NO. 3576 AMPELISCIDAE — BARNARD 5 



Ampelisca eschrichtii Kr0yer 



Figure lo 



Ampelisca Eschrichtii Kr0yer, 1842, p. 155. — Sars, 1895, pp. 174-176, pi. 61, 



fig. 1.— Stephensen, 1925, pp. 139-141. 

 Ampelisca eschrichtii. — Stebbing, 1906, p. 100. — Shoemaker, 1930, pp. 27-28; 



1931, pp. 9-10. 

 Ampelisca eschrichti. — Stephensen, 1933, pp. 23-24, fig. 9 (map); 1935, pp. 121- 



123. 

 Ampelisca eschrichti eschrichti. — Gurjanova, 1955, p. 170, fig. 169. 



The shape of the head and article 2 of pereopod 5 distinguish this 

 species from A. maorocephala Liljeborg. The obUquely truncated 

 ventral margin of pereopod 5 is a contrast to the transversely trun- 

 cated margin in A. macrocephala (see Stephensen, 1935). In A. 

 eschrichtii the ventrolateral corneal lens occurs posterior to the anter- 

 oventral cephaUc corner, and the ventral cephalic margin posterior 

 to the lens is straight or convex, not excavate as in A. macrocephala. 

 The ventrolateral lens of A. macrocephala forms the corner of the head. 

 The presence or absence of a long distal spine on the outer ramus of 

 ui'opod 2 is an invahd character in distinguishing the two species, 

 as both species have the spine (contra J. L. Barnard, 1954a, key). 



The Pacific specimens at hand seemed so unlike Sars' (1895) draw- 

 ings of A. eschrichtii that the materials were compared with similar 

 large specimens (20-27 mm) from the western Atlantic Ocean in 

 Smithsonian collections. These large individuals differ materially 

 from Sars' drawings in several conspicuous characters: the shortened 

 uropod 1; the deeper recessment of the ventral pair of corneal lenses; 

 and the greater convexity of the ventral cephalic margin posterior to 

 the lenses. Pacific and some western Atlantic materials are com- 

 parable in these characters. A specimen from Bedford Basin, Halifax, 

 Nova Scotia (reported in Shoemaker, 1931), has uropod 1 reaching only 

 halfway along the rami of uropod 2 ; specimens from Hebron, Labrador, 

 1908, 75 fms, have uropod 1 reaching two-thirds along the rami of 

 uropod 2; and specimens from Ungava Bay (1883, USNM 9413) have 

 uropod 1 extending to the end of the rami of uropod 2 as shown by 

 Sars (1895). The specimens from Ungava Bay are remarkable also 

 for the development of a high dorsal crest on the posterior pereonal 

 and anterior pleonal segments. 



Gurjanova (1955) has figures of A. eschrichtii eschrichtii and her 

 A. e. pacifica with uropod 1 extending about two-thirds along the rami 

 of uropod 2] A. e. pacifica has the indented ventral corneal lens and 

 slightly tumid ventral cephaHc margin. Specimens at hand have 

 these characters more exaggerated than previously shown. A repre- 

 sentative head is given in figure lo. The Pacific specimens are justi- 

 fiably identified as A. eschrichtii, sensu lato, and this extends the range 



