Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Scolecitrichidae ( Family )
            Scolecocalanus ( Genus )
Scolecocalanus infrequens  (Tanaka, 1969)   (F)
Syn.: Scottocalanus infrequens Tanaka, 1969 (p.271, Descr.F, figs.F); Park, 1983 (p.198, 199); Bradford & al., 1983 (p.115)
Vyshkvartzeva, 2001 (p.80: Rem.)
Species Scolecocalanus infrequens - Plate 1 of morphological figuresissued from : O. Tanaka in Publ. Seto Mar. Lab., 1969, XVII (4). [Fig.10]. As Scottocalanus infrequens.
Female (from Pacific): a, habitus (dorsal); b, forehead (lateral); c, last thoracic segment and urosome (lateral right side); d, idem (lateral left side); e, genital segment (ventral); f, A1; g, A2; h, Md.

Nota Female:
- Body abut 3 times as long as wide.
- Head with a triangular median crest.
- Head and 1st pediger fused, 4th and 5th pedigers fused.
- Proportional lengths of cephalothorax and abdomen 78 : 22.
- Rostrum biramous, suddenly attenuates in the distal half.
- Last thoracic segment asymmetrical; right side acutely pointed, left side narrowly rounded, but pointed at the distal lateral margin.
- Abdomen 4-segmented; segments and caudal rami in proportional lengths 44 : 23 : 14 : 8 : 11 = 100.
- Genital segment asymmetrical, swollen on the right lateral margin; a very acute process arises on the dorsal surface near the distal margin; genital area considerably produced below.
- 2rd abdominal segment with dorsal surface swollen, the lateral corner fusnished with a small spine on the left side accompanied by a bunch of spinules.
- Anal segment furnished with a row of spinules on the distal margin.
- Caudal rami as long as wide, with 4 long marginal setae and 1 small inner marginal seta.
- A1 22-segmented, extends at the end of prosome.
- A2 exopod 6-segmented, 1.5 times as long as endopod with 5 estae on the outer lobe, and 7 setae on the outer lobe.
- Md exopod as long as endopod; exopod 5-segmented, carries 6 setae; endopod 2-segmented, 1st segment with 2 setae, 2nd segment with 10 setae on the distal margin; mandibular palp with 2 marginal setae,

Species Scolecocalanus infrequens - Plate 2 of morphological figuresissued from : O. Tanaka in Publ. Seto Mar. Lab., 1969, XVII (4). [Fig.11]. As Scottocalanus infrequens.
Female: a, Mx1; b, Mx2; c, Mxp; d, P1; e, P2; f, P3 (endopod); g, P4; h, P5.

- Mx1 with 9 setae on outer lobe; 8 setae on exopod; 4+3 setae on endopod; 5 setae on the 2nd basal segment: 3 setae on the 3rd inner lobe; 2 on the 2nd inner lobe; 11 setae on the 1st inner lobe (= arthrite).
- Mx2 endopod with 8 worm-like filaments; spine of 5th lobe very strong.
- Mxp with the 1st basal segment robust; 1st lobe furnished with, in addition to a long seta, a brunch of hairs; 2nd basal segment with the inner margin provided with a row of spinules; endopod 5-segmented, the 2nd segment very long.
- P1 exopod 3-segmented and endopod 1-segmented; 1st exopodal swollen on the inner margin.
- P2 exopod 3-segmented and endopod 2-segmented; exopod and endopod furnished with rows of spinules on posterior surface.
- P3 and P4 exopods and endopods 3-segmented each.
- P4 posterior surface of 2nd and 3rd exopodal segments ornamented with a longitudinal row of spinules; on both segments the row contains a large spine.
- P5 1-segmented, furnished with a strong spine on inner distal margin of the basal segment, which is much longer than the segment itself; Right P5 not found in the specimen/ (may be abnormal).

Species Scolecocalanus infrequens - Plate 3 of morphological figuresissued from : O. Tanaka in Publ. Seto Mar. Lab., 1969, XVII (4). [p.274]. As Scottocalanus infrequens.
Female A1.
- Segments 8 to 10 fused and 24-25 fused.

NZ: 5

Distribution map of Scolecocalanus infrequens by geographical zones
Philippines, off Honshu Is., off California, Queen Charlotte Is.
N: 1
(105) F: 4,76; {F: 4,76}
Rem.: According to Vyshkvartzeva (2001, p.80) Scottocalanus infrequens Tanaka, 1969 actually fits well Scolecocalanus (comb. nov.).
Last update : 27/03/2017
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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 May 18, 2024]

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