Mesorhabdus brevicaudatus - Species Card - Marine Planktonic Copepods

Mesorhabdus brevicaudatus Wolfenden, 1905 (F,M)

Taxonomy

Order Calanoida

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Superfamily Arietelloidea

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Family Heterorhabdidae

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Genus Mesorhabdus

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Abbreviations or symbols

Synonymy

Heterorhabdus brevicaudatus Wolfenden, 1905 a (p.12, Descr.F, figs.F); Sars, 1912 a (p.655); Lysholm & al., 1945 (p.36);
Mesorhabdus annectens Sars, 1905 c (p.9); Pearson, 1906 (p.27);
Mesorhabdus gracilis: Park, 1970 (p.477)

References

List of the studied authors

Farran, 1908 b (p.67); Sars, 1925 (p.234, figs.F,M); Farran, 1926 (p.285); Rose, 1933 a (p.206, figs.F,M); Jespersen, 1934 (p.108); Lysholm & al., 1945 (p.36); Farran, 1948 d (n°15, p.3, figs.F,M); Tanaka, 1964 a (p.30, figs.F,M, Rem.); Grice & Hulsemann, 1965 (p.224, 247: Rem.); Chihara & Murano, 1997 (p.817, Pl.115: F,M); Ohtsuka & al., 1997 (p.579, figs.F); Park, 2000 (p.29, figs.F,M, Rem.); Vives & Shmeleva, 2007 (p.317, figs.F,M, Rem.)

Figures

Plate 1 issued from : T. Park in Bull. Scripps Inst. Oceanogr. Univ. California, San Diego, 2000, 31. [p.162, Fig.10].
Female: a, habitus (left side); b, urosome (dorsal); c, d, forehead (dorsal, left, respectively); e, f, genital somite (ventral, left, respectively); g, left A1 (ventral); h, left A2 (posterior); i, left Md (posterior); j, masticatory edge of left Md (posterior); k, masticatory edge of right Md (posterior).

Species Mesorhabdus brevicaudatus - Plate 2 of morphological figures

Plate 2 issued from : T. Park in Bull. Scripps Inst. Oceanogr. Univ. California, San Diego, 2000, 31. [p.163, Fig.11].
Female: a, left Mx1 (posterior); b, left Mx2 (posterior); c, right Mxp (anterior); d, second middle marginal seta of Mxp basis; e, P1 (anterior); f, basipod of P1 (posterior); g, P2 (anterior); h, P3 (anterior); i, P4 (anterior); j, P5 (anterior). P1-5 = swimming legs 1-5.

Species Mesorhabdus brevicaudatus - Plate 3 of morphological figures

Plate 3 issued from : T. Park in Bull. Scripps Inst. Oceanogr. Univ. California, San Diego, 2000, 31. [p.164, Fig.12].
Male: a, b, urosome (right, left, respectively); c, left A1 (ventral); d, P5 (anterior); e, P5 (with endopods and distal exopodal segments omitted), anterior; f, right P5 (with endopod omitted), anterior; g, exopod of right P5 (posterior); h, idem (tilted counterclockwise); i, j, exopod of left P5 (anterior, posterior, respectively).

Species Mesorhabdus brevicaudatus - Plate 4 of morphological figures

Plate 4 issued from : O. Tanaka in Publs Seto Mar. Biol. Lab., 1964, XII (1). [p.31, Fig.189].
Female: a, habitus (dorsal); b, last thoracic segment and urosome (lateral left side); c, genital somite (lateral left side); d, masticatory edge of Md; e, Mx2; f, P5.
Nota: The urosome segments and furca are in the proportional lengths as 35:15:13:14:23 (left) = 100.

Male: g, P5. Nota: Right A1 extends about to the end of the 4th urosomal segment. Left A1 forming a grasping organ.
According to Sars's figure the Mx2 has only 4 setae on the 1st lobe but in the present specimen the lobe 12 has, beside 3 long setae, 2 spine and a pointed process.

Species Mesorhabdus brevicaudatus - Plate 5 of morphological figures

Plate 5 Issued from : G.O. Sars in Résult. Camp. Scient. Prince Albert I, 69, pls.1-127 (1924). [Pl.LXV, figs.1-15].
Female (from aound Azores Islands): 1, habitus (dorsal); 2, idem (lateral left side); 3, A2; 4, left Md; 5, right Md (cutting edge); 6, Mx1; 7, Mx2; 8, Mxp; 9, P1; 10, P2; 11, P3; 12, P5; 13, anal segment and caudal rami (dorsal).

Male: 14, habitus (dorsal); 15, P5.

Species Mesorhabdus brevicaudatus - Plate 6 of morphological figures

Plate 6 issued from : S. Ohtsuka, H.Y. Soh & S. Nishida in J. Crustacean Biol., 1997, 17 (4). [p.580, Fig.1, D].
Female (from S. Japan): D, mandibular cutting edge.
v = ventral tooth; c = central teeth; d, dorsal teeth.
Scale bar = 0.100 mm.

Plate 7 issued from : S. Ohtsuka, H.Y. Soh & S. Nishida in J. Crustacean Biol., 1997, 17 (4). [p.583, Fig.4, C, D].
Female (from S. Japan): C, right side of labrum (posterior surface); D, idem : medial pair of gland openings (arrowed).
Scale bars : 0.010 mm (C, D).

Species Mesorhabdus brevicaudatus - Plate 8 of morphological figures

Plate 8 issued from : R.N. Wolfenden in Plankton Studies Part I. Copepoda. 1905 [Pl. IV, 1-2]. As Heterorhabdus brevicaudatus.
Female: 1, habitus (dorsal); 2, A2.

Nota: Forehead with papilla, but no spine. Endopod of A2 3 times as long as exopod and much wider.

Plate 9 Mesorhabdus brevicaudatus female:
1 - Genital somite without spinules along posterior margin; oral cone with low anterior labral lobe; Coxa of Mxp not with 1+2+3 setae.
2 -Coxa of Mxp with 1+2+2 setae; endopod of Mx1 with 4 setae, exopod with 6+4 setae; Mx2 normally with 6 setae on 1st lobe and 3 setae on 2nd lobe; dorsally, caudal ramus without a large pore close to posterior end.
3 - Dorsally, posterolateral corners of prosome pointing posteriad (Fig.10-b); dorsally, caudal ramus normally wuth a pore at middle; Mx2 with 3 setae on 2nd lobe (Fig.11-b); lateral margin of 1st exopodal segment of P1 not conspicuously bulging (Fig.11-e).

Plate 10 Mesorhabdus brevicaudatus male:
1 - In right P5, 2nd exopodal segment with medial projection at distal end of segment.
2 - Mx1 with 4 setae on endopod and 6+4 seta on exopod; dorsally, caudal ramus without pores on posterior half.
3 - Dorsally, caudal ramus with pores; anteriorly, coxa of P5 with several pores (Fig.12-e).
4 - Dorsally, caudal ramus with a single pore (Fig.11-k); Mx2 with 3 setae on 2nd lobe (Fig.11-b).

Complementary References

List of the studied authors

Sewell, 1948 (p.504); Grice, 1963 a (p.496); Mazza, 1966 (p.72); Grice & Hulsemann, 1967 (p.18); Itoh, 1970 (tab.1); Park, 1970 (p.477); Roe, 1972 (p.277, tabl.1, tabl.2); Deevey & Brooks, 1977 (p.256, tab.2, Station "S"); Vives, 1982 (p.293); Kovalev & Shmeleva, 1982 (p.84); Roe, 1984 (p.358); Lozano Soldevilla & al., 1988 (p.59); Padmavati & al., 1998 (p.347); Lapernat, 2000 (tab.3); Holmes, 2001 (p.17)

Distribution

NZ: 9

Distribution map of Mesorhabdus brevicaudatus by geographical zones

Distribution map of Mesorhabdus brevicaudatus for the Zone Mediterranean Sea, Black Sea

Distribution map of Mesorhabdus brevicaudatus for the Zone Indian Ocean

Additional Maps & Charts

Species Mesorhabdus brevicaudatus - Distribution map 4

Map 4 Chart of 1996

Localisations

Geographical glossary

Atlant. (S tropical), off NW Cape Verde Is., off Mauritania, Canary Is., off Madeira, off SW Portugal, off W Cape Finisterre, Bay of Biscay, Azores, G. of Mexico, Caribbean Sea, off Bermuda: Station ‘’ S’’ (32°10’N, 64°30’W), Sargasso Sea, S Strait of Davis, off Ireland (S & W), Medit. W (Alboran Sea, Liguro-provençal Channel, Arabian Sea, NE Indian, Japan (Sagami Bay), Pacif (W central tropical), off NE Cook Is., Pacif (NE & SE subtropical), off California

Quotations

N: 16

Dimensions (mm)

References of the authors concerning dimensions

(1) F: 3,5; (38) F: 3,3; M: 3,6; (121) F: 3,38; M: 3,62; (199) F: 3,65-3,34; M: 3,5-3,27; (824) F: 4,24-3,76; M: 3,88-3,6; {F: 3,30-4,24; M: 3,27-3,88}

Remarks

meso-bathypelagic. After Pearson (1906, p.27): vertical range down to 700 m at SW of Valentia Island (Ireland). Overall Depth Range in Sargasso Sea: 500-1500 m (Deevey & Brooks, 1977, Station "S");
For Itoh (1970 a, fig.2, from co-ordonates) the Itoh's index value of the mandibular gnathobase = 955.
For Park (2000, p.143), this species occurred in all three major oceans and was the most common, representing 44 % of the total found for the genus. M. gracilis and M. paragracilis also occurred in all three major oceans but accounted for only 8 % and 14 % of specimens, respectively;M. angustus and M. poriphorus were found only in Atlantic and Pacific Ocean samples, representing 29 % and 6 %, respectively; M. angustus has been recorded from the Indian Ocean (Sewell, 1932).

Last update : 17/10/2017

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