Paraphronima Claus 1879

Genus Paraphronima Claus, 1879

Paraphronima Claus, 1879: 6–7. — Bovallius 1885: 9–10. Carus 1885: 424. Gerstaecker 1886: 489. Stebbing 1888: 1335–1337. Bovallius 1889: 23–25. Chevreux & Fage 1925: 389. Pirlot 1929: 104. Hurley 1955: 136. Vinogradov et al. 1982: 256. Vinogradov 1999: 1177.

? Daira Milne­Edwards, 1830: 392­393. — Milne­Edwards 1840:83.

Dairinia — (part) Bate 1862: 309.

Type species

Paraphronima gracilis Claus, 1879. Type material could not be found at the ZMB or ZMH and is considered lost. However, Paraphronima is a readily recognisable genus.

Diagnosis

The characters of the family are also those of the genus.

Two species.

Sexual dimorphism

Paraphronima is unusual in that coxae 2–5 are separate in females, whereas in males all of the coxae are fused with the pereonites.

As with most hyperiideans, the morphology of the antennae is a useful means to differentiate the sexes. The first antennae are slightly shorter than the head in males and less than half the length of the head in females, and the callynophore of males is slightly inflated, with a two­field brush of aesthetascs on the medial surface. The second antennae of females are reduced to two articles, and are only about half as long as the first antennae, whereas in males they are about as long as the first antennae, with the basal and terminal article greatly elongated. The head of males also seems to be slightly smaller and more rounded than in females.

Remarks

Paraphronima is a very distinctive genus that does not resemble any other hyperiidean. There are six nominal species referable to Paraphronima, but only two are recognised in this review.

The large eyes indicate an active pelagic life­style, and in freshly caught plankton samples Paraphronima is usually the most active hyperiidean. Both species are often found in surface waters but rarely below 500 m (Vinogradov et al. 1982), and seem to undergo diurnal vertical migrations (Brusca 1967a, Thurston 1976). The main reproductive period seems to be at the end of Summer and in Autumn (Brusca 1967b, Vinogradov et al. 1982), although females with eggs are found throughout the year (Brusca 1967b). Only one species, P. crassipes, has been found in association with siphonophores (Lo Bianco 1909, Harbison et al. 1977, Laval 1980).

The two species are very similar morphologically, and many errors in identifications were found in the various collections examined. Often both species are present in the one sample! It is therefore pointless to provide a full reference list for each species, and only synonymies are given in the following text.

It should be noted here that Claus (1878: 270) mentions Paraphronima in a general paper on hyperiideans but does not provide any characters to distinguish it from other genera. Obviously Claus intended this paper to follow his diagnosis of the genus in 1879. As Claus (1878) did not diagnose the genus, and for the sake of nomenclatural stability, Paraphronima should be credited with Claus (1879).