Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Euchaetidae ( Family )
            Euchaeta ( Genus )
Euchaeta acuta  Giesbrecht, 1892   (F,M)
Syn.: Euchäta acuta Giesbrecht, 1892 (p.246, 262, 772, figs.F,M);
Euchaete acuta : With, 1915 (p.187, figs.F);
Paraeuchaeta acuta : Bradford al., 1983 (p.25, figs.F,M); Siokou-Frangou, 1999 (p.476); Brugnano & al., 2010 (fig.8); Brugnano & al., 2012 (p.207, Table 3); Minutoli & Guglielmo, 2012 (p.91, carbon requirement vs vertical distribution); in CalCOFI regional list (MDO, Nov. 2013; M. Ohman, comm. pers.);
Pareuchaeta acuta : Heinrich, 1995 (tab.1); Hafferssas & Seridji, 2010 (p.353, Table 3); Uysal & Shmeleva, 2012 (p.909, Table I);
Euchaeta acuta s;l. : Brinton & al., 1986 (p.228, Table 1)
Ref.:
Giesbrecht & Schmeil, 1898 (p.38, Rem. F,M); I.C. Thompson, 1903 a (p.18); Thompson & Scott, 1903 (p.234, 244); Esterly, 1905 (p.157, figs.M); Farran, 1908 b (p.40); A. Scott, 1909 (p.65, figs.F); Wolfenden, 1911 (p.299); Pesta, 1920 (p.511); Sars, 1925 (p.108, figs.F,M); Farran, 1926 (p.256); 1929 (p.208, 237); Rose, 1933 a (p.114, figs.F,M); Lysholm & al., 1945 (p.22); Brodsky, 1950 (1967) (p.199, figs.F,M); Vervoort, 1957 (p.84, 85, Rem.); Paiva, 1963 (p.42); Gaudy, 1963 (p.23); Mazza, 1964 b (p.273, figs.F,M); Crisafi, 1965 a (p.66, fig.F); Owre & Foyo, 1967 (p.52, figs.F,M); Mazza, 1967 (p.152, 161, 390, figs.F,M, juv.); Vidal, 1968 (p.30, figs.F); Bradford, 1972 (p.40, figs.F); Tanaka, 1973 (p.130, figs.F,M); Park, 1978 (p.208, figs.F,M); Björnberg & al., 1981 (p.633, 635, figs.F,M); Park, 1995 (p.23, Redescr.F,M, figs.F,M); Mauchline, 1999 (n°182, p.8, figs.F,M); Lapernat, 1999 (p.17, 55); Bradford-Grieve & al., 1999 (p.880, 925, figs.F,M); Braga & al., 1999 (p.84, 89, Rem.: Biol. mol., Table 1, figs.6, 7, 8); Avancini & al., 2006 (p.84, Pl. 53, figs.F,M, Rem.); Vives & Shmeleva, 2007 (p.646, figs.F,M, Rem.)
Species Euchaeta acuta - Plate 1 of morphological figuresissued from : T. Park in Antarctic Res. Ser. Washington, 1978, 27. [p.211, Fig.69].
Female: A, forehead (lateral); B, last metasomal and genital segments (left side); C, idem (right side); D, genital segment (ventral); E, urosome (dorsal); F, outer lobe of Mx1; G, P1; H, P2; P1-2: legs (anterior).

Nota : Proportional lengths of prosome and urosome 67 : 33.
Frontal eminence of forehead pronounced, bearing auprafrontal sensilla ; rostrum large, pointing obliquely forward at angle about 70° with reference to body.
Posterolateral corner of metasome not prolonged posteriorly; its posteror margin broadly rounded in either dorsal and lateral view.
Dorsally or ventrally, genital segment asymmetrical with conspicuous conical protuberance anteriorly on its left side and more convex margin on its right side. Genital field, when viewed ventrally, also asymmetrical with dissimilar genital flanges. Genital prominence arising from anterior half of genital segment, in lateral view, pointing anteroventrally, with genital field facing in the same direction. Right genital flange produced at middle into pointed process; posterior half of left genital flange enlarged into large lobe.
Appendicular caudal setae straight, much thicker and longer than terminal setae.
A1 extending beyond distal end of metasome by its last 2 segments.
Mx1 : outer coxal lobe with 5 setae of about equal length.
Mx2 : 1 of 6 apical setae bearing long, widely separated spines in addition to short spinules found throughout its entire length
Mxp : long endopodal setae terminating in spinule.
P1 : 1st and 2nd exopodal segments fused without visible trace of segmentation ; resulting compound segment with single external spine reaching distal end of following segment.
P2 : external spine of 2 nd exopodal sgment reaching middle of 1st external spine od 3rd. In 3rd exopodal segment, 1st and 3rd external spines about equally small ; 2 nd large, reaching close to distal end of segment ; incision posterior to 2nd spine deep.


Species Euchaeta acuta - Plate 2 of morphological figuresissued from : T. Park in Antarctic Res. Ser. Washington, 1978, 27. [p.212, Fig.70].
Male: A, forehead (lateral); B, last metasomal and genital segments (lateral); C, P5 (anterior); D, middle part of exopod of left P5 (medial); E, idem (anterior)


Species Euchaeta acuta - Plate 3 of morphological figuresissued from : T. Park in Bull. Scripps Inst. Oceanogr. Univ. California, San Diego, 1995, 29. [p.122, Fig.12].
Female: a, forehead (left side); b, urosome (left); c, d, e, f, genital somite (left, dorsal, right, ventral, respectively); g, outer lobe of Mx1; h, endopod of Mx2; i, Mxp (coxa separated, posterior, the rest anterior); j, P1 (anterior); k, P2 (anterior).

Male: l, forehead (left); m, last pedigerous and genital somites (left); n, P5 (anterior); o, p, exopod of left 5th leg (anterior, medial, respectively).


Species Euchaeta acuta - Plate 4 of morphological figuresissued from : J.M. Bradford, L. Haakonssen & J.B. Jillett in Mem. N.Z. Oceanogr. Inst., 1983, 90. [p.26, Fig.9]. As Paraeuchaeta acuta.
Female: A, habitus (lateral right side); B-D, genital segment (dorsal, right lateral, left lateral, respectively); E, exopod of P1; F, exopod segment 3 of P2.
Nota: - P2 exopod: Aa ± AB; Bb ≤ 1/3 BC; Cc = CD. (see code of lengths outer spines in the Genus' figure of Paraeuchaeta, or in Paraeuchaeta sp. A).

Male: G, habitus (lateral left side); H, P5; I, terminal part of left P5 exopod.


Species Euchaeta acuta - Plate 5 of morphological figuresIssued from : G.O. Sars in Résult. Camp. Scient. Prince Albert I, 69, pls.1-127 (1924). [Pl.XXX, figs.12-15].
Female: 12, habitus (lateral left side); 13, forehead (lateral); 14, genital segment (lateral left side).

Male: 15, P5.


Species Euchaeta acuta - Plate 6 of morphological figuresissued from : A. Scott in Siboga-Expedition, 1909, XIX a. [Plate XX, Figs.1-9].
Female (from Indonesia-Malaysia) : 1, habitus (dorsal); 2, forehead (lateral); 3, last thoracic and genital segments (left side); 4, genital segment (dorsal); 5, A1; 6, Mxp (end hair); 7, P1; 8, P2; 9, part of terminal spine of exopodite of P3.


Species Euchaeta acuta - Plate 7 of morphological figuresIssued from : W. Giesbrecht in Systematik und Faunistik der Pelagischen Copepoden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. – Fauna Flora Golf. Neapel, 1892. Atlas von 54 Tafeln. [Taf.16, Figs.18, 21]. As Euchäta acuta.
Male: 18, exopodal segments 2 and 3 of P5; 21, 21, P5 (anterior view), with spermatophore. Pd = right leg; Ps = left leg.


Species Euchaeta acuta - Plate 8 of morphological figuresIssued from : W. Giesbrecht in Systematik und Faunistik der Pelagischen Copepoden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. - Fauna Flora Golf. Neapel, 1892. Atlas von 54 Tafeln. [Taf.16, Fig.10]. As Euchäta acuta.
Male: 10, outer margin of exopodal segments 2 and 3 of P2.


Species Euchaeta acuta - Plate 9 of morphological figuresIssued from : W. Giesbrecht in Systematik und Faunistik der Pelagischen Copepoden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. - Fauna Flora Golf. Neapel, 1892. Atlas von 54 Tafeln. [Taf.16, Fig.27]. As Euchäta acuta.
Male: 27, Mx1.


Species Euchaeta acuta - Plate 10 of morphological figuresIssued from : W. Giesbrecht in Systematik und Faunistik der Pelagischen Copepoden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. - Fauna Flora Golf. Neapel, 1892. Atlas von 54 Tafeln. [Taf.16, Fig.6]. As Euchäta acuta
Female: 6, Mx1 (anterior view).


Species Euchaeta acuta - Plate 11 of morphological figuresIssued from : W. Giesbrecht in Systematik und Faunistik der Pelagischen Copepoden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. - Fauna Flora Golf. Neapel, 1892. Atlas von 54 Tafeln. [Taf.16, Fig.39]. As Euchäta acuta.
Female: 39, Mxp ( posterior view).


Species Euchaeta acuta - Plate 12 of morphological figuresIssued from : W. Giesbrecht in Systematik und Faunistik der Pelagischen Copepoden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. - Fauna Flora Golf. Neapel, 1892. Atlas von 54 Tafeln. [Taf.16, Fig.14]. As Euchäta acuta.
Female: 14, exopodal segments 2 and 3 of P2. (posterior view).


Species Euchaeta acuta - Plate 13 of morphological figuresIssued from : W. Giesbrecht in Systematik und Faunistik der Pelagischen Copepoden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. - Fauna Flora Golf. Neapel, 1892. Atlas von 54 Tafeln. [Taf.37, Figs.47, 48]. As Euchäta acuta.
Female: 47-48, urosome (lateral and ventral, respectively).


Species Euchaeta acuta - Plate 14 of morphological figuresissued from : C.O. Esterly in Univ. Calif. Publs Zool., 1905, 2 (4). [p.158, Fig.23];
Male (from San Diego Region): a, P5 (Ri.dx = endopodite of right P5; re1, 2, sn = 1st and 2nd segments of exopodite of left P5; proc = process; sph = spermatophore); b, 2nd and 3rd segments of exopod of left P5; c, P2; d, Mx1 (Le.1 = 1st lobe of outer margin; ri = endopodite; re = exopodite; b1 and b2 = basipodites 1 and 2).


Species Euchaeta acuta - Plate 15 of morphological figuresissued from : J.M. Bradford in Mem. N. Z. Oceonogr. Inst., 1972, 54. [p.42, Fig.9, (1-4)].
Female (from Kaikoura, New Zealand): 1, habitus (dorsal); 2, urosome (lateral, right side); 3, genital segment (ventral); 4, exopod segment 3 of P2.
Scale bars: 1 mm (1, 2); 0.1 mm (3, 4).
Nota: A1 does not reach the hind border of the cephalothorax.


Species Euchaeta acuta - Plate 16 of morphological figuresissued from : J. Mauchline in ICES Ident. Leafl. Plankton, 1999, N°182. [p.3, Fig.2: 6a-6b].
Female (Northeast Atlantic): 6a, genital double-somite (left side); 6b, same (dorsal).


Species Euchaeta acuta - Plate 17 of morphological figuresissued from : J. Mauchline in ICES Ident. Leafl. Plankton, 1999, N°182. [p.4, Fig.3: 6c].
Male (Northeast Atlantic): 6c, terminal two segments, exopodal segments of left P5.


Species Euchaeta acuta - Plate 18 of morphological figuresissued from : C. With in The Danish Ingolf-Expedition, 1915, III (4). [Pl. VI, Fig.12, a]. As Euchaete acuta.
Female (from 47°-51°N, 8-11°43'W): a, last thoracic segment and genital segment (left lateral).


Species Euchaeta acuta - Plate 19 of morphological figuresissued from : C. With in The Danish Ingolf-Expedition, 1915, III (4). [Pl. VI, Fig.12, b-c]. As Euchaete acuta.
Female: b, labrum (oral view); c, lamina labialis and serrula 6-dentata.


Species Euchaeta acuta - Plate 20 of morphological figuresIssued from : W. Giesbrecht in Systematik und Faunistik der Pelagischen Copepoden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. - Fauna Flora Golf. Neapel, 1892, 19 , Atlas von 54 Tafeln. [Taf.37, Fig.52]. As Euchäta acuta.
Female: 52, forehead (lateral).
R = rostrum.


Species Euchaeta acuta - Plate 21 of morphological figuresissued from : O. Tanaka in I O B C Handbook, 1973, IV. Cochin, India [p.131, Fig.1].
Female (from Arabian Sea): A, genital segment (lateral); B, forehead (lateral); C, P2.
Nota: Abdominal segments and caudal rami in proportional lengths 35 : 25 : 20 : 6: 14 = 100.
A1 23-segmented, extends to the end of the last thoracic segment.
Exopod of A2 7-segmented, endopod 2-segmented. Endopod with 6 setae on the outer lobe, and 7 setae on the inner lobe.
Md: cutting blade with 6 teeth and 1 inner marginal seta; 2nd basal segment with single seta; exopod with 6 setae, endopod with 1 seta on the 1st segment and 9 setae on the distal segment.
Mx1: 6 setae on the outer lobe, 10 on the 1st inner lobe, 1 on the 2nd inner lobe, the 3rd inner lobe is absent.

Male: D, forehead (lateral); E, distal segment of left P5.
Nota: Abdominal segments and caudal rami in the proportional lengths 19 : 26 : 22 : 18 : 5 : 10 = 100.
Caudal rami 1.4 times as long as it is wide at the proximal part.
Right A1 exceeds slightly the end of the thoracic segment.
mouth parts reduced much. Mx1 agrees with that figured by Giesbrecht in which the outer lobe is firnished with 4 setae, however, it is replaced by 2 setae in the present specimen.


Species Euchaeta acuta - Plate 22 of morphological figuresissued from : O. Tanaka in I O B C Handbook, 1973, IV. Cochin, India [p.148, Fig.9: 5].
Female: 5, genital segment (dorsal).


Species Euchaeta acuta - Plate 23 of morphological figuresEuchaeta acuta Female:
1 - See Key to acuta species Group.
2 - Dorsally, genital somite asymmetrical.
3 - Dorsally, genital somite without notch on right side (Fig.12-d).


Species Euchaeta acuta - Plate 24 of morphological figuresissued from : O. Tanaka in I O B C Handbook, 1973, IV. Cochin, India [p.131].
Proportional lengths of A1 segments from female and male.


Species Euchaeta acuta - Plate 25 of morphological figuresissued from : O. Tanaka in I O B C Handbook, 1973, IV. Cochin, India [p.131, Fig.1].
Female (from Indian Ocean): A, genital segment (lateral); B, forehead (lateral); C, P2.
Nota: Abdominal segments and caudal rami in the proportional lengths 35 : 25 : 20 : 6 : 14 = 100.

Male: D, forehead (lateral); E, distal segment of left P5.
Nota: Abdominal segments and caudal rami in the proportional lengths 19 : 26 : 22 : 18 : 5 : 10 = 100.

Compl. Ref.:
Cleve, 1904 a (p.190); Pearson, 1906 (p.17); Wilson, 1942 a (p.185); Massuti Alzamora, 1942 (p.110); Sewell, 1948 (p.345, 487); Wilson, 1950 (p.211); Fagetti, 1962 (p.21); Gaudy, 1962 (p.93, 99, Rem.: p.106); Duran, 1963 (p.16); Giron-Reguer, 1963 (p.30); V.N. Greze, 1963 a (tabl.2); Grice, 1963 a (p.495); Gaudy, 1963 (p.23, Rem.); Ahlstrom & Thrailkill, 1963 (p.57, Table 5, abundance); Björnberg, 1963 (p.39, Rem.); Bary, 1963 a (p.1519, Table 1); 1964 (p.183, T-S diagram-occurrences); Unterüberbacher, 1964 (p.23); De Decker & Mombeck, 1964 (p.12); Mazza, 1964 (p.293, weight); Shmeleva, 1965 b (p.1350, lengths-volume -weight relation); Mullin, 1966 (p.546, Table I, III, diet); Pavlova, 1966 (p.43); Mazza, 1966 (p.70); 1967 (p.367); Ehrhardt, 1967 (p.738, geographic distribution, Rem.); Fleminger, 1967 a (tabl.1); De Decker, 1968 (p.45); Vinogradov, 1968 (1970) (p.268); Morris, 1970 (p.2300); Deevey, 1971 (p.224); Gamulin, 1971 (p.382, tab.3); Binet & al., 1972 (p.55); Bainbridge, 1972 (p.61, Appendix Table III: occurrence); Apostolopoulou, 1972 (p.327, 349); Roe, 1972 (p.277, tabl.1, tabl.2); 1972 b (p.526); Björnberg, 1973 (p.329, 386); Nival & al., 1974 (p.231, respiration & excretion); Vives & al., 1975 (p.42, tab.II, III); Deevey & Brooks, 1977 (p.256, tab.2, Station "S"); Carter, 1977 (1978) (p.35); Dessier, 1979 (p.205); Vaissière & Séguin, 1980 (p.23, tab.1); Vives, 1982 (p.291); Kovalev & Shmeleva, 1982 (p.83); Scotto di Carlo & Ianora, 1983 (p.150); Gaudy & Boucker, 1983 (p.37, Table 1, Rem.: metabolism); Tremblay & Anderson, 1984 (p.5, Rem.); Brenning, 1984 (p.3, T-S diagram, Rem.); Guangshan & Honglin, 1984 (p.118, tab. as acutus); De Decker, 1984 (p.316, 349: carte); Roe, 1984 (p.357); Scotto di Carlo & al., 1984 (p.1041); Regner, 1985 (p.11, Rem.: p.30); Brenning, 1985 a (p.28, Table 2); Madhupratap & Haridas, 1986 (p.105, tab.1); Rudyakov, 1986 (tab.2); Jimenez-Perez & Lara-Lara, 1988; Lozano Soldevilla & al., 1988 (p.58); Herman, 1989 (p.247); Cervantes-Duarte & Hernandez-Trujillo, 1989 (tab.3); Suarez & al., 1990 (tab.2); Scotto di Carlo & al., 1991 (p.271); Hattori, 1991 (tab.1, Appendix); Suarez & Gasca, 1991 (tab.2); Suarez, 1992 (App.1); Mauchline, 1992 a (p.2); 1994 a (p.561); Hays & al., 1994 (tab.1); Kouwenberg, 1994 (tab.1); Hajderi, 1995 (p.542); Tranter, 1996 (p.596, 598); Hure & Krsinic, 1998 (p.48, 101, 112); Mauchline, 1992 a (p.3); Suarez-Morales & Gasca, 1998 a (p.109); Mauchline, 1998 (tab.42); Lapernat, 2000 (tabl. 3, 4); Razouls & al., 2000 (p.343, Appendix); Seridji & Hafferssas, 2000 (tab.1); Lopez-Salgado & al., 2000 (tab.1); Madhupratap & al., 2001 (p. 1345, vertical distribution vs. O2, figs.4, 5: clusters, p.1353); d'Elbée, 2001(tabl. 1); Lapernat & Razouls, 2001 (tab.1); Holmes, 2001 (p.51); Fransz & Gonzalez, 2001 (p.255, tab.1); Beaugrand & al., 2002 (p.1692); Beaugrand & al., 2002 (p.179, figs.5, 6); Vukanic, 2003 (139, tab.1); CPR, 2004 (p.54, fig.153); Lo & al., 2004 (p.89, tab.1); Berasategui & al., 2005 (p.313, fig.2); Isari & al., 2006 (p.241, tab.II); Lavaniegos & Jiménez-Pérez, 2006 (Tab.2, 3, Rem.); Valdés & al., 2007 (p.103: tab.1); Ayon & al., 2008 (p.238, Table 4: Peruvian samples); Morales-Ramirez & Suarez-Morales, 2008 (p.519); Raybaud & al., 2008 (p.1765, Table A1); Licandro & Icardi, 2009 (p.17, Table 4); Schnack-Schiel & al., 2010 (p.2064, Table 2: E Atlantic subtropical/tropical); Dias & al., 2010 (p.230, Table 1); Mazzocchi & Di Capua, 2010 (p.425); Medellin-Mora & Navas S., 2010 (p.265, Tab. 2); Tutasi & al., 2011 (p.791, Table 2, abundance distribution vs La Niña event); Miloslavic & al., 2012 (p.165, Table 2, transect distribution); Lidvanov & al., 2013 (p.290, Table 2, % composition); Zakaria & al., 2016 (p.1, Table 1); Benedetti & al., 2016 (p.159, Table I, fig.1, functional characters); Benedetti & al., 2018 (p.1, Fig.2: ecological functional group); Belmonte, 2018 (p.273, Table I: Italian zones); Acha & al., 2020 (p.1, Table 3: occurrence % vs ecoregions, Table 5: indicator ecoregions).
NZ: 20

Distribution map of Euchaeta acuta by geographical zones
Species Euchaeta acuta - Distribution map 4issued from : A.A. Shmeleva in Bull. Inst. Oceanogr., Monaco, 1965, 65 (n°1351). [Table 6: 20 ]. Euchaeta acuta (from South Adriatic).
Dimensions, volume and Weight wet. Means for 50-60 specimens. Volume and weight calculated by geometrical method. Assumed that the specific gravity of the Copepod body is equal to 1, then the volume will correspond to the weight.
Species Euchaeta acuta - Distribution map 5issued from : U. Brenning in Wiss. Z. Wilhelm-Pieck-Univ. Rostock - 33. Jahrgang 1981. Mat.-nat. wiss. Reihe, 6. [p.2, Fig.1].
T-S Diagram for Euchaeta marina, E. acuta, E. hebes (= Paraeuchaeta hebes), E. paraconcinna from Cap Blanc (Mauritania).
SO: Southern Surface Water (S °/oo: 34,50; T°C: 29,0); ND: Northern Water of the Surface Layer (S °/oo: 37,5; T°C: 21,0); SD: Southern Deep Water of the surface layer (S °/oo: 35,33; T°C: 13,4). See commentary in Temora stylifera and Brenning (1985 a, p.6).
Species Euchaeta acuta - Distribution map 6Issued from : P.-E. Lapernat in DEA Océanogr. Biol., Univ. P. & M. Curie, Paris VI. July 5, 2000. [Fig.9 c ].
Verical distribution of Euchaeta acuta at an eutrophic site (off Mauritanian coast: 20°32 'N, 18°36' W) in females (F) and males (M) (ind. per m3) in the day (white circle) and night (black circle).

Nota: Sampling in the water column 0-1000 m, one during the day and another during the night with BIONESS multiple-net: 0-75; 75-150; 150-250; 250-350; 350-450; 450-550; 550-700; 700-850; 850-965 m. In May-June 1992.
Loc:
sub-Antarct. (S Tasmania), South Africa (E & W), Namibia, Tristan da Cunha Is., Congo, off Lagos, Ivorian shelf, off Ascension Is., off E St. Paul Is., Cape Verde Is., off Mauritania, Morocco-Mauritania, Canary Is., off Madeira, off W Cabo Finisterre, Bay of Biscay, Azores, Argentina, Brazil, off Macaé, off Amazon, Caribbean Sea, Caribbean Colombia, G. of Mexico, Florida, off Bermuda: Station "S" (32°10'N, 64°30'W), S Cape Hatteras, Cabot Strait, Flemish Cap, off Rockall Is., W & SW Ireland, North Sea, Ibero-moroccan Bay, Mediterranean Sea (Alboran Sea, Marseille (rare), Ligurian Sea, Tyrrhenian Sea, Strait of Messina, off Malta, Adriatic Sea, Ionian Sea, Aegean Sea, W Egyptian coast, Lebanon Basin, Marmara Sea), Natal, Arabian Sea, S Indian Ocean, off S Madagascar, off SE La Réunion Is., W Australia, Indonesia-Malaysia, Philippines, China Seas (East China Sea), Japan, off Sanriku, off Hokkaido SE, Okhotsk Sea, Pacif. (W equatorial), New Caledonia, New Zealand (Kaikoura), off Hawaii, California, W Baja California, Gulf of California, W Mexico, Central America, Costa Rica (Dome), W Costa Rica, off Galapagos, Galapagos-Ecuador, off Peru, E Easter Is., E Marquesas Is., Fidji Is., Chile, off Valparaiso
N: 149
Lg.:
(1) F: 4,3; (3) F: 4,28-3,6; M: 4,08-3,36; (5) F: 4,2; (7) F: 4,02; (9) F: 4,1- 3,4; M: 3,3-3,2; (20) F: 4,04-3,68; M: 3,92-3,28; (24) F: 4,4; (38) F: 4,15-4,1; M: 3,72-3,6; (47) F: 4,1; M; 3,8-3,55; (73) F: 4,05; (98) F: 3,59; M: 3,20; (116) F: 4,2; (142) F: 4; M: 4-3,5; (187) F: 4-3,88; (199) F: 4,1-3,57; M: 3,8-3,42; (207) F: 4,08-4; M: 3,8-3,5; (237) F: 4,5-4,0; M: 4,0; (244) F: 4; (340) M: 3,45; 3,4; (393) F: 4,413-4,055; M: 4,13-3,753; (432) F: 4,7-3,9; (449) F: 4,1; M: 4,8-3,5; (920) F: 3,92; (1111) F: 3,5-4,41; M: 3,5-4,03; {F: 3,40-4,70; M: 3,20-4,80}

The mean female size is 4.041 mm (n = 33; SD = 0.2945), and the mean male size is 3.677 mm (n : 26; SD = 0.3617). The size ratio (male : female) is 0.92 (n = 8; SD = 0.0305). In samples, the sex ratio (female : male) is temporary 1.57.
Rem.: Oceanic, epi-mesopelagic, 2000-3000 m (off Malta).
Sampling depth (Antarct., sub-Antarct.) : 0-1000 m. Sargasso Sea: 0-1000 m (Deevey & Brooks, 1977, station "S").
For Park (1995, p.22) this species belongs to ‘’acuta ’’ Group, characterized by : Mx1 with 1 anterior, and 1 posterior seta on 1st inner lobe and a single seta on 1st endopodal segment. Only 1 endopodal seta of Mx2 armed with long spinules in addition to rows of fine spinules. Basis of Mxp without long spinules along medial margin. In male left P5, basis greatly enlarged ; exopod without poorly scerotized lobes ; serrated lamella of exopod far sgort of reaching tufts of stiff hairs. Park found this species from the northeastern Atlantic, the eastern tropical Pacific, and the western Indian Ocean, and have been examined for purposes of comparison and no significant morphological variations were found.
After Björnberg (1963, p.39) this species was only found in cooler very saline surface waters off the Brazilian coast.
For Vervoort (1963 b, p.161) this species is closely related E. media Giesbrecht, 1892. The two species can be separated by the following characters: E. acuta : 1- Posterolateral thoracic border not produced but gently and uniformaly rounded. 2- Tubercle on the left side of the genital somite obtuse, triangular in outline; the top of this tubercle is rounded. Protuberance on the right side of the genital somite more developed than in E. media. 3- A1 do not reach the postero-lateral thoracic border; extending to the middle of the fused 4th-5th somites of thorax. 4- Appendicular seta of the caudal rami as in E. media; remaining setae shorter than the abdomen, geniculated at half their length.
Certain confusions are possible between this species and E. paracuta.
For Braga & al. (1999, p.88) this species may need to be reclassified within Paraeuchaeta.
After Benedetti & al. (2018, p.1, Fig.2) this species belonging to the functional group 1 corresponding to large sac-spawning carnivorous.
Last update : 22/06/2020
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Razouls C., de Bovée F., Kouwenberg J. and Desreumaux N., 2005-2020. - Diversity and Geographic Distribution of Marine Planktonic Copepods. Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed September 25, 2020]

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Marine Planktonic Copepods

Marine Planktonic Copepods

 

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