PELAGIC EGGS AND LARVAE OF THE DEEPSEA SOLE, 



EMBASSICHTHYS BATHYBIUS (PISCES: PLEURONECTIDAE), 



WITH COMMENTS ON GENERIC AFFINITIES 



Sally L. Richardson^ 



ABSTRACT 



Two eggs o{ Embassichthys bathybius are 3.0 mm in diameter, pelagic, spherical, transparent, with a 

 homogeneous yolk, narrow perivitelline space, and no oil globule. Embryos in late stage eggs have 

 pigmentation characteristic of larvae, including pigment over the hindgut and three prominent 

 postanal pigment bands. This pigment pattern and the high number of myomeres (>60) serve as 

 distinguishing characters for larvae in the size series described from recently hatched specimens 

 9.8 mm standard length to a specimen beginning eye migration at 16.2 mm standard length. 



Eggs and larvae of E. bathybius are extremely rare in extensive plankton and midwater trawl 

 collections from the northeast Pacific with only eight specimens recorded to date. Occurrences 

 were between March and June in the upper 185 m or less of the water column over bottom depths of 

 59-2,850 m. 



Within the tribe Pleuronectini of the subfamily Pleuronectinae, larvae of Glyptocephalus, Tanakius. 

 Embassichthys, and Microstomas form a distinct and logical group sharing similarities of a banded 

 pigment pattern; angular, oblique jaw; elongate, slender form; and tendency toward a leptocephalus- 

 like shape. If intense pigment banding and pronounced leptocephaluslike shape are derived characters, 

 then the group is probably a naturally related one, with Microstomus the least and Glyptocephalus the 

 most specialized. 



The deepsea sole, Embassichthys bathybius (Gil- 

 bert), occurs in the northeast Pacific Ocean from 

 Santa Catalina Island, southern California, to 

 Pratt Seamount, Gulf of Alaska, in depths from 

 320 to 1,432 m but mostly >730 m (Miller and Lea 

 1972; Hart 1973). It grows to 47 cm and is report- 

 edly uncommon (Miller and Lea 1972; Hart 1973). 

 Life history data are minimal and nothing is 

 known about its reproduction or early life. 



Pelagic eggs and larvae of this species are de- 

 scribed here for the first time based on collections 

 taken off the Oregon coast. Knowledge of these 

 early stages provides some insight into reproduc- 

 tive strategy as well as information on larval mor- 

 phology which may be useful for examining sys- 

 tematic relationships. 



METHODS 



The pelagic specimens were collected (Table 1) 

 with 70 cm bongos having 0.571 mm mesh nets and 

 a 3.1 m Isaacs-Kidd midwater trawl with a 5 mm 



mesh liner and a 0.5 m diameter cod end of 0.571 

 mm mesh. The bongos were towed obliquely 

 through the water column. The midwater trawl 

 was towed near the surface in the upper 10 m. 



All material was preserved in 10% Formalin^ 

 and stored in 5% Formalin except the 16.2 mm 

 larva which was transferred to 36% isopropyl 

 alcohol. 



Measurements made on larvae included: 



Standard length (SL) = snout tip to notochord 

 tip until notochord is fully flexed and the posterior 

 margin of the forming hypural elements is verti- 

 cal, then to posterior margin of hypurals. 



Head length = snout tip to cleithrum. 



Snout to anus length = distance along body 

 midline from snout tip to vertical through posteri- 

 or margin of anus. 



Eye diameter = horizontal diameter of pig- 

 mented portion of left eyeball. 



Depth at cleithrum = vertical distance from 

 dorsal body margin, excluding finfold or fin, to 

 ventral tip of cleithrum. 



'School of Oceanography, Oregon State University, Corvallis, 

 Oreg.; present address: Gulf Coast Research Laboratory, East 

 Beach Drive, Ocean Springs, MS 39564. 



^ Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



Manuscript accepted June 1980. 



FISHERY BULLETIN: VOL. 79, NO. 1. 198L 



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