Elachistocleis sikuani, Acosta-Galvis & Tonini & De Sá, 2022

Acosta-Galvis, Andrés R., Tonini, João F. R. & De Sá, Rafael O., 2022, Two new species of Elachistocleis Parker, 1927 (Anura: Microhylidae: Gastrophryninae) from Colombia, Zootaxa 5099 (5), pp. 527-548 : 529-535

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https://doi.org/ 10.11646/zootaxa.5099.5.2

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scientific name

Elachistocleis sikuani

sp. nov.

Elachistocleis sikuani sp. nov.

( Figures 1 View FIGURE 1 , 3 View FIGURE 3 )

Holotype. IAvH-Am–11748 (field number ARA 5924. Figs 1 View FIGURE 1 , 3 View FIGURE 3 ) an adult female collected on 3 December 2010 by Andrés R. Acosta-Galvis and Luis Daniel Prada.

Type locality ( Fig. 2 View FIGURE 2 ). Colombia, Casanare Department, Maní Municipality, vereda El Viso, Caracaro Farm, a locality that is part of the “Llanos Orientales”. 04°5’19.8”N, 072°21’56.6”W, 191 m a.s.l. GoogleMaps

Paratypes (6 specimens) ( Fig. 3 View FIGURE 3 , Table 1 View TABLE 1 ). IAvH-Am–13074, adult male, IAvH-Am–13071–13073 and IAvH-Am –13075, adult females, collected on 13 May 2016 by Andrés R. Acosta-Galvis, Rafael O. de Sá, Travis Cuddy, and Luis Daniel Prada in Colombia, Casanare Department, Maní Municipality, Guaranito Farm, a locality that is part of the “Llanos Orientales”, 04°53’42.8”N,0 72°22’0.5”W, 187 m a.s.l., GoogleMaps IAvH-Am–11791 adult male collected on 20 April 2011 by Andrés R. Acosta-Galvis in Colombia, Casanare Department, Orocué Municipality , Vereda Cumaco , site Cachicamo , Mare Stream 4°49’34.79”N, 71°46’14.35”W, 152 m a.s.l. GoogleMaps

Referred specimens (3 specimens). IAvH-Am–11747 an juvenile, collected on 26 November 2010 by Andrés R. Acosta-Galvis and Luis Daniel Prada., same locality as the holotype, IAvH-Am–11364 adult female, IAvH-Am– 11365–11366 juveniles, collected on 19 November 2013 in Colombia, Casanare Department, Maní Municipality , Vereda Santa María , Corocito Farm , a locality that is part of the “Llanos Orientales”. 04°38’11.2”N,0 72°05’31”W, 153 m a.s.l. GoogleMaps

Etymology. The specific epithet sikuani refers to the native south American ethnic groups of Sikuani, Guahibo, or Jivi (Jiwi) who inhabit the Llanos del Orinoco, between the Guaviare, Meta, and Arauca River basins, area that includes the distribution range of the new species.

Diagnosis ( Figs. 1 View FIGURE 1 , 3 View FIGURE 3 ). A medium size species of Elachistocleis (males SVL= 27.3–28.8 mm, χ = 28.0 1.1 mm, females SVL = 28.7–33.2 mm, χ = 31.6 1.8 mm), diagnosed by the following combination of characters: (1) an ovoid body form, (2) triangular head, slightly wider than long, (3) a barely developed and complete occipital fold, (4) snout rounded in lateral and dorsal views, (5) canthus rostralis slightly concave and loreal region is convex, (6) nostrils laterally oriented, (7) post-commissural glands well defined, (8) tympanic annulus and membrane absent, (9) dentigerous process of vomer absent, (10) upper jaw projects beyond the lower jaw, (11) tongue large and ovoid, occupying the entire buccal floor, (12) choanae ovoid, large, and widely separated, (13) arms slender without tubercles on forearm, (14) hands without interdigital membranes and supernumerary tubercles, (15) finger lengths are I<II<IV<III, (16) subarticular tubercles ovoid, as wide as fingers, (17) thenar tubercle prominent and palmar tubercle bilobate, (18) foot lacks interdigital membranes and supernumerary tubercles, toes lack discs, (19) inner plantar tubercle equal in size to subarticular tubercles, (20) relative toe lengths I<II<V<III<IV, (21) THL is slightly longer than TBL, (22) dorsal surface of body with sparse dermal spines, (23) cloacal area lacks glands and tubercles, but bears poorly distinct dermal spines, (24) in preservative dorsal coloration dark gray to dark brown with scattered cream spots, (25) ventral surfaces of fore and hind limbs mottled, (26) mid-dorsal line absent, (27) light colored, broad, and irregular femoral stripe on posterior surface of thighs, (28) axillae with a light color spot, (29) groin light spotted, (30) all toes fringed and slightly webbed in females and male, (31) dermal spines absent on ventral surfaces, except on chin of adult breeding males.

Description of Holotype ( Fig. 1 View FIGURE 1 ). Body small (SVL = 31.6 mm), slender, and slightly ovoid, head triangular in shape, broader than long ( Table 1 View TABLE 1 ), snout short, snout tip rounded, nostrils located closer to the tip of snout than to the eye, slightly protuberant, directed laterally, inter-nostril distance smaller than eye–nostril distance and smaller than eye diameter ( Table 1 View TABLE 1 ), canthus rostralis slightly defined, loreal region slightly convex, lips flared, eyes small, slightly protruding, inter-orbital slightly concave, occipital fold complete, tympanum indistinct, upper jaw projecting beyond the lower one, tongue big, ovoid, and covers the entire buccal floor, premaxillae, maxillae, and vomerine teeth absent, choanae small, subovoid, widely separated, positioned anterolaterally to eye. Arms slender and lacking tubercles on forearm. Hands not webbed, fingers slightly fringed with not expanded and rounded tips, fingers lacking dermal spines, finger lengths I<II<IV<III, subarticular tubercles well developed and rounded, proximal subarticular tubercles larger than others, supernumerary tubercles absent, thenar tubercle well developed and subovoid, palmar tubercle bifid. Legs short, moderately robust, knee and heel lacking tubercles, tibial and tarsal ridges absent. Foot not webbed, toes slightly fringed, toe tip rounded lacking disks, subarticular tubercles well developed and ovoid, supernumerary tubercles absent, an oval inner, but no outer, metatarsal tubercle. Toe lengths I<II<V<III<IV, toes lacking dermal spines, tibia length slightly shorter than thigh length, combined thigh, and tibia lengths approximately 43.3% of snout-vent length, foot length approximately 37.9% of snout-vent length. Skin smooth, dorsal surfaces of body lacking dermal spines. Throat smooth, without dermal spines on chin and snout. Cloaca with para-cloacal tubercles or glands.

Color of holotype in preservative ( Fig. 1 View FIGURE 1 ). Dorsum dark brown with a few small and diffuse cream spots and blotches, dorsal surface of limbs dark brown with cream blotches and small spots, particularly on proximal forelimb, palm of hands pale cream and marbled brown on subarticular region, foot dark brown with pale cream blotches, belly surface pale cream with dark brown reticulated pattern, throat dark brown with small irregular cream spots. Ventral surface of anterior thighs pale cream, medial region of thighs and ventral surfaces of tibia pale cream with dark brown reticles. Body and limbs lack distinct lines.

Color of holotype in life ( Fig. 3 A–B View FIGURE 3 ). Dorsal body and limbs surfaces pale gray with black reticulations, cephalic flank black with small, pale gray, and irregular spots, yellow pale blotches in the anterior region of the arm, flanks dark brown with dense pale yellow blotches, surface of venter pale cream with pale brown reticulations and dense pale yellow blotches, throat pale brown with pale cream irregular spots, axillary region, groin, and anterior thigh pale yellow, ventral surfaces of thighs pale cream with pale brown reticulations and pale yellow blotches, iris pale gray.

Measurements of Holotype (in mm). SLV 31.6, HDL3 6.1, HDL4 4.3, HL 6.5, HW 7.5, ED 2.2, IOD 3.2, IND 2.1, END 1.9, THL 10.7, TBL 10.3, FL 11.9, FAL 4.9, FD3 0.5, TD4 0.6.

Variation of type series ( Figs. 3 View FIGURE 3 , 6 View FIGURE 6 ; Table 1 View TABLE 1 ). In this section, coloration refers to live specimens and is based on field notes and digital photographs, unless otherwise noted. Flanks coloration varies from pale yellow with distinct pale-yellow blotches (e.g., IAvH-Am–11748, Fig. 3A View FIGURE 3 ) to moderate (e.g., IAvH-Am–13073, Fig. 3D View FIGURE 3 ), and diffuse (e.g., IAvH-Am–13071–2, Fig. 3C View FIGURE 3 ; IAvH-Am–11747, Fig. 3 View FIGURE 3 E-F; IAvH-Am–11791, Fig. 4C View FIGURE 4 ). Femoral light stripe varies from a longitudinal band (e.g., IAvH-Am–13073–4) to irregular and broad (e.g., IAvH-Am–13072). The post-commissural with light-colored spots (i.e., pale yellow) that can vary from densely pigmented (e.g., IAvH-Am– 11747–8, IAvH-Am–11791) to moderate (e.g., IAvH-Am–13071–3). The variation in the skin texture is noteworthy in both sexes, noticeable dermal spines on chin of adult males (e.g., IAvH-Am–11791 IAvH-Am–13074) that are absent in females (e.g., IAvH-Am–11364, IAvH-Am–11747–8, and IAvH-Am–13071–3). HL approximately equal to HW in adult females, HL 78.0–92.2 % of HW whereas in adult males HL is longer HL 102.8–107.1 % of HW.

Advertisement calls analysis ( Fig. 7 View FIGURE 7 ). Males of Elachistocleis sikuani called at night on ephemeral ponds formed after heavy rains in the typical open savannas environment, that in the area, have numerous termite mounds. The analyzed call belongs to voucher specimen: IAvH-Am–13074 (https://doi.org/10.6084/m9.figshare.16943425) recorded on May 14, 2006 at 19:12 hrs., air temperature of 28.7°C, and 71% relative humidity and unvouchered male (https://doi.org/10.6084/m9.figshare.16944232), recorded from Guaranito farm, at 187 m a.s.l., in the Municipality of Maní (4°53’42.8”N, 72°22’0.5W), Casanare Department, Colombia on May 13, 2016 at 19:00 hrs., air temperature of 25.8°C, 68% relative humidity. The call of Elachistocleis sikuani sp. nov. (n = 21 calls) consists of a sustained trill made by a long, strong, and continuous note (one pulsed note, Guild C sensu Emmrich et al. 2020) lasting between 1158 and 3106 milliseconds (χ = 2429 ms 0.49) and interval between notes between 13365 and 21215 ms (χ = 18129 ms 2.72), dominant frequency between 1042 and 1842 Hz (χ = 1521 Hz 342.7). Each note consists of a series of sustained and long multi-pulses (260–410 pulses per note) with a rate of 236 to 269 pulses per seconds (χ = 261.2 pulses/s.), the duration of each pulse is 3.0 msec. The calls have an ascendant modulation frequency where the first segment consist of 33 to 49 initial pulses (χ = 38.1) with lower frequencies between 2695 and 3231.9 Hz (χ = 3056.3 Hz) and the maximum frequency, at the end of the call, between 4863 and 5028 Hz (χ = 4941.2 Hz).

Tadpole. Unknown

Distribution. Elachistocleis sikuani sp. nov. is known from the savanna like environments called “Llanos Orientales” in the Casanare Department; all localities are associated with the sub-basin of the Meta River, at elevation between 138 to 325 m a.s.l. The localities are within the Llanos ecoregion ( Dinerstein et al. 1995) in the Orinoco region ( Fig. 7 View FIGURE 7 ).

Natural history. The specimens were found active during the rainy season (March to May and August to December). A species typical of plains habitats, being reported in grasslands and flooded forested areas in aeolian savannas, the annual rainfall in localities varies between 1400 to 5600 mm with bimodal seasonality. Elachistocleis sikuani sp. nov. is active entirely in the rainy season when seasonal ponds are established in flooded grasslands, being remarkably active after very heavy rains or during moderate rains. The species was active between 21.6–27.6 C° and 71–91% relative humidity during the dry season between December and March. The species remains submerged in the sandy substrate or under termite mounds in open savannas, but it can also be found buried in the substrate mixed with gallery forests. Males vocalize partially submerged and hidden at the base of flooded grasslands or in seasonal ponds. The amplexus is axillary and performed submerged in shallow pools.


Departamento de Geologia, Universidad de Chile













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