Rana crassiovis Boulenger, 1920

Inger, Robert F. & Iskandar, Djoko T., 2005, A Collection Of Amphibians From West Sumatra, With Description Of A New Species Of Megophrys (Amphibia: Anura), Raffles Bulletin of Zoology 53 (1), pp. 133-142 : 139-140

Rana crassiovis Boulenger

Seventy two males, 13 females. As this represents the first sample of this species reported since the original description ( Boulenger, 1920b), we provide a full description:

Description. – Habitus moderately slender, head length slightly greater than head width; SVL of males with nuptial pads 29-35 mm, females with mature oviducts 58-70 mm (see Table 6). Snout obtusely pointed, weakly projecting; nostril slightly closer to tip of snout than to eye; canthi sharp, constricted behind nostrils; lores oblique, deeply concave; diameter of eye usually greater than length of snout; interorbital about equal to width of upper eyelid; tympanum distinct, 0.5-0.7 of eye diameter; vomerine teeth in oblique groups between the choanae.

Finger discs large, with circummarginal grooves, width of disc of third finger 1 / 2 to 3 / 4 diameter of tympanum; first finger equal to or slightly longer than second, third finger the longest; second and third fingers with narrow, movable flaps of skin on outer phalanges; subarticular tubercles distinct. Discs of toes smaller than those of fingers; fourth toe longest, fifth extending slightly farther than third; toes 1-3 and 5 fully webbed to base of discs, fourth toe with one phalange free; an oval inner but no outer metatarsal tubercle; no tarsal fold.

No dorsolateral fold; skin above finely granular; usually with large, rounded tubercles scattered over back, not evident in rare individuals; sides coarsely granular; venter smooth except rugose or granular posteriorly.

Color in preservative brown with many large black or dark brown spots, the lighter areas forming an irregular network; sides becoming lighter ventrad, many large dark spots; venter whitish, throat and chest with brown speckling, or mottling, very dark in about half of individuals; abdomen with speckling or mottling but lighter than throat; legs with heavy cross bars dorsally; ventrally legs dusted with dark pigment; rear of thigh with dark vertical bars and spots separated by narrow whitish areas.

Body proportions shown in Table 6.

Secondary sex characters. – Females are much larger than males and have smaller tympana (Table 6). Gravid females have non-pigmented ova. Males have grayish, velvety nuptial

1 SVL = snoutvent length; T = tibia length; HW = head width; HL = head length; Tym = tympanum diameter; E = eye diameter; Sn = length of snout.

2 Mean SE for SVL.

pads on the dorsomedial surface of the inner finger and paired subgular vocal sacs with openings near the rear lateral corners of the floor of the mouth. Males lack gular pouches and humeral glands.

Comparisons. – This sample matches the original description ( Boulenger, 1920a) in almost every detail of form and coloration. Boulenger said head length equalled head width; in the present series head length was slightly but consistently greater than head width. The types were smooth or finely granulate dorsally, but in the present series large tubercles are present dorsally save in three individuals. This sample was obtained approximately 140 km north of the type locality of R. crassiovis , which was given by Boulenger (1920a) as “Barong Bharu … West Sumatra 2º8’S ”, within the same mountain range of western Sumatra.

Boulenger (1920b) provided a new name, Rana kampeni , for R.. pantherina (non Fitzinger) van Kampen (1910), type locality Bandar Bahru, Sumatra (3º 16’N), about 550 km north of the type locality of R. crassiovis . The descriptions of these nominate species presented by Boulenger (1920b) are very similar and Boulenger noted only the following differences: R. kampeni with a larger tympanum, a narrower interorbital relative to the upper eyelid, the first finger shorter than the second, and the belly granulate. As the type of R. kampeni is probably a male, judging by its size, 36.5 mm ( van Kampen, 1910), and the types of R. crassiovis females ( Boulenger, 1920a), the presumed difference between taxa in size of tympanum is merely a matter of sex dimorphism (Table 6). The relative length of the first finger varies slightly in the present series from slightly shorter to slightly longer than the second. In our sample the belly is smooth except posteriorly where it is granulate. Van Kampen (1910) said the skin of R. pantherina ( kampeni Boulenger ) was smooth, but later van Kampen (1923) said the skin was “smooth, or finely granulate, or with a few tubercles on the back.” Most of the specimens in our sample have large, rounded tubercles on the back. We conclude that R. kampeni Boulenger and R. crassiovis may be conspecific and that clear separation of these taxa requires examination of additional specimens from northern Sumatra. We apply the name R. crassiovis to this sample because of proximity to the type locality.

The other species similar to R. crassiovis in many ways is R. hosii Boulenger. Both have moderately slender habitus, enlarged discs on the fingers having circummarginal grooves, fully webbed toes, no outer metatarsal tubercle, males without humeral glands or gular pouches, and large non-pigmented ova. In life, these R. crassiovis had a strong, unpleasant odor just as does R. hosii . They differ, however, in the following ways: R. hosii has a weak, though distinct dorsolateral fold, R. crassiovis has none; R. hosii has granular dorsal skin but no dorsal tubercles, most R. crassiovis have conspicuous, round tubercles scattered over the back; R. hosii is larger [males 42-66, females 86-98 mm ( Inger, 1966)], than R. crassiovis (males 29-35, females 58-70 mm).

Three species of Rana recorded from Sumatra differ from R. crassiovis in having dorsolateral folds, in having an outer metatarsal tubercle, toes 3 and 5 not webbed to base of discs, and males with a humeral gland: R. baramica , R. nicobariensis , and R. persimilis . Other species recorded from Sumatra differing from R. crassiovis in having an outer metatarsal tubercle and males with humeral glands include R. chalconota , R. erythraea , R.glandulosa , R. luctuosa , R. nigrovittata , R. picturata , and R.siberu . Rana debussyi van Kampen , known only from the type specimen collected at Bandar Baru, central Sumatra, differs markedly from R. crassiovis in having reduced webbing (only as far as the distal subarticular tubercle of the third and fifth toes) and in having a light stripe extending from the lip to the rear of the body ( van Kampen, 1910). In lacking conspicuous light lines, stripes, or spots, R. crassiovis differs markedly from R. erythraea , R. luctuosa , R. picturata , and R. siberu .

The entire present sample was obtained along the banks of Batang Tarusan and two of its tributaries at elevations between 1166 and 1320 m AMSL.