Mimonecteola macronyx Barnard

Zeidler, Wolfgang, 2009, A review of the hyperiidean amphipod superfamily Lanceoloidea Bowman & Gruner, 1973 (Crustacea: Amphipoda: Hyperiidea), Zootaxa 2000, pp. 1-117 : 100-103

Mimonecteola macronyx Barnard

( Figs 38 & 39)

Mimonecteola macronyx Barnard, 1932: 251–252 , fig. 158. Vinogradov 1964: 124-125.

Type material. The unique type, an immature male specimen measuring 9.3 mm, is in the BMNH (1936.77.2.247a), in spirit. The type locality is the eastern mid-Atlantic [02°49’S 09°25’W]; Discovery Stn. 287, 800– 1000 m, 19 Aug. 1927.

Material examined. Types. The holotype as detailed above.

Other material examined. North-East Atlantic: Two males, three females ( ZMUC); W. of Sierra Leone [08°26’N 15°11’W]; Dana Stn. 4003 I, IV & V, 6000, 3000 & 2000 mw, 9 Mar. 1930 . Two males ( ZMUC); W. of Senegal [13°31’N 18°03’W]; Dana Stn. 4005 II, 3500 mw, 12 Mar. 1930 . South-East Atlantic : Male, female, juvenile ( ZMUC); off South Africa [23°26’S 03°56’E]; Dana Stn. 3980 VII, 5000 mw, 17 Feb. 1930 . Male , female ( ZMUC); S.W. of Gulf of Guinea [07°34’S 08°48’W]; Dana Stns 3998 IX & X, 3000 & 2000 mw, 1 Mar. 1930 . North Pacific : Male, female ( SAMA C6307 ); off Pismo Beach, California [35º50’N 122º40’W]; Monterey Bay Aquarium Res. Inst., 450-650 m, 15 May 2006 . Male , two females ( ZMUC); Gulf of Panama [06°48’N 80°33’W]; Dana Stns 1208 V & XIV, 3000 & 3100 mw, 16 Jun. 1922 . South Pacific : Female ( ZMUC); SE of Panama [00°18’S 99°07’W]; Dana Stn. 3558 II, 2000 mw, 18 Sept. 1928 . Female ( ZMUC); near Samoa [11°00’S 172°37’W]; Dana: Stn. 3587 IV, 3000 mw, 2 Nov. 1928 . Juvenile ( ZMUC); N. of New Zealand [25°47’S 172°24’E]; Dan a Stn. 3621 IV, 2000 mw, 8 Dec. 1928 . Indo-Pacific : Female ( ZMUC), Banda Sea [05°52’S 131°14’E]; Dana Stn. 3676 IX, 3000 mw, 23 Mar. 1929 . Indian Ocean : Four males ( ZMUC); S. of Nicobar Is. [05°18’N 90°55’E]; Dana: Stns 3904 II & IV, 3000 & 2000 mw, 18 Nov. 1929 . Three females ( ZMUC); S. of Sri Lanka [05°21’N 80°38’E]; Dana Stns 3909 IV & V, 3000 & 2500 mw, 22 Nov. 1929 . Two females ( ZMUC); N. of Madagascar [11°18’S 50°03’E]; Dana Stn. 3933 II, 3500 mw, 20 Dec. 1929 .

Diagnosis. Body length of females may exceed 12.0 mm, of males 11.0 mm. Antennae 1 as long as head and first 1.5 pereonites combined (medially); peduncular articles and callynophore relatively broader and longer in males; terminal article elongate, almost twice as long as preceding two articles combined. Antennae 2 similar in length to A1. Gnathopod 1; basis barely shorter than remaining articles combined; dactylus straight or slightly curved, length about half propodus. Gnathopod 2; length about 1.6x G1; basis slightly shorter than remaining articles combined; dactylus length 0.3–0.4x propodus. Pereopods 3 & 4 similar in structure and length; basis length about twice merus; carpus slightly expanded with row of setae on posterior margin, length about twice merus; propodus relatively narrow, slightly longer than basis; dactylus slender, length 0.3–0.4x propodus. Pereopod 5; length about 0.9x P4; basis length about 1.8x merus; carpus length 1.3x merus; propodus marginally shorter than carpus; dactylus slender, length 0.5x propodus. Pereopod 6 marginally longer than P4, the longest pereopod; basis length twice merus; carpus length 1.6–1.8x merus; propodus slightly longer than carpus; dactylus slender, length about 0.4x propodus. Pereopod 7; length 0.6x P6; basis length 2.8x merus; carpus length almost twice merus; propodus length about 1.3x carpus; dactylus slender, length almost half propodus. Telson triangular, pointed; length about half peduncle of U3.

Colour of female from off California (SAMA C6307) recorded as “yellow”.

Remarks. An examination of the type and additional material from the Dana collections has enabled me to determine the validity of this species. It is most similar to M. beebei but is readily distinguished from it by the relatively longer dactyls and shorter telson. Also in M. beebei pereopod 5 is marginally longer than pereopod 4.

None of the material examined seems to be mature, judging by the lack of aesthetasc development of the first antennae of males and the lack of oostegite development in females. Thus, mature specimens may be larger in size than observed.

Distribution. The type was collected from the tropical east Atlantic. The Dana also collected specimens from near the type locality and further south [23°26’S] and also from the North Pacific (Gulf of Panama), South Pacific (including the Banda Sea) and Indian Ocean. All of the Dana specimens were collected with 2000–6000 m of wire.