108 



S. OHTSUKA, G.A. BOXSHALL AND H.S.J. ROE 



MATERIALS AND METHODS 



The present study is based on collections deposited in The 

 Natural History Museum, London, the New Zealand 

 Oceanographic Institute, the United States National 

 Museum, Smithsonian Institution, the Zoological Museum, 

 University of Oslo, the University of Sao Paulo, and 

 Hiroshima University. Sampling data and locality are summa- 

 rized in Table 1. Specimens, except for those previously 

 mounted, were dissected and mounted in Gum-chloral and 

 observed with a differential interference contrast microscope 

 (Olympus BH-2). The genital double-somites of females of 

 several species were observed with a scanning electron micro- 

 scope (Hitachi S-800). The morphological terminology is 

 based on Huys & Boxshall (1991). Type specimens of the new 

 genera are deposited in The Natural History Museum and the 

 New Zealand Oceanographic Institute. 



Phylogenetic relationships between genera were analyzed 

 using PAUP version 3.0 prepared by D. Swofford, Illinois 

 Natural History Survey. The character matrix (Tables 2,3) 

 summarizes the character distributions among the 10 genera 

 available for study. A multistate scoring system was 

 employed and missing characters were scored 9. A hypotheti- 

 cal composite ancestor was included in the analysis which 

 scored for all characters. The options employed in the 

 analysis were Branch and Bound, which guaranteed to find 

 all the most parsimonious trees, and the MINF optimisation, 

 which assigns character states so that the f-value is mini- 

 mized. All characters were set as irreversible using the 

 Camin-Sokal option. 



The abbreviations used in the text and figures 1 to 37 are as 

 follows: cd: copulatory duct; cp: copulatory pore; g: gonop- 

 ore; o: oviduct; rd: receptacle duct; s: spermatophore rem- 

 nant; sr: seminal receptacle. 



SYSTEMATICS 



Family Arietellidae Sars, 1902 



Diagnosis (emend.) Female. Body of variable size (from ca. 

 0.8 to 7 mm), relatively robust, rarely compressed. Cephalo- 

 some and first pedigerous somite separate or weakly fused; 

 fourth and fifth pedigerous somites completely fused. Cepha- 

 losome round or pointed at apex; rostrum produced ven- 

 trally, with pair of filaments. Posterior corner of prosome 

 sharply or weakly produced, with or without dorsolateral 

 and/or ventrolateral process. Urosome comparatively short, 

 4-segmented; genital double-somite with single or paired 

 gonopores and copulatory pores; gonopore(s) located ventro- 

 laterally or ventrally, with or without opercular plate; copula- 

 tory pore sharing common opening with gonopore or 

 separate from gonopore, located ventro-medially or 

 -posteriorly, rarely ventrally on right side; seminal recep- 

 tacles usually paired, rarely left receptacle entirely lacking. 

 Egg-sac present or absent. Caudal rami well defined, sym- 

 metrical or slightly asymmetrical, relatively short, with vesti- 

 gial seta I, well developed or reduced setae II— III, well 

 developed setae IV- VI and small seta VII. 



Antennules symmetrical or asymmetrical, longer on left 

 side than on right, sometimes differing in fusion pattern and 



armature; 16- to 22-segmented; segments I to III, rarely up to 

 VI fused; segments X to XII more or less fused; segments 

 XXIII and XXIV separate or fused; segments XXV and 

 XXVI completely or incompletely fused; segments II, XXII- 

 XXIV, XXVI and XXVII lacking aesthetasc; segment IV, 

 VI, VIII-X, XII and XIII with or without aesthetasc; seg- 

 ment XIII with 1 or 2 setae; compound segment XXVI- 

 XXVIII with 8 or 9 elements; posterior margin of proximal 

 segments fringed with row of setules or not. Antenna: basal 

 seta present; both rami separate from basis; endopod 

 2-segmented, first segment with 0-1 inner seta at midlength, 

 second segment elongate, with 1-3 inner setae medially and 5 

 or 6 setae terminally; exopod indistinctly 6- to 10-segmented, 

 ancestral segments I— III and IX unarmed. Mandible: gnatho- 

 base well chitinized, with 3 or 4 sharp teeth; endopod 

 rudimentary, 1-segmented with 1 or 2 setae terminally or 

 completely absent; first exopod segment with normal or 

 reduced seta, fifth segment carrying 2 setae, one of which 

 sometimes vestigial. Maxillule: praecoxal arthrite with 0-6 

 elements; coxal endite with 1 seta or unarmed; coxal epi- 

 podite carrying 5-9 setae; inner basal seta representing endite 

 vestigial or absent; endopod bulbous, 1-segmented, with 0-3 

 setae or completely incorporated to basis; exopod lobate, 

 bearing 3 long setae. Maxilla well developed; first praecoxal 

 endite with 1 or 2 setae and 1 vestigial element, second 

 praecoxal endite having 1 or 2 setae; first and second coxal 

 endites each with 2 setae; basal spine stout, spinulose or bare; 

 endopod 4-segmented, with chitinized long setae, setal for- 

 mula 1,3,2,2. Maxilliped elongate; syncoxa with 1 medial and 

 2 terminal setae; basis with patches of setules or spinules and 

 2 setae medially; endopod 6-segmented, first segment almost 

 fully incorporated into basis, setal formula 1,4,4,3 (rarely 2) ,3 

 (rarely 2),4, sixth segment with 2 outermost terminal setae 

 (setae 'a' and 'b\ see Fig. 5C) reduced or not. 



Legs 1^1 with distinctly 3-segmented rami or, very rarely, 

 with endopod segments of leg 1 incompletely fused. Seta and 

 spine formula of legs 1-4 as shown in Table 4. 



Leg 5 variable but not natatory, almost symmetrical; coxae 

 and intercoxal sclerite separate or fused; basis and endopod 

 separate or fused; endopod with 0-4 setae; exopod 1- to 

 3-segmented or completely fused with basis, carrying 0-5 

 elements. 



Male. Body similar to that of female, but urosome 

 5-segmented. Left antennule geniculate, 16- to 20-segmented; 

 segments I to IV fused; segments XI to XV more or less 

 fused; segments XXI and XXII fused or rarely separate; 

 segments XXIII and XXIV separate; segments XXV and 

 XXVI completely or incompletely fused; segments II and III 

 with 1 or 2 setae; segments X, XII-XIV and XX with anterior 

 process; segments XIX and XXI with 2 processes; segment 

 XIII with 0-1 seta; segments XV, XXII and XXIV with or 

 without process; proximal segments often with row of setules 

 along posterior margins. Mouthparts and legs 1^1 similar to 



Table 4 Spine and seta formula of legs 1-4. 



Coxa Basis Exopod segment Endopod segment 



I— 1 ;I— 1;II/1, 1/1,4 0-l;0-2;l,2,2 



I-1;I-1;III,I,5 0-l;0-2;2,2,4/3 



I-1;I-1;III,I,5 0-l;0-2;2,2,4/3 



I-1;I-1;III,I,5 0-l;0-2;2,2,3/2 



Legl 



0-1 



1-1 



Leg 2 



0-1 



0-0 



Leg 3 



0-1 



0-0 



Leg 4 



0-0/1 



1-0 



