Elachistocleis magnus, Toledo, Luís Felipe, 2010

Toledo, Luís Felipe, 2010, A new species of Elachistocleis (Anura; Microhylidae) from the Brazilian Amazon, Zootaxa 2496, pp. 63-68 : 64-67

Elachistocleis magnus sp. n.

Holotype. ZUEC 11384, adult male, collected at Fazenda Jaburi, in the municipality of Espigão do Oeste, (11º35' – 11º38' S, 60º41' – 60º45' W; 280 m a.s.l.) ( Bernarde, 2007), state of Rondônia, Brazil, on January 1997 by P. S. Bernarde and M. N. C. Kokubum ( Figure 1 ).

Paratopotypes. CFHB 5156, 5158 (adult female and male, respectively) collected on May 2001 by P. S. Bernarde; CFBH 5157 (juvenile) collected on April 2001 by P. S. Bernarde; ZUEC 11381-83 (adult females), and 11385-86 (adult males) collected with the holotype.

Diagnosis. Elachistocleis magnus is recognized by the following combination of characters: 1) ventral coloration in preserved individuals is white with gray spots or gray with white spots (depending on the prevalence of one of the colors); 2) grayish dorsum in preserved individuals; 3) presence of postcommissural glands, behind the corner of mouth; 4) lack of red blotches in the interior portion of legs or red stripes in the legs; and 5) SVL larger than 31 mm in adult individuals.

Description of the holotype. ZUEC 11384. Adult male ( Figure 1 ). Body robust, ovoid, SVL 31.76 mm, AGL 43.51 % of the SVL. Texture of the dorsal skin and undersurface of the body smooth. Skin on ventrolateral surfaces of body and area around the cloacal smooth. Anal flap absent; vent opening positioned posterodorsally. Head small and triangular, broader than long, HL 20.87 % of the SVL. No cranial crests. A conspicuous dorsolateral skin fold from back of the head to the anterior insertion of the arm. Another conspicuous lateral skin fold from the upper region of arm to the groin. A third skin fold crossing the chest between the axillae. Small eyes, slightly prominent. Snout pointed in dorsal view, protruding in lateral view. Nostrils directed anterolaterally, slightly protuberant. Choanae relatively small and round. Internarial distance narrow. Canthus rostralis distinct, slightly convex. Loreal region slightly concave. Interorbital space slightly convex. Lips nearly horizontal. Presence of large post-commissural glands (PCGL 53 % of HL) behind the corner of mouth. Tympanum concealed. Supratympanic fold absent. Upper jaw projects 1.69 mm beyond the lower jaw. Subgular vocal sac not expanded externally. Vocal slits present. Vomerine odontophores absent. Tongue large, elliptic. Arms robust and short. Fingers robust, short, free. Finger length I<IV<II<III. Legs extremely robust. Almost equal lengths of thigh, tibia and foot THL 11.75 mm, TBL 11.86 mm and FL 14.65 mm. Toes robust and free. Toe length I<II<V<III<IV. Finger and toes without webbing, fringes or ridges. Finger and toes tips rounded not flattened or expanded into discs. Conspicuous subarticular tubercles present on the basis of hands and feet. Supernumerary tubercles absent in hands and feet. Large oval inner metatarsal tubercle. Outer metatarsal tubercle absent. Presence of a large oval thenar tubercle and a longitudinally divided palmar tubercle in hand. Nuptial asperities on males' thumb absent. No prepollex or forearm fold.

Coloration. In preservative (70 % ethanol), dorsum and limbs are uniform dark grayish, with scarce minute brighter dots in the outer boundaries of the dorsum. Presence of a slim mid-dorsal (vertebral) white stripe, from the vent to the anterior third of the dorsum. Belly gray with minute scattered with white spots, mainly in the belly and ventral surfaces of legs. There are large irregular white spots in the groin and in the axillary region. There is also a broad, not well defined femoral light stripe. Throat brownish dark, darker than chest and belly. The chest presents a large yellowish blotch. In life the general coloration was quite the same but the inguinal spots and femoral stripe were yellow (P. S. Bernarde, personal communication).

Va r ia ti o n. Females are larger than males (see Table 1 ). The throat of males is darker than the ones of the females ones (the throat of females is of the same color of the belly). The vertebral stripe may or may not be present in adult individuals. When present, it never reached the read in the observed individuals. The ventral spots may reach the flanks and the groin region of the animals. The white blotches in the groin and inner portions of the legs vary in size and shape. In half of the individuals blotches are present in the dorsal surface of feet.

Geographical distribution. Only known from the type locality.

Natural history notes. Elachistocleis magnus was misidentified as E. ovalis by Bernarde (2007) during anuran fauna study in Jaburi farm. This species calls during October to March (wet season) in temporary ponds in the pasture areas ( Bernarde, 2007).

Etymology. The specific name is an adjective derived from Latin meaning large, in allusion to the great size of this species in comparison to its congeners. It is one of the largest described species for the genus Elachistocleis .

Comparison with other species. From Elachistocleis bicolor and E. ovalis the new species is readily distinguished by not presenting the immaculate, yellow, ventral coloration (belly gray with minute scattered with white spots in E. magnus ) (see Lavilla et al., 2003 and Figure 2 ). From E. erythrogaster Kwet and Di- Bernardo, 1998 it is distinguished by the absence of the reddish coloration of the ventral portion of its body. From E. surinamensis (Daudin, 1802) it is distinguished by differences in body coloration (see plate XIII in Kenny, 1969 and Figure 3 in Toledo et al., 2010), bluish dorsum and presence of red blotches in the internal region of the legs of E. surinamensis and grayish dorsum and absence of red stripes in the legs in E. magnus . From E. skotogaster it is distinguished by presenting large post-commissural glands (absent in E. skotogaster ). From E. bicolor , E. cesarii , E. piauiensis Caramaschi and Jim, 1983 , and E. skotogaster it is distinguished by having a larger SVL in males (greater than 31 mm in males of E. magnus and smaller than 29 mm in males of the other referred species). Elachistocleis magnus is also larger than E. erythrogaster , but there is a small overlap in the SVL of these species (SVL range 29.1 – 32.3 mm in E. erythrogaster , and SVL range 31.8 – 36.6 in E. magnus ).

Discussion. While investigating museum specimens and pictures of live individuals from different sites in South America, I have noticed several different morphotypes (in regard to external morphology and classic measurements) assigned to the genus Elachistocleis . These different forms (in body coloration and shape) may represent different species that need to be evaluated, such as early suggestions based on the record of different advertisement calls ( Nelson, 1973). Therefore, further taxonomical work within this group is a necessity, reinforced by the fact that habitat destruction is getting faster recently and declines of undescribed species may be ongoing.

Post-commissural gland maximum length 3.68 ± 0.46 4.68 ± 0.43 3.5

(3.4 – 4.4) (4.4 – 5.3)

Esteban O. Lavilla and Miguel Vences reviewed the manuscript. Paulo S. Bernarde provided unpublished information about live individuals. Célio F. B. Haddad, José Pombal Jr., and Hussan Zaher allowed the access to the amphibian collections CFBH, MNRJ, and MZUSP, respectively. Samira Rolim prepared the line drawings. FAPESP provided a grant (proc. no. 2008/50325-5) and a scholarship (proc. no. 2008/52847-9).

Figures

FIGURE 1. Elachistocleis magnus sp. n., ZUEC 11384 (holotype; adult male). (A) Dorsal and (B) lateral views of head. Ventral views of hand (C) and foot (D).

FIGURE 2. Ventral (A) and dorsal (B) views of the holotype (ZUEC 11384; adult male) of Elachistocleis magnus sp. n.

Tables

TABLE 1. Measurements of the holotype and paratypes of Elachistocleis magnus.

	Males including the holotype (N=4)	Females (N=4)	Holotype (male; ZUEC 11384)
Sonut-vent length	33.80 ± 2.05 (31.8 – 36.6)	41.81 ± 1.94 (39.8 – 43.8)	31.8
Axila-groin length	15.99 ± 1.51 (13.8 – 17.1)	21.53 ± 1.46 (20.2 – 23.1)	13.8
Head length	7.09 ± 0.41 (6.6 –7.6)	7.94 ± 0.76 (7.0 – 8.7)	6.6
Head width	8.48 ± 0.51 (8.0 – 9.1)	10.01 ± 0.60 (9.2 – 10.5)	8.0
Eye diameter	1.89 ± 0.62 (1.4 – 2.8)	1.85 ± 0.08 (1.7 – 1.9)	1.4
Upper eyelid width	1.23 ± 0.07 (1.1 – 1.3)	1.32 ± 0.19 (1.2 – 1.6)	1.3
Eye-nostril distance	2.65 ± 0.45 (2.1 – 3.1)	3.10 ± 0.35 (2.6 – 3.5)	2.1
Interorbital distance	3.56 ± 0.23 (3.3 – 3.8)	4.28 ± 0.53 (3.5 – 4.6)	3.5
Internostril distance	1.96 ± 0.31 (1.7 – 2.2)	2.20 ± 0.16 (2.1 – 2.4)	1.7
Snout-eye distance	3.83 ± 0.29 (3.5 – 4.2)	4.51 ± 0.38 (4.2 – 5.0)	3.5