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Marine Planktonic Copepods
Euchirella formosa  Vervoort, 1949   (F,M)
Taxonomy
Order Calanoida
Superfamily Clausocalanoidea
Family Aetideidae

Synonymy

Euchirella trigrada Tanaka, 1957 b (p.184, figs.F);
E. orientalis : Tanaka & Omori, 1969 (p.52, figs.F,M)

References

Vervoort, 1949 (p.29, Descr.F, figs.F); 1963 b (p.134: Rem.); Morris, 1970 (p.2300, 2304, figs.F); Bradford & Jillett, 1980 (p.35, figs.F, Rem, fig. 73, distribution chart); Vaupel Klein, 1984 a (p.38, Table II: characters, Rem.); Markhaseva, 1996 (p.154, figs.F, M); Bradford-Grieve & al., 1999 (p.879, 921, figs.F,M)

Figures

Plate 1 issued from : Tanaka O. in Publ. Seto mar. Biol., Lab., 1957, 6 (2). [Fig.49, p.185]. As Euchirella trigrada.
Female from Suruga): habitus (dorsal aspect); b, head (lateral aspect); c, last thoracic segment and urosome (lateral view, left side); d, A2;: e, Mxp.; f, P1; g, outer margin of exopodite of P2; h, inner margin of basal joints of P4.

Nota Female:
- Cephalothorax about 4.83 the abdomen length.
- Head and 1st pediger segmant separate, 4th and 5th thoracic segments fused.
- Rostrum directs straight forwards , rostral spine moderately long..
- Abdomen 4-segmented; segments and caudal rami in the proportional lengths 60 : 20 : 8 : 6 : 16 = 100.
- Gental segment which is as deep as wide is shorter than wide; segment in dorsal view slightly asymmetrical; there are on the left side 3 lamellous proeesses of which the distal 2 are broad at the base; there is a blunt process on the right side; genital area as that of E. truncata.
- Caudal rami shorter than wide.
- A1 23-segmented, reaches back to distal end of caudal rami.
- A2 exopod about 3.7 times as long as endopod; 1st basal segment with a tuft of hairs on the posterior surface.
- Mx1 as that of E. messinensis; 2nd basal segment with 3 setae; endopod with 4 setae; exopod with 11 setae.Mx2 as that of E. rostrata.
- Mxp with sinuate anterior margin on 2nd basal segment.
- P2 with strong outer edge spines on exopodal segments.
- Terminal spines of exopod of P2 to P4 with each 20 teeth.
- P4 with 2 subequal spines on posterior surface of coxa.
Plate 2 issued from : E.L. Markhaseva in Proc. Zool. Inst. RAN, St. Petersburg, 1996, 268. [p.155, Fig.117].
Female (specimen from Kuril). P.md: mandibular palp; Ce: forehead (lateral).
Plate 3 issued from : J.M. Bradford & J.B. Jillett in Mem. N.Z. Oceanogr. Inst., 86, 1980. [p.37, Fig.22].
Female: A, habitus (lateral right side); B, idem (dorsal); C, genital segment (lateral left side); D, basipod 1 of P4.
Plate 4 Issued from : W. Vervoort in Zool. Verh., Leiden, 1949, 5. [p. 30, Fig.14].
Female (from Timor Sea): a, habitus (dorsal); b, forehead (lateral); c, urosome (dorsal).

Nota: A1 (24-free segments) reaches the distal margin of the 1st urosomal segment.The abdominal segments and furca in the proportional lengths 55:10:11:10:14 = 100.
Plate 5 Issued from : W. Vervoort in Zool. Verh., Leiden, 1949, 5. [p. 31, Fig.15].
Female (from Timor Sea): a,urosome (lateral right side); b, idem (lateral left side); c, P1; d, basal portion of P4, showing the spines of the 1st basal segment.
Plate 6 issued from : J.C. von Vaupel Klein in Crustaceana, Supplt 9, Studies on Copepoda, III, 1984. [p.74, Fig.12, a, g].
Female: a, setal armature of exopod of Mx1 (left one in posterior aspect; all setae are plumose as shown in one).
Nota: 11 setae, the wide-spread condition in the other genera and in most Euchirella spp.; g, spinules on the distal margin of the 5th endite of Mx2 basipod (left appendage in postero-medial aspect).
Plate 7 issued from : O. Tanaka & M. Omori in Publ. Seto mar. Biol. Lab., 1969, XVII, 1. [p.53, Fig.7]. As Euchirella orientalis.
Female (from Izu Region, Japan): a, forehead (lateral); b-c, last thoracic segment and urosome (lateral and dorsal, respectively).

Male: d, forehead (lateral); e, Mx1; f, P1; g, P5; h, left P5 (distal segment of exopod; i, idem (another specimen).
Plate 8 issued from : J.C. von Vaupel Klein in Crustaceana, Supplt 9, Studies on Copepoda, III, 1984. [p.82, Fig.17, j].
Female:terminal part of basipodal segment 2 and endopod of right Mxp (medial view).
Scale bar 0.2 mm.
Nota: Compare grossly enlarged endopodal segment 2 in Undeuchaeta as opposed to the regular condition found in (see fig.17, i in U. incisa).
Plate 9 issued from : J.C. von Vaupel Klein in Crustaceana, Supplt 9, Studies on Copepoda, III, 1984. [p.80, Fig.16, x].
Female: o, arrangement of medial spines on the posterior face of basal segment 1 of right P4 .
Scale bar 0.1 mm.
Nota: 2 subequal stout spines on a common base, situated under a wider angle than E. pulchra and E. messinensis indica, but as also usually observed in E. slendens and E. venusta; both spines of E. messinensis indica and E. formosa are generally representative of the species, but individual variation in the angle between the two spines is not uncommon.
Plate 10 issued from : B. Morris in J. Fish. Res. Bd Canada, 1970, 27 (12). [p.2305, Fig.3].
Female (from N Pacif. sbutropical): A, forehead (lateral); B, urosome (lateral); C, same (dorsal); D, right A1; E, A2; F, Md (madibular palp); G, Mx1; H, Mx2; I, Mxp; J, P1 (anterior); K, basipodite 1 of P4 (posterior).
Plate 11 Euchirella formosa female:
1 - Genital segment asymmetrical.
2 - Crest absent.
3 - Genital segment with left lateral side swelled, right projection also present, smaller than the left one (dorsal view).
4 - Coxopodite of P4 with 2 spines.
5 - Endopodal segment 1 of Md without seta.
6 - Posterior part of dorsal side of genital segment with 3 projections (left lateral view).
Plate 12 Euchirella formosa male:
1 - P5 biramous, endopod of left leg rudimentary. Exopodal segment 2 and endopod of right leg elongated and shapened in their distal parts forming tongs. Endopod of right P5 significantly exceeding distal border of exopodal segment 1 of right leg.
2 - Crest present, low.
3 - Basipodite of left P5 nearly as long as right coxopodite of right P5.
4 - Parts of exopodal segment 3 of left P5 tongs not equal in length.
Plate 13 issued from : Tanaka O. in Publ. Seto mar. Biol., Lab., 1957, 6 (2). [p.185]. As Euchirella trigrada.
Female A1: proportional lengths of segments.
- A1 23-segmented, reaches back to distal end of caudal rami.
- Segments 3, 7, 9, 14 and 18, each with a long seta; aesthetascs found on segments 9, 2, 14 and 19/
Plate 14 Issued from : J.C. von Vaupel Klein in Crustaceana, Supplt 9, Studies on Copepoda, III, 1984. [p.70, Fig.10, e].
Euchirella formosa: Setal armature on proximo-distal corner of basis, adjacent to the endopod of Mx1 (left appendage in postrior view; secondary structures on large setae are not shown, and neither are the hairs on the basis proper). The usual Euchirella condition of 1 long, stout seta plus 2 small and slender, densely plumose setae.
Plate 15 Issued from : J.C. von Vaupel Klein in Crustaceana, Supplt 9, Studies on Copepoda, III, 1984. [p.70, Fig.11, i].
Euchirella formosa: Setal armature of the endopod of Mx1 (detail of left appendage in posterior aspect; setules/spinules omitted). 4 well developed setae.
Plate 16 Issued from : J.C. von Vaupel Klein in Crustaceana, (Supplement) 9, 1984. [p.93, Table II].
Euchirella formosa Female: Datamatrix stating observed states of characters from Table I (p.87-90) presently examined; nos. refer to the input nos. used in Table I (see to the family Aetideidae).
Plate 17 Issued from : J.C. von Vaupel Klein in Crustaceana, (Supplement) 9, 1984. [p.94, Table II (cont' d)I].
Datamatrix stating observed states of characters from Table I (p.87-90) presently examined; nos. refer to the input nos. used in Table I (see to the family Aetideidae).
Plate 18 Issued from : J.C. von Vaupel Klein in Crustaceana, (Supplement) 9, 1984. [p.95, Table II (cont' d)].
Datamatrix stating observed states of characters from Table I (p.87-90) presently examined; nos. refer to the input nos. used in Table I (see to the family Aetideidae).

Complementary References

De Decker & Mombeck, 1964 (p.12); Fleminger, 1967 a (tabl.1); Grice Hulsemann, 1967 (p.15); 1968 (tab.2); Björnberg, 1973 (p.324, 386); Galbraith, 2009 (pers. comm.); C.E. Morales & al., 2010 (p.158, Table 1); in CalCOFI regional list (MDO, Nov. 2013; M. Ohman, comm. pers.)

Distribution

NZ: 10

Distribution map of Euchirella formosa by geographical zones


Additional Maps & Charts

Map 3 Issued from : J.M. Bradford & J.B. Jillett in New Zealand Ocean. Inst. Memoir, 86, 1980. [p.88-89, Figs.65-67].
Distribution of several species of Euchirella in the Tasman Sea and around New Zealand.
Nota: Euchirella indica (= Euchirella massinensis indica).

Localisations

E South Africa, S Brazil, E & SW Indian, Timor Sea, Strait of Macassar, off Philippines, Japan, Kuril-Kamchatka, Pacif. (central N), Vancouver Is., Pacif. (N central subtropical), New Zealand, California, off IJuan Fernandez Is., Chile (S, Concepcion).

Type locality: 10°49'S, 123°59'E.

Quotations

N: 18

Dimensions (mm)

(37) F: 5,5-4,8; M: 5,2-4,75; (41) F: 5,2-5,1; (56) F: 5,23; (92) F: 5,38-4,75; (110) F: 5,25; M: 5,2-4,75; (201) F: 5,5-4,8; (1257) F: 5,1-5,75; {F: 4,75-5,50; M: 4,75-5,20}

The mean female size is 5.151 mm (n = 10; SD = 0.2837) and the mean male size is 4.975 mm (n = 4; SD = 0.2598). The size ratio (male : female) is 0.96.

Remarks

epiplagic.
According to Vervoort (1949, p.32) the species resembles E. intermedia, but differs in the shape of the gental segment female.
Bradford & Jillett (1980, p.35) do not accept the synonymy of Tanaka & Omori (1969) between E. formosa and E. orientalis Sewell, 1947.
Last update : 19/06/2023

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