REVISION OF DANIELSSENIA AND PSAMMIS 



49 



developed, spinulose in distal portion (Fig. IE); seta VII 

 tri-articulate (Fig. 8C). 



Antennule (Fig. 2A-B) 6-segmented; segment 1 with 2 

 spinule rows on outer margin and a plumose seta at outer 

 distal corner. Segment 2 with 5 pinnate and 1 naked setae on 

 outer margin and 2 pinnate and 1 naked setae posteriorly 

 directed on dorsal margin. Segment 3 with 2 pinnate and 6 

 naked setae at outer distal corner. Segment 4 with 6 naked 

 setae and an aesthetasc. Segment 5 with 3 pectinate spines, 3 

 naked and 2 pinnate setae. Segment 6 with 1 pectinate spine 

 and 7 naked setae. 



Antenna (Fig. 2C-D). Coxa with a row of spinules proxi- 

 mally. Allobasis with long spinules at base of abexopodal, 

 pinnate seta. Exopod 3-segmented with armature formula 

 [2-1-3]; distal segment elongate with subterminal row of 

 spinules. Endopod with 2 spinule rows on outer margin; 2 

 spines, a geniculate seta and a naked seta subdistally (Fig. 

 2C); distal margin with a pectinate spine, 4 geniculate setae, a 

 small plumose seta (Fig. 2C) and a very small naked seta (Fig. 

 2D). 



Mandible (Fig. 3A-B). Coxa (Fig. 3B) elongate, slender, 

 with 2 median rows of spinules; gnathobase with bidentate 

 and unidentate teeth and a pinnate seta at inner distal corner. 

 Palp biramous. Basis (Fig. 3A) with patch of spinules medi- 

 ally and 4 pinnate setae on distal margin. Exopod 

 2-segmented; proximal segment with 2 pinnate setae laterally 

 and a row of large spinules distally; distal segment with 3 

 apical setae. Endopod 1-segmented with 3 lateral and 6 distal 

 setae. 



Labrum (Fig. 3C) with numerous spinule rows near median 

 distal margin of posterior face. 



Maxillule (Fig. 3D). Praecoxal arthrite with 2 juxtaposed 

 setae medially on anterior surface and 9 bidentate or pinnate 

 spines and 1 naked seta on distal margin. Coxal endite with 5 

 armature elements on distal margin. Basal endite with 2 

 subdistal setae and 4 setae on distal margin. Rami 

 1-segmented and each with 3 setae. 



Maxilla (Fig. 4B). Syncoxa with spinule row at outer 

 proximal corner and with 3 endites each with 1 fused and 2 

 articulating pinnate spines. Allobasal endite with a fused 

 pinnate claw, a pinnate spine and 2 setae. Endopod 

 1-segmented with a pinnate spine and 3 setae. 



Paragnaths (Fig. 4A) well developed; with several rows of 

 fine spinules laterally and medially; anterior face with coarse 

 teeth. 



Maxilliped (Fig. 4C). Syncoxa with numerous spinule rows, 

 1 large subterminal and 1 smaller terminal pinnate seta. Basis 

 with row of spinules and a naked seta on palmar margin. 

 Endopodal claw as long as basis, spinulose distally and with 2 

 accessory setae proximally. 



PI (Fig. 5A). Intercoxal sclerite rectangular with 2 groups 

 of setules on each side. Coxa with rows of spinules on 

 anterior face and outer margin. Basis with row of spinules on 

 inner and distal margin and around base of inner pectinate 

 spine (Fig. ID) and outer pinnate seta. Exopod 3-segmented, 

 | each with row of spinules on outer margin, outer spines 

 pectinate, distal outer spine on exp-3 longer than middle 

 outer spine. Endopod longer than exopod, 2-segmented; 

 proximal segment slightly longer than broad, distal segment 

 about 4.5 times longer than broad, inner seta implanted 

 medially. 



P2-P4 (Figs. 6A, 7A, 8A). Intercoxal sclerite with row of 

 spinules or setules on each side. Both rami 3-segmented, 

 equal in length in P2 but with endopod shorter than exopod in 



P3 and P4; all segments with rows of spinules on outer 

 margin; P2 and P3 with a large spinule at base of each inner 

 seta on enp-2 and -3. Exp-1 with inner seta; enp-2 with outer 

 distal margin somewhat attenuated. Armature formula of 

 swimming legs as in generic diagnosis. 



Fifth pair of legs (Fig. 11D) not fused medially; exopod and 

 baseoendopod separate. Baseoendopod with short row of 

 spinules at base of exopod and setophore of outer seta; 

 endopodal lobe well developed, tapering distally, with 5 

 pinnate setae, second outer seta longest. Exopod wider than 

 long, boundary with baseoendopod straight, not reaching to 

 distal margin of endopodal lobe; with 5 pinnate setae, 4 

 grouped together on distal outer margin and 1 well separated 

 near inner distal corner. 



Description of male. As in female except for following 

 characters. 



Body (Fig. 9). Length 1.008 mm (n = 1); second and third 

 urosomites not fused and ornamental spinules on urosome 

 somewhat more robust (Fig. 11 A). 



Antennule (Fig. 10) 9-segmented, subchirocer with 6th 

 segment very swollen, geniculation between 6th and 7th 

 segments. Segmental fusion pattern: I, II, III— VIII, IX-XII, 

 XIII, XIV-XX, XXI-XXIII, XXIV-XXV, XXVI-XXVIII. 

 Armature formula: [1, 1, 11,8, 1, 14+ae, 4, 3, 8]. Segment 6 

 very swollen with a complicated pattern of ridges and teeth 

 on anterior surface (Fig. 10C-D). Segment 7 with 4 setae, 3 

 of which sagittiform, on anterior surface (Fig. 10E). 



PI. Coxa with fewer spinule rows on anterior surface. 

 Inner spine on basis without spinule row at base; inner spine 

 less well developed and with finer spinules (Fig, 5E) than in 

 female (Fig. 5D). Segments of both rami (Fig. 5B) more 

 elongate than in female. Spinules on outer and distal margin 

 of endopod segments much finer than in female, particularly 

 on distal margin of enp-1 (Fig. 5C). 



P2 (Fig. 6B-C). Basal pedestal and articulating surface of 

 endopod enlarged. Enp-1 much larger than in female and 

 inner seta transformed into a non-articulating process with a 

 flagellate tip; outer spinules small. Enp-2 without inner seta 

 or spinule row on outer margin; outer distal corner attenu- 

 ated into an apophysis reaching well beyound the distal 

 margin of enp-3. Enp-3 (Fig. 6C) reduced in size with no 

 outer spinule row; outer distal spine shorter but stouter than 

 in female with spinules reduced to coarse blunt teeth; termi- 

 nal and inner setae also reduced in size compared to female. 



P3 endopod (Fig. 7B-C). Enp-2 without outer spinule row; 

 outer and inner distal corners much more attenuated than in 

 female, apophysis at outer corner with hooked tip (Fig. 7C); 

 inner seta much smaller than in female. 



P5 (Fig. 11B). Baseoendopods of each leg fused medially; 

 not fused to exopod. Endopodal lobe reduced with 2 pinnate 

 setae of very unequal length. Exopod with 5 pinnate setae, 

 inner seta small, middle seta longest. 



P6 a single plate fused to somite proximally (Fig. 11 A), 

 with 3 pinnate setae on each side (Fig. 11C). 



REMARKS 



(i) Synonymy 



The Alaskan material on which the above redescription is 

 based, was first described in detail in an excellent paper by 



