GENERIC CONCEPTS IN CLYTEMNESTRIDAE 



segments in 6"; transformed aesthetasc-like setae present on seg- 

 ments 3, 4 and 6(or 7) in 9, and segments 3, 5 and 7 in 6. Antenna 

 with separate basis and 2-segmented endopod; basis and proximal 

 endopod segment unarmed; distal endopod segment with 1 lateral 

 and 4-5 apical elements; exopod a minute segment with 1-2 long 

 setae. Mandibles, maxillules and maxillae reduced. Mandible with 

 stylet-like gnathobase, palp represented by 1 short seta. Maxillule a 

 small segment with 1 or 3 elements. Maxilla with 1-2 endites on 

 syncoxa; allobasis with articulating claw and 2 accessory elements. 

 Maxillipeds very large with elongate syncoxa and basis; syncoxa 

 with 1 seta, basis with 1 short seta and 1 pad-like element on palmar 

 margin; endopod represented by sexually dimorphic claw and 5 

 accessory elements. 



PI with 1 -segmented exopod and 3-segmented non-prehensile 

 endopod; basis without inner seta/spine. P2-P4 with transversely 

 elongated basis bearing short outer seta; rami 3-segmented with 

 endopods longer than exopods. Outer spines of exopod segments 

 typically setiform, often with flagellate tip. Armature formula as 

 follows: 



exopod 



endopod 



exopod 



endopod 



PI 

 P2 

 P3 

 P4 



[0-1 ]21 

 L.1.22[2-3] 

 l.l.32[2-3] 

 1.1.32[2-3] 



1.1.220 

 1.2.221 

 1.2.321 

 1.2.221 



P5 uniramous, comprising basis and 1 -segmented exopod; later- 

 ally displaced; exopod elongate, with 5-6 setae. 



Female genital field positioned anteriorly; genital apertures paired 

 or fused to median slit; closed off by vestigial P6 bearing 1 element; 

 copulatory pore unpaired. P6 8 with 1 or 3 elements; closing off 

 median or asymmetrically positioned (sinistral/dextral) genital ap- 

 erture. 



Caudal rami conical or rectangular, short; rear margin between 

 setae III and IV produced into conical process bearing apical pore; 

 setae I — II spiniform and strongly developed (seta I longer than II); 

 setae IV-V fused at base, without fracture planes. 



One median egg-sac; spermatophores elongate, with very long 

 recurved neck. 



Holoplanktonic, marine. 



Type GENUS. Clytemnestra Dana, 1 847 

 Other GENUS. Goniopsyllus Brady, 1883 



Genus Clytemnestra Dana, 1847 



Goniopelte Claus, 1891 a [type species: G. gracilis Claus, 1891 -by 

 monotypy] 



Diagnosis. Clytemnestridae. Body without dorsal pattern of 

 denticles or spinules on urosomites. Antennule distinctly 7-seg- 

 mented in both sexes; 6 segmental homologies: 1— I, 2— (II— VIII), 

 3-(IX-XIII), 4-(XIV-XVII), 5-(XVIII), 6-(XIX-XX), 7-(XXI- 

 XXVIII); segment 5 in 6 with large spine. Antenna with 1 lateral 

 and 5 apical elements on distal endopod segment; exopod repres- 

 ented by well defined segment bearing 2 long setae. Maxillule 

 represented by bilobed segment with 1 lateral seta and 2 apical 

 spines. Maxillary syncoxa with 1-2 endites; proximal endite repres- 

 ented by very long seta, sometimes absent; distal endite bearing 3 

 setae. 



PI with outer seta on basis; exopod with 4 setae. P2 without outer 

 spine on exp-1. P1-P4 armature formula: 



PI 

 P2 

 P3 

 P4 



121 



1.1.22[2-3] 



1.1.32[2-3] 



1.1.32[2-3] 



1.1.220 

 1.2.221 

 1.2.321 

 1.2.221 



P5 exopod with 5 or 6 setae in both sexes. 



Genital apertures paired in 9; closed off by paired P6 bearing 1 

 vestigial element; copulatory pore small, located anteriorly between 

 genital apertures; copulatory duct probably very short and definitely 

 not strongly chitinized. 



Male P6 almost symmetrical, fused medially forming membra- 

 nous operculum closing off single median genital aperture; produced 

 into cylindrical process bearing 3 small setae. 



Caudal rami parallel, almost cylindrical; sexually dimorphic with 

 setae IV-V short and pinnate in 9, long and multiplumose in S\ 

 additional sexual dimorphism also noted in setae III and VI. 



TYPE SPECIES. Clytemnestra scutellata Dana, 1 847 [by monotypy] . 



OTHER SPECIES. C. gracilis (Claus, 1891a) comb, nov., C.farrani 

 sp. nov., C. longipes sp. nov., C. asetosa sp. nov. 



Species inquirendae. 

 Poppe, 1891 



Clytemnestra hendorffx var. quinquesetosa 



Remarks. Various authors, including Giesbrecht (1892), Sars 

 ( 1 92 1 ). Mori (1937) and Boxshall ( 1 979), have erroneously described 

 the 9antennule as 8-segmented. From the illustrations of Giesbrecht, 

 Sars and Mori it appears that the basal pedestal has been repeatedly 

 misinterpreted as an additional segment. Although his description 

 contradicts the accompanying illustration, the proportional segment 

 lengths given by Boxshall (1979) for the C. scutellata antennule 

 suggest a similar observational error. 



Clytemnestra scutellata Dana, 1 847 



Clytemnestra Hendorffx Poppe, 1891: 132-136, Taf. I. 



The form of the maxilliped and the 6-segmented urosome clearly 

 identify Dana's (1854) illustrated specimen as a male. The append- 

 age labelled "extremity of a maxilliped' (his Fig. 12d) is almost 

 certainly the P5 exopod. We concur with Claus ( 1 863, 1 89 \a-b) that 

 the original description of C. scutellata does not provide the bare 

 minimum for unequivocal identification. In fact, the synonymy of 

 Clytemnestra with Goniopelte advocated by Giesbrecht (1891a, 

 1892) is justified solely by the long terminal setae of the caudal rami 

 figured in Dana's (1854) habitus drawing. This sexually dimorphic 

 feature is the only character in Dana's description which both 

 positively identifies his species as a Clytemnestra and excludes it 

 from the genus Goniopsyllus. If Dana had figured a female specimen 

 even this generic determination would not have been possible. 



Since both Clytemnestra and C. scutellata have now been widely 

 accepted for almost a century, we have retained both names in the 

 interest of stability of nomenclature even though they are virtually 

 unidentifiable on the basis of Dana's description. The original type 

 material no longer exists and the male specimen figured in Dana 

 (1854) is so badly illustrated that we have refrained from designat- 

 ing it as the lectotype. In order to settle the issue a neotype has been 

 designated from BMNH material collected from the Great Barrier 

 Reef by Farran (1936) which forms the basis of the description 

 below. 



Type LOCALITY. The determination of the type locality presents 

 some difficulty. In his original diagnosis Dana (1847) listed three 



