SPHENOPHRYNE - American Museum of Natural History

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124 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 253 er discs, is also riparian, but the habits of archboldi and hooglandi are unknown. The only information on A. guttata is that it calls from sheltered leaf-litter sites not closely associated with water. The advertisement calls of four species of the Large group are prolonged bouts of short, pulsed notes: derongo, guttata, macrorhyncha, and rivularis. If, as I suspect, this is a derived call, the similarity may indicate a close relationship; calls of this sort are unknown elsewhere in Austrochaperina. I anticipate that such calls will characterize three of the other four species of the Large group as well. The fourth species, A. palmipes, may utter soft, clicking sounds (see species account). The difference in vocalization, if confirmed, may be a derived character of this species, along with lack of vocal slits, concealed tympanum, vomerine spikes, and webbed toes. Austrochaperina palmipes is morphologically the most derived species of the Large group, but its primitive 2N 26 karyotype contrasts with the 2N 24 of A. derongo. A peculiar feature uniting A. rivularis and A. palmipes is a mosaic appearance to the dorsal skin; this shows well in figure 31E and F. The possession of slight toe webbing would seem to place A. basipalmata in a phylogenetic position between palmipes and the more primitive species lacking webbing. However, the unusual character of the skin suggests that palmipes and rivularis are closest relatives. An anatomical peculiarity, presumably a derived condition, unites some species of the Large group. In these frogs the snout is rather elongate, projecting conspicuously past the lower jaw (fig. 21). Adult males tend to be more extreme in this respect, and the snout tip usually is pale, often quite white. Juveniles of both sexes generally have dark snout tips, and females only occasionally show some lightening. Parker (1940) was the first to call attention to this sexual dimorphism in A. basipalmata (as Sphenophryne macrorhyncha). The pale condition is well developed in A. palmipes and present in A. rivularis. Adult males of three morphologically similar species—archboldi, derongo, and hooglandi—generally show this condition. In contrast to other species of the Large group, guttata and macrorhyncha have a more rounded, less projecting snout and they do not appear to develop a pale tip. Menzies and Tyler (1977: 434) cited as one of the diagnostic characteristics of the genus Copiula, ‘‘a hypertrophied serous dermal gland whose location is distinguished externally by a translucent white, and sometimes uptilted, tip to the snout.’’ Apparently the condition in Copiula is not sexually dimorphic. The histology of the pale snout tip in Austrochaperina has not been investigated, so there is no assurance that the conditions are homologous. If they are, this would suggest a possible derivation of Copiula (a leaf-litter genus with a more derived pectoral girdle) from within the clade of large Austrochaperina. A. derongo and Copiula fistulans share the derived chromosome number, 2N 24 (Mahony et al., 1992), which may be another indication of relationship. RELATIONSHIPS WITHIN LIOPHRYNE Liophryne similis and L. rhododactyla are an allopatric sibling pair distinguished only by different advertisement calls and by the absence of vocal slits in one. Three other species, L. rubra, L. dentata, and L. schlaginhaufeni, are morphologically distinct but more similar to one another than either is to any other species, whereas L. allisoni stands somewhat apart. The latter species is much the smallest Liophryne and has a considerably less well-defined external ear than do the other species. The relatively large size of similis and rhododactyla is unusual within the Genyophryninae and may be considered as a derived state. The absence of teeth or toothlike structures in these species may also be a derived condition, considering that allisoni, dentata, rubra, and schlaginhaufeni all have teeth (albeit vestigial ones) or toothlike structures (see Morphology, Dentition). In karyology, however, rhododactyla has the presumably plesiomorphic chromosome number 2N 26, whereas schlaginhaufeni is 2N 30 (see Morphology, Karyology). Within the context of Liophryne, the small size and indistinct tympanum of allisoni may be primitive characters.
2000 ZWEIFEL: PARTITION OF SPHENOPHRYNE 125 RELATIONSHIPS WITHIN OXYDACTYLA Frogs of this genus are adapted to a cryptic existence, dwelling in such habitats as grass tussocks, saturated moss, and deep leaf litter. Morphological features that appear to relate to habits include absence or reduction of digital expansion, short hind legs, and small eyes. Considering principally these features, the five species may be arranged in an essentially linear sequence from least to most derived. O. crassa and O. coggeri are at the bottom of the scale, O. brevicrus is intermediate, with O. alpestris and O. stenodactyla occupying the most derived position. In alpestris and stenodactyla the toetips and fingertips are rounded, showing no flattening, expansion, or terminal grooving. These species have the shortest hind legs in the genus, and stenodactyla has the smallest eyes, with those of alpestris slightly larger but matched by one other species. These two species also share the presumably derived character of a robust premaxillary bone (see Morphology, Osteology). O. brevicrus has fingertips like those of alpestris and stenodactyla, but the toe tips, Although not expanded and lacking terminal grooves, are somewhat flattened. The legs The zoogeographic relationships of the New Guinean microhylid subfamilies Genyophryninae and Asterophryinae are obscure and will remain so until a satisfying cladistic analysis of the microhylid subfamilies can be achieved. Conflicting hypotheses—perhaps better called scenarios—of Savage (1973) on the one hand and of Zweifel and Tyler (1982) and Zweifel (1985b) on the other have the Australopapuan microhylids derived from Gondwana by way of Australia or from Southeast Asia across Wallace’s Line. Either is compatible with the likely Gondwanan origin of microhylids, although the latter requires a more circuitous route by way of a drifting Indian subcontinent. Whatever their origin, microhylids dominate the New Guinea frog fauna in number of species, constituting more than half of the ZOOGEOGRAPHY are slightly longer and eyes slightly larger than in alpestris and stenodactyla. Fingertips of coggeri and crassa are rounded to slightly flattened, but not clearly disclike, and may show a weak terminal groove. The toe tips of both are disclike with terminal grooves but are scarcely if at all broader than the penultimate phalanges. The legs are slightly longer than and the eye size within the range of the other species. Whereas alpestris and stenodactyla are unquestionably each other’s closest relative, the relationship at the other end of the sequence is less certain. The features associating coggeri and crassa, while derived with respect to other genera, are plesiomorphic within Oxydactyla. The geography of the situation also raises questions. O. crassa is isolated at moderately high elevations on the southeastern tail of New Guinea, more than 600 km from the closest Oxydactyla populations in the Eastern Highlands. The intervening region has not been fully explored, but forms similar in habitat preference to crassa and other Oxydactyla have been found in the genera Aphantophryne and Austrochaperina. The possibility that including crassa within Oxydactyla renders that genus paraphyletic deserves further study if adequate material becomes available. total of more than 200 species. Austrochaperina has the widest distribution of the four genera treated in this monograph, with species throughout most of mainland New Guinea and on some adjacent islands as well as one species on New Britain (where only one other microhylid is known, an Oreophryne) and a disjunct center of diversity in northern Australia. Four of the Australian species are endemic, and the fifth, A. gracilipes, inhabits seasonally dry country and may have dispersed to New Guinea when lowered sea level in the Pleistocene afforded a land connection. Liophryne and Sphenophryne are widely distributed in New Guinea but have no known insular populations and are absent from Australia. Species of Oxydactyla are likewise restricted to New Guinea and are
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