4 



R. HUYS AND S. CONROY-D ALTON 



With Giesbrecht's (1891a) claim that Goniopelte had already 

 been described under three different generic names the synonymy 

 issue surrounding Clytemnestra appeared to have come to a close. 

 Claus (1891b), however, continued to defend his genus Goniopelte 

 with extraordinary persistence. After re-examination of Poppe's 

 ( 1 89 1 ) material, confirming the presence of the male P6, and the 

 vestigial antennary exopod, he acknowledged the conspecificity of 

 G. gracilis and C. hendorffi. Nevertheless, he adhered to his earlier 

 decision (Claus, 1863) to dismiss Clytemnestra as a valid genus. He 

 based this course of action on the rules drawn up by Raphael 

 Blanchard and Maurice Chaper and adopted, in part, at the First 

 International Congress of Zoology (Paris, 1889). They stipulated in 

 § 7 that the valid name should be the oldest one provided that '. . . ce 

 nom etc. aura ete clairement et suffisament defini'. Claus (1891b) 

 rejected Poppe's (1891) arguments as insufficient for the proposal of 

 a new family and instead created a third subfamily Goniopeltidinae 

 in the Peltididiidae. In this subfamily he recognized two genera, 

 Goniopsyllus (syn. Sapphir) and Goniopelte, which were differenti- 

 ated on the basis of antennule segmentation, antennary exopod 

 setation and caudal ramus sexual dimorphism. 



Claus' (1891b) generic concepts were finally rejected by 

 Giesbrecht (1892) who reviewed the intricate synonymy and rein- 

 stated Clytemnestra as the only valid genus on the basis of the 

 Principle of Priority. Giesbrecht (1891b, 1892) recognized only two 

 species, C. scutellata and C. rostrata, and regarded all other species 

 as subjective synonyms with the possible exception of C. tenuis. 

 This course of action was adopted by most subsequent authors such 

 as Lang (1944, 1948) and Boxshall (1979). The rapid accumulation 

 of plankton data during the 20th century fed the conjecture that both 

 species assumed a cosmopolitan distribution. Unfortunately, this 

 presumption made people loose sight of the possible existence of 

 other undescribed species and of the true identitiy of C. scutellata 

 and G. rostratus. 



PRIORITY OF THE FAMILY NAME 



Although various authors (Car, 1891b; Claus, 189 la) had expressed 

 the need to introduce a new family or subfamily for Goniopsyllus, 

 Goniopelte and Sapphir it was finally Poppe (1891) who coined the 

 family name Pseudo-Peltididae for the only included genus 

 Clytemnestra. Claus (1891b) rejected the family status of Pseudo- 

 Peltididae and established a new subfamily Goniopeltidinae for 

 Goniopelte and Goniopsyllus. Giesbrecht (1892) did not consider 

 familial assignment which probably misled A. Scott (1909) who did 

 not consult the earlier literature and consequently proposed the new 

 family name Clytemnestridae for the type and only genus 

 Clytemnestra. Mori (1929) placed this genus in the Harpacticidae 

 whereas Wilson (1932) referred it to the Tachidiidae for some 

 unknown reason, an inexplicable assignment followed also by 

 Carvalho (1952) and Krishnaswamy (1953). 



Mostworkers (e.g. Sars, 1921; Monard, 1927; Sewell, 1940; Klie, 

 1943) adopted Clytemnestridae as the valid family name until Lang 

 (1944, 1948) pointed out that Poppe's Pseudo-Peltididae took prior- 

 ity over the latter. Boxshall (1979) remarked that this course of 

 action contravened ICZN Art. 11.7.1.1 since a family-group name 

 must, when first published, be based on the name then valid for a 

 contained genus. Poppe's (1891) family name with its alternative 

 spellings Pseudo-Peltididae (Poppe, 1891), Pseudo-Peltidiidae 

 (Lang, 1944) and Pseudopeltidiidae (Wells, 1976) is therefore una- 

 vailable. Boxshall (1979) reinstated Clytemnestridae as the valid 

 name, but unfortunately ignored Claus' (1891b) older and validly 



introduced family-group name Goniopeltidinae. Other authors con- 

 tinued using Pseudopeltidiidae (e.g. Bowman & Abele, 1982). 



Were priority to be rigorously enforced, Goniopeltididae should 

 replace its junior synonym Clytemnestridae and hence leave Claus, 

 at best, a pyrrhic victory. However, since the senior synonym 

 Goniopeltidinae has remained unused as a valid name since 1899 

 (ICZN Art. 13.9.1.1) and the junior synonym Clytemnestridae has 

 been used as the presumed valid name in at least 25 works 

 (Krishnaswamy, 1957; Marques, 1957; Bruce et ai, 1963; 

 Kasturirangan, 1963; Cheng et al, 1965; Owre & Foyo, 1967; 

 Fagetti, 1962; Chen etal., 1974; Boxshall, 1979; De Decker, 1984; 

 Citarella, 1986; Hicks, 1988; Huys & Boxshall, 1991; Razouls & 

 Durand, 1991; Campos Hernandez & Suarez Morales, 1994; Huys 

 & Bottger-Schnack, 1994; Kazmi & Muniza, 1994; Hirota, 1995; 

 Huys et al, 1996; Razouls, 1996; Bodin, 1997; Chihara & Murano, 

 1997; Hure & Krsinic, 1998; Reid, 1998; Suarez Morales & Gasca, 

 1998) published by at least 10 authors in the immediately preceding 

 50 years (and encompassing a span of not less than 10 years) (ICZN 

 Art. 13.9.1.2.) it is to be considered a forgotten name (nomen 

 oblitum). In accordance with Art. 23.9.1. prevailing usage is main- 

 tained and the junior name Clytemnestridae is treated as a nomen 

 protectum. 



SYSTEMATICS 



Claus' (1891b) generic concepts of Goniopelte and Goniopsyllus 

 were based on differences in antennule segmentation, antennary 

 exopod setation and caudal ramus sexual dimorphism. Re-exam- 

 ination of material attributed to C. scutellata and C. rostrata have 

 revealed additional differentiating characters in mouthpart struc- 

 ture, swimming leg setation and female genital field morphology, 

 substantiating Claus' recognition of two distinct genera. Secondly, 

 there is accumulating evidence that both C scutellata and C. rostrata 

 represent species complexes, each of which can be justifiably 

 assigned generic rank. It has not been our intention to verify every 

 published record of these species since in most cases the information 

 contained in the numerous marine plankton studies did not permit 

 unambiguous identification. This paper is based almost solely on 

 BMNH collections and serves as a baseline study for future species 

 discrimination in the Clytemnestridae. It is aimed primarily at 

 reviving and elaborating Claus' (1891b) original generic concepts, 

 albeit partly under different taxonomic names. 



Family CLYTEMNESTRIDAE A. Scott, 1909 



Diagnosis. Body distinctly tapering posteriorly. Prosome dors- 

 oventrally flattened, urosome slender and cylindrical. First 

 pedigerous somite incorporated in cephalosome forming bell-shaped 

 cephalothorax. Pedigerous somites bearing P2-P4 with posteriorly 

 directed alate projections. Genital and first abdominal somites of 9 

 completely fused forming genital double-somite; original segmen- 

 tation marked by small chitinized internal ribs ventrally or laterally. 

 Anal operculum obsolete; anus terminal. 



Sexual dimorphism in antennule, maxilliped, P6, urosomal orna- 

 mentation and in genital segmentation; often in rostrum shape, 

 occasionally in caudal ramus. No distinct sexual dimorphism in PI- 

 PS. 



Rostrum large, fused to cephalic shield. Antennules slender; 6- or 

 7-segmented in 9; haplocer and distinctly or indistinctly 7-seg- 

 mented in 6\ with geniculation between segments 6 and 7; aesthetascs 

 present on 4th and apical segments in 9, on 3rd, 5th and apical 



