Metalanceola chevreuxi Pirlot 1931

Metalanceola chevreuxi Pirlot

(Figs 25 & 26)

Metalanceola chevreuxi Pirlot, 1931: 1–7, fig 1–3. Pirlot 1939: 13–16, pl. 1, figs 6–8. Shoemaker 1945: 215. Vinogradov 1960a: 210–211, figs 6, 7; 1964: 118. Vinogradov et al. 1982: 86–88, figs 27, 28.

Type material. The unique male holotype is in the MOM (37 2105) mounted on microscope slides. According to Pirlot (1931) the specimen measured 4 mm from the head to the bend of the abdomen, but the total length is about 6 mm, according to the scales with his illustration of the whole animal. The type locality is the North Atlantic, near Madeira [31°06’N 24°06’45”W]; Princesse Alice II Stn. 1781 (not 1871 as published), 0–5000 m, 21 Aug. 1904.

Material examined. North-East Atlantic: Female (ZMUC); W. of Sierra Leone [08°26’N 15°11’W]; Dana Stn. 4003 V, 2000 mw, 9 Mar.1930. Two males, two females (ZMUC); Bay of Biscay [46°28’N 08°01’W]; Dana Stns 4158 XVI & XXII, 2000 & 5500 mw, 17 Jun. 1930. South–East Atlantic: Male (ZMUC); off Gabon [04°00’S 08°25’E]; Galathea Stn. 66, 6300 mw, 5 Dec. 1950. Three males (ZMUC); off South Africa [23°26’S 03°56’E]; Dana Stn. 3980 X, 2000 mw, 17 Feb. 1930. South-East Pacific: Male (ZMUC); tropical S.E. Pacific [04°20’S 116°46’W]; Dana Stn. 3561 IV, 2000 mw, 24 Sept. 1928. Central South Pacific: Male (ZMUC): N. of Tahiti [14°01’S 147°51.5’W]; Dana Stn. 3570 II, 3000 mw, 7 Oct. 1928. Male, female (ZMUC); N. of Cook Is. [18°53’S 163°02.5’W]; Dana Stn. 3580 IX, 2000 mw, 25 Oct. 1928. Male (ZMUC); E. of New Caledonia [20°00’S 174°29’E]; Dana Stn. 3602 VII, 3000 mw, 22 Nov. 1928. Male, female (ZMUC CRU-9931); N. of New Zealand [28° 17.6’S 177° 01’E]; Dana: Stn. 3624 IV, 2000 mw, 10 Dec. 1928. West Indian: Male (ZMUC); btwn. Maldive Is. & Madagascar [01°06’S 62°25’E]; Dana Stn. 3920 VI, 1000 mw, 9 Dec. 1929.

Diagnosis. Body length up to 8 mm. Cuticle relatively thin, without keels or spines. Head relatively short, without rostrum. Pereon slightly inflated, more so in females than males. Pereonite 2 projected forward dorsally over pereonite 1, almost reaching head. Pereonites 4–6 with slight dorsal depression. Eyes very small, roundish. Antennae 1 almost as long as head and first two pereonites combined (slightly shorter in males); peduncular articles and callynophore relatively broader in males; callynophore of male as broad as peduncle, in females slightly narrower than peduncle, tapering gradually and relatively longer than in males; terminal article rounded with convex margins, slightly longer than preceding article which is in turn about twice as long as preceding article; the latter two with slightly convex margins. Antennae 2 shorter than A1, about 0.6x A1 for females and 0.5x A1 (or less) for males. Gnathopod 1 simple; basis slightly broadened, a little longer than remaining articles combined; propodus relatively more conical than species of Lanceola. Gnathopod 2 relatively slender; slightly longer than G1. Pereopod 3 similar to, but slightly longer than P4; basis length more than twice merus; carpus length about 1.3x merus (slightly less for P4); propodus length 1.2x carpus; dactylus relatively long, about 0.6x propodus. Pereopods 5–7 slender with relatively large, retractile and fully hooded dactyls; spoon-shaped formation hypertrophied. Pereopod 5 slightly shorter than P3 or P4; basis length almost 2.4x merus; carpus slightly longer than merus; propodus length slightly more than 1.6x carpus. Pereopod 6, slightly longer than P3, 1.2x length P5; basis length 1.6x merus; anterior margin of merus distinctly concave; carpus slightly longer than merus; propodus length almost 1.5x carpus. Pereopod 7 slightly stronger in males; length 0.8x P6; basis length 2.5x merus; carpus slightly shorter than merus; propodus length 2.3x carpus. Peduncle and rami of uropoda relatively narrow, lanceolate; margins of rami highly denticulate. Telson rounded; length slightly more or less than half peduncle of U3.

Colour of living specimens not recorded but Vinogradov et al. (1982) record the eye colour as carmine–red in unfixed specimens.

Remarks. This seems to be a very rare species with only four previous records of specimens collected. The Dana collections (and one from Galathea) comprising of five females and twelve males represent the largest single collection of this species to date.

Distribution. A widely distributed, although rare, species. Previously recorded from the North Atlantic near Madeira and Bermuda; from the tropical Pacific between the equator and 28°55’S and from the tropical Indian Ocean between the equator and 05°S. The Dana collected it from all major oceans with new records for the South Atlantic. In the North Atlantic its distribution is extended north to the Bay of Biscay [46°28’N] but most of the other specimens came from tropical waters, with most coming from the Atlantic and Pacific Oceans. It remains to be recorded from the North Pacific and northern parts of the Indian Ocean. According to Vinogradov et al. (1982) it has been found in catches of 985–2000 m and 1900–3300 m and in total catches from depths of more than 1800 m to the surface. Similarly, the Dana collected only one specimen with 1000 m of wire, the remainder were all collected with at least 2000 m of wire.