GENERIC CONCEPTS IN CLYTEMNESTRIDAE 



7 



localities, i.e. the South China Sea (300 miles NE of Singapore), 

 near Pitt's Island (Kingsmill Group, Kiribati) and the eastern Pacific 

 Ocean at 18°S 124°W, but he did not designate a type locality. In his 

 illustrated description (Dana, 1854) he mentioned that the descrip- 

 tion and figures were based on specimens from the eastern Pacific 

 which could arguably be considered as the type locality. 



Farran ( 1 936) recorded a total of 1 1 specimens of C. scutellata 

 from 6 different stations sampled during the Great Barrier Reef 

 Expedition in 1928-29. Five specimens were found in serial 

 townettings inside the reef and another six specimens were discov- 

 ered in deeper waters outside the reef. Examination of Farran's spirit 

 preserved material in the Natural History Museum (BMNH 

 1948.4.28.121) revealed 3 99, 5 66 and 1 damaged 9 prosome, 

 representing at least 3 different species. According to Farran (1936) 

 the specimens from the reef flat were significantly smaller (0.8-0.9 

 instead of 1 .05- 1 .20 mm) except for one male which measured 1.15 

 mm. The small specimens (2 99, 2 66) are present amongst the 

 NHM material and represent a new species. The larger male could 

 also be identified and is described below as C. longipes sp. nov. 

 Among the remaining material, which must therefore have been 

 collected outside the reef, 1 female and 1 male agreed with (or at 

 least did not contradict) Dana's (1854) description and are here 

 identified as C. scutellata primarily on the basis of cephalothorax 

 shape. Moreover, the close size correlation between Dana's male of 

 C. scutellata ('1— 24th of an inch' = 1058 urn) and the male from the 

 Great Barrier Reef (1064 um) is striking. The single female speci- 

 men is designated here as the neotype, defining Farran's (1936) 

 stations 19, 20 and 28 collectively as the new type locality (ICZN 

 Art. 76.3.) despite previously published statements of the place of 

 origin of Dana's material. All three stations are situated outside the 

 Trinity opening to the reef off Port Douglas at 16°19-20'S, 146°3- 

 7'E (Queensland). The depth ranges from 225 (stn 19) to >600 m 

 (stns 20, 28) 



Type material. Neotype 9 dissected on 11 slides (BMNH 

 1 999.996); designated from material labelled Clytemnestra scutellata 

 (BMNH 1948.4.28. 121); collected either on 20 October 1928(stns 

 19, 20) or 23 November 1928 (stn 28) during the Great Barrier Reef 

 Expedition 1928-29 (Farran, 1936). 



Other material examined. One 6 dissected on 10 slides 

 (BMNH 1948.4.28.121); sampling data as for neotype. 



Redescription. 



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

 of caudal rami: 1121 urn. Maximum width (355 um) measured at 

 posterior margin of cephalic shield. Posterolateral angles of 

 cephalothorax laterally expanded (Fig. 1 A). Somites bearing P2-P4 

 successively decreasing in width posteriorly and bearing back- 

 wardly produced alate processes. 



Genital double-somite (Fig. 5A) slightly constricted bilaterally; 

 original segmentation marked by paired transverse chitinous ribs 

 lateroventrally and laterally. Copulatory pore slit-like, located medi- 

 ally between genital apertures; leading to short posteriorly directed, 

 membranous duct connected to bilobate seminal receptacle. Genital 

 apertures located far anteriorly; closed off by small opercula derived 

 from vestigial P6; each with 1 vestigial seta at inner distal corner and 

 anterior tube-pore near base. 



Urosomites without dorsal ornamentation (Figs 1 A, 4E); penulti- 

 mate and anal somites with multiple rows of spinules around ventral 

 hind margin (Fig. 5A). 



Caudal rami (Fig. 4E) about twice as long as wide, parallel; 

 slightly tapering towards rear margin, with stepped outer margin 

 marking insertion sites of setae I, II and III; produced into conical 



process bearing terminal pore; posterior third with ventral spinular 

 patch (Fig. 5 A). Setae I— II minutely bipinnate, spiniform and strongly 

 developed. Seta III bipinnate. Setae IV-V basally fused; about 

 equally long and only slightly longer than caudal ramus; without 

 fracture planes, multipinnate and spiniform. Seta VI minute, bare; 

 seta VII small, biarticulate at base, bare. 



Rostrum (Fig. 1 A) triangular with rounded anterior margin, com- 

 pletely fused to cephalothorax; with numerous dorsal surface pores 

 as figured, none on ventral surface; with minute lateral sensillae near 

 apex. 



Antennule (Fig. 2A) slender, 7-segmented; segment 7 longest. 

 Plumose setae present on segments 1—4. Segment 1 with small pore 

 near seta and few short spinules along anterior margin. Armature 

 formula: 1-[1 plumose], 2-[9 + 3 plumose], 3-[4 + 3 plumose + 1 

 transformed], 4- [1 + 1 plumose + (l transformed + ae)],5-[l],6-[3], 

 7-[8 + acrothek]. Apical acrothek consisting of aesthetasc, long 

 transformed seta and short bare seta. Transformed setae on segments 

 3, 4 and 7 long and aesthetasc-like, with rounded tip; those on 

 segments 4 and 7 basally fused to aesthetasc. Rudimentary element 

 present at base of acrothek. 



Antenna (Fig.3A) 4-segmented, comprising coxa, basis and 2- 

 segmented endopod. Coxa well developed, bare. Basis and proximal 

 endopod segment without ornamentation; unarmed. Exopod inserted 

 in membranous area between basis and endopod; represented by 

 small, well defined segment bearing 2 strong recurved setae apically ; 

 exopodal setae multipinnate with long setules in proximal third. 

 Distal endopod segment (Fig. 3A, B) with several surface frills and 

 minute spinules on outer surface and patch of long setules on medial 

 surface; lateral armature consisting of 1 naked seta; distal armature 

 consisting of 5 apical, non-geniculate, bipinnate or multipinnate 

 elements, 2 of which spiniform, recurved and bearing long spinules 

 proximally. 



Labrum (Fig. 3C) large, with 6 secretory pores on anterior sur- 

 face; distal margin spinulose medially and with spinular patch on 

 either lateral lobe. 



Mandible (Fig. 3D) reduced. Palp represented by single naked 

 seta. Gnathobase long and narrow, stylet-like; produced into number 

 of cuspidate processes apically and subapically; without dorsal 

 seta(e). 



Paragnaths (Fig. 3C) well developed hirsute lobes. 



Maxillule (Fig.3E) reduced; represented by small bilobed seg- 

 ment bearing 2 naked apical spines and raised seta along outer 

 margin; posterior surface with distinct pore. 



Maxilla (Fig. 3F) 2-segmented, comprising elongate syncoxa and 

 allobasis. Syncoxa with expanded basal portion and 2 endites; exit 

 of maxillary gland large (arrowed in Fig. 3F), partly concealed under 

 lobate extension; proximal endite represented by small cylindrical 

 process bearing very long plumose seta, distal endite cylindrical, 

 with 1 naked and 2 pinnate spines apically. Allobasis with large 

 articulating claw distally, smaller inner pinnate spine and naked seta 

 along outer margin. 



Maxilliped (Fig. 4A, B) very large, articulating with well devel- 

 oped pedestal; 3-segmented, comprising syncoxa, basis and endopod. 

 Syncoxa extremely elongate, longer than basis; without ornamenta- 

 tion but with 1 anterior, plumose seta near membranous articulation 

 with basis. Basis elongate; distal third of palmar margin with double 

 spinule row (anterior spinules coarser than posterior ones) and 2 

 elements located closely to articulation with endopod; proximal 

 element spiniform and bare (arrowed in Fig. 4B), distal element pad- 

 like and spinulose. Endopod represented by short segment bearing 

 short naked claw; accessory armature consisting of 3 anterior and 2 

 posterior elements. 



Swimming legs with wide, narrow intercoxal sclerites and well 



