Microphasma Woltereck 1909

Microphasma a gassizi Woltereck

(Figs. 33 & 34)

Microphasma agassizi Woltereck, 1909: 153–154, pl. 4, fig. 11. Pirlot 1929: 52. Stephensen & Pirlot 1931: 539–543, figs 15, 16. Pirlot 1939: 17. Shoemaker 1945: 218–219, fig. 23. Vinogradov 1957: 205; 1960a: 217–218; 1964: 126; 1970: 385 (table). Vinogradov et al. 1982: 105–107, fig 41. Vinogradov 1990: 51. Vinogradov & Semenova 1996: 617. Browne et al. 2007: 819 (table), fig. 4.

Type material. The unique female holotype could not be found in any major European museum or in the USNM and is considered lost. The type locality is detailed above.

Material examined. North Atlantic: Male, two females (USNM); near Bermuda, 800–1000 fathoms, 1929–1931. Female (ZMUC); S. of Newfoundland [40º15’N 50º37’W]; Michael Sars Stn. 67, 1200 m, 27 Jun. 1910. Female (ZMUC CRU-9934); S.W. of Cape Verde Is. [12°11’N 35°49’W]; Dana Stn. 1165 VII, 4000 mw, 9 Nov. 1921. South Atlantic: Female (ZMUC); off Gabon [04°00’S 08°25’E]; Galathea Stn. 66, 6300 mw, 5 Dec. 1950. Indian Ocean: Female (ZMUC CRU-9933); S. of Sri Lanka [05°21’N 80°38’E]; Dana Stn. 3909 IV, 3000 mw, 22 Nov. 1929. Southern Ocean: Female (USNM); between S. America & Antarctic Pen. [59°29’– 59°39’S 68°01’– 68°31’W]; Eltanin Stn. 247, 1830 m, 5 Oct. 1962. Female (USNM); south-eastern Pacific sector of Antarctic [60°00’– 60°18’S 82°40’– 82°41’W]; Eltanin Stn. 782, 3074m, 20 Oct. 1962.

Diagnosis. Body length of females up to 9.0 mm, of males up to 8.0 mm. Antennae 1 with peduncular articles and callynophore relatively broader and longer in males; terminal article elongate, slightly longer than preceding two articles combined. Antennae 2 length 0.8x A1 for females, slightly less for males; antennal gland grossly inflated, slightly deeper than long, almost as long as following articles combined. Gnathopod 1; basis slightly shorter than remaining articles combined; dactylus slightly curved, length about 0.6x propodus. Gnathopod 2; length about 1.3x G1; basis as long as remaining articles combined (excluding dactylus); dactylus length about 0.5x propodus. Pereopods 3 & 4 similar in structure and length, longer and stronger than other pereopoda; basis length about 2.3x merus; carpus slightly longer than merus (only marginally longer for P4); propodus almost as long as basis, broadened medially with about ten, relatively strong setae on distal half of posterior margin; dactylus elongate, almost half-length propodus, forming weak subchela with propodus. Pereopod 5; length 0.8x P4; basis length about twice merus; carpus length almost 0.7x merus; propodus slightly shorter than basis, slightly broadened distally with about seven pairs of relatively strong setae distally and for most of distal half of anterior margin; dactylus elongate, about half-length propodus, forming weak subchela with propodus. Pereopod 6 with relatively slender articles; slightly shorter than P5; basis length almost twice merus; carpus slightly shorter than merus, propodus length almost twice carpus, dactylus slightly shorter than half of propodus. Pereopod 7; length 0.8x P6; basis length almost 2.4x merus; carpus marginally longer than merus; propodus length about twice carpus; dactylus length about half propodus. Peduncles and rami of uropoda relatively narrow, lanceolate; margins of rami denticulate. Telson triangular, rounded; length slightly less than half of peduncle of U3.

Colour of unfixed specimens scarlet or vermilion (Shoemaker 1945) or cherry-red (Vinogradov 1957).

Remarks. This is a distinctive but relatively rare species with only nine previous records of specimens collected. The current material examined comprises one male and eight females.

Distribution. Previously recorded from the North Atlantic near Bermuda, Madeira, the Azores and Bay of Biscay; from the northern Indian Ocean including the Arabian Sea and from the north-western Pacific in the Kurile-Kamchatka region, the south-western Pacific near the Kermadec Islands and the tropical eastern Pacific ranging from off Mexico to Chile. Amongst the material examined are new records from the Southern Ocean and the tropical South Atlantic with range extensions in the North Atlantic south to the Cape Verde Islands. It remains to be recorded from the southern Indian Ocean. According to Vinogradov et al. (1982) it has been found in catches of 970–1920 m and 1900–3750 m and in total catches from depths of more than 2000 m to the surface. The Galathea collected one specimen with 6300 m wire.