A Complete Larval Description of Pandalus Jordani Rathbun (Decapoda, Pandalidae) and Its Relation to Other Members of the Genus Pandalus 1)

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A COMPLETE LARVAL DESCRIPTION OF PANDALUS JORDANI RATHBUN (DECAPODA, PANDALIDAE) AND ITS RELATION TO OTHER MEMBERS OF THE GENUS PANDALUS 1)

BY PETER C. ROTHLISBERG CSIRO, Division of Fisheries and Oceanography,North-Eastern Regional Laboratory, P.O. Box 120, Cleveland, Queensland 4163, Australia INTRODUCTION

The genus P andaluJ Leach, 1814, containing 12 to 13 species, is restricted to the northern hemisphere, all species occurring higher than 33° north latitude. The largest number of species (eight) occur in the north-eastern Pacific, followed by seven in the north-western Pacific and three in the northern Atlantic (table I). TABLE I

Geographic distribution of species in the genus Pandalus Species Pacific Pacific Atlantic Atlantic Western Eastern Western Eastern P. boreali.rKr6yer, 1838 + + + + P. danae Stimpson, 1857 + P. goniurus Stimpson, 1860 + + P. gurneyi Stimpson, 1871 + P. hypsinotusBrandt, 18511 + + P. jordani Rathbun, 1902 + P. ke.r.rleriCzern., 1878 + P. montagui Leach, 1814 + + P. montagui triden.rRathbun, 1902 + P. platycero.rBrandt, 18511 + + P. pren.rorStimpson, 1860 + P. propinquu.rSars, 1869 + + P..rtenolepi.rRathbun, 1902 + Totals 6 8 3 3

The descriptions of larvae, except for Pandalus montagui Leach (cf. Lebour, 1940; Pike & Williamson, 1964) and P. propinquu.r Sars (cf. Pike & Williamson, 1964), are restricted to eastern and western Pacific species (table II). The descriptions are predominantly a mixture of laboratory hatched first zoeae and plankton reconstructions of older stages. Only one study (Pike & Williamson, 1967), before the present investigation, compared laboratory reared material to specimens obtained in the plankton.

1) Researchundertaken at Marine ScienceCenter, Oregon State University,Newport, Oregon, U.S.A. 20

TABLE II

Summarization of accounts of larval development in Pandalu.r

Modin & Cox (1967) have published an account of laboratory reared larvae of P. jordani Rathbun. The description, thought to be complete, fails to show the last two larval instars and the early juvenile stages. Several intermediate stages are not figured or described in detail and no measure of variation in morphological characters used in staging the larvae were given. It was necessary therefore to re-examine the larvae of P. jordani from both laboratory culture and plankton samples to assemble a complete description of the larvae. This included cross checks between laboratory reared and field sampled specimens to see the degree to which some "stages" seen in the laboratory culture might be artifacts. Because there was appreciable variability and often only subtle differences between late larval stages suites of anatomical characters were used. As much of the description as possible is in tabular form for ease of access and brevity. Because of the low degree of development on hatching, the high number of larval stages and the prolonged period of larval development found in P. jordani, comparisons are made with other members of the genus. Possible relationships between range, habitat and larval development are examined. ' MATERIAL AND METHODS

Larval Pandalus jordayai, from the plankton, were obtained on a series of 34 cruises from January 1971 to August 1972, from stations one to 60 nautical miles off the central Oregon coast (Rothlisberg, unpubl.). Routine sampling was done with bongo nets (0.7 m diameter, 571 ,m mesh), performing stepped-oblique tows from 150 m or near bottom, whichever was less, to the surface. Large num- bers of early juveniles were obtained using an epibenthic sampler designed to take discrete samples of animals on or just off the bottom (Rothlisberg & Pearcy, 1977). Berried female P. jordani were obtained, using a small (5 m) otter trawl,