BASAL LAOPHONTID EVOLUTION 



87 



1-[1], 2-[8 + 1 pinnate], 3-[7], 4-[2], 5-[8 + 1 pinnate spine + 1 

 spinous process + (2 + ae)], 6-[l + 3 processes], 7-[8 + acrothek]. 

 Apical acrothek consisting of aesthetasc and 2 bare setae. 



P3 endopod (Fig. 24C, G) 2-segmented; enp-1 as in 9; enp-2 with 

 3 inner setae (proximal one being distinctly shorter than in 9), 2 long 

 apical setae and short pinnate outer spine (fused basally to segment); 

 tube-pore present near outer apical seta. 



P5 (Fig. 24D) medially fused, positioned ventrolaterally. 

 Baseoendopod without endopodal lobe or armature; medial margin 

 with few setules and 2 tube-pores (longest arrowed); outer basal seta 

 arising from long, articulating, cylindrical setophore. Exopod free, 

 rectangular; with 1 long pinnate setaapically; inner margin proximal 

 seta and distal bipinnate spine; outer margin with 2 bare setae. 



Sixth legs represented by well developed opercula, one articulat- 

 ing and closing off left or right genital aperture; each produced into 

 cylindrical process bearing 1 lateral and 1 apical seta. 



Remarks. Drzycimski (1969) corrected two major errors in Sars' 

 (1908) description. First, he pointed out the presence of the thin 

 inner seta on the proximal endopod segment of PI. Within the 

 Laophontidae this element is further only found in Arehilaophonte 

 maxima. Secondly, Drzycimski remarked that the inner seta on the 

 baseoendopod of the male P5 is not well developed as in Sars' 

 illustration but greatly reduced. In reality, Drzycimski referred to the 

 short hyaline tube-pore located closely to the exopod whereas in 

 Sars' (1908) illustration it was the longer medial tube-pore (arrowed 

 in Fig. 24D) which was misinterpreted as a genuine seta. One 

 character that has traditionally been used to differentiate A. typhlops 

 from A. longiremis is the setation of the female P5 exopod. This 

 distinction is invalid since it is based on the erroneously reported 

 absence of the proximal surface seta in Sars' description of A. 

 typhlops. The same error also served to distinguish E. typhlops 

 pontoica from the type population (Por, 1959, 1964a). 



Reliable records of A. typhlops include Flekkero (Sars, 1908), 

 Bergen ( Drzycimski, 1969) and Frierfjord/Langesundfjord (this 

 account) in Norway, Gullmar Fjord (Lang, 1948) and the Isle of 

 Bonden (Por, 1964a) in Sweden, and Norfolk in England (this 

 account). The Scottish records from the River Ythan (Aberdeen- 

 shire) by Hockin & Ollason ( 198 1 ) and Hockin ( 1982a-o, 1984) and 

 that from Newbiggin (Northumberland) by Moore (1973) may be 

 based on A. longiremis. 



Archesola longiremis (T. Scott, 1905) comb. nov. 



Laophonte longiremis T. Scott, 1905 



Esola longiremis (T. Scott, 1905) Lang (1948) 



Type LOCALITY. Granton, Firth of Forth, Scotland; old quarry 

 opening to the sea (T. Scott, 1905, 1906). 



Type material. T. Scott (1905) recorded an unspecified number 

 of females; this material has not been deposited in any of the British 

 museums (London, Newcastle-upon-Tyne, Edinburgh) and is there- 

 fore almost certainly lost. 



Remarks. This species is very close to A. typhlops and can be 

 differentiated primarily by the shorter caudal rami (only twice as 

 long as wide) and the smaller body size (0.6 mm). Lang (1948) 

 pointed out that T. Scott's (1905) drawing of the P5 showed an 

 aberrant setation on the endopodal lobe (total of 7 setae: 3 inner, 3 

 apical, 1 outer). The short apical seta is almost certainly the equiva- 

 lent of the long tube-pore found in this position in A. typhlops, 

 however, the presence of the supernumerary outer seta is more 

 difficult to explain since no laophontoidean is known to display 

 more than 5 elements on the endopodal lobe of the female P5 (Huys, 



1990a; Huys & Lee, 1999). We suspect that this seta is the result of 

 an observational error. 



The species has never been figured again since T. Scott ( 1 905 ) nor 

 has the male been discovered. Wells ( 1961 ) illustrated some features 

 of a male specimen from St. Martin's (Isles of Scilly) which he 

 attributed to E. longiremis. The P5 shows only 3 setae on the exopod 

 and the endopodal armature is represented by 2 fine setae (one of 

 which likely to be a tube-pore). The P6 bears 2 strong setae but is not 

 drawn out into a cylindrical process as in other species of the genus. 

 These characters in conjunction with his statement that the male 

 antennule is subchirocerate and the endopod 3-segmented clearly 

 exclude the possibility that Wells was dealing with a species of 

 Archesola or any other esolinid genus. Wells (1963) also recorded 

 the species from Exmouth (Devon) but this record remains uncon- 

 firmed. 



The genus Archesola consists of a complex of closely related 

 species which can be differentiated primarily by morphometric 

 characters, such as caudal ramus length and PI exopod: endopod 

 ratio, and various setal length differences on the P5. Coull's (1971) 

 identification of E. longiremis from North Carolina suggests an 

 amphi-Atlantic distribution for the genus Archesola, however, in 

 view of the relatively subtle differences between congeners, the 

 specific identity of his record remains to be confirmed. 



Archesola hamondi sp. nov. 



Type locality. 53°10.34'N 00°56.34'E; depth 12-13 m; fine 

 sand with high silt and shell gravel content. 



TYPE MATERIAL. This species is only known from the holotype 9 

 (leg. R. Hamond; 06 May 1992) which unfortunately was acciden- 

 tally destroyed before the description could be completed. The brief 

 description below provides sufficient information to warrant the 

 proposal of a new species. 



ETYMOLOGY. This patronym is dedicated to Dr Richard Hamond 

 who collected the holotype, in recognition of his significant contri- 

 butions to laophontid systematics. 



Description. 



female. Body length from anterior margin of rostrum to posterior 

 margin of caudal rami 600 pm. 



Body (Fig. 21 A) dorsoventrally depressed and much wider than 

 in A. typhlops; covered with dense pattern of minute surface lamel- 

 lae dorsally and laterally. Cephalothorax bell-shaped, distinctly 

 widening towards posterior margin; lateral and hind margins fringed 

 with long setules; without paired cup-shaped pores. Setular fringes 

 also present laterally on pedigerous somites and urosomites, some- 

 times forming tufts locally. Posterior margin of urosomites without 

 distinct ornamentation dorsally except for penultimate somite bear- 

 ing transverse row of fine spinules. 



Genital double-somite (Fig. 21 A) wide and dorsoventrally flat- 

 tened; original segmentation marked by bilateral constriction only; 

 without cup-shaped pores in anterior half; lateral lobes without 

 backwardly directed strong spinules. Genital field as in A. typhlops. 



Anal somite (Fig. 24E) with distinct setular fringe around anal 

 opening; anal operculum completely bare; posterolateral margins 

 with fine spinules. 



Caudal rami (Fig. 24E) cylindrical and slightly swollen in anterior 

 half; distinctly wider than in A. typhlops; about 3 times as long as wide. 

 Seta II shorter and seta III posteriorly displaced compared to A. 

 typhlops; seta IV reduced, lacking fracture planes, shorter than caudal 

 ramus; seta V well developed, pinnate, without fracture planes; setae 

 VI-VII naked. Large vent-pore present at outer subdistal corner. 



