Gnathothlibus collardi is a moth of the family Sphingidae. It is a hybrid between a female Philodila astyanor and a male Gnathothlibus eras. It is known from Tahiti. The length of the forewings is about 35 millimetres (1.4 in). It is similar to Gnathothlibus eras but the forewings are rather more similar to Gnathothlibus saccoi and the hindwings are identical to Gnathothlibus dabrera. The forewing outer margin is slightly angled. The underside of the thorax are darker and more orange-pink, thus contrasting less with the underside of the abdomen than in Gnathothlibus eras. The forewing upperside pattern is more contrasting than in Gnathothlibus dabrera or Gnathothlibus eras, but most similar to Gnathothlibus saccoi. The forewing underside is lacking the narrow black line running inward from