Certain genera of Ptiliidae posses species that exhibit forms of polymorphism
(Dybas, 1978; Taylor 1981, 1980). The polymorphic states are generally
divided into two categories: a 'normal morph' which possesses all the
'normal' characters composing featherwing beetle adult morphology, and
'vestigial morphs' that exhibit reduced or absent eyes and wings, shortened
elytra, and absence of body coloration. At times the appearance of the
two morphs varies so much that they may be mistaken for separate species.
'Normal' and 'vestigial' morphs are present in both sexes, and both
forms occur at the same time within a population.
Polymorphism is known within species of Ptinella, Pteryx and Ptinellodes.
Taylor (1981) observed that polymorphism occurs in Ptinella aptera and
P. errabunda seasonally in wild populations and was influenced by temperature
in laboratory cultures, leading Taylor to conclude that "morph determination
is based on a physiological switch sensitive to temperature and possibly
other adaptively relevant environmental factors." Though both morphs
produce offspring, Taylor notes "Ptinella alatae are reproductively
superior to apterae."
Above left: Pteryx sp., normal morph, exhibiting normal
eyes, wings and coloration.
Above right: Ptinella sp., vestigial morph, exhibiting reduced eyes,
wings and color.
Dybas, H.S. 1978b. Polymorphism in featherwing beetles, with a revision of the genus Ptinellodes (Coleoptera: Ptiliidae). Annals of the Entomological Society of America 71(5): 695-714.
Taylor, V. 1980. Coexistence of two species of Ptinella Motschulsky (Coleoptera: Ptiliidae) and the significance of their adaptation to different temperature ranges. Ecological Entomology, 5: 397-411.
Taylor, V. 1981. The adaptive and evolutionary significance of wing polymorphism and parthenogenesis in Ptinella Motschulsky (Coleoptera: Ptiliidae). Ecological Entomology, 6: 89-98.
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Polymorphism in Ptiliidae
W. Eugene Hall.
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