Species Card of Copepod
Calanoida ( Order )
    Diaptomoidea ( Superfamily )
        Pseudodiaptomidae ( Family )
            Pseudodiaptomus ( Genus )
Pseudodiaptomus siamensis  Srinui, Nishida & Ohtsuka, 2013   (F,M)
Srinui & al., 2013 (p.42, Descr.F, M, figs.F, M, Rem.)
Species Pseudodiaptomus siamensis - Plate 1 of morphological figuresIssued from : K. Srinui, S. Nishida & S. Ohtsuka in ZooKeys, 2013, 338. [p.43, Fig.2].
Female (from 12°41.14'N, 101°42.49'E): A-B, habitus (dorsal and lateral, respectively); C, rostrum (ventral view); D, right A1 (arabic numerals denote segment numbers); E, right A2; F, Md; G, Mx2.

Nota : Cephalosome and 1st pedigerous somite fused, 4th and 5th pedigerous somites fused.
Dorsolateral spines on 5th on 5th pedigerous somite.
Urosome 4-segmented.
Genital double-somite asymmetrical in dorsal view, elongate (ca. 2.54 times as long as wide) ; postero-dorsal and lateral margins with somewhat irregular row of spinules in ventral view ; genital area firnished with blunt, linguiform process midway, transverse rows of spinules anteriorly and paired flaps originating from genital opercula. Eaxh of paired egg-sacs consisting of 9-14 eggs, attached to lateral of genital opening.
Proportional lengths of urosomites and caudal ramus 43 : 15 : 15 : 7 : 20 = 100.
2 nd and 3rd urosomites with row of minute spinules along postero-dorsal and lateral margins.
Caudal rami with hair on inner margin and symmetrical with 6 setae (seta I absent, seta II with fine setules only along inner margin, setae III-VI plumose, seta VII located dorsally.
A1 reaching beyond posterior end of genital double-somite, symmetrical, 22-segmented (segments 6-7 incompletely fused, segmenys 6, 15, 16, 18-21 each without aesthetasc.
A2 coxa with single seta ; basis with 2 setae at inner corner ; endopod 2-segmented (1st segment with 2 setae, 2 nd segment with 7 and 8 setae on terminal and subterminal lobes, respectively, and lateral row of fine setules ; exopod 4-segmented (1st segment with 1 seta, 2 nd segment with 1 proximal, 2 medial and 1 terminal setae, 3rd segment with 3 setae, 4th segment with 1 medial and 3 terminal setae).
Md with basis bearing 4 setae along inner margin ; endopod 2-segmented (1st segment with 4 setae, 2 nd with 9 setae ; exopod 5-segmented (1st to 5th segments with 1, 1, 1, 1, 2 setae, respectively. Gnathobase (coxa) with serrate dorsal seta and 3 cuspidate and 4 blunt teeth.
Mx2 with 1st and 2 nd praecoxal endites having 4 and 3 setae, respectively ; 1st coxal endite with 3 long setae, 2 nd endite with 1 short strong and 2 long setae ; basis with 1 short and 2 long setae ; endopod with 9 setae.

Species Pseudodiaptomus siamensis - Plate 2 of morphological figuresIssued from : K. Srinui, S. Nishida & S. Ohtsuka in ZooKeys, 2013, 338. [p.45, Fig.3].
Female: A, Mx1; B, Mxp; C, P1 (posterior view); D, P2 (posterior view); E, P3 (anterior view); F, P4 (posterior view); G, P5 (posterior view).

Nota : Mx1with praecoxal arthrite bearing 9 trong and 6 fine setae and small spinules; coxa with 4 setae on endite and 9 setae on epipodite ; basis with 4 and 5 setae on proximal and distal endites, respectively ; basal exite with 1 seta ; endopod 3-segmented with 4, 4 and 6 setae from 1st to 3rd segments, respectively; exopod foliaceius with 10 setae along outer margin.
Mxp with praecoxa and coxa completely fused ; endites with 0, 2, 3, 4 setae, respectively ; basis with 3 setae ; endopodal segment 6-segmented (1st segment with 2 setae, 2 nd segment with 2 bifurcated setae and 1 seta, 3rd and 4th segments with 1 bifurcated seta and 1 seta, 5th and 6th segments with 3 and 4 setae, respectively.
P5 uniramous and almost symmetrical ; in posterior view, basis with short medial seta and spinular rows ; exopod 3-segmented, 1st segment produced into small pointed process at inner subterminal corner, with disto-lateral spine and one or two rows of spinules ; 2 nd segment having short and thickned disto-lateral process and medial serrate spine ; 3rd segment spiniform, tapering distally with inner spinules and proximo-medial spine.

Species Pseudodiaptomus siamensis - Plate 3 of morphological figuresIssued from : K. Srinui, S. Nishida & S. Ohtsuka in ZooKeys, 2013, 338. [p.44].
Female: Setae (arabic numerals) and spine (Roman numerals) formula of swimming legs P1 to P4.

Species Pseudodiaptomus siamensis - Plate 4 of morphological figuresIssued from : K. Srinui, S. Nishida & S. Ohtsuka in ZooKeys, 2013, 338. [p.48, Fig.5].
SEM micrograph of ventral side of genital double-somite of female Pseudodiaptomus siamensis, showing blunt process anterior to genital area.

Species Pseudodiaptomus siamensis - Plate 5 of morphological figuresIssued from : K. Srinui, S. Nishida & S. Ohtsuka in ZooKeys, 2013, 338. [p.47, Fig.4].
Male: A-B, habitus (lateral and dorsal, respectively); C, right A1 (arabic numerals denote segment numbers); D, P5 (anterior view); E, P5 (posterior view); F, anterior view of exopod of right P5; G, postrior view of inner process and outer process of endopod of left P5.

Nota : Urosome 5-segmented. Proportional lengths of urosomites and caudal ramus 13 : 25 : 21 : 17 : 11 : 13 = 100.
Genital somite nearly symmetrical with 1 or 2 rows of spinules ventrally.
Urosomites 1-4 with spinular row along posterior margin
Caudal rami symmetrical, with 6 setae as in female.
Right A1 geniculate and indistinctly 20-segmented

NZ: 1

Distribution map of Pseudodiaptomus siamensis by geographical zones
Gulf of Thailand (Prasae River Estuary).

Type locality: 12°42.66'N, 101°42.37'E.
N: 1
(1146) F: 1,29-1,41; M: 0,94-1,02; {F: 1,29-1,41; M: 0,94-1,02}
Rem.: Brackish waters. Euryhaline in the Prasae Estuary (Salinity between 0.7 and 23.3)
Last update : 05/02/2014
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Razouls C., Desreumaux N., Kouwenberg J. and de Bovée F., 2005-2024. - Biodiversity of Marine Planktonic Copepods (morphology, geographical distribution and biological data). Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed July 25, 2024]

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