Microphasma Woltereck, 1909

Zeidler, Wolfgang, 2009, A review of the hyperiidean amphipod superfamily Lanceoloidea Bowman & Gruner, 1973 (Crustacea: Amphipoda: Hyperiidea), Zootaxa 2000, pp. 1-117 : 89-90

Genus Microphasma Woltereck, 1909

Microphasma Woltereck, 1909: 153 . Pirlot 1929: 52. Stephenson & Pirlot 1931: 539. Bowman & Gruner 1973: 17. Vinogradov et al. 1982: 105.

Type species. Microphasma agassizi Woltereck, 1909 by monotypy. The unique type, a female measuring about 6.5 mm (according to Woltereck’s figure), could not be found in any major European museum or in the USNM and is considered lost. Fortunately , this is a very distinctive species, readily distinguished by Woltereck’s description and figure. The type locality is the eastern tropical Pacific, off Peru [11º20’S 88º55’W]; Albatross Stn. 4663 .

Diagnosis. Body length of females up to 9.0 mm, of males up to 8.0 mm. Head without rostrum. Eyes small, poorly discernable. Antennae 1 relatively short; in female slightly shorter than head and first pereonite combined, slightly longer in male. Antennae 2 slightly shorter than A1 with enlarged antennal gland. Mandibles with body narrowed distally; palp as long as body, third article only marginally shorter than second. Gnathopoda simple. Pereopods 3–5 subchelate with dactylus closing against distally broadened propodus. Pereopods 6 & 7 simple.

Monospecific.

Sexual dimorphism. Males are readily distinguished from females by relatively larger first antennae that are as long as the head and first two pereonites combined if measured ventrally. Males also have small genital papillae, medially near the base of the seventh pereopods and in females the pereon is slightly more inflated.

Remarks. This is a very distinctive genus, readily distinguished by the subchelate pereopods 3–5. It is very similar to Microphasmoides Vinogradov, 1960 , especially in the general habitus, antennae and structure of the mouthparts, differing mainly in that pereopods 3 & 4 are simple in Microphasmoides .

Microphasma is similar to Lanceola in the general structure of the mouthparts but the second antennae are similar to that found in Chuneola in that they have an enlarged antennal gland.