Leptodactylus, 2008

Angulo, Ariadne & Reichle, Steffen, 2008, Acoustic signals, species diagnosis, and species concepts: the case of a new cryptic species of Leptodactylus (Amphibia, Anura, Leptodactylidae) from the Chapare region, Bolivia, Zoological Journal of the Linnean Society 152 (3), pp. 59-77 : 62-67

LEPTODACTYLUS COCA SP. NOV. ( FIGS 1 , 2 )

Holotype: Adult male, NKA 3630 , field number SR 99.134, collected near Carretera Antigua from Villa Tunari to Cochabamba (c. 800 m above sea level), just above the Village of El Palmar , Province of Chapare, Department of Cochabamba, Bolivia, on September 25, 1997 by S. Reichle and J. Aparicio. The holotype is also a call voucher for the species, recorded by S. Reichle.

Paratypes: Two additional specimens were collected at the type locality: a gravid female ( CBF 4298 ), and a male, which is also a call voucher ( CBF 2619 ), recorded by S. Reichle and collected by S. Reichle and J. Aparicio on September 25, 1997 .

DIAGNOSIS

Leptodactylus coca differs in its advertisement call from all other known members of the L. marmoratus group for which acoustic data are available. Leptodactylus araucaria ( Kwet & Angulo, 2002) and L. nanus can be distinguished from L. coca by their small size [maximum SVL in L. araucaria males, 18.8 mm ( Kwet & Angulo, 2002); maximum SVL in L. nanus males, 19.4 mm ( Kwet, 2007)], whereas Leptodactylus lutzi ( Heyer, 1975) differs from the new species by its large size [SVL in males, 25.7–33.5 mm ( Kok et al., 2007)], the presence of a dark triangular seat patch, and distinct spotting on the posterior face of the thigh ( Heyer, 1975). Individuals of Leptodactylus bokermanni Heyer, 1973 have not been found to possess a light mid-dorsal stripe extending from above the vent to the middle of the body, whereas this is a possible pattern for individuals of L. coca . The new species differs from Leptodactylus martinezi Bokermann, 1956 in lacking four longitudinal series of dark glands on the dorsum ( Bokermann, 1956). L. andreae , L. diptyx , L. hylaedactylus , Leptodactylus marmoratus Steindachner, 1867 , and Leptodactylus thomei Almeida & Angulo, 2006 all have distinct, different advertisement calls to those of L. coca . There is a recently described species of Leptodactylus of the marmoratus group from French Guiana, Leptodactylus heyeri ( Boistel, de Massary & Angulo, 2006) , which has a similar call to that of L. coca . However, even with similar calls, there are differences in acoustic patterns. For example, even if the call rate is often influenced by the motivation of callers, the call of L. heyeri is issued at a much lower call rate than that of L. coca , and the call of L. heyeri does not show evidence of pulse structure, whereas it is present in L. coca . The species also differ morphologically: L. heyeri has a relatively broader head in proportion to the body; the dorsal coloration is very distinct, with stripes and bands, and well-defined black lumbar glands; and males of this species have a yellow throat and belly.

DESCRIPTION OF HOLOTYPE

Body small, robust, with relatively short limbs. Dorsal outline of snout rounded ( Fig. 1 ), in profile snout nearly acuminate; head wider than long; nostrils positioned dorsolaterally, closer to tip of snout than to corner of eye; internarial distance about a quarter of head width. Tympanum distinct, slightly more than half the diameter of eye; tympanic membrane translucid, possible to observe tympanic canal; supratympanic fold weakly developed, extending from back of eye to arm insertion, dark, contouring outline above fold extending from back to eye to about half or two thirds of the way down to the arm; oval creamcoloured gland below angle of jaw, and supratympanic fold present and distinct; canthus rostralis indistinct. Vocal sac single and internal, paired elongate vocal slits present. Vomerine teeth posterior to choanae in transverse series parallel to choanae, separated from each other by approximately the length of one vomerine tooth row. Arms short and robust; fingers slender, finger lengths III> I = II> IV; finger tips rounded, without fringes or expansions; palms of hand with two large ovoid-shaped cream-coloured metacarpal tubercles; smaller inner metacarpal tubercle a little less than half the size of larger metacarpal tubercle; fingers with conspicuous, distinct cream-coloured rounded subarticular tubercles, absence of nuptial asperities. Hindlimbs robust, shank slightly longer than thigh; toe lengths IV> III> V> II> I; toe tips very slightly flattened or not, with very minor expansions (character state B of Heyer, 1973); toes without fringes. Metatarsal tubercles conspicuous, distinct; inner tarsal fold weakly developed, lined with scant, small white tubercles; tarsus also with small white tubercles, although not profuse; sole of foot with very sparse, scant white tubercles. Texture on dorsal surface mostly smooth, becoming tuberculate around the sacral area; thighs mostly smooth, shanks with very small, mostly scant, tubercles. Dorsolaterally, a dark longitudinal glandular fold starting just behind shoulder and running discontinuously posterior to sacral region; beneath it a second cream coloured glandular lateral fold extending along the same length as the darker fold. Surface of venter smooth.

COLOUR IN PRESERVATIVE

Preserved in 70% alcohol, the dorsum is a light brown colour, with the discontinuous upper dorsolateral glandular lines a darker shade of brown. There is a dark marking in the shape of an inverted U on the dorsum between the shoulders. Tips of glands on lower back dark brown; dorsal surface of limbs, a uniform light brown, except for the white-tipped tubercles and a dark bar on left foot. Tip of snout to back of head at about tympanum level a darker shade of brown, with a slight milky/foggy aspect to it. Venter white, immaculate; skin on edges of lower lip sparsely dotted with melanophores.

COLOUR IN LIFE

The coloration in life does not differ much from the colour described in preservative, just more intense.

MEASUREMENTS OF HOLOTYPE (IN MM)

SVL, 24.1; HL, 8.0; HW, 8.7; ED, 2.6; TYD, 1.4; END, 1.6; IOD, 2.4; IND, 2; FAL, 4.3; HDL, 5; THL, 9.7; SL, 10.3; TSL, 6.5; FL, 11.5.

MORPHOLOGICAL VARIATION

Female slightly larger than males ( Table 1 ). The dorsal pattern of the male specimen CBF 2619 is similar to that of the holotype, except that it lacks the fogginess observed in the snout and head of the holotype; it does not have the inverted U-shaped dark marking between the shoulders; the two dark brown dorsolateral discontinuous glandular lines are ventrally flanked by broad cream lateral stripes that run parallel to them. In addition, it appears to have an inverted triangular-shaped interorbital spot, which, although fainter on the left side of the specimen, is dark brown from its base between the eyes to the back of the head, with a lighter spot within the triangle close to the right eye. Furthermore, specimen CBF 2619 has two symmetrical inguinal dark blotches on either side of the lower dorsum, and another two symmetrical dark blotches lower down, flanking the base of the hairline cream stripe that extends from the base of the vent to the lower back, and very sparse dark spots on the upper dorsum. The supratympanic fold is more pronounced from just behind the eye to behind the tympanum; it is weaker from the back of tympanum to the arm. An accompanying dark brown bar follows the outline of the supratympanic fold only to the back of the tympanum. In contrast with the holotype, this specimen shows distinguishable irregular crossbars on the hindlimbs. The toe tips are expanded (character states C-D or D sensu Heyer, 1973) and flattened.

Female specimen CBF 4298 is morphologically the most different of the three specimens collected. It has a cream-coloured patch on the dorsum between shoulders; an inverted triangular-shaped interorbital spot that is dark brown from its base between the eyes to the level of the posterior edge of the tympanum, with the exception of a couple of lighter-coloured irregular spots within the triangle that take the appearance of eyes on a mask; it then takes a lighter shade from the apex of this spot posteriorly until it reaches the anterior edge of the shoulder-level cream patch. The ‘mask’ is flanked by two lighter coloured trapezoidalshaped spots, one on either side of the head, behind the eyes. The supratympanic fold is well developed from the back of the eye to the arm, with a dark brown bar following the contour of the fold nearly to the arm. There is a cream-coloured mid-dorsal hairline stripe running from above the vent to the creamcoloured shoulder patch, becoming progressively thinner anteriorly, and two lateral thin creamcoloured stripes run from the back of the tympanum to the groin, one on either side of the body. Two symmetrical inguinal dark blotches are located on either side of the lower dorsum. The remainder of the dorsum is marked with an irregular pattern of darker spots against a lighter brown background, which roughly resembles broken discontinuous lines running along the anterior–posterior axis. Irregular crossbars are present on both arms and hindlimbs. The toe tips are slightly expanded (character state C sensu Heyer, 1973) and mildly flattened or not flattened.

In contrast to the holotype, both paratypes have profuse white-tipped tubercles on the soles of the feet. All specimens have rounded snouts in dorsal outline, although in profile the snout of the female appears to be more rounded than that of the males; all specimens have white-tipped tubercles on the dorsal surfaces of shanks and thighs (although these are more profuse on the shanks than they are on the thighs), and they all have immaculate creamish-coloured venters.

ADVERTISEMENT CALL

Acoustic parameter measurements for the two recorded voucher males are listed in Table 2 . Figure 3 depicts both temporal and spectral patterns of the call. The advertisement call of L. coca has been previously described in Angulo (2004) as Adenomera ‘Chapare’; it is here directly associated to the species name L. coca . The description is based on the combined calls from both vouchers, which were recorded at 21.1 °C and 20.8 °C, respectively. The advertisement call of the new species can be heard as a sound file on track 6, CD 2 of Márquez et al. (2002).

In comparison with other species of the L. marmoratus group (see Kwet & Angulo, 2002; Angulo et al., 2003; and references within; Kok et al., 2007; and this study, for acoustic parameters for other species) the advertisement call of L. coca is intermediate in duration, ranging from 110 to 145 ms, emitted at an intermediate to low call rate (66 and 84 calls/min). Call rise time is highly variable (11.6–96 ms), a fact reflected by associated standard deviations for both call vouchers. The signal undergoes quite strong amplitude modulation for most of its duration, before going into its final decay phase. This amplitude modulation creates some pulse structure, but because these pulses tend to meld together, it is difficult to specify an amplitude pattern. In one of the vouchers these modulations vary between 10 and 15 per call, emitted at an average rate of 120 pulses/s. The fundamental frequency ranges between 1695 and 1914 Hz, and a harmonically related second frequency, ranging between 3449 and 3748 Hz, is the main carrier. Up to five or six frequency bands can be detected at any time (this is also a function of recording conditions); nevertheless, given the fact that the energy peaks of upper harmonics are considerably lower than that of the main carrier, these frequency peaks are not depicted in the spectrum image of Figure 3 , as they fall below the cut-off point of -30 dB. There is either no or some frequency modulation of the main carrier (0–775 Hz).

NATURAL HISTORY

The new species was found on open ground and at the base of dense, grassy vegetation in montane rainforests at about 800 m above sea level in the cocagrowing region of Chapare, Bolivia. Voucher males were recorded in the evening after a heavy downpour during the day; individuals vocalized from dense clusters of grass as well as from open areas. Many individuals were heard calling, and some of them were very close (within 5 m) to each other. No water bodies were found close by, and we suspect that the species could display direct development (e.g. as has been reported for L. marmoratus ; Lutz, 1931, 1947).

ETYMOLOGY

The new species is named after the coca plant, Erythroxylon coca , given its occurrence near coca plantations of the Chapare region, in Bolivia.

CONSERVATION STATUS

The three type specimens are the only known representatives of the new species. They were all collected on the same day, after heavy rain. Given the available information, we suggest that this species be considered as Data Deficient following the IUCN’s Red List categories ( IUCN, 2001).

Figures

Figure 1. Leptodactylus coca sp. nov. Dorsal (A) and ventral (B) view of holotype male NKA 3630, snout–vent length (SVL) = 24.1 mm.

Figure 2. Leptodactylus coca sp. nov. Ventral view of left palm of hand (A) and left sole of foot (B) of holotype male NKA 3630.

Figure 3. Advertisement call of Leptodactylus coca sp. nov. A, sequence of ten calls. B, one of these calls at higher resolution. C, section of call in (B) showing detail of waveform. D, power spectrum of (B). E, spectrogram of the first three calls in (A). Modified from Angulo (2004).