146 



S. KARAYTUG AND G.A. BOXSHALL 



pits. Caudal rami shorter than female. First antennulary segment 

 armed with 8 setae plus an aesthetasc, 1 seta large (seta A) and 

 modified. 



Coxobasis of antenna with spinular row on caudal surface near 

 base of two inner setae (arrowed in Figure 32D); spinules more 

 elongate than those of female. One seta on terminal exopodal 

 segment of leg 1 spinulose (Figure 30C). Outer seta of fifth leg 

 (Figure 32C) plumose and less developed than that of female. Sixth 

 leg (Figure 32B,C) armed with 1 inner spine, longer than second 

 urosomal somite, and 2 outer plumose setae. 



Differential diagnosis. P. hardingi differs from other Para- 

 cy clops species by the combination of the following characters; the 

 presence of the spinular row on the caudal surface near the base of 

 the 2 inner setae (arrowed in Figures 29B; 32D) of the coxobasis of 

 the antenna in both sexes; by the structure of the seminal receptacle 

 (Figure 28A); by the absence of the spinular rows on the posterior 

 surface of the first and second exopodal segments of leg 4 (Figure 

 31 A); by the wide anal operculum (Figure 28B); by the length of the 

 anterolateral seta (II) on the caudal ramus (Figure 28B); and by the 

 absence of cuticular pits from the urosomal somites in both sexes 

 (Figures 28A,B; 32A,B). 



Remarks 



P. hardingi, P. altissimus Karaytug, Boxshall & Defaye (in press), 

 P. longispina Karaytug, Boxshall & Defaye (in press) and P. 

 imminutus Kiefer 1929 are closely related. All four species pos- 

 sess a well-developed spinular row near the base of the two inner 

 setae on the coxobasis of the antenna in both sexes (arrowed in 

 Figures 29B; 32D). P. hardingi can easily be differentiated from P. 

 altissimus by the length and spinulation of the outer seta of leg 5, 

 the structure of the seminal receptacle (Figure 28A), the presence 

 of the mid-distal spinular rows on the posterior surface of the coxa 

 of legs 1-3, and the relative length of the anterolateral seta (II) on 

 the caudal ramus (Figure 28B). It differs from P. imminutus by 

 having a shorter outer seta of leg 5 (Figure 28C), in the structure 

 of seminal receptacle, the position of the mid-distal spinular row 

 on the posterior surface of the coxa of leg 1 , the absence of the 

 surface pits on the genital somite and urosomal somites in the 

 male, and the length of the anterolateral seta (II) on the caudal 

 ramus. P. hardingi can be differentiated from P. longispina by the 

 shorter outer seta of leg 5, the absence of the surface pits on the 

 genital somite and urosomal somites in the male, the presence of 

 the aesthetasc on the first segment of the male antennule, the 

 structure of the seminal receptacle, and the length of the anterola- 

 teral seta (II) on the caudal ramus. 



P. hardingi was first described by Lindberg ( 1 957) under the name 

 P. fimbriatus andinus, but Kiefer used the name P. andinus (Kiefer, 

 1957) earlier in the same year. Therefore. Lindberg's P. fimbriatus 

 andinus and Kiefer's P. andinus are primary homonyms. According 

 to the priority principle P. andinus Kiefer, 1957, published 1 March 

 1957, takes precedence over P. fimbriatus andinus Lindberg, 1957 

 published on 10 July 1957. The name P. fimbriatus andinus is a 

 junior homonym and is invalid (Article 52 (b)). P. fimbriatus andinus 

 Lindberg, 1957 must be replaced by a new name (Article 60). 



Etymology. The new name has been given in honour of the late 

 Dr. J. P. Harding. 



Distribution. P. hardingi was recorded only once, by Loffler 

 (1963), under the name P. fimbriatus andinus Lindberg, 1957 from 

 Ecuador, since its original description from Peru. 



Original description. Paracyclops fimbriatus baicalensisMaze- 

 pova, \96\:Trud.limnol.Inst.Moscou,2,22: 172-195 (p.177, fig. 2). 



TYPE LOCALITY. Russia, Lake Baikal 



Type material. 

 material. 



Mazepova (1961) did not designate any type 



Material examined. The redescription was based on two 

 topotypic females, collected on 19-20 August 1990 from a depth of 

 200 and 300 m in Lake Baikal. 



Redescription of adult female 



Body length excluding caudal setae 788-983 urn, mean = 886 |im. 

 n = 2. Fifth pedigerous somite without fringe of elongate setules at 

 posterior margin (arrowed in Figure 34A). Genital double-somite, 

 second and third abdominal somites without surface pits on dorsal 

 and ventral surfaces (Figure 34A.B). Seminal receptacle difficult to 

 observe, anterior lobe apparently small and narrow (Figure 34B). 

 Anal operculum broad and smooth (Figure 34A,D). Caudal rami 

 (Figure 34A,B) very short, about 1.3 times longer than broad. 

 Anterolateral seta (II) long and plumose with spinules at base; 

 posterolateral seta (III) spinulose with spinular row laterally at base 

 extending dorsally; terminal accessory seta spinulose (VI); outer 

 terminal seta (IV) and inner terminal seta (V) well developed and 

 heterogeneously ornamented (Figure 34B). 



Antennule short, compact, 8-segmented (Figure 35A,B): segment 

 3 with partial suture line and spiniform seta. Segment 5 with 

 characteristic short aesthetasc. Another short aesthetasc located 

 distally on anteroventral margin on segment 7. Apical segment with 

 aesthetasc fused to adjacent seta at base. Most of setal elements 

 highly spinulated. Setal formula 8, 12, 6, 5, 2 + aesthetasc, 2, 2 + 

 aesthetasc, 7 + aesthetasc. Coxobasis of antenna (Figure 35C.D) 

 with complex ornamentation on caudal and frontal surfaces; with 

 spinular row near base of inner setae on caudal surface (arrowed in 

 Figure 35D). Setal elements highly spinulated. 



Labrum (Figure 33C) broad posteriorly; posterior margin form- 

 ing strong teeth and ornamented with 2 patches of spinules on frontal 

 surface; ornamented with paired clusters of long spinules near 

 posterior margin. Mandible (Figure 33D) consisting of well devel- 

 oped coxal gnathobase with 3 lateral spinules distally. Palp 

 represented by 3 spinulose setae, 1 of which very long. 



Intercoxal sclerites of legs 1-3 (Figures 36A-D; 37A,B) without 

 spinular rows on anterior and posterior surfaces. Leg 1 with 3 setae on 

 terminal segment of exopod semispinulose; 2 setae on terminal 

 segment of endopod spinulose (arrowed in Figure 36C). Terminal 

 endopodal spine of leg 2 strong, naked and shorter than segment; three 

 setae on terminal segment of exopod and 1 seta on terminal segment of 

 endopod semispinulose (arrowed in Figure 36A). Leg 3 with 3 setae 

 on terminal segment of exopod and 1 seta on terminal segment of 

 endopod semispinulose (arrowed in Figure 37A). Intercoxal sclerite 

 of leg 4 without spinules on anterior surface (Figure 37C) and with 

 spinular row on posterior surface (Figure 37D); second endopodal 

 segment with 3 spinules on posterior surface; 3 setae on terminal 

 segment ofexopod (one arrowed in Figure 37C) and 1 seta on terminal 

 segment of endopod semispinulose and 1 seta on terminal segment of 

 endopod spinulose (arrowed in Figure 37C). 



Spine and seta formula as follows: 



Paracyclops baicalensis Mazepova, 

 (Figures 33-37) 



1961 





Coxa 



Basis 



Exopod 





Endopod 



Leg 1 



0-1 



1-1 



I— 1 ;I- 



1;III,5 



0- 



-1;0- 



4; 1,1.4 



Leg 2 



0-1 



1-0 



I— 1 ;I- 



-1;III,I,5 



0- 



-1;0- 



-2; 1,1,4 



Leg 3 



0-1 



1-0 



I-1;I- 



1;III,I,5 



0- 



-1;0- 



-2; 1.1,4 



Leg 4 



0-1 



1-0 



I-1;I- 



1;III,5 



0- 



-1;0- 



-2:1.11.2 



