SPHENOPHRYNE - American Museum of Natural History

112 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 253
Fig. 70. Lateral view of left posteromedial
process of the hyoid of Liophryne allisoni, BPBM
9631, with the ventromedian process projecting
from its anterior end. The right (posterior) end of
the posteromedial process angles toward the viewer.
Scale line marked in millimeters.
stenodactyla, where four of six specimens
show no mineral deposits and two others
show only slight amounts. Dense staining of
cartilage may mask mineral deposits in my
specimen of A. robusta, and the sternum is
damaged in specimens of L. allisoni and O.
alpestris.
MYOLOGY
I offer here only a few comments on myology,
as this topic was not within the intended
scope of the work. This is not to deny
the potential importance of further myological
study, the value of which in microhylid
systematics has been amply demonstrated
(e.g., Burton, 1984, 1986).
JAW MUSCULATURE: Burton (1986) noted
that in almost all genyophrynines the M. depressor
mandibulae arises largely from the
dorsal fascia, as illustrated for ‘‘Sphenophryne
schlaginhaufeni’’ (probably L. rubra) by
Burton (1986: fig. 11D). L. rhododactyla and
O. stenodactyla (fig. 74) also have this common
condition. The exceptions, assigned to
the genus Albericus, have the origin of this
muscle largely restricted to the otic ramus of
the squamosal and the prootic region (Burton
and Zweifel, 1995, fig. 3).
SUPERFICIAL MANDIBULAR MUSCULATURE:
The Asterophryinae exhibit variation in the
number and placement of supplementary
slips of the M. interhyoidius, whereas the
Genyophryninae show only a single slip,
presumably a primitive condition (Burton,
1986). Burton (1984) called attention to differences
in the supplementary slip that distinguish
Sphenophryne (in the earlier, broad
sense) from Cophixalus: ‘‘Supplementary
slip . . . narrow, arising from either a posterior
tendon or from dentary, and oriented
parallel to the mandible’’ (Cophixalus), or
‘‘broad, arising from ventral fascia of angulosplenial,
and oriented medially and only
slightly anteriorly’’ (Sphenophryne). Zweifel
(1985b) confirmed these observations for
additional Australian species of the two genera.
Typical conformation of the supplementary
slip for two Australian Austrochaperina
is illustrated for A. fryi (as Sphenophryne, sp.
nov.) in Burton (1984: fig. 1B) and A. robusta
(as S. robusta) in Zweifel (1985b: fig.
55B). Six New Guinean species, A. palmipes,
Liophryne dentata, L. rhododactyla, L.
schlaginhaufeni (fig. 75C), Oxydactyla crassa,
and O. stenodactyla (fig. 75A), resemble
these closely, but Sphenophryne cornuta (fig.
75B) differs in that the muscle bundle is
abruptly tapered posteriorly and has its fiber
orientation more nearly parallel to that of the
mandible. While awaiting confirmation of
the situation in additional species, a tentative
conclusion is that the condition in cornuta is
derived relative to that common to other species.
KARYOLOGY
Information is available for just nine species
of Austrochaperina and Liophryne, four
of them Australian endemics (Kuramoto and
Allison, 1989; Mahony et al., 1992; James
Menzies (personal commun.). Sphenophryne
and Oxydactyla have not been karyotyped.
Seven species have the presumably primitive
diploid number 2N 26 (see discussion
in the papers cited above and in Bogart and
Nelson, 1976) consisting of five large and