GENERIC CONCEPTS IN CLYTEMNESTRIDAE 



15 



P2-P4 exp-3 and 6 elements on the P5 exopod in both sexes. They 

 can be separated by body size, length of caudal ramus setae IV- V, 

 length of the P5 in both sexes and urosome ornamentation in the 

 female (Table I). 



Clytemnestra gracilis (Claus, 1891a) comb. nov. 



Goniopelte gracilis Claus, 1891a: 1-10; Taf. I— II. 



Clytemnestra scutellata Dana, 1847 sensu Giesbrecht (1892): 568- 



572; Taf. 1, fig. 9; Taf. 45, figs. 16-18, 21, 23-24, 27-30, 32, 



34-38. 

 Clytemnestra rostrata (Brady, 1883) sensu T. Scott (1894): 106- 



107; PL XII, figs. 47-57; PI. XIII, figs. 1-3. 

 Clytemnestra scutellataDana, 1847 sensu Sars (1921): 100-101; PI. 



LXVIII. 

 Clytemnestra scutellata Dana, 1847 sensu Vilela (1968): 44; Est. 



XVII, fig. la-c. 

 Clytemnestra scutellata Dana, 1847 sensu Boxshall (1979): 232; 



Fig. 15A-K. 

 Clytemnestra scutellata Dana, 1847 sensu Huys et al. (1996): 301; 



Fig. 120H. 



TYPE LOCALITY. Claus (1891a) collected his material from an 

 unspecified locality in the eastern Mediterranean. The neotype 

 designation below redefines the type locality as follows: North-east 

 Atlantic, south-west of Azores, 35°N 33°W, 0-1 m. 



TYPE material. Claus' (189 la) description was based on a single 

 specimen of either sex. Since the type material no longer exists a 

 neotype is designated here to secure stability of nomenclature: adult 

 9 in alcohol (BMNH 1999.1024); collected during RRS Discovery 

 Cruise 1 2 1 (5-26 June 1 98 1 ), station 1 0379; 1 3 June 1 98 1 , at night; 

 torpedonet; leg. Institute of Oceanographic Sciences. 



Other material examined. 



(a) from type locality: 11 99 and 8 66 in alcohol (1 9 and 1 6 

 dissected in half, in separate vials), 1 9dissected on 6 slides (BMNH 

 1983.53); 2 99and 1 6 on SEM stub; collection data as for neotype; 



(b) Gulf of Guinea, Telegraph Steamer Buccaneer (BMNH 

 1999.1007-1016): 9 99(2 damaged) and 1 6 (damaged); misla- 

 belled as Clytemnestra rostrata; January-February 1886; leg. J. 

 Rattray, det. T. Scott, [body length of 7 99: 1381-1541 um,x= 1444 

 urn]; 



(c) South Adriatic, Croatia: 1 9in alcohol (BMNH 1999.1071); leg. 

 F. Krsinic. [body length: 1309 um]. 



DESCRIPTION, (based on Discovery material) 



FEMALE. Total body length from tip of rostrum to posterior margin 

 of caudal rami: 1330-1562 um (x = 1450 urn; n = 10). Maximum 

 width (382 um) measured at posterior margin of cephalic shield. 

 Posterolateral angles of cephalothorax slightly expanded (Fig. 8 A). 

 General body shape as in type species. 



Genital double-somite (Fig. 8B) slightly constricted bilaterally; 

 original segmentation marked by paired transverse chitinous ribs 

 lateroventrally and laterally, joining medially forming continuous 

 but weakly defined rib. Copulatory pore slit-like, located medially 

 between genital apertures (arrowed in Fig. 27B); leading to short 

 posteriorly directed, membranous duct connected to bilobate semi- 

 nal receptacle. Genital apertures (Fig. 1 ID) separated by number of 

 rounded swellings (also present in type species: Fig. 5A); closed off 

 by small opercula derived from vestigial P6; each with 1 vestigial 

 seta (coarser than in C. scutellata) at inner distal corner and anterior 

 tube-pore near base (arrowed in Fig. 11D). 



Urosomites without dorsal ornamentation; penultimate and anal 

 somites with multiple rows or patches of spinules around ventral 



hind margin and lateroventral patches on second abdominal somite 

 (Fig. 8B). 



Caudal rami (Fig. 8B) as in C. scutellata but setae IV distinctly 

 shorter than seta V 



Rostrum (Figs 8A; 10C) triangular with rounded anterior margin, 

 completely fused to cephalothorax; with numerous dorsal surface 

 pores; minute lateral sensillae flanking middorsal raised pore. 



Antennule 7-segmented, with armature formula as in type species. 

 Antenna, mandible (Fig. 10A), maxillule and maxilla (proximal 

 endite on syncoxa present) as in type species. Palmar elements of 

 maxilliped as in Fig. 10B; proximal element fused to basis and with 

 apical pore; distal element pad-like, forming barbed, linguiform 

 extension posteriorly and bearing double spinule row and tube pore 

 anteriorly. 



P2-P4 armature formula: 



exopod 



endopod 



P2 

 P3 

 P4 



1.1.223 

 1.1.323 

 1.1.323 



1.2.221 

 1.2.321 

 1.2.221 



P5 (Fig. 8B) elongate, extending clearly beyond posterior margin 

 of genital double-somite. Exopod about 2.4 times as long as basis, 

 with 6 setae. 



MALE. Total body length from tip of rostrum to posterior margin of 

 caudal rami: 1420-1531 um(x = 1479um;n = 8). Body with similar 

 projections as in 9; urosome more slender with genital and first 

 abdominal somites separate (Fig. 9A). 



Antennule with armature as in C. scutellata. Maxilliped much 

 larger than in 9; middle and distal thirds of palmar margin forming 

 longitudinal furrow bordered by single row of spinules on both 

 anterior and posterior sides (Fig. 10D). 



P5 (Fig. 9A) very similar to that of 9, extending to distal margin 

 of first abdominal somite. 



Sixth pair of legs (Fig. 9A) weakly asymmetrical, forming highly 

 membranous midventral area covering single, large median genital 

 aperture (Fig. 1 1 A); each P6 produced into cylindrical process (Fig. 

 1 IB) with 1 apical and 2 lateral bare setae. 



Urosomites 4-5 and anal somite with spinules around ventral hind 

 margin (Fig. 9A). 



Caudal rami (Fig. 9A-B) longer and more slender than in 9; setae 

 I — II bare; setae IV-V long (68% of urosome length; Fig. 9A) and 

 plumose; seta VI longer than in 9 and sparsely plumose. 



Variability. Some variability was noticed in the caudal ramus 

 length of the Buccaneer females, the majority having a slightly 

 longer ramus than in Fig. 8C. In the Adriatic 9 the spinular patches 

 on the first postgenital somite are wider medially forming an almost 

 continuous zone around the posterior margin. 



REMARKS. Claus (1891 ft) himself surmised that Goniopelte graci- 

 lis was conspecific with Clytemnestra hendorffi which in turn 

 became relegated to a junior subjective synonym of C. scutellata by 

 Giesbrecht (1892). It is beyond any doubt that Giesbrecht's excel- 

 lent redescription of C. scutellata was based on C. gracilis. His 

 illustrations were based on Naples material only, however, it is 

 likely that he included specimens of C. scutellata from the Pacific 

 (Giesbrecht, 1891ft) in his length measurements, possibly account- 

 ing for the lower end of his size range (9: 1.05-1.2 mm; 6: 1.07-1.3 

 mm). C. gracilis is distinctly larger than C. scutellata and can be 

 distinguished from the latter by the slender caudal rami and the 

 longer P5 which extends clearly beyond the posterior margin of the 

 genital double-somite in the female and reaches to the rear margin of 



