PACHYCHELES MONILIFER (DANA, 1852): THE DEVELOPMENT IN THE LABORATORY OF LARVAE FROM AN ATLANTIC SPECIMEN WITH A DISCUSSION OF SOME LARVAL CHARACTERS IN THE GENUS (CRUSTACEA: DECAPODA; ANOMURA.

The complete larval development from hatching through megalopal stage is described and illustrated for Pachycheles monilifer, a shallow water porcellanid crab. The development at room temperature (27.8° C) under laboratory conditions consisted of a prezoeal stage of approximately one hour duration, two zoeal stages of approximately five and six days duration, respectively, and a megalopal stage of about eight days duration. The entire larval/postlarval portion of the life cycle is completed under the conditions described herein in approximately three weeks. The zoeal and megalopal stages of P. monilifer were compared with larvae known from two other western Atlantic species, and two species each from the eastern Pacific and Indo-Pacific oceans. As might be expected, larvae of the genus are quite similar in many respects, and difficulty may be encountered in separating them at the specific level. However, certain morphological features are recurrent in the zoeal stages and may be indicative at the generic level; among these are the presence of three spines on the antennal exopodite, four setae on the maxilliulary endopodite, and the hook-like spinules on the first two elongate plumose setae of the telson. A provisional synopsis is provided utilizing the most salient features occurring in all known Pachycheles larvae as an aid in recognizing such larvae, at least at the generic level, in the plankton.