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Marine Planktonic Copepods
Megacalanus ericae  Bradford-Grieve, Blanco-Bercial & Boxshall, 2017   (F,M)
Taxonomy
Order Calanoida
Superfamily Calanoidea
Family Megacalanidae

Synonymy

Megacalanus princeps: Tanaka, 1956 (pp 262-264, fig.3.
Megacalanus princeps: Brodsky & al. 1983 (pp 197-198, fig. 87) [pronably lapsus calami: pp.191-193, Fig.84].
Megacalanus princeps: Bradford-Grieve, 1994 (pp 18-20, figs 4, 5).

References

Bradford-Grieve, Blanco-Bercial & Boxshall, 2017 (p. 41, Descr. F,M, figs. F,M, Rem.)

Figures

Plate 1 Issued from : J.M. Bradford-Grieve, L. Blanco-Bercial & G.A. Boxshall in Zootaxa, 2017, 4229 (1). [p.42, fig.15].
Female (from 21.376°N, 158.307°W): A-B, habitus (dorsal and lateral, respectively); C, anterior head (lateral); D, A1 ancestral segments I-V (hs= hair sensillum, mc = macula cribrosa) (dorsal); E, A1 ancestral segments XV-XVI.
Scale bars: 1.0 mm (A, B, D); 0.1 mm on remaining figures.

Nota:
- Head bluntly rounded.
- Base of rostrum hardly visible in dorsal view.
- Posterior corners of pediger 5 with triangular lappets extending more than half way along genital double-somite in dorsal view and beyond ventral genital bulge in lateral view; lappets pointed (in dorsal view).
- A1 ancestral segments XIV to XVII with 21, 39, 41, 36 teeth on ventral surface, respectively (n = 4). Hair sensillum on dorsal surface of segments I-IV each accompanied by macula cribrosa; segments XV and XVI smooth, without distoposterior row of teeth.
- P1 outer spine on exopod segments 1 and 2 extend not quite half distance between bases of following two spines; 1 macula cribrosa at base of outer spine on exopodal segment 2.

Morphological variation: Ancestral segments XIV to XVII of female A1 with 16-21, 34-39, 34-41, 31-36 ventral teeth
Plate 2 Issued from : J.M. Bradford-Grieve, L. Blanco-Bercial & G.A. Boxshall in Zootaxa, 2017, 4229 (1). [p.43, fig.16].
Male (from 21.376°N, 158.307°W): A-B, habitus (dorsal and lateral, respectively); C, P5 (posterior view); D, inner distal margin of exopod segment 2 of left leg; E, right A1 ancestral segments XIX-XX; F, right A1 ancestral segments XXI-XXIII.
Scale bars: 1.0 mm (A, B); 0.1 mm on remaining figures.

Nota:
- Rostral points directed ventrally.
- Posterior borders of pediger 5 extend slightly beyond posterior border of urosomite 1, lappets short and triangular in lateral view.
- A1 right ancestral segment XIX with fused gripping element extending slightly beyond base of aesthetasc, 1 macula cribrosa (mc), 1 aesthetasc (a); Segmnt XXI with 1 small fine gripping element, 1 mc and 1a. Left A1 with clavate seta on ancestral segment XI (apparently broken off leaving short setal vestige)
- P5 inner distal border of basis with setules, left exopodal segment 2 specialised seta with basal part quat, usually wider than long, and lash shorter than basal part. Right exopodal segment 3 inner border completely lined by fine spinules as far as inner articulated spine.

Morphological variation: Proportions of basal part of male left P5 specialised seta variable but lash appears to be consistently short. Ancestral segments WIV- XV on right with 27-31 and 34-49 ventral teeth, respectively (n = 5). Right A1 ancestral segment XXI gripping element usually small but a specimen has this element larger and stronger (similar to that of M. frosti although the specialised seta on the left leg P5 exopodal segment 2 is squat with a short lash as in other M. ericae.
Plate 3 Issued from : O. Tanaka in Publ. Seto Mar. Biol. Lab., 1956, V (2). [p.263, Fig.F]. As Megacalanus princeps.
Female (from Sagami & Suruga Bay): a, habitus (dorsal); b, forehead (lateral); c, posterior corner of prosome and urosome; d, coxa, basis and endopod of P1.
Plate 4 Issued from : J.M. Bradford-Grieve inN. Z. Oceanogr. Inst. Memoir 102, 1994. [p.19, fig.4, A-I]
As Megacalanus princeps.
Female (from 41°47' S, 175°01'E): A-B, habitus (dorsal and lateral, respectively); C, A1; D, A2; E, Md palp; F, Md gnathobase; G, Mx1; H, Mx2; I, Mxp.
Plate 5 Issued from : J.M. Bradford-Grieve inN. Z. Oceanogr. Inst. Memoir 102, 1994. [p.20, fig.4J-N]
As Megacalanus princeps.
Female: J, P1; K, P2; L, P3; M, P4; N, P5.
Plate 6 Issued from : J.M. Bradford-Grieve inN. Z. Oceanogr. Inst. Memoir 102, 1994. [p.21, Fig.5, A-I] As Megacalanus princeps.
Male (from 41°47' S, 175°01'E): A-B, habitus (dorsal and lateral, respectively); C, right A1; D, left A1; E, A2; F, Md; G, Mx1; H, Mx2; I, Mxp.
Plate 7 Issued from : J.M. Bradford-Grieve inN. Z. Oceanogr. Inst. Memoir 102, 1994. [p.21, Fig.5, J-O]. As Megacalanus princeps.
Male: J, P1; K, P2; L, P3; M, P4; N, right P5; O, left P5.
Plate 8 Issued from : K.A. Brodsky, N.V. Vyshkvartzeva, M.C. Kos & E.L. Markhaseva in Opred. Fauna SSSR, Isdav. Zool. Inst., Acad. Sci. SSSR. [p.192, Fig.84].
Female (from N Pacif.): habitus (dorsal and lateral, respectively; Ce, cephalome; Mx1; bP1, exopodal 2nd segment of P1; Mx2.
Male: habitus (lateral); P5 (np = right leg, nb = left leg)
Plate 9 Issued from : J.M. Bradford-Grieve, L. Blanco-Bercial & G.A. Boxshall in Zootaxa, 2017, 4229 (1). [p.66, Table 7].
Morphological characters after identification key of Megacalanus females and males.
Compare to other species of genus.

Main characters identification after species key :
1 - Head without crest in males and females.
2 - Posterolateral lappets of pediger 5 triangular in females and males.
3 - Female A1 ancestral segments XV and XVI posterior border smooth; male right A1 segment XIX with 1 distal fused gripping element.

Distribution

Additional Maps & Charts

Map 5 Issued from : J.M. Bradford-Grieve, L. Blanco-Bercial & G.A. Boxshall in Zootaxa, 2017, 4229 (1). [p.34, fig.9].
Distribution of Megacalanus princeps (filled triangle), Megacalanus frosti (open triangle), Megacalanus ericae (filled square) and Megacalanus ohmani (open square).

Localisations

Pacific Ocean, northeast Pacific; Indian Ocean (04.517°N, 125.583°E)

Type locality: 21.376° N, 158.307° W.

Quotations

N: 4

Dimensions (mm)

(125) F: 10,24; (131) F: 8,7-11,9; M: 7,9-10,8; (196) F, 9,9-10,4; (1316) F: 7,8-11,00; M: 8,50-11,00; {F: 7,8-11,00; M: 8,50-11,00}

Remarks

Bathypelagic species, extending to mesopelagic depths (< 500 m to > 2000 m).
For Bradford-Grieve & al. (2017, p.43) females of this species and M. ohmani are similar in that ancestral segments XV and XVI of A1 have a smooth distoposterior border (compared with congeners that have a distoposterior row of blunt teeth). Females can be distinguished by differences in yje shape of the posterior borders of pediger 5 in latertal view. In M. ericaethese borders ate triangular and extend beyond the genital double-somite ventral bulge in lateral view. In M. ohmani these borders are shorter and rounded.
Last update : 22/01/2020

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