PHYLOGENY OF ARIETELLID COPEPODS 



155 



Leg 1 (Fig. 34G): first exopod segment missing element on 

 outer corner, third segment with tuft of minute setules 

 medially and spinulose spine subterminally along outer mar- 

 gin. Leg 5 of paratype missing. 



Genus Sarsarietellus Campaner, 1984 



Diagnosis (emended). Only female known. Body relatively 

 large, 3 to 5 mm in length. Prosome oblong in dorsal view; 

 cephalosome separate from first pedigerous somite; ventro- 

 lateral corner of last prosomal somite slightly produced; 

 urosome about one-third as long as prosome. Genital double- 

 somite longer than wide, produced ventrally; pair of gonop- 

 ores located anteroventrally, single copulatory pore 

 posteromedially; paired copulatory ducts medially fused to 

 form common duct, heavily chitinized; seminal receptacle 

 elongate, slender, with terminal part bulbous. Caudal rami 

 symmetrical, longer than wide, with setae II and III well 

 developed. 



Antennules symmetrical, reaching to end of prosome, 

 22-segmented; posterior margin of ancestral segments I to X 

 fringed with long setules; segment III separate from IV; 

 segment IV without aesthetasc; segment XIII with 2 setae; 

 segment XXIII separate from XXIV. Antenna: second endo- 

 pod segment with 5 setae and 1 vestigial seta terminally; 

 exopod indistinctly 8-segmented. Mandibular gnathobase 

 lacking tuft of setules; 3 teeth on cutting edge, dorsalmost of 

 which bifid at tip. Mandibular palp: endopod rudimentary, 1- 

 segmented endopod with 2 setae; seta on first exopod seg- 

 ment not reduced; outer seta on fifth exopod segment 

 relatively long. Maxillule: praecoxal arthrite with 6 elements 

 (5 spines and 1 process); coxal epipodite with 8 setae; coxal 

 endite with 1 long seta; endopod bearing 2 setae and 1 

 vestigial seta. Maxilla: first praecoxal endite with 2 well- 

 developed setae; basal spine with 2 rows of long spinules. 

 Setal formula of endopod segments of maxilliped: 1,4,4,3,3,4; 

 seta a on sixth endopod segment vestigial, seta b relatively 

 long. 



Third exopod segment of leg 1 with 2 outer spines. Leg 5: 

 coxa and intercoxal sclerite separate; basis fused to endopod. 

 Endopod represented by process with 2 terminal and 2 inner 

 setae. Exopod composed of 3 almost fused segments, bearing 

 3 outer spines and 2 terminal spines of unequal lengths. 



Type species. Scottula abyssalis Sars, 1905. 



Other SPECIES. Sarsarietellus natalis Heinrich , 1993. 



Remarks. Sars (1905) assigned this species to the genus 

 Scottula Sars, 1902. Scottula was synonymized with the genus 

 Metacalanus Cleve, 1901 by Campaner (1984), but he pointed 

 out that Scottula abyssalis was not congeneric with Metacala- 

 nus, and established Sarsarietellus to accommodate it. A 

 second species of Sarsarietellus, S. natalis, has been recently 

 described from the near-bottom (1083-1090 m depth) in the 

 southwestern Indian Ocean (Heinrich, 1993). S. natalis 

 exhibits a few more apomorphic characters than S. abyssalis: 

 (1) asymmetry in the genital double-somite; (2) reduction of 

 the elements on the exopod of the fifth leg. 



Ecological note. Campaner (1984) suggested that the 

 genus is only loosely associated with the deep-sea near- 

 bottom as is Scutogerulus. The recent discovery of a second 

 congener from the near-bottom supports his opinion. 



Sarsarietellus abyssalis (Sars, 1905) (Figs 35,36) 



Material examined. $, Holotype, Zoological Museum, 

 University of Oslo, Catalog No. F5447-5448. 



Body length. 3 mm (after Sars, 1925). 



Description. Female. Genital double-somite (Fig. 35A,B) 

 longer than wide; its posterior end damaged, but single 

 copulatory pore possibly present posteroventrally (fragment 

 of copulatory pore still remained on slide); anterior paired 

 gonopores located ventro-laterally (since the specimen was 

 dried up, the urosome was so depressed t> at the internal 

 structures have become artificially asymmetrical); copulatory 

 duct heavily chitinized, divergent anteriorly, each connecting 

 with elongate seminal receptacle (Fig. 35B) which curved 

 anteriorly and reaching to half length of somite with 

 expanded bulbous part terminally. 



Antennule (Fig. 36A) 22-segmented; suture between seg- 

 ments XXIV-XXVI visible. Fusion pattern and armature as 

 follows: I— III— 7 + aesthetasc, IV-2, V-2 + aesthetasc, VI-2 

 + aesthetasc, VII-2 + aesthetasc, VIII-2 + aesthetasc, IX-2 

 + aesthetasc, X-2 + aesthetasc, XI-2 + aesthetasc, XII-2 + 

 aesthetasc, XIII-2 + aesthetasc, XIV-2 + aesthetasc, XV-2 

 + aesthetasc, XVI-2 + aesthetasc, XVII-2 + aesthetasc, 

 XVIII-2 + aesthetasc, XIX-2 + aesthetasc, XX-2 + aes- 

 thetasc, XXI-2 + aesthetasc, XXII-1, XXIII-1, 

 XXIV-XXV^ + aesthetasc, XXVI-XXVIII-8 + aesthetasc. 

 First to eighth (X) segments fringed with row of setules 

 posteriorly. 



Antennary endopod: first segment without inner seta; 

 second segment (Fig. 36B) with 3 setae of unequal lengths 

 medially, and 5 setae and 1 vestigial seta terminally. Anten- 

 nary exopod (Fig. 36C) indistinctly 8-segmented, first to fifth 

 segments almost fused or incompletely fused, setal formula as 

 follows: 0,1,1,1,1,1,0,3. Mandibular gnathobase with 3 stout 

 teeth, dorsalmost of which bifid at tip, lacking medial tuft of 

 setules as found in Crassarietellus sp.; basis fringed by row of 

 long setules along inner margin, and not furnished with 

 minute spinules as in male of Crassarietellus sp. Mandibular 

 palp (Fig. 36D): endopod rudimentary, 1-segmented, with 2 

 setae of unequal lengths; exopod indistinctly 5-segmented, 

 seta on first segment not reduced, outer seta on fifth segment 

 relatively long. 



Maxillule (Fig. 36E) praecoxal arthrite with 5 naked spines 

 and 1 process; coxal endite carrying long serrate seta; coxal 

 epipodite with 8 plumose setae; second basal endite bearing 1 

 vestigial seta; endopod bulbous, 1-segmented, bearing 3 

 setae, one of which rudimentary. Maxilla: first praecoxal 

 endite (Fig. 36F) with 2 spinulose setae and vestigial element; 

 basal spine (Fig. 36G) stout, bearing 2 rows of long spinules. 

 Maxilliped: fourth endopod segment (Fig. 35C) with rela- 

 tively developed spinulose innermost seta, fifth segment (Fig. 

 36D) also having spinulose innermost seta, but much shorter 

 and thinner than on fourth segment; sixth endopod segment 

 (Fig. 36E) with seta a reduced, seta b over half length of 

 medial-length seta c, medium-length spinulose seta c, spinu- 

 lose seta d elongate. 



Leg 4 without inner coxal seta. Leg 5 (Fig. 36H): intercoxal 

 sclerite more or less fused; endopod almost fused with basis, 

 medial suture visible; exopod separate from basis, indistinctly 

 3-segmented, sutures between segments visible, terminal 

 outer spine almost fused with segment. 



Remarks. Sars (1924, 1925) overlooked the vestigial seta on 



