Crossodactylus trachystomus

Pimenta, Bruno V. S., Caramaschi, Ulisses & Cruz, Carlos Alberto Gonçalves, 2015, Synonymy of Crossodactylus bokermanni Caramaschi & Sazima, 1985 with Crossodactylus trachystomus (Reinhardt & Lütken, 1862) and description of a new species from Minas Gerais, Brazil (Anura: Hylodidae), Zootaxa 3955 (1), pp. 65-82 : 68-73

Crossodactylus trachystomus ( Reinhardt & Lütken, 1862 “1861”)

Tarsopterus trachystomus Reinhardt & Lütken, 1862 “1861”— Hensel, 1867.

Leptodactylus gaudichaudii — Boulenger, 1882 (part).

Crossodactylus bresslaui Müller, 1924 — Müller, 1927; B. Lutz, 1951, 1952.

Crossodactylus gaudichaudii (non Duméril & Bibron, 1841)— Miranda-Ribeiro, 1926 (part); A. Lutz, 1930 (part).

Phyllobates fuscigula (non Fitzinger, 1860)— A. Lutz, 1930 (part)

Crossodactylus trachystoma — Cochran, 1955; Lynch, 1971.

Crossodactylus trachystomus ( Reinhardt & Lütken, 1862 “1861”)— Bokermann, 1966; Caramaschi & Sazima, 1985; Caramaschi & Kisteumacher, 1989; Nascimento et al. 2005b; Weber & Caramaschi, 2006; Canelas & Bertoluci, 2007; Leite et al. 2008; Pimenta et al. 2008; Pimenta et al. 2014b.

Crossodactylus bokermanni Caramaschi & Sazima, 1985 — Caramaschi & Kisteumacher, 1989; Bastos & Pombal, 1995; Eterovick & Sazima, 2004; Eterovick et al. 2005; Nascimento et al. 2005a; Nascimento et al. 2005b; Afonso & Eterovick, 2007a, b; Pimenta et al. 2005; Leite et al. 2008; Pimenta et al. 2008; Caldart et al. 2011; Pimenta et al. 2014a, b—new synonymy.

Crossodactylus cf. bokermanni — Nascimento et al. 2005b.

Crossodactylus gr. gaudichaudii — Nascimento et al. 2005b. Crossodactylus sp.— Nascimento et al. 2005b.

Holotype. R 11126 (formerly ZMUC 128), adult male, collected in Lagoa Santa (19º37’S, 43º53’W, approx. 750 m elevation), Minas Gerais state, Brazil, in 01/10/1856, by J. Reinhardt ( Figs. 1–2 ).

Referred specimens. BRAZIL: Minas Gerais: Ouro Preto, MG ( USNM 98047–50, 98052–5, 98057, 98062– 3).

Diagnosis. (1) body slender; (2) head longer than wide; (3) snout rounded in dorsal view, protruding in lateral view; (4) canthus rostralis sharp; (5) tympanum distinct; (6) vocal sac subgular, median; (7) thumb spines small or developed; (8) toe and tarsal fringes broadly developed in males, reduced in females; (9) finger tips dilated; (10) toe tips truncate, dilated; (11) postrictal tubercle continuous; (12) presence of a glandular crest on the anterior surface of the arm; (13) dorsal skin posteriorly granular; (14) dorsolateral glandular ridges weakly marked; (15) white or cream stripe from the snout to the shoulder; (16) presence of partial oblique lateral stripe; (17) belly reticulated.

Comparisons with other species. Character states for the other species are shown in parentheses. Crossodactylus trachystomus differs from C. dispar and C. grandis due to its slender body (robust), head longer than wide (nearly as long as wide in C. dispar and wider than long in C. grandis ), sharp canthus rostralis (rounded), males with extensively fringed feet (moderate), dilated finger tips (undilated), truncate and dilated toe tips (rounded, undilated), postrictal tubercle continuous (fragmented into small granules), and reticulated belly (immaculate). Crossodactylus trachystomus also differs from C. grandis by its smaller size (males 18.7–25.1 mm and females 20.5–27.5 mm SVL in C. trachystomus ; males 31.5–42.0 mm and females 29.6–39.2 mm in C. grandis ).

Crossodactylus trachystomus could be distinguished from C. aeneus , C. dantei , C. gaudichaudii , and C. werneri due to its slender body (robust), and from C. boulengeri , C. caramaschii , C. cylospinus , C. dantei , C. lutzorum , and C. timbuhy by its rounded snout in dorsal view (nearly pentagon-shaped; variable in C. aeneus and C. gaudichaudii ). Crossodactylus trachystomus is distinguished from C. schmidti and C. werneri by its well marked canthus rostralis (rounded), and from C. boulengeri , C. caramaschii , C. dantei , and C. lutzorum due to its median subgular vocal sac (not expanded in C. dantei and C. lutzorum ; bilobate subgular in the other species).

Crossodactylus trachystomus could be distinguished from C. dantei , C. lutzorum , and C. schmidti due to the truncate toe tips (rounded) and from C. caramaschii and C. lutzorum by the developed postrictal tubercle (a slight ridge). The presence of dorsolateral glandular ridges separates C. trachystomus from C. cyclospinus , C. dantei , C. lutzorum , and C. schmidti (ridges absent) and the presence of a glandular ridge on the anterior surface of the arm differs C. trachystomus from these species and C. aeneus , C. caramaschii , and C. gaudichaudii (absent). Crossodactylus trachystomus is distinguished from C. aeneus , C. boulengeri , C. dantei , C. dispar , C. gaudichaudii , C. lutzorum , and C. timbuhy due to the occurrence of a white or cream stripe from the snout to the shoulder (poorly defined marbled/dotted area from the snout to the shoulder; variable in C. werneri ). The presence of an oblique lateral stripe distinguishes C. trachystomus from C. dantei , C. dispar , C. lutzorum , and C. timbuhy (no stripe; variable in C. boulengeri and C. caramaschii ). Crossodactylus trachystomus differs from C. aeneus , C. boulengeri , C. caramaschii , C. dantei , C. gaudichaudii , C. lutzorum , and C. schmidti due to its reticulated belly (immaculate; variable in C. werneri ).

Description of the holotype. Body slender. Head slightly longer than wide; nostrils protuberant, situated and directed anterolaterally, closer to the tip of snout than to the eye. Snout approx. 31% of HL, rounded in dorsal view, protruding in lateral view ( Fig. 2 ). Canthus rostralis well marked, sharp; loreal region oblique, slightly concave. Eyes approx. 38% of HL. Tympanum distinct, approx. 39% of ED, rounded; supratympanic fold weakly marked, extending from the superior margin of the tympanum to the shoulder. Skin on the gular region slightly folded, indicating the presence of a median subgular vocal sac. Upper lip spines small, white, appearing on the whole extension of lip. Tongue ovoid, covering half of the mouth floor surface, not notched behind. Choanae ovoid, very distant from each other. No vomerine teeth.

Arms slender; forearms thicker than upper arms; fingers tips slightly dilated; finger lengths I<II~IV<III; three developed spines on each thumb, arranged triangularly; the spine on the inner margin of thumb is smaller than the others. Scutes poorly developed on upper surfaces of finger tips, more evident on fingers III and IV; small dermal folds with rounded margins on the joints of distal phalanges; fringes on fingers II and III weakly developed. Carpal tubercle rounded, large; thenar tubercle elongated, as long as the greater diameter of the carpal tubercle; subarticular tubercles rounded, protruding, more developed on finger I; supernumerary tubercles arranged in line on finger bases ( Fig. 2 ).

Legs slender; the sum of tibia, thigh, and foot lengths 1.6 times the SVL; toes slender, extensively fringed, with truncate, moderately dilated tips; toe lengths I<II<V<III<IV. Scutes on upper surfaces of toe tips more developed than on fingers, less evident on toe I; small dermal folds with rounded margins on the joints of distal phalanges. Inner metatarsal tubercle elongated, protruding; outer metatarsal tubercle small, rounded, protruding; subarticular tubercles rounded, protruding; no supernumerary tubercles. Fringes joined at base; tarsal fringe very developed, continuous distally with outer fringe of toe I, almost reaching the joint with the tibia; outer fringe of toe V ends at the posterior margin of the basal tubercle of toe ( Fig. 2 ).

Dorsal skin posteriorly granular; a pair of faintly marked dorsolateral glandular ridges from the posterior corner of eyes to inguinal region. Ventral surfaces smooth, except for thighs and belly, which are coarsely granular. Scarce small granules on sacral region and cloacal region with developed granules. Postrictal tubercle elongated, continuous, poorly evident. A thin glandular crest on the anterior surface of the arm.

Color in preservative (70% ethanol) light brown and nearly uniform due to specimen fading. Stripe from snout to shoulder and oblique lateral stripe cream (white in the original description; Reinhardt & Lütken, 1862). Cream vertebral line from snout to the cloacal region, interrupted in midbody. Venter cream, immaculate due to specimen fading.

Measurements of the holotype: SVL = 21.8; HL = 8.1; HW = 7.7; TL = 10.0; THL = 9.5; FL = 15.0; TD = 1.2; ED = 3.1; END = 1.6; NSD = 0.9; IND = 2.6; IOD = 2.2.

Variation. Pimenta et al. (2008) found some differences between males and females (females are larger than males and also have longer and wider heads, larger eye and tympanum diameters, and longer eye-to-nostril distance; toe and tarsal fringes are broadly developed in males and very reduced in females; forearms are thicker in males than in females) and also among specimens of the same sex regarding distinctiveness and extension of supratympanic fold; presence, color, and distribution of upper lip spines; development, number, and arrangement of thumb spines; finger lengths; extension of outer fringe of toe V; and color pattern. Measurements (in mm) are shown in Table 1 .

Males (N = 67) Females (N = 34) Vocalization. The advertisement call and its variation were described in Pimenta et al. (2008) as Crossodactylus bokermanni . It was characterized as a long call, ranging from 1.4– 10.1 s, and consisting of 13–121 notes with harmonic structure. A curious feature of the call is the dominant frequency, which may be found in the second to the third harmonic or, more rarely, in both harmonics.

Geographic distribution and natural history. Pimenta et al. (2008) recognized the occurrence of Crossodactylus trachystomus in 17 localities (referred as C. bokermanni in 16) comprising the whole portion of Serra do Espinhaço within the state of Minas Gerais ( Fig. 3 ). Data on natural history were presented by Caramaschi & Sazima (1985) and Pimenta et al. (2008), both as C. bokermanni . Specimens are found during the day in permanent streams with sandy or rocky bottom at campos rupestres, where marginal vegetation consists of shrubs and grasses, or in transitional or typical patches of semideciduous Atlantic Forest in the eastern slope of Serra do Espinhaço, inside primary or secondary gallery forests. Males call exposed on stones near the margins of the streams or from sandy margins, close to relatively fast waters. Some were also observed on floating leaves or, more rarely, on emergent rocks in the middle of the streams.

Tadpole. Data on tadpole external morphology were presented by Caramaschi & Sazima (1985), Pimenta et al. (2014a) (both as Crossodactylus bokermanni ), and Caramaschi & Kisteumacher (1989). It was described as having a nearly triangular body and rounded snout on lateral view; nostrils small, located dorsolaterally; spiracle sinistral, small, located halfway between dorsum and belly; oral disc small, with poorly developed lips marginated by a single row of papillae interrupted on upper lip; tooth row formula 2(2)/3(1); strong, serrated jaw sheaths; and anal tube dextral, short, and wide. Internal oral morphology was described by Weber & Caramaschi (2006).

Remarks. In the original description of Crossodactylus caramaschii, Bastos & Pombal (1995) cited specimens ZUEC 3485–8 and ZUEC 3714 as C. gaudichaudii and also as C. trachystomus . These specimens are, in fact, topotypes of C. gaudichaudii from Tijuca, Rio de Janeiro, Rio de Janeiro state, southeastern Brazil.

Nascimento et al. (2005a) separate Crossodactylus cyclospinus from C. trachystomus (referred to as C. bokermanni ) by the absence of spines on the upper lip on the latter, among other characters. However, Caramaschi & Sazima (1985) had already reported on the occurrence of such structures in some specimens of the type-series of C. bokermanni . Pimenta et al. (2008) found these spines in 87.3% of the specimens analyzed, and that they vary on their degree of development and color. Nascimento et al. (2005a) also used the presence of the oblique lateral stripe (therein called “lateral cream stripe on the posterior half of flanks”) to distinguish C. cyclospinus from C. trachystomus (referred to as C. bokermanni ). The oblique lateral stripe is very conspicuous in all specimens of C. trachystomus examined, varying from partial to complete and white or cream.

Figures

FIGURE 1. Crossodactylus trachystomus: (A) R 11126, holotype (adult male, SVL 21.8 mm), dorsal view; (B) plate from Reinhardt & Lütken (1862 “ 1861 ”), dorsal view; (C) holotype, ventral and (D) lateral views.

FIGURE 2. Crossodactylus trachystomus (Reinhardt & Lütken, 1862 “ 1861 ”) (R 11126, holotype, SVL 21.8 mm). Dorsal (A) and lateral (B) views of head and ventral views of hand (C) and foot (D). Scales = 5 mm.

FIGURE 3. Geographic distributions of Crossodactylus trachystomus (circles, including the capital city of Belo Horizonte) and Crossodactylus franciscanus (squares) in the state of Minas Gerais, Southeastern Brazil.

Tables

TABLE 1. Means, standard-deviations (SD) and range of some measurements (in mm) of Crossodactylus trachystomus (N = number of specimens).

	Mean	SD	Range	Mean	SD	Range
SVL	22.2	1.23	18.7–25.1	24.2	1.51	20.5–27.5
HL	8.2	0.45	7.0–9.4	8.6	0.49	7.6–9.5
HW	7.4	0.37	6.7–8.5	7.8	0.43	6.7–8.8
TL	11.2	0.77	10.0–13.2	11.8	0.72	10.2–12.9
THL	10.9	0.75	9.1–13.3	11.6	1.05	9.1–13.3
FL	17.4	1.21	15.1–21.2	18.5	1.38	15.4–20.6
TD	1.5	0.23	1.1–2.0	1.6	0.19	1.1–2.0
ED	3.0	0.25	2.4–3.5	3.0	0.25	2.5–3.5
END	1.7	0.22	1.2–2.3	1.8	0.27	1.3–2.3
NSD	1.0	0.22	0.5–1.4	1.0	0.20	0.5–1.4
IND	2.7	0.20	2.3–3.1	2.8	0.20	2.3–3.2
IOD	2.7	0.28	1.9–3.3	2.6	0.28	2.2–3.1