Description of the glochidia of <i>Westralunio albertisi</i> Clench, 1957 (Bivalvia: Unionida: Hyriidae) from the Fly River system, Papua New Guinea

Larvae (glochidia) of the freshwater mussel, <i>Westralunio albertisi</i> were obtained from the marsupia of a preserved female at the Western Australian Museum. Glochidial shells of <i>W. albertisi</i> are subtriangular and scalene in shape outline with a convoluted surface dotted with pores and have a protruding ventral apex. Glochidial shells (n = 60) measured 260.0 μm long (L) (±1.11 SE), 233.1 μm high (H) (± 1.32 SE), with a size of 246.6 μm (± 0.99 SE), hinge length (Hg) of 183.6 μm (± 0.99 SE), larval tooth length (LTL) of 53.6 μm (± 0.84 SE) and angle of obliquity (Á) of 12.9° (± 0.28 SE). Larval teeth are singular in each valve, lack microstylets, have convex or concave basal protuberances on opposing valves and terminate as blunt outward facing spoon-like to peg-like cusps. In comparison to <i>Westralunio carteri</i>, <i>W. albertisi</i> is smaller (d.f., 178; <i>P</i> &lt; 0.001) for L (<i>t</i> = 33.85), H (<i>t</i> = 12.80), Size (<i>t</i> = 28.98), Hg (<i>t</i> = 21.32), H/L (<i>t</i> = −15.06) and Hg/L (<i>t</i> = −4.21). <i>Westralunio albertisi</i> also has a more acute Á than <i>W. carteri</i> (d.f., 71; <i>t</i>, 10.17; <i>P</i> &lt; 0.001), but displays no difference in LTL (d.f., 6; <i>t</i>, 0.16, <i>P</i> = 0.44).