Microkayla chilina, Riva & Chaparro & Castroviejo-Fisher & Padial, 2018

Riva, Ignacio De La, Chaparro, Juan C., Castroviejo-Fisher, Santiago & Padial, José M., 2018, Underestimated anuran radiations in the high Andes: five new species and a new genus of Holoadeninae, and their phylogenetic relationships (Anura: Craugastoridae), Zoological Journal of the Linnean Society 182, pp. 129-172 : 152-154

MICROKAYLA CHILINA SP. NOV.

( FIG. 13)

u r n: l s i d: z o o b a n k. org:act: 95C71601-FCC2-46A9-9A9B-6E7DDEB9B340

Holotype: MUBI 5355 (field number 4580), adult male from the joint of rivers Sayaco and Huacuyo , province Sandia, department Puno, Peru, 14°26 ′ 42.2 ″ S, 69°34 ′ 11.5 ″ W, 3792 m ( Fig. 10), collected on 14 February 2006 by I. De la Riva, J. M. Padial, S. Castroviejo-Fisher, J. C. Chaparro and J. Bosch.

Paratopotypes: MUBI 5352 (field number 4573) (male) ; MUBI 5350-51 , 5353 (field numbers 4569, 4572, 4574) and MNCN 43770–75 (field numbers 4570, 4571, 4575, 4577, 4578, 4579) (females) ; MUBI 5354 (field number 4576) (juvenile), same data as the holotype .

Diagnosis: Microkayla chilina is characterized by: (1) skin on dorsum warty to coarsely warty (warts round, low, subconical to conical), with slightly larger warts on flanks; conspicuous and incomplete dorsolateral ridges; belly, throat, groin and chest coarsely areolate; (2) tympanic membrane and annulus not discernible beneath the skin, tympanic fold prominent; (3) snout short, rounded in dorsal and lateral views; (4) upper eyelid lacking tubercles, bearing conical warts, cranial crests absent; (5) dentigerous processes of vomers absent; (6) vocal slits present, vocal sac subgular, nuptial pads absent; (7) Finger I slightly shorter than Finger II, tips of digits rounded, lacking circumferential grooves and ungual flap; (8) fingers lacking lateral fringes; (9) ulnar region bearing warts, sometimes coalescing in an irregular ridge; (10) heel lacking tubercles; tarsus warty, lacking tubercles and folds; (11) two metatarsal tubercles, inner slightly larger than outer; supernumerary plantar tubercles low, numerous; (12) toes markedly short, lacking lateral fringes; webbing absent; Toe III longer than V, tips of digits rounded, lacking circumferential grooves and ungual flap; (13) dorsal coloration from reddish-brown to dark brown or black, sometimes with scattered yellow irregular blotches; ventral coloration dark grey to black with greyish-white and orange irregular blotches; groin, axillae, shanks and distal portions of hands and feet with orange flash marks; (14) females larger than males, SVL 25.5 in an adult female, 23.2–24.3 mm in adult males (n = 4) ( Table 3).

The sister and geographically closest species to M. chilina is M. boettgeri ( Lehr, 2006) (type localities separated by 36.6 km straight line distance). Microkayla boettgeri possesses a protruding snout, a sharp ulnar ridge formed by small conical granules, and sharp and protruding eyelids. Microkayla chilina has a more slen- der body than M. boettgeri , which has globular body shape ( Fig. 14). In M. chilina the tympanic membrane and annulus are not discernible, while they are in M. boettgeri , in which the tympanic membrane reaches c. 50% of eye length in diameter. Some differences are also evident in coloration. Microkayla chilina often has irregular yellowish-cream blotches on dorsum, which are not present in M. boettgeri ; this species usually has some reddish-orange coloration on venter, digits, axillae, and groins, while in M. chilina these areas are yellowish-orange. To the east, M. chapi sp. nov. is found at 33.7 km (straight line) from the type locality of M. chilina and is sister to the clade formed by M. boettgeri and M. chilina . Microkayla chilina is readily distinguished from M. chapi by having incomplete dorsolateral ridges (sharp and well-developed dorsolateral folds in M. chapi ), tympanic membrane and annulus not discernible beneath the skin (a large and conspicuous tympanic membrane), and shorter toes, more areolate belly, and warty skin (smooth to granular).

Description of the holotype: An adult male, 24.3 mm SVL. Body robust; dorsal skin warty, with small irregular warts scattered all over; ventral skin areolate; dorsolateral folds present, incomplete, running from above ocular region to level of midbody, from where they continue as interrupted ridges of warts; two oblique and inconspicuous middorsal folds on central part of dorsum; pectoral fold absent; head wider than long, HW 33.7% of SVL, HL 32.9% of SVL; snout moderately short, rounded in dorsal view and in profile; nostrils not prominent, closer to snout than to eyes; canthus rostralis straight in dorsal view, concave in profile; eye–nostril distance 74.2% of eye length; loreal region concave; cranial crests absent; tympanic membrane and tympanic annulus not visible externally; supratympanic fold barely visible; tongue large, oval; choanae small, rounded, broadly separated; dentigerous process of vomers absent; vocal slits present; a subgular vocal sac; ulnar tubercle and fold absent (a ridge formed by connected warts); inner palmar tubercle nearly oval, slightly smaller than round outer; no nuptial pads; fingers moderately short, not fringed, lacking circumferential grooves and ungual flap; subarticular tubercles round, bulky; supernumerary tubercles round, of variable sizes; first finger approximately equal or slightly shorter than second, relative length of fingers 1 ≤ 2 = 4 <3; limbs short; tibia length 30.0% of SVL; tarsal fold absent; two metatarsal tubercles, oval inner slightly larger than round outer; supernumerary and subarticular tubercles low, irregular; toes lacking basal webbing or lateral fringes, toe tips round, lacking circumferential grooves and ungual flap; relative length of toes 1 <2 <3 = 5 <4; foot length 37.4% of SVL.

In preservative, dorsal surfaces uniformly grey, venter and throat brownish-grey with an irregular beige area in central part of venter; palmar and plantar surfaces and inner surface of forelimbs mostly brown, digits pale cream. In life, the dorsum was mostly uniformly brown above; there were small orange irregular blotches on axillae and groins; the venter was greyish-brown with an irregular dirty-yellow pattern; the digits were yellowish-orange; the iris was dark brown.

Measurements (in mm) of the holotype: SVL, 24.3; HL, 8.0; HW, 8.2; IND, 2.4; END, 2.3; ED, 3.1; TL, 7.3; FL, 9.1.

Variation: All specimens are nearly identical in skin texture and overall colour pattern. MNCN 43773, 43774, and, especially, 43775, have some small, irregular pale grey blotches on dorsum (dirty-yellowish in life); a dark brown spot can be present on the anterior surface of the forearm (e.g. MUBI 5351, MNCN 43771) and/or the inner surface of the shank (MNCN 43772). Males are small and lack vocal slits, external vocal sac and nuptial excrescences.

Distribution and natural history: Known only from the type locality. Individuals were found during the day under stones in open wet puna. They were not common; almost two hours of collecting by five persons yielded only 12 specimens.

Etymology: The species epithet is used as a name in apposition, and derives from the Quechua word ‘chilina’, meaning the colour of a ripe orange (reddishyellow), and refers to the spots of this colour present in this new species.