Cophixalus ateles (Boulenger, 1898)

Sphenophryne ateles Boulenger, 1898: 708 . Oreophryne ateles van Kampen, 1923: 115. Cophixalus ateles Parker, 1934: 172 .

Cophixalus sisyphus Kraus and Allison, 2006: 214 .

Because the original description of C. ateles is rather sparse on comparative details, the recent detailed description of C. sisyphus (Kraus and Allison, 2006) will serve that purpose well. Hence, there is no need to provide a redescription here.

Cophixalus ateles is known with certainty only from the region of the type locality and from the western slopes of Mt. Obree approximately 50 km to the east of that (Fig. 2). Several close relatives of C. ateles occur throughout the southeastern region of New Guinea and offshore islands (see below), but the exact distributions of these species are not yet well known. It is clear, however, that C. ateles is syntopic with at least one of these ( C. variabilis) in the Moroka region (both having been taken at 2.2 km S and 3.1 km W of Wori Wori Bluff, 9.39575˚S, 147.5699˚E, Central Province). Based on the type series of C. sisyphus, C. ateles is known to range in elevation from 600–1870 m asl.

It should be mentioned that, despite the shared feature of the first finger being reduced in size and lacking a circum-marginal groove, C. ateles is not particularly closely related to C. shellyi, as implied in earlier literature. That implication derived from the early state of study of Papuan Cophixalus, when only two species with reduced first fingers were known (Zweifel, 1956a, b; Tyler, 1963a, b). But several more species with that attribute have subsequently been described, and C. ateles and C. shellyi now appear to belong to separate species groups—whether monophyletic or paraphyletic—that have independently simplified the first finger—the two look nothing alike in habitus, color pattern, or other morphological details, yet each is closely similar to more recently described species. Based on overall appearance, call similarities, and similar lifestyles, C. ateles is clearly closely related to C. timidus and C. variabilis (both of which have welldeveloped first fingers with terminal grooves), which is why they were described as sibling species. And the more recently described C. linnaeus Kraus and Allison, 2009 and C. phaeobalius Kraus and Allison, 2009 (which have well-developed first fingers with terminal grooves) as well as C. tomaiodactylus Kraus and Allison, 2009 (which has the reduced first finger lacking a terminal groove) probably belong to this species group too. All these species lack a black face mask; all are variegated in color pattern with brown, gray, and/ or black; all are scansorial; and all are known only from the Papuan Peninsula of New Guinea. In contrast, relatives of C. shellyi (including C. bewaniensis Kraus and Allison, 2000, C. iovaorum Kraus and Allison, 2009, C. pipilans Zweifel, 1980, and C. desticans Kraus and Allison, 2009) share the feature of a black face mask; all except C. desticans also share a smooth dorsum (although C. desticans has narrow dermal ridges dorsally, these are small and difficult to see, and the species does not have the tuberculate appearance of members of the C. ateles group). Collectively, these species inhabit a broader portion of New Guinea, being found in the Papuan Peninsula as well as the Central Highlands, Huon Peninsula, and North Coast Ranges. Additional species ( C. humicola Günther, 2006, C. kethuk Kraus and Allison, 2009, C. sphagnicola Zweifel and Allison, 1982, and C. tridactylus Günther, 2006) also have reduced first fingers, but it remains uncertain whether they are closely related to either of the above two groups. Judging from very different body morphology, at least C. kethuk and C. sphagnicola likely represent additional independent acquisitions of this feature. The first appears closely related to C. tagulensis Zweifel, 1963, based on overall phenotypic similarity and the synapomorphic presence of toe webbing, and C. tagulensis has a normal-sized first finger, suggesting that C. kethuk has again independently acquired the reduced character state of that structure. And the habitus and morphology of C. sphagnicola are unlike all the other Cophixalus having reduced first fingers, suggesting that it too may represent an independent lineage not closely related to the others. Given the small size of all these species, it may be that reduced first-finger size is a frequent morphological corollary of size miniaturization, the latter perhaps acquired (at least in several species) in response to a lifestyle devoted to inhabiting leaf litter, as seen in other miniaturized frogs (Lehr and Coloma, 2008; Lehr and Catenazzi, 2009; Kraus, 2010, 2011).