Discussion

There seem to be no differences between the specimens from Thysites atun and Jordanidia solandri except that the combined second and third thoracic segments are longer in the latter (1.43 mm - 1.67 mm) than in the former (1.71 mm - 2.26 mm).

Lernanthropus foliaceus was found and named, but not described, by Richiardi (1878, p.20). Goggio claimed to have identified this species and gave a description and figure (pl. 2 (1), fig. 1). Like Richiardi (1878, p.20, 1880, p. 150), Goggio obtained his specimens from Thyrsites pretiasus from the Mediterranean. Goggio's specimens are considerably larger than mine (15.5 mm compared to 6.5 mm - 6.8 mm) but this difference by itself is not systematically significant.

The figure and description given by Goggio agree well with the present material in the general form of the body and in those details of the appendages that Goggio recognised. In particular the one-segmented first antennae, the vertically directed third pereiopod, convexly curved anteriorly, the lateral margins directed posteriorly and the fourth pereiopods extending well beyond the plate of the fourth thoracic segment and with their rami narrowing to filiform posterior extensions leave little doubt that the present specimens belong to Goggio's species.

Further confirmation is given by Goggio's statement that the egg strings are "aggrovigliati" (entangled) beneath the dorsal plate. This coiling of the egg strings further indicates that this species must be transferred to the genus Paralernanthropus as defined in this paper.

The genus Pseudolernanthropus was erected by Yamaguti and Yamasu (1960, p.146) who made P. epinephali the type species. They suggested that Lernanthropus peter si van Beneden, 1857 should be transferred to this new genus. Later, Yamaguti (1963, p.153 - 154) expanded the genus to include Sagum posteli Delamare-Debouttville and Nunes-Ruivo, 1954, Lernanthropus angulatus Krøyer (which Wilson, 1922, p.28, had considered a species of Sagum) and Sagum texanus Pearse, 1952, p.32. In no case does Yamaguti discuss the reasons for transferring these species to Pseudolernanthropus.

Pillai and Sebastian (1967, p.73) redescribed P. epinephali and gave good grounds for considering that it should be placed in the genus Sagum. With much less discussion they also placed all the other species placed by Yamaguti as Pseudolernanthropus in the genus Sagum.

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However, descriptions of L. petersi, S. posteli and S. texanus (in the case of L. petersi van Beneden, the original description was not available and figures by Yamaguti (1963, pl. 168, fig. 6) and Barnard (1955, fig. 19) were consulted) make it clear that in all cases (1) the eggs are coiled up between the fourth pereiopods and plate of the fourth segment. (2) the fourth pereiopods are clearly visible in ventral view, and (3) posterolateral extensions of the third and fourth thoracic segments are not fused with the exopod of the third pereiopod; on these criteria I consider these species belong to Paralernanthropus as defined in this paper.

Krøyer in his description of L. angulatus suggests that the third pereiopod ("Femte Fodpar") is fused in part to the thorax and further, that the fourth pereiopod ("Sjette Fodpar") has a soft, whip-like flagellum as later described by Wilson for Sagum flagellatum. Krøyer queries the function of these structures, as did Wilson fifty-nine years late. It is clair that the soft flagellum is not just a sudden narrowing of the lamellar ramus as found in most species of Paralernanthropus. I therefore agree with Wilson (1922, p.28) and Pillai and Sebastian (1967, p.79) that L. angulatus is referable to Sagum and should be Sagum angulatus (Krøyer).

The present species, P. foliaceus, is quite unlike any of the other described species of Paralernanthropus. It differs from P. posteli and P. texanus in lacking the sudden narrowing of the fourth pereiopods. In P. foliaceus and P. petersi these pereiopods narrow gradually towards the posterior tip. P. foliaceus differs from P. petersi in having broadly laminate fourth pereiopods (width about half length) and a long fourth thoracic segment plate (more than half body length) while in P. petersi the length of the fourth pereiopods are many times their width and the fourth thoracic segment plate is much less than half body length.

In some characters, e.g. the longer body shape and form of the fourth pereiopods, P. foliaceus resembles members of the genus Lernanthropus to a greater extent than do other species of Paralernanthropus.