BASAL LAOPHONTID EVOLUTION 



;i 



MALE. Body length from anterior margin of rostrum to posterior 

 margin of caudal rami 581 urn (n=3, range 570-595 urn). Maximum 

 width (248 urn) measured at posterior margin of cephalothorax. 

 Length of 6* copepodid V: 571 urn. 



Body (Fig. 19A) very dorsoventrally depressed, covered with 

 dense pattern of minute spinules as in 9. Pattern of cup-shaped pores 

 as in 9 except for paired lateral pores present on genital somite. 

 Cephalothorax much wider than free somites, posterolateral angles 

 backwardly produced. Posterior margin of cephalothorax and all 

 body somites with row of long spinules dorsally and laterally. 

 Pedigerous somites decreasing in width posteriorly. Urosome (Fig. 

 19B) slender and narrow; pleurotergite of P5-bearing somite nar- 

 row; posterolateral corners of all urosomites with spinular tuft and 

 posterior margin with spinules all around. 



Genital somite with large cup-shaped pores laterally, each partly 

 closed off by fringe of setular extensions (Fig. 19D); ventral surface 

 without spinular ornamentation except for spinule row around pos- 

 terior margin. Sixth legs represented by membranous flaps, one 

 articulating and closing off left or right genital aperture; without 

 armature at outer corner. 



Antennule (Fig. 20A-C) 7-segmented, subchirocer, with 

 geniculation between segments 5 and 6. Segment 1 with spinules/ 

 setules around anterior margin. Segment 2 with minute knob near 

 dorsal posterior margin. Segment 4 minute, represented by incom- 

 plete sclerite. Segment 5 with spinous outgrowth on anterior margin, 

 probably interlocking with similar processes on segment 6 (Fig. 

 20C); forming cylindrical process bearing long aesthetasc. Segment 

 6 with bilobed outgrowth on ventral surface near posterior margin. 

 Distal portion of segment 7 elongate, displacing acrothek to position 

 isolated from other armature. Armature formula: 1-[1 pinnate], 2-[4 

 + 5 pinnate], 3-[7 + 1 pinnate], 4-[2], 5-[7 + 1 pinnate + 1 spine + (2 

 + ae)], 6-[l +2 processes], 7-[7 + acrothek]. Apical acrothek 

 consisting of aesthetasc and 2 bare setae. 



P2 exopod (Fig. 17G). Outer spines of all segments with much 

 longer pinnules than in 9. 



P3 (Fig. 18B, E). Exopod more robust than in 9, slightly bent 

 medially; outer spine of exp-1 with longer pinnules than in 9; middle 

 and distal outer spines and apical spine of exp-3 enlarged, with 

 minute spinules; inner and inner apical setae reduced in length. 

 Endopod 3-segmented; enp-1 larger than in 9, densely setulose 

 along outer margin; enp-2 with inner seta and short outer apophysis 

 bearing small spinous processes along both inner and outer margin 

 (Fig. 18E); enp-3 small, with long tube-pore and 4 setae. 



P4 exopod (Fig. 18D). Proximal segment slightly more robust 

 than in 9. Outer spines of exp-2 and -3 stubby and somewhat 

 enlarged; spinules typically longer than in 9. 



P5 (Fig. 19C) medially fused (Fig. 19B) positioned ventrolater- 

 ally. Baseoendopod without endopodal lobe; medial margin with 

 setules and tube-pore; outer basal seta arising from short spinulose 

 pedestal. Exopod free; with 3 multipinnate ( 1 apical, 2 outer) and 2 

 bipinnate (inner) setae, all well developed. 



Remarks. Thompson & A. Scott (1903) illustrated the female P5 

 with only 3 setae on the baseoendopod, a character included with 

 hesitation by Lang (1948) in the diagnosis of the species. Re- 

 examination revealed that the innermost seta on the endopodal lobe 

 was overlooked. This seta is implanted medially at considerable 

 distance from the others and was also missed by Norman (191 1) in 

 his description of Laophonte bulbifera. According to Lang's (1948) 

 table XXIV the swimming leg armature formula is constant within 

 the longicauda-group, including amongst other patterns the pres- 

 ence of the outer spine on P2 enp-2. One cannot but conclude that 

 Lang (1948) must have overlooked Gurney's (1927) statement that 



this segment has 2 inner and 2 apical setae. The present redescription 

 has revealed the sexual dimorphism of the exopods of P2 and P4, the 

 presence and pattern of integumental cup-shaped pores, and the 

 detailed morphology of the genital area in both sexes. 



Krishnaswamy's (1957) redescription is grossly inadequate and 

 potentially misleading. The ramus labelled 'P2 end 6*' is the male P3 

 endopod, his illustration of the female P2 is in fact based on the P3 

 and the real P2 is figured as the P7(!). In view of these inaccuracies 

 the tabulated setal formula and the author's remarks on the generic 

 placement of the species are best ignored. Krishnaswamy's descrip- 

 tion of the first copepodid is of similarly abominable quality. 



Genus Archesola gen. nov. 



This genus is proposed to include Esola typhlops and a number of 

 closely related species. It is difficult to understand why Lang ( 1 965 ) 

 regarded Laophonte lamellipes Nicholls as most closely related to E. 

 typhlops. This doubtful statement was based on the similarity in the 

 long caudal rami and the erroneous fact that males of both species 

 show no modifications on the P3 endopod. Noodt (1955) suggested 

 a relationship with the Laophonte setosa-group but did not elaborate 

 on this view. Re-examination of Nicholls' (1944) type material 

 (BMNH 1947.10.6.23-27) revealed the true nature of the modified 

 male P2 endopod, confirming close affinity with the genus 

 Paralaophonte Lang. 



DIAGNOSIS. Laophontidae. Body cylindrical or dorsoventrally 

 depressed; posterolateral corners of 9 genital double-somite and 

 second abdominal somite laterally but not backwardly produced. 

 Integument of cephalothorax and body somites with irregular pat- 

 tern of minute surface lamellae. Rostrum large, partly delimited at 

 base by surface furrow. Integumental cup-shaped pores absent on 

 cephalothorax, genital (double-)somite and caudal rami. Anal oper- 

 culum smooth or bordered with spinules. Caudal rami cylindrical 

 and elongate; not sexually dimorphic. 



Sexual dimorphism in antennule, P3 endopod, P5, P6 and in 

 genital segmentation. 



Antennules slender; 7-segmented in 9, haplocer and 7-segmented 

 in 6; segments 1-2 without spinous processes along posterior margin; 

 with aesthetasc on segment 4 ( 9) or 5 ( 6) and as part of apical acrothek 

 on distal segment; segment 5 6 not swollen, without anterior out- 

 growth but with very long cylindrical pedestal for aesthetasc; proximal 

 aesthetasc fused to 2 setae. Antenna with 4 setae on exopod; allobasis 

 with abexopodal seta. Labrum with distal spinular ornamentation. 

 Mandible with discrete 1 -segmented exopod bearing 1 seta; endopod 

 (3 setae) and basis (2 setae) incompletely fused. Maxillule with 

 minute, defined exopod. Maxilla with 3 endites on syncoxa; endopod 

 represented by 4 setae. Maxilliped slender; syncoxa with 2 setae; 

 palmar margin naked; endopodal claw elongate. 



PI with 3-segmented exopod bearing 4 setae on exp-3 and 

 elongate endopod; enp- 1 with inner seta, enp-2 with minute seta and 

 strong claw. P2-P4 with 3-segmented exopods and 2-segmented 

 endopods. P2 basis with long outer spine. Outer spine of P2-P4 enp- 

 2 setiform and very long in P3-P4. P3 endopod 6 2-segmented; 

 enp-2 with 3 inner setae and short outer basally fused spine. Arma- 

 ture formula as follows: 



Exopod 



Endopod 



P2 



0.1.123 



1.221 



P3 



0.1.223 



1.321 



P4 



0.1.223 



1.221 



[9andcJ] 



