Callulops stellatus, Kraus, 2019

Kraus, Fred, 2019, A revision of Callulops doriae (Anura: Microhylidae), with descriptions of four new species, Zootaxa 4612 (1), pp. 1-28 : 16-18

publication ID	https://doi.org/ 10.11646/zootaxa.4612.1.1
publication LSID	lsid:zoobank.org:pub:33E82826-EF18-47F0-B804-CC877BD2AFFE
DOI	https://doi.org/10.5281/zenodo.5586567
persistent identifier	https://treatment.plazi.org/id/CD549CFF-DF24-4242-A508-E18028B72BB6
taxon LSID	lsid:zoobank.org:act:CD549CFF-DF24-4242-A508-E18028B72BB6
treatment provided by	Plazi
scientific name	Callulops stellatus
status	sp. nov.

Treatment

Callulops stellatus View in CoL , sp. nov.

Figs. 1E, F View FIGURE 1 , 6 View FIGURE 6

urn:lsid:zoobank.org:act:CD549CFF-DF24-4242-A508-E18028B72BB6

Holotype. BPBM 39980 (field tag FK 16097), adult male, collected by F. Kraus along stream on S slope Mt. Trafalgar , 9.2238º S, 149.1561º E, 190 m a.s.l., Cape Nelson, Oro Province, Papua New Guinea, 7 November 2011. GoogleMaps

Paratypes (n = 8). Same data as holotype ( BPBM 39981 ) ; same data as holotype, except collected 2 November ( BPBM 39979 ) GoogleMaps , 8 November ( PNGNM 25280 ) GoogleMaps ; along Ajoa River , S slope Mt. Victory, 9.2248° S, 149.1062° E, 530 m a.s.l., Cape Nelson, Oro Province, Papua New Guinea, F. Kraus, 22 September 2010 ( BPBM 37122 ) GoogleMaps , 24 September 2010 ( BPBM 37123–24 ) GoogleMaps , 1 October 2010 ( BPBM 37125 ) ; along Ajoa River , S slope Mt. Victory, 9.2388° S, 149.1356° E, 400 m a.s.l., Cape Nelson, Oro Province, Papua New Guinea, F. Kraus, 2 October 2010 ( BPBM 37126 ) GoogleMaps .

Diagnosis. Callulops stellatus sp. nov. is distinguished from all other members of the genus by its unique combination of moderately large size (adult male SV = 59.3–71.3 mm); narrowly expanded finger and toe discs (3rdF/SV = 0.026 –0.028, 4thT/SV = 0.029 –0.035); circum-marginal grooves absent on fingers and toes, but either may have shallow terminal puckerings at tips; short leg (TL/SV = 0.37–0.40); pustulose dorsum; short EN (EN/SV = 0.057 –0.069, IN/SV = 0.064 –0.078, EN/IN = 0.84–0.93); slightly swollen loreal region; small eye (EY/SN = 0.61–0.73, EY/SV = 0.058 –0.076); thick fingers; basal subarticular tubercle of 4th toe well developed; dorsum and limbs typically black but may be dark brown or dark gray, spotted with white, at least laterally; groin, and hidden surfaces of legs blotched with yellow or orange; under thighs and shanks with a light-brown ground color; venter gray with charcoal-gray chin and throat speckled with blue white; and a long (2.60– 3.84 s) multi-note call with relatively short notes (0.242 – 0.392 s) and a high repetition rate (0.86–1.41 notes/s).

Comparisons with other species. Callulops stellatus sp. nov. differs from all other species of the genus except C. doriae , C. neuhaussi , C. argus sp. nov., and C. bicolor sp. nov. in having large yellow or orange blotches in the groin and on the hidden surfaces of the hindlimbs. From all of these other members of the C. doriae complex it differs in its black, dark-gray, or dark-brown dorsum spotted with white dots or flecks (at least laterally) and in having a well-developed (vs. absent or poorly developed in the other species) subarticular tubercle under the 4th toe. Paler specimens of C. stellatus sp. nov. are superficially similar in appearance to C. argus sp. nov. (cf. Fig. 1E View FIGURE 1 vs. Fig. 1C View FIGURE 1 ), but C. stellatus sp. nov. differs from that species in its larger tympanum (TY/SV = 0.56–0.65 vs. 0.49 in C. argus sp. nov.), wider head (HL/HW = 0.69–0.81 vs. 0.88 in C. argus sp. nov.), and smaller white spots (cf. Fig. 1E View FIGURE 1 vs. Fig. 1C View FIGURE 1 ).

Description of holotype. An adult male with right-lateral incision, liver removed. Head wide (HW/SV = 0.37), wider than long (HL/HW = 0.69), with slightly swollen loreal region, inflated immediately anterior to eye, concave posterior to naris; upper lip inflated; canthus absent; nostrils horizontally compressed, directed laterally but slightly dorsally too, closer to tip of snout than to eyes; internarial distance more than distance from naris to eye (EN/IN = 0.84; IN/SV = 0.068; EN/SV = 0.057); snout slightly rounded, almost truncate when viewed from side, dorsal portion acutely rounded and ventral portion truncate when viewed from above; eyes small (EY/SV = 0.058); eyelid slightly less than half width of interorbital distance; tympanum distinct, sunken, slightly larger than eye (TY/EY = 1.08; TY/SV = 0.063), annulus overlain or bordered posteriorly and dorsally by heavy supratympanic fold that extends from behind eye to posterior of tympanum, where it bends sharply to end in front of forearm insertion at approximately level of jaw; supratympanic fold a clearly demarcated ridge ventrally but smoothly continuous with dorsal skin, continuing medially to form transverse fold behind head. Dorsum and sides slightly rugose to obviously pustulose and heavily glandular, clearly pustulose in life ( Fig. 1E, F View FIGURE 1 ); ventral surfaces smooth anteriorly, weakly granular on abdomen. Fingers unwebbed, thick, all bearing discs lacking terminal grooves; relative lengths 3>4≈2>1. Finger discs slightly wider than penultimate phalanges (3rdF/SV = 0.028). Subarticular tubercles low, large, better developed on F1 and F2; inner metacarpal tubercle low, large, oval; outer very narrow, shallow oval, narrowly separated from similarly narrow, low medial metacarpal tubercle. Toes unwebbed, all bearing discs without terminal grooves; relative lengths 4>3>5>2>1. Toe discs barely wider than penultimate phalanges (4thT/SV = 0.034), larger than those of fingers (3rdF/4thT = 0.85). Subarticular tubercles well developed, rounded, proximalmost tubercle on fourth toe as well developed as others; inner metatarsal tubercle a large, prominent oval; outer only a vague, slightly whitened skin thickening. Legs short (TL/SV = 0.39).

In preservative, dorsal ground color medium brown, densely mottled with dark brown; the dark-brown markings laterally forming ocelli with cream centers; additional, irregular cream markings present ventrolaterally. Face dark brown. Large cream blotches present in axilla, groin, and hidden surfaces of thighs, shanks, and feet but absent from tops of thighs. Venter pale straw yellow; chin, throat, and anterior chest densely suffused with brown with a few scattered straw-yellow spots. Iris black.

Measurements of holotype (in mm). —SV = 63.5, TL = 24.9, HW = 23.3, HL = 16.0, IN = 4.3, EN = 3.6, SN = 6.1, EY = 3.7, TY = 4.0; 3rdF = 1.80, 4thT = 2.13, mass = 35.4 g.

Variation. Mensural variation is slight among the sample of adult males ( Table 4 View TABLE 4 , Appendix II). Males can mature by 59 mm, but the single female is immature at slightly more than 63 mm. Ontogenetic variation is greater: juveniles have relatively larger snouts and eyes than do adults ( Table 4 View TABLE 4 ). Snout shape is always broadly rounded when viewed from the side but varies from acutely rounded to truncate when viewed from above. Other important features tend toward invariance too. All specimens are pustulose dorsally, have the tympanum bordered above and behind by a strong skin fold, and this skin fold continues medially behind the eyes. This forms an evident crease behind the head in all specimens, but none of them has it as well developed as seen in the holotype. Terminal grooves are absent on all digits, although shallow creases may develop on some of the toes if left out of alcohol for very long. All specimens have a distinct subarticular tubercle at the base of the 4th toe, at the junction of the metatarsal and last phalanx.

Color pattern is somewhat more variable. All specimens are dark gray brown or dark brown in preservative and vaguely mottled with small lighter and darker patches. Most specimens are considerably darker than the holotype, being charcoal gray, but two are are only slightly darker than the holotype. White lateral spots are present in all specimens but are confined to the lower sides in most, extending anteriorly as far as the rictus and continuing under the chin and throat with less contrast to the dark coloration there; these white spots also continue well dorsally in BPBM 37122 and BPBM 37123 ( Fig. 1E View FIGURE 1 ). Under magnification, many of these white spots form the centers of vaguely defined ocelli. All specimens have pale-gray venters suffused with darker gray on chin and throat. The holotype and two additional specimens have lighter throats than the others; BPBM 37125 also has a fair amount of dark suffusion on the abdomen, especially laterally. The large cream blotches on the thighs are confined to the hidden surfaces on the front and rear in five specimens but are also evident on the dorsal surfaces in four.

Color in life. Dorsal color in life varies from dark brown or gray with darker-gray spots ( Figs. 1F View FIGURE 1 , 6 View FIGURE 6 ) to uniform black, usually with white spots on the dorsum and limbs, sometimes extending across the entire dorsum ( Fig. 1E View FIGURE 1 ) or sometimes being restricted to the sides. Ventrally, white spotting is evident as well but faded. The large cream blotches in the axilla, groin, and on the hidden surfaces of the legs in preserved specimens are a striking yellow orange in life ( Figs. 1E View FIGURE 1 , 6 View FIGURE 6 ). The iris is gray brown.

Call. The call is a series of deep-voiced croaks delivered at long intervals. I was able to record ten calls from two individuals. Calls comprised a short series of 3–6 notes emitted at a rate of 0.86–1.47 notes/s; calls ranged from 2.60– 3.84 s in duration, with a mean of call means of 0.310 s ( Table 2 View TABLE 2 , Fig. 3G, I View FIGURE 3 ) and were delivered at intervals of 57–128 s. Each note was relatively brief, with a mean of note means of 0.289 s (range 0.242 – 0.392 s). The interval between notes was longer, with a mean of internote means of 0.516 s and a range from 0.291 – 0.942 s. Notes were highly pulsed, had a rounded amplitude envelope ( Fig. 3G View FIGURE 3 ), and lacked frequency modulation ( Fig. 3I View FIGURE 3 ). The dominant frequency of calls varied minimally ( Fig. 3H View FIGURE 3 ), with a mean of call means of 485 Hz and a range from 377–858 Hz.

Etymology. The name is a masculine Latin adjective meaning starry in reference to the usual pattern of white flecks on a black or charcoal-gray ground color.

Range. Known only from 190–530 m a.s.l. on the southern slopes of Mt. Victory and Mt. Trafalgar, two adjacent volcanos that, along with their alluvial fans, form the Cape Nelson Peninsula, Oro Province, PNG ( Fig. 4 View FIGURE 4 ).

Ecological notes. I found most animals either sitting on the forest floor at night or calling from under rocks, inside hollow logs, among the flanks of tree buttresses, or on landslips. One animal was found in a dry, rocky riverbed; another was captured in a drift fence. This species called only on nights following heavy rains.

These frogs produce white, sticky secretions from their dorsal glands that undoubtedly serve an anti-predator function. One of the subadult males (SV = 53.3 mm) exhibited a defensive display in which the body was inflated with air while either being held to the ground ( Fig. 6A View FIGURE 6 ), with the rear of the body elevated off the ground ( Fig. 6B View FIGURE 6 ), or with the entire body held off the ground ( Fig. 6C View FIGURE 6 ). The entire display serves to clearly exhibit the bright-orange blotches in the groin and on the rear of the legs ( Fig. 6D View FIGURE 6 ), which presumably serve as a signal to warn of the thick glandular secretions that are readily exuded from the dorsum.