SYSTEM ATICS AND PHYLOGENY OF ZAUSODES 



75 



P2o" enp-2 with or without apophysis, inner seta not modified; enp- 

 3 with 1 apical seta (inner one lost), outer spine not fused to segment. 

 P3cf enp-2 outer distal corner not attenuated. 

 Swimming leg setal formula: 



exopod 



endopod 



P2 



0.1.223 



0.1.221 [9] 

 0.1.211 [cf] 



P3 



0.1.323 



1.0.221 



P4 



0.1.323 



1.0.121 or 1.121 



P5 exopod elongate-oval in both sexes. P5 endopodal 

 lobe 9 expressed; 3rd and 4th inner setae much shorter than others 

 (or 1 seta lost in Z. septimus). 



Sexual dimorphism in rostrum, antennule, P2 endopod, P5, P6, 

 genital segmentation and size. 



Type species. 

 monotypy). 



Other species. 



Zausodes arenicolus C.B. Wilson, 1932 (by 



Z. septimus Lang, 1965. 



Zausodes arenicolus C.B. Wilson, 1932 



Type LOCALITY. Katama Bay, Martha's Vineyard, Woods Hole 

 (Massachusetts); beach sand washings. 



Material examined. 



National Museum of Natural History (Smithsonian Institution), 

 Washington, D.C.: Woods Hole region; type series consisting of one 

 vial containing > 50 specimens (USNM 63877); 1 9 and lcfdissected 

 for examination. According to the USNM catalogue files the 

 holotypeo* has gone missing since at least 1 983 when the harpacticoid 

 collections were inventoried. It is assumed that in reality the holotype 

 was never segregated by C.B. Wilson although the empty vial, 

 which supposedly contained the specimen, received a separate 

 registration number (no. 63423). 



The Natural History Museum, London: syntypes(4 9 9,4o*cf)in 

 alcohol; from type locality; coll. C.B. Wilson, 15 August 1927; 

 BMNH 1948.9.10.37. 



Gulf of Mexico: 29°5 1 'N, 84°3 1 'W (about 50 m north of day mark 

 #2), St. George Sound, Florida, 5 m depth, unvegetated medium 

 sand (median grain size = 0.254 mm); a seagrass meadow occurs 

 about 150 m to the north; see Foy & Thistle (1991) for additional 

 description. Deposited at the Natural History Museum, London are 

 99 9and 3cfcfin ethanol (BMNH 1999.176-187) and 29 9and 

 2o"o"on slides (BMNH 1999.188-191). Deposited at the 

 Smithsonian, Washington, D.C are 9 9 9 and 2o" o"in ethanol (USNM 

 288445^146) and 1 9 and 2o"o" dissected on slides (USNM 288444). 



REDESCRIPTION. All illustrations and text are based on specimens 

 from the Gulf of Mexico. Illustrations were compared to type 

 material obtained from the Smithsonian in order to verify the species 

 identification. 



Female. Body length: measured from anterior margin of rostrum 

 to posterior margin of caudal rami: 433 urn (x = 0.499, n = 4); 

 without rostrum and caudal rami: 394 um (x = 0.456, n = 4). Body 

 (Figs 1 A-B, 2C-D) dorsoventrally flattened. Greatest width 200um 

 (x = 0.202, n = 4), measured near posterior margin of cephalothorax. 

 Nauplius eye distinct; reddish brown in fresh, unstained specimens; 

 invisible in cleared specimens. Integument with surface ornamenta- 

 tion/sculpturing consisting of irregular pattern of fine striations (not 

 illustrated). Sensillae present dorsally and dorsolaterally on 

 cephalothorax and body somites except penultimate one (not all 



shown). Ventrolateral margin of cephalic shield with sensillae. 

 Epimera of thoracic somites thickly chitinized laterally. All somites 

 but anal with fine spinular rows dorsally and dorsolaterally; penul- 

 timate somite with ventral spinular row; anal somite with spinular 

 rows dorsally, ventrally, and laterally on the posterior margin. 

 Lateral margins of free thoracic somites with 3 sensillae. Ventral 

 posterolateral corners of urosomites 3-5 and lateral margins of 

 urosomites \-<\ with spinules. Genital double-somite with continu- 

 ous chitinous internal rib ventrolaterally and ventrally (but not 

 dorsally). Anal somite cleft medially; anus located terminally, 

 triradiate, bordered by incised frill that is partially exposed in dorsal 

 aspect; with two ventral pores near posterior margin; anal opercu- 

 lum rounded, smooth; pseudoperculum present, weakly developed. 

 Caudal rami (Figs 1A-B, 2C-D) approximately as long as wide, 

 with 7 setae: setae I — III bare, setae IV-V bipinnate, seta VI bipinnate, 

 dorsal seta (VII) carried on a biarticulate socle. Gelatinous string 

 (Figs 1 A-B) extending posteriorly from each caudal ramus present 

 in some specimens. 



Rostrum (Fig. 1C) prominent, bell-shaped in dorsal view, with 

 membranous fringe, defined at base; with two short sensillae 

 anteriorly and one sensilla on each mediolateral margin; with mid- 

 dorsal pore. 



Antennule (Fig. 2B) 8-segmented; segments 2 and 3 longest; first 

 segment widest with several spinular rows; fourth segment with an 

 aesthetasc (50 um long); eighth segment with acrothek consisting of 

 3 elements (probably 2 setae and 1 aesthetasc, however, we were 

 unable to distinguish which elements were setae and which was an 

 aesthetasc); with armature formula 1-[1], 2-[9 + 1 pinnate], 3-[7 + 

 2 pinnate], 4-[3 + 1 pinnate + (1 + ae)], 5-[l + 1 pinnate], 6-[2 + 2 

 pinnate], 7-[4], 8-[4 + acrothek]. 



Antenna (Fig. 2A). Coxa short and unornamented; allobasis with 

 several spinular rows, abexopodal spinulose seta, and membranous 

 insert marking original segment boundary between basis and first 

 endopodal segment; free endopod 1 -segmented; lateral armature 

 consisting of a spine, 1 short seta and 1 long seta; distal armature 

 comprising 1 seta, 1 pinnate, curved spine, and 4 geniculate spines, 

 longest one of which bearing spinules proximal to geniculation and 

 fused at base to a slender seta; with spinular rows and hyaline 

 surface frill as indicated in Fig. 2 A; exopod 1 -segmented with 2 

 distal, unequal setae. 



Labrum well developed, medially incised. 



Mandible (Fig. 3A). Gnathobase with seta at dorsal corner; coxa 

 with proximal row of spinules; palp biramous, comprising basis and 

 1 -segmented exopod and endopod; basis produced transversely, 

 with proximal spinular row and 4 bipinnate setae; endopod longer 

 than exopod, with 1 bare and 1 pinnate lateral seta and 6 apical setae; 

 exopod with 1 pinnate and 2 bare lateral setae, 3 distal setae, and 

 spinules subdistally and along outer margin. 



Maxillule (Fig. 3C). Praecoxa with spinular row along outer edge 

 and with arthrite bearing 8 spines around distal margin, 2 anterior 

 surface setae, and posterior spinular row; coxal endite with 4 setae 

 and a spinular row; basal endite with 6 setae; endopod with 1 bare 

 and 2 pinnate setae distally; exopod with 1 bare inner seta, 1 pinnate 

 outer seta, 2 distal setae, and a spinular row. 



Maxilla (Fig. 3B). Syncoxa with spinular row along outer margin 

 and 3 endites; praecoxal endite with 2 bare and 2 bipinnate setae; 

 coxal endites each with 2 bare setae and 1 pinnate spine; allobasis 

 with claw and 3 bare setae; endopod 1-segmented with 4 bare setae. 



Maxilliped (Fig. 3D). Syncoxa with a bipinnate seta and numer- 

 ous spinular rows as indicated; basis with a spinular row and seta 

 along palmar margin, with spinules along outer distal margin and on 

 anterior face; endopod represented by acutely recurved claw with 

 spinules along inner margin and proximal accessory seta. 



