Diasporus citrinobapheus, Hertz, Andreas, Hauenschild, Frank, Lotzkat, Sebastian & Koehler, Gunther, 2012

Hertz, Andreas, Hauenschild, Frank, Lotzkat, Sebastian & Koehler, Gunther, 2012, A new golden frog species of the genus Diasporus (Amphibia, Eleutherodactylidae) from the Cordillera Central, western Panama, ZooKeys 196, pp. 23-46 : 26-33

Diasporus citrinobapheus sp. n. Figures 1 A, B235

Holotype.

Adult male SMF 89814: collected on June 26, 2010 at 19:13 by Andreas Hertz and Sebastian Lotzkat at Quebrada Rasca (8.4851°N, 81.1727°W, 790 m elevation), near Paredón, Comarca Ngöbe-Buglé, western Panama, approximately 50 airline km NNW of the city of Santiago and 20 airline km N of Cañazas, Veraguas.

Paratypes.

All collected by Andreas Hertz and Sebastian Lotzkat at the type locality on June 26, 2010: MHCH 2370-71; SMF 89816; all adult males.

Referred specimens.

Adult males SMF 89817 and MHCH 2372: collected on July 01, 2010 by Andreas Hertz and Sebastian Lotzkat at the private reserve Willie Mazú, Comarca Ngöbe-Buglé (8.7903°N, 82.1989°W, 681 m elevation); female SMF 89820: collected on March 31, 2009 by Andreas Hertz, Sebastian Lotzkat and Arcadio Carrizo at Cerro Negro, Parque Nacional Santa Fé, Veraguas (8.5691°N, 81.0988°W, 730 m elevation).

Diagnosis.

A member of the genus Diasporus based on the following combination of characters: vocal slits and a single subgular vocal sac present, adult males without nuptial thumb pads; Finger I shorter than Finger II; Toe III much shorter than Toe V; subarticular tubercles on hands and feet flattened; no supernumerary tubercles on hands and feet; no tarsal fold or tubercle. Diasporus citrinobapheus differs from alldescribed members of its genus by the following combination of characters (for accounts, see Table 1): coloration bright yellow to orange in life (Fig. 1 A); head almost as broad as long, but comparatively broad in relation to SVL; skin of dorsum smooth; venter coarsely areolate; tympanum covered by skin but annulus clearly visible; TD about 41% of ED; EL on average narrower than IOD; snout subacuminate in profile and rounded to subovoid in dorsal outline; disks of fingers and toes slightly expanded, disk covers of most fingers and toes spadate, but lacking papillae; disk pads of most fingers and toes triangular; subarticular tubercles of hands and feet rounded, very flat, almost not visible; vomerine odonthophores longish oval and widely separated; vomerine teeth weakly developed; upper eyelid usually smooth, very low pustules in some individuals; heel smooth. Its bright yellow to orange coloration distinguishes Diasporus citrinobapheus from almost all described Central American Diasporus , which, in spite of considerable variation, are all tan to gray or brownish to almost black. In Diasporus hylaeformis and Diasporus ventrimaculatus , the dorsal ground color can be suffused with pink or red. Only Diasporus tigrillo from Costa Rica, a species known only from two specimens, shows a yellowish coloration in life according to the original description ( Savage 1997). Diasporus citrinobapheus differs from the two known specimens of Diasporus tigrillo in the following characters (character for Diasporus tigrillo in parentheses): SVLinadult males 17.3-19.7 mm (16.0-17.5 mm); dorsal skin absolutely smooth (dorsal skin with scattered low pus tules, best developed on dorsum); TD 32-45% of ED (54-57%); TL 40% of SVL (about 48%); distal subarticular tubercle of Finger and Toe I flat and rounded (weakly bifid); many weakly developed vomerine teeth in three to four close rows (a few vomerine teeth in two obliquely aligned and widely separated rows); dorsal surface uniformly bright yellow to orange, sometimes with irregularly distributed dark blotches (yellow to orange dorsal coloration with dark brown spots confined to the pustules); ventral surfaces almost colorless and transparent, in some individuals with a fine dirty white speckling, except male vocal sac that is suffused with yellow (undersurfaces, including venter, yellow); coloration in preservative grayish-white with only a suggestion of yellow (brownish-ocher with dark brown dots; see comments in Discussion section for the usage of different preservation methods). Furthermore, Diasporus citrinobapheus superficially resembles the South American Diasporus gularis from western Ecuador and western Colombia in coloration (see photo in Lynch 2001, page 295 Fig. 7). Diasporus gularis has been described comprehensively by Lynch and Duellman (1997). According to them, adult Diasporus gularis are larger (SVL in males 20.2-21.6 mm, in females 23.3-24.8 mm) than Diasporus citrinobapheus (males 17.3-19.7 mm, single known female 21.8 mm). Moreover, Diasporus gularis shows basal webbings between toes and some specimens have papillae at the apex of the disk pad on some toes, whereas there are no such papillae, and no webbing between toes of Diasporus citrinobapheus . The posterior surfaces of thighs are brown in Diasporus gularis , but yellow to orange in Diasporus citrinobapheus . Moreover, the choanae are long, oval, and not concealed by the palatal shelf of the maxillary arch in Diasporus gularis , whereas they are round, orientated extremely laterally on palate, and partially concealed by the palatal shelf of the maxillary arch in Diasporus citrinobapheus .

Description of the holotype.

An adult male; measurements (in mm): SVL 18.4, LF III 2.4, LT IV 4.2, DWF III 0.6, DWT IV 0.5, HL 7.2, HW 7.0, TL 7.8, EL 2.6, IOD 2.9, TD 0.8, ED 2.4; dorsal skin smooth; venter coarsely areolate; no discoidal fold; upper eyelid smooth; snout subovoid in dorsal outline and subacuminate in profile; nostrils weakly protuberant, directed dorsolaterally; head slightly longer than wide, width 97% of length; HW 38% of SVL; canthus rostralis indistinct; ED 36% of HL and 13% of SVL; EL 90% of IOD; TD 33% of ED (Fig. 2 A); choanae round, orientated extremely laterally on palate, partially concealed by palatal shelf of maxillary arch; elliptical vomerine odonthophores, posteromedian to choanae, which are widely separated from each other, with four rows of weakly developed, short teeth; legs short in relation to body; TL 42% of SVL; relative finger length: I<II=IV<III; all fingers with disks, slightly wider than digits, on Fingers II–IV wider than on Finger I; relative toe length: I<II<III<V<IV, Toe V much longer than toe III; tip of Toe V extending to distal subarticular tubercle on Toe IV; tip of Toe III extending to penultimate subarticular tubercle on Toe IV; disks on Toes III–V larger than on I–II; disk covers spadate, lacking papillae; no supernumerary tubercles (Figs 2 B,C).

Etymology.

The specific name citrinobapheus is a noun in apposition and is derived from the Greek words citrinos (citrin-yellow) and bapheus (dyer) referring to the yellow body color that dyes one’s fingers yellowish when the frog is handled. Although we could observe this phenomenon in a few other species of Diasporus too, it is notably evident in the new species.

Coloration in life.

All examined specimens show shades of bright yellow and orange dorsally; some have dark grayish and/or whitish-grayish spots (Fig. 3). Ventral surfaces are almost achlorophyllaceous and transparent apart from the yellow male vocal sac.

MHCH 2372 (Fig. 3 C): Dorsal ground color Orange Yellow (18); posterior and anterior surfaces of thighs Chrome Orange (16); Raw Umber (23) interorbital and postocular stripes formed by very fine mottling; dorsum with five Dark Grayish Brown (20) blotches, forming a pattern like the five dots on a dice; scattered Dark Grayish Brown (20) blotches on dorsal surfaces of limbs; disk covers Blackish Neutral Gray (82), with white rings at the base; ventral surface of hind limbs Chrome Orange (16); ventral surface of body transparent with dirty white mottling; vocal sac white with a suggestion of Spectrum Yellow (55).

SMF 89820 (Fig. 3 A): In the only female, coloration in life has been recorded as follows: Dorsal surface Yellow Ocher (123 C); a Chamois (123 D) interorbital bar; anterior and posterior surfaces of thighs Chrome Orange (16); venter almost transparent; upper surfaces of disks Sepia (119) with dirty white spots and a dirty white ring around base; gular region Smoke Gray (44).

Coloration in preservative (70% alcohol).

In preservation the bright yellow and orange colors fade rapidly to a pale grayish yellow (Fig. 1 B) with scattered dark gr ayish blotches in some individuals. Legs pale orange; vocal sac pale yellow in males; gular area in females pale gray; tips of digits dark grayish black. Dark grayish black eyeballs shining through skin when head is viewed dorsally.

Variation.

Compared to other species of this genus, the individuals of Diasporus citrinobapheus available to us exhibit only little variation in their coloration (Fig. 3). All show a yellow to orange dorsal ground color in life. This can either appear bright and clear or somewhat dirty, depending on the pigment translocation within the melanophores in the frog’s skin. In some individuals, higher concentrations of melanophores in certain areas of the dorsum form dark blotches or stripes. This is especially the case in the two specimens from Willie Mazú (Figs 3 C, D). The most frequent pattern of this type is an interorbital bar, which in most cases is darker than ground color along the anterior edge of the bar and lighter than ground color along the posterior edge. In addition, some individuals show dark brown blotches on the limbs and less frequently also on the dorsum. Most individuals show additional small whitish spots, in particular under and around the eyes, as well as scattered across the forelimbs. In the male SMF 89816 from the type locality (Fig. 3 B) the dark and white markings on and around the disk covers are not as pronouncedly contrasting as in the other individuals examined.

Molecular genetics.

The distinctiveness of Diasporus citrinobapheus is supported by the analysis of the 16S mitochondrial rRNA gene (Fig. 4). The four individuals we examined form a distinct cluster that appears separated from the other members for which 16S sequences are available. The mean genetic distance among the four specimens of Diasporus citrinobapheus is 0.3%. In our consensus tree (Fig. 4 A) it appears to be most closely related to the candidate species Diasporus aff. diastema from El Copé, from which it is separated by a mean genetic distance of 1.8%. In the haplotype network analysis (Fig. 4 B) both clades form unconnected subnetworks, indicating a differentiation at species level (Fig. 4 C). The mean genetic distance to the next closest relative Diasporus quidditus is 6.6% for Diasporus citrinobapheus and 7% for Diasporus aff. diastema .

Vocalization of holotype.

We recorded a 3 min, 43.5 seconds portion of the advertisement call of the holotype that yielded a total of 63 calls. An exemplary visualization of the call structure is given in Fig. 5 A. Relative humidity during recording was 95.3% at an air temperature of 24.5 °C. As in other members of the genus, the call consists of a single note, even though calls sound like a “whistle,” rather than the typical “tink” usually emitted by members of the genus Diasporus ( Savage 2002; Chaves et al. 2009). The 63 recorded calls are organized in five call groups of 8-17 calls per group (12.8 ± 3.2). A call group lasts 19.8-34.1 s (25.0 ± 5.7). Intervals between call groups range from 15.7-33.2 s (21.6 ± 8.0) and intervals between calls within a call group range from 0.57-5.77 s (1.93 ± 1.2). Call group rate is 1.34 call groups per minute; call rate within a call group varies from 23.4-40.8 calls per minute (32.0 ± 6.3). Call duration varies from 0.13-0.18 s (0.16 ± 0.01). There is a rather weak frequency modulation of 190-470 Hz (370 ± 65). The spectrum of frequencies within a call range from a mean minimum of 2890 ± 44 Hz to a mean maximum of 3260 ± 44 Hz. Fundamental and dominant frequencies are identical at about 2950 Hz. The dominant frequency, as the frequency with the greatest energy in the signal, is reached about 0.05 s after initiation of the call.

Vocalizations of paratypes and referred specimens.

In addition to the holotype, we recorded and analyzed the advertisement calls of two paratypes (SMF 89816, MHCH 2371) and one referred specimen (SMF 89817). Summing up, the advertisement call of Diasporus citrinobapheus sounds like a whistle, is organized in call groups, has a call duration of 0.14-0.16 s in average and a dominant frequency of 2860-3040 Hz (see all parameters in Table 2). While the paratypes vary only little in call parameters, SMF 89817 shows obvious differences regarding call duration, call interval, and call rate (see Discussion section for details).

Geographical distribution and natural history notes.

So far, Diasporus citrinobapheus has been found on the Caribbean slopes of the western Serranía de Tabasará and on both Pacific and Caribbean slopes of the eastern Serranía de Tabasará (Fig. 6) at intermediate elevations from 680 to 790 m.a.s.l. Males call from very dense vegetation and are difficult to spot. They are almost only detectable by following their characteristic vocalization. Vocal activity is highest just after dusk and finally stops when it becomes dark. Calling height ranges from near ground level up to three meters above ground. Calling position can be either on the upper side of a leaf or on its underside (Figs 4 B–D). The only female (SMF 89820) was found at daytime (15:00 h) inside an involute, young plantain leaf that apparently served as a daytime hiding place. The species does not seem to be limited to mature forest, but is also found in secondary growth and plantations. However, it appears to avoid open habitats like pasture land.