62 



R. HUYS AND J. M. GEE 



of the middle segment is distinctly shorter than in the typical 

 male and its outer margin might bear spinules as in the 

 female; the inner seta — completely missing in the male — is 

 represented by a vestigial spine which is either entirely (Fig. 

 12C) or partly (Fig. 12D) invaginated. The distal segment is 

 almost identical to the female condition. The P3 endopod is 

 modified as in the male except that the inner seta of the 

 middle segment is distinctly longer than in the typical male 

 (but shorter than in the female). The P4 endopod grossly 

 resembles the male condition. The P5 also has the basic male 

 outline but the endopodal lobe is slightly more pronounced 

 and the inner exopodal seta is distinctly longer. 



Intersexuality within the Harpacticoida appears to be very 

 rare. Klie (1944) describes a female specimen of Amphias- 

 coides debilis (Giesbrecht, 1881) from Helgoland which dis- 

 played the male condition for the antennules (i.e. haplocer) 

 and the first thoracopods (i.e. modified basis) and the female 

 condition for the genital somite and the remaining append- 

 ages except for the P2 endopod which combined both male 

 and female features. Recently, Moore & Stevenson (1991) 

 found that 90% of a population of Paramphiascella hyper- 

 borea (T. Scott, 1903) in the vicinity of a sewage outfall in the 

 Firth of Forth, Scotland, were intersex specimens. In the 

 majority of these the prosome (including the antennules and 

 swimming legs) exhibited the female condition whilst the 

 urosome had the male condition of 6 distinct somites and a 

 plate-like P6, although the P5 was more similar to that of the 

 female. At the same site, a small number of intersex speci- 

 mens of Stenhelia gibba Boeck, 1864 and Halectinosoma 

 similidistinctum Lang, 1965 were also found. Intersexuality is 

 more common in other orders of copepods, particularly the 

 calanoids Eudiaptomus vulgaris (Schmeil, 1898), Arctodiap- 

 tomus (Rhabdodiaptomus) alpinus (Imhof, 1885), Eudiapto- 

 mus gracilis (Sars, 1863), Pseudocalanus elongatus (Boeck, 

 1864), Calanus hyperboreus Kr0yer, 1838, Paracalanus par- 

 vus (Claus, 1863) (Bremer, 1914; Pirocchi, 1940; Cattley, 

 1949; Francois, 1949; Conover, 1965; Ianora etal, 1987) and 

 cyclopoids Megacy clops gigas (Claus, 1857) and Megacy clops 

 viridis (Jurine, 1820) (Mrazek, 1913; Coker, 1938). 



In natural populations the frequency of occurrence of 

 intersexuality appears to be very low and may be a result of 

 infrequent chromosomal aberrations during embryonic devel- 

 opment. In cases of higher incidence, various causes of 

 intersexuality have been postulated. Coker (1938) attributed 

 it to low temperature during naupliar development; Cattley 

 (1949) to parasitism of the developmental stages by the 

 marine ectoparasitic dinoflagellate Blastodinium contortum 

 hyalinum Chatton; and Moore & Stevenson (1991) argued 

 that the very high incidence of intersexuality in the vicinity of 

 a sewage outfall strongly implicated some form of chemical 

 pollution as the causative factor. 



Genus Danielssenia Boeck, 1872 



Since the publication of Lang's (1948) monograph a number 

 of new species have been assigned to the genus Danielssenia 

 but recent analyses have shown this to be a heterogeneous 

 assemblage. In previous papers (see also Table 1) we have 

 removed D. intermedia Wells, 1965 to the genus Fladenia; D. 

 perezi Monard, 1935 (syn. D. paraperezi Soyer, 1970) and D. 

 eastwardae Coull, 1971 to the genus Sentirenia and propose to 

 remove D. spinipes Wells, 1967 and D. minuta Coull, 1969 to 

 two other new genera (Gee & Huys, 1990; Huys & Gee, 

 1992, in press). This has restricted the genus Danielssenia to 



the following species: D. typica; D. quadriseta Gee, 1988; D. 

 reducta Gee, 1988; D. robusta Sars, 1921 and D. similis 

 Chislenko, 1971. The status of D. fusiformis (Brady, 1880), 

 previously been synonymized with D. typica (cfr. Shen & Bai, 

 1956; Gee, 1988b) is reconsidered here. 



(i) Danielssenia fusiformis (Brady, 1880) nee Sars (1910) 



Brady (1880) created the genus Jonesiella to accommodate 

 two new species, /. fusiformis (Brady & Robertson) and J. 

 spinulosa (Brady & Robertson), and provided illustrated 

 descriptions for these species. Brady remarked that both 

 species had already been listed in an earlier report (Brady & 

 Robertson, 1876) as Zosime (?) fusiformis and Z. spinulosa, 

 respectively, and therefore unjustly concluded that both 

 authors had to be credited with the authorship. This state of 

 affairs has perpetuated in the nomenclature, even to the 

 present (e.g. Gee, 1988b), though it is clear that Brady & 

 Robertson's species names are mere nomina nuda and only 

 Brady (1880) should be cited as the author of both Jonesiella 

 species. Norman & Scott (1906) were the first to list J. 

 spinulosa Brady, 1880 as a junior synonym of Danielssenia 

 typica Boeck, 1872 and also changed J. fusiformis Brady, 

 1880 into D. fusiformis. Both species were redescribed and 

 illustrated by Sars (1910) who admitted that they were very 

 similar. It were also Sars' descriptions that led Shen & Bai 

 (1956) to conclude that both species were identical, and after 

 careful examination of Sars' material Gee (1988b) formally 

 relegated D. fusiformis sensu Sars (1910) to a junior synonym 

 of D. typica. There is, however, considerable evidence that 

 what Sars (1910) considered to be D. fusiformis in Norway is 

 clearly different from Brady's (1880) original material from 

 the Scilly Islands. Brady's type material does no longer exist, 

 but his illustrations (Plate XL VIII, Figs 1-13) of the female 

 antennule, mandible, maxilliped, PI, the fifth legs in both 

 sexes and the male endopod P2 leave no doubt that his 

 species is identical with D. perezi Monard, 1935, originally 

 described from Roscoff and later also recorded from the 

 Scilly Islands (Wells, 1968) — the type locality of J. fusi 

 formis. Huys & Gee (1992) recently synonymized D. para- 

 perezi Soyer, 1970 with D. perezi and established a new genus 

 Sentirenia to include the latter species and D. eastwardae 

 Coull, 1971. Sentirenia Huys & Gee, 1992, therefore, has to 

 be relegated to a junior synonym of Jonesiella, thus encom- 

 passing the type species /. fusiformis Brady, 1880 nee Sars 

 (1910) (syn. nov.: Danielssenia perezi Monard, 1935; D. 

 paraperezi Soyer, 1970) and/, eastwardae Coull, 1971 comb. 

 nov. 



Thompson's (1893) illustration of the female antennule 

 suggests that his record of/, fusiformis from Liverpool Bay is 

 correct. Re-examination of specimens (7 $9 labelled D. 

 fusiformis; Norman collection, reg. no. 1911.11.8.43561-565, 

 gift from T. Scott; October 1899) collected in the Firth of 

 Clyde indicates that the species might be distributed along the 

 entire west coast of Britain. Lang's (1936a, b) specimens from 

 the Oresund and Spitzbergen clearly belong to D. typica. All 

 other records of D. fusiformis have to await confirmation (see 

 list in Lang, 1948). 



(ii) Danielssenia robusta Sars, 1921 



Lang (1948) was of the opinion that D. robusta (and D. 

 perezi) probably would require the definition of additional 

 species groups inside the genus but as the males were still 





