Metaeus timidus Girard, 1853

Lavilla, Esteban O., Rabanal, Felipe E., Langone, José A., Vásquez, Dayana & Castro-Carrasco, Camila, 2019, The identity of the Chilean Amphibians collected by the United States exploring expedition, Zootaxa 4567 (1), pp. 183-192 : 186-189

Metaeus timidus Girard, 1853

(Figs. 11–16)

Described among the Bufonidae , Metaeus timidus was seldom cited in the herpetological literature (the few available papers include, among others, De Marschall 1873; Neave 1940; Plötz 1855; Scuddar 1882, and Troschel 1854). In its redescription, Girard (1858a: 97) pointed out that this was a particularly small species, in which the sum of head and body lengths did not exceed one inch. As discussed under Bufo thaul (see above), in the Valparaíso Region there are no amphibians with adults of such small size. This fact led us to consider that Girard based his new genus and species on a juvenile. In analyzing immature specimens of the various species recorded in the area, we saw that the extensive redescription of Metaeus timidus by Girard (1858a) differs from the juveniles of all except one species of Valparaíso Region. In fact, Metaeus timidus differs from (only key characters are noted): Rhinella arunco , R. atacamensis , and R. spinulosa due to absence of parotid glands, non-visible tympanum and the presence of a dark band from snout to shoulder.

Pleurodema thaul due to absence of lumbar glands; in certain populations the non-visible tympanum can also be a discriminating character.

Calyptocephalella gayi due to the presence of the dark band on the sides of the head, the non-visible tympanum, the lack of a cranial co-ossifications and the texture of the dorsal skin.

Batrachyla taeniata due to the non-visible tympanum, the pointed shape of the tip of the digits, and because the black band does not involve the eye.

In turn, coincidences between Metaeus timidus and the juveniles of what we currently known as Alsodes nodosus are overwhelming. The following paragraph is a verbatim transcription of Girard’s (1858a) redescription, in which the coincident character states are referred to photographs of the specimen SSUC-AM 261 (see appendix):

Descr. The head forms the third of that length (fig. 11); it is depressed, almost flat upon its upper surface, and rounded upon the snout (fig. 13). It is a little longer than broad, and, when viewed from above, has an ovoid appearance (fig. 11). The body, itself, is elongated, narrowest posteriorly, the general aspect being more ranine than bufonine. The legs are proportionally small, though quite as much developed as in many ranoids (figs. 11; 12). The entire absence of both palatine and maxillary teeth entitles it to a place amongst bufonoids (fig. 14). The inner nostrils are very large, oblong-shaped, in the longitudinal direction of the head (fig. 14). The openings of the Eustachian tubes are exceedingly minute. The tongue is of medium size, subcircular, or subelliptical, entire posteriorly, and free upon the half of its length (fig. 15). The eyes are of medium size, elliptical in form, their longitudinal diameter being equal to the distance between their anterior rim and the extremity of the snout (fig. 13). The inter-ocular space is broader than the eyelid (fig. 11). The nostrils are elevated, situated at the upper, terminal end of the snout, though equidistant between the eyes and the margin of the upper jaw. There are no parotid glands. The tympanum is entirely hidden under the skin (fig. 13).

The forelegs are almost exiguous, and, though short, reach the groins when brought backwards alongside with the body. The fingers are subcylindrical; the first one longer than the second, which is nearly equal to the fourth; the third being the longest. The articulations are all provided beneath with conspicuously developed tubercles, and the tip of the fingers slightly swollen beneath, into a tuberculous-like knob. Smaller tubercles may be seen on the palm of the hand, arranged in series in the direction of the fingers, each series composed of at least two tubercles. There is a comparatively large, horny, metacarpal disk, and a horny knob at the base of the first finger (fig. 12). The hind legs are slender but not very long; measured from their origin to the base of the fifth toe, they equal in length the head and body together. The toes exhibit the same structure as the fingers; there are but a few small granules on the sole of the feet, situated towards the base of the toes. The inner metatarsal tubercle is elongated; the outer one is rounded. The inner edge of the tarsus exhibits a very inconspicuous horny ridge (fig. 12).

The skin is smooth, although provided above with small pustules, spread over the head, body, and legs, though fewer on the latter (fig. 11).

The ground color above is greenish-brown. A deep chestnut-brown vitta starts from the margin of the upper jaw, ascends the snout towards the nostrils, thence along the line of the canthus rostralis to the eye, and passing over the latter, extends obliquely down to near the insertion of the anterior limbs. A transverse brown patch is observed upon the occiput, between the eyes. A larger patch of the same color is seen on the anterior portion of the trunk, and another still smaller, upon its posterior portion. These three patches are united together by means of diverging, narrow branches, giving the back a stellated appearance. Transverse narrow bars of brownish-black are observed upon the legs, more conspicuously on the posterior than on the anterior ones, where two such bars only are seen. The hands and feet above are maculated (fig. 16). Underneath, the color is dull-yellow, under the head and abdomen, with a few small black spots on the latter region. The legs being reddish, with indistinct yellowish dots.

As noted above, the identity of Metaeus timidus with Alsodes nodosus is evident and unquestionable. Consequently, Metaeus timidus Girard, 1853 is a junior synonym of Cystignathus nodosus Duméril and Bibron, 1841 , and Metaeus is a junior synonym of Alsodes Bell, 1843 .