 3300 m above sea level, collected by Paul Székely, Diego Armijos-Ojeda and Dan Cogălniceanu on 8 July 2016.

Diagnosis. We assign this species to Pristimantis based on phylogenetic evidence (Fig 1) and on the general morphological similarity to other members of the genus. Pristimantis tiktik is a small species distinguished by the following combination of traits: (1) skin on dorsum tuberculated; skin on venter coarsely areolate; discoidal fold weak, more evident posteriorly; thoracic fold absent; dorsolateral folds absent; low mid dorsal fold present; (2) tympanic membrane absent but tympanic annulus evident, its length about 30% of the length of eye; supratympanic fold present; (3) snout short, subacuminate in dorsal view, rounded in profile; canthus rostralis weakly concave in dorsal view, rounded in profile; (4) upper eyelid bearing several small tubercles, similar in size and shape with the ones from the dorsum, about 80% IOD in females and 70% IOD in males; cranial crests absent; (5) dentigerous processes of vomers inconspicuous, elongated, but each processes bearing 3 to 5 evident teeth; (6) males with a large subgular vocal sac, extended onto the chest; vocal slits present; nuptial pads absent; (7) Finger I shorter than Finger II; discs on fingers just slightly expanded, rounded; circumferential grooves present; (8) fingers bearing narrow lateral fringes; subarticular tubercles prominent; supernumerary palmar tubercles present, rounded, smaller than subarticular tubercles; palmar tubercle inconspicuous, bifurcated; thenar tubercle oval; (9) ulnar tubercles coalesced into low ulnar fold; (10) heel lacking enlarged tubercles; outer edge of tarsus with row of small tubercles; inner edge of tarsus bearing a long fold; (11) inner metatarsal tubercle broadly ovoid, about 3x round outer metatarsal tubercle; supernumerary plantar tubercles present; (12) toes bearing narrow lateral fringes; webbing absent; Toe V slightly longer than Toe III; discs on toes just slightly expanded, rounded, about same size as those on fingers; circumferential grooves present; (13) evident sexual dimorphism: in life, the males with dorsum of various shades of gray, brown, orange or green (brownish gray or gray in females), the flanks, chest, groins and ventral surface of the limbs have usually a reddish mottling and the venter is whitish or pinkish yellow (venter, axillae and groins white with black reticulum in females); iris bronze, with lower half darker, and with fine black reticulations; (14) SVL 19.7–20.4 mm in adult females (20.1 ± 0.36 SD, n = 3) and 16.1–18.4 mm in adult males (16.9 ± 0.79 SD, n = 6).

Fig 10. Habitat of Pristimantis tiktik sp. nov.  in the wetland complex of Oña, Nabón, Saraguro and Yacuambi.
A. One of the many glacial lakes from the wetland complex; B. General view of the herb páramo (montane grassland); C. Microhabitat with grasses and shrubs; D. Grass microhabitat near a stream from the wetland complex.

Distribution. Pristimantis tiktik is known only from the wetland complex of Oña, Nabón, Saraguro and Yacuambi (Fig 9) which spreads over three provinces, Loja, Azuay and Zamora-Chinchipe, in Southern Ecuador. This area has an altitudinal range between 3000 and 3400 m a.s.l. and consists of herb páramo (montane grasslands and shrublands) and a wetland complex of almost 100 glacial lakes (Fig 10). We found this species above 3000 m along the road that crosses this area from Urdaneta to Tutupali, but it is probably widespread in the entire wetland complex.


Fig 9. Distribution of Pristimantis tiktik sp. nov.  (red dots) in Ecuador. 

Natural history. All the specimens were encountered during the night on the grassy vegetation, very close to the ground (usually at 5–15 cm above the ground). The distinctive call of the males was heard throughout the year (usually after 18:00), regardless of the weather conditions, i.e. rain or strong winds. All the females were caught in the vicinity of the calling males. This seems to be one of the most common frog species from the wetland complex, along with Pristimantis aff. riveti. Other sympatric frog species include Gastrotheca pseustes and a currently undescribed species of Pristimantis.

Conservation status. Pristimantis tiktik is known only from the wetland complex of Oña, Nabón, Saraguro and Yacuambi, above 3000 m a.s.l., which is estimated to have an area of 192 km2. Even though this is one of the most commonly encountered species in the wetland complex, we consider it to be Endangered following B1ab(i,ii,iii)+2ab(i,ii,iii) IUCN criteria because: (1) its Extent of occurrence (EOO) and Area of occupancy (AOO) are estimated to be less than 200 km2; (2) it is known from only one location; and (3) its habitat is currently affected (or could be severely affected in the near future) by mining activities, invasive species (especially pines from the nearby pine plantations), grazing, wildfires and road constructions.

 Paul Székely, Juan Sebastián Eguiguren, Diana Székely , Leonardo Ordóñez-Delgado, Diego Armijos-Ojeda, María Lorena Riofrío-Guamán and Dan Cogălniceanu. 2018. A New Minute Pristimantis (Amphibia: Anura: Strabomantidae) from the Andes of southern Ecuador.   PLoS ONE. 13(8): e0202332.  DOI: 10.1371/journal.pone.0202332

No comments:

Post a Comment