Observations on the Family Gnathophyllidae Dana, 1852 (Crustacea: Decapoda)

Abstract

ABSTRACT The first zoeal larva of the shrimp Gnathophyllum americanum Guerin is described and illustrated. The morphology of the larva is typical of pontoniine larvae of the family Palaemonidae. The morphology of most adult gnathophyllid shrimps shows no consistent differences from some of the more highly specialized commensal pontoniine shrimps, although exhibiting extreme forms of trends apparent in that subfamily. The adult and larval morphology indicate that the gnathophyllid shrimps are modified members of the Palaemonidae and should be included in that family. There also appears to be no adequate reason to separate most of them from the subfamily Pontoniinae as presently defined. However, the genera Hymenocera and Phyllognathia possess a unique form of third maxilliped, which suggests a separate origin from Gnathophyllum, Gnathophylloides, Pycnocaris, and Levicaris. In contrast, the larvae of the genus Anchistioides Paulson are considered so aberrant amongst the Palaemonidae that they cannot be considered as members of the Palaemoninae or Pontoniinae. They should be given the status of belonging to a separate subfamily on the basis of their larval characters, in conjunction with some of their adult characters, as was originally proposed by Gurney (1938). A key to the revised subfamilies of the Palaemonidae incorporating these proposed changes is provided.