Paraphronima gracilis Claus 1879

Paraphronima gracilis Claus (Fig. 37)

Paraphronima gracilis Claus, 1879: 7 (65)–8(66), pl. 1, figs 4 & 5.

Paraphronima edwardsi Bovallius, 1885: 12.

Type material

Type material of P. gracilis could not be found at the ZMB or ZMH and is considered lost. However, the description and figures provided by Claus (1879) are sufficient to characterise this species. The type locality is the “Atlantic Ocean”. No specific locality is given by Claus (1879).

Type material of synonyms

Type material of P. edwardsi could not be located at the SMNH, ZMUC or in Uppsala and is considered lost. Bovallius (1889) regards it a synonym of P. gracilis, which is consistent with his original description.

Material examined (> 100 specimens)

Tasman Sea: 8 lots (SAMA), 8 specimens. North Atlantic: 1 lot (BMNH), 2 lots (CMN), 13 lots (USNM), 8 lots (ZMB), several lots (ZMUC), numerous specimens. South Atlantic: 3 lots (BMNH), 3 specimens. North Pacific: 2 lots (CMN), several lots (LACM), 13 lots (USNM), numerous specimens. Indian: 1 lots (BMNH), 1 specimen. Arabian Sea: 1 lot (BMNH), 3 specimens. Central Indo­Pacific: 3 lots (USNM), 5 specimens.

Diagnosis

Body length up to 17 mm, but usually 10 mm. Head slightly shorter than deep. Pereonites 1–2 much narrower than pereonite 3. Pereopods 5–7; anterior margin of ischium to propodus with several small robust setae. Pereopod 7 only as long as basis to carpus of P6. Pleonite 1; ventral margin of epimeral plate forms acute angle with body axis anteriorly.

Remarks

This species closely resembles its only congener, P. crassipes, and Hurley (1956) even suggested (but rejected) the idea that P. crassipes may be a later moult stage, because it tends to be larger and more robust than P. gracilis. However, the characters given in the key and the above diagnosis readily distinguish P. gracilis. According to Brusca (1981), the spination of pereopods 5–7 and the shape of pleonite 1 are particularly reliable characters.

This species has not been recorded with a gelatinous plankton associate but because of its similarity to P. crassipes, like that species, it is probably associated with siphonophores.

Distribution

This species is widely distributed in tropical and temperate regions, including the eastern part of the Mediterranean Sea. It does not occur beyond the limits of the Subtropical Convergences (Vinogradov et al. 1982).