SPHENOPHRYNE - American Museum of Natural History

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98 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 253 Fig. 54. Lower surfaces of feet and hands of Liophryne. A. L. rubra, UPNG 9290. B. L. allisoni, AMNH A81221. C. L. similis, AMNH A130577. D. L. schlaginhaufeni, AMNH A77589. E. L. dentata, AMNH A87205. Scale bars marked in 1-mm intervals. ing skin. More often the annulus is indistinct and the covering skin undifferentiated. In a semiaquatic, riparian species Austrochaperina palmipes there is no external sign of the ear. I noted no sexual dimorphism of tympanum size in the species studied for this report, but Tyler et al. (1991) reported that females of an Australian species, A. adelphe, have a strikingly larger tympanum than do the males. This is unusual because where dimorphism is present in frogs, the male typically has the larger tympanum. External appearance and variation in the relative size of the tympanic annulus notwithstanding, the ear in the 13 species dissected (including examples of all four genera) is complete, with the tympanum distinct from the overlying skin (fig. 60). Wever (1985) examined four species of three microhyline genera: Gastrophryne carolinensis, G. olivacea, Hypopachus variolosus (‘‘cune- us’’), and Kaloula pulchra. He found that ‘‘All four are closely similar in general ear structure, lacking a true tympanic membrane but with an effective substitute in the form of a cartilaginous plate (the pars externa of the columella in a flattened form) located immediately beneath the skin.’’ Earlier authors (e.g. Parker, 1934) have generally referred to these species as having a ‘‘hidden tympanum.’’ Presumably the condition Wever described is derived. Thirteen species treated in the present study that I dissected share the primitive structure of a true, albeit concealed, tympanum, and probably the rest do, too. But Wever’s description suggests that, in comparative studies of other genera and subfamilies, examination of the ears should be more than skin deep. For example, Smirnov (1986, fig. 1) illustrated the middle ear apparatus of five species of Microhyla: three with a tympanum
2000 ZWEIFEL: PARTITION OF SPHENOPHRYNE 99 Fig. 55. Lower surfaces of feet and hands of Austrochaperina. A. A. derongo, AMNH A79975. B. A. guttata, MCZ A92812. C. A. archboldi, AMNH A66719. D. A. hooglandi, AMNH A77592. E. A. adamantina, AMNH A78185. F. A. aquilonia, AMNH A78186. Scale bars marked in 1-mm intervals. (berdmorei, pulchra, ornata) and two without (heymonsi and butleri). All five are characterized in the literature as ‘‘tympanum hidden.’’ ONTOGENETIC CHANGE IN PROPORTIONS As mentioned in the introductory section on Methods, body proportions typically change with growth. I present here some examples from species treated in this monograph, using nine standard measurements. I have chosen five species, with the choice having been determined by availability of samples of adequate size and range of body sizes and by their different ecologies: (1) Oxydactyla stenodactyla, a high montane burrower in grass clumps; (2) Austrochaperina derongo, a streamside-associated species; (3) Sphenophryne cornuta, a scansorial form that calls from shrubs and low trees; (4) Liophryne schlaginhaufeni, a terrestrial, surface-active species sometimes out in daytime; and (5) Austrochaperina palmipes, a more highly adapted semiaquatic species. Relative tibia length generally decreases slightly with growth (that of O. stenodactyla the most), but L. schlaginhaufeni goes counter to this trend (fig. 61A). Adult head width is relatively narrower in all but schlaginhaufeni, too (fig. 61B), and the same trend appears in eye size and eye–naris distance (fig. 61C). Internarial span decreases in all five species (fig. 61D). Hand size increases in three species and decreases in two, whereas foot length increases in two and decreases in three (fig. 62A, B). Among the four species with digital discs, three show some increase in the finger disc whereas derongo does not (fig. 62C). One species, cornuta, shows a slight increase in toe disc size whereas the other three do not (fig. 62D).
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SPHENOPHRYNE - American Museum of Natural History

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