Caligus undulatus Shen and Li, 1959

Venmathi Maran, B. A., Ohtsuka, Susumu & Shang, Xu, 2012, Records of Adult Caligiform Copepods (Crustacea: Copepoda: Siphonostomatoida) in Marine Plankton from East Asia, Including Descriptions of Two New Species of Caligus (Caligidae), Species Diversity 17 (2), pp. 201-219 : 212

Caligus undulatus Shen and Li, 1959

( Fig. 8D, E )

Caligus undulatus Shen and Li, 1959: 12 ; Yamaguti 1963: 60; Pillai 1966: 123; 1985: 360; Montú 1982: 329; Venmathi Maran and Ohtsuka 2008: 202; Nagasawa et al. 2010: 103.

Material examined. Two adult ♀♀ (one ovigerous) (KMNH IvR 500,505) and one adult ♂ (KMNH IvR 500,506), Takamatsu Port , Kagawa Prefecture, Japan (St. 6), 3 October 2008 ( Table 1) .

Description. Female. Body ( Fig. 8D ) 4.26, 4.29 mm long, excluding caudal setae. Cephalothoracic shield longer than wide, 2.02–2.05× 1.51–1.53 mm. Fourth pediger wider than long, 0.27–0.29× 0.37–0.39 mm. Genital complex longer than wide with irregular lateral margins, 1.21–1.23× 0.89–0.91mm. Abdomen long, 0.75–0.77× 0.31– 0.34 mm. Caudal ramus longer than wide, carrying 3 long terminal and 3 short subterminal setae.

Male. Body ( Fig. 8E ) 3.54 mm long, excluding caudal setae. Cephalothoracic shield longer than wide, 1.89× 1.29 mm. Fourth pediger slightly constricted anteriorly. Genital complex longer than wide, 0.56× 0.39 mm. Abdomen distinctly 2-segmented, subequal in length and width. Caudal ramus as in female.

Remarks. The present female specimens generally agree in size and morphology with those recently reported from plankton samples in Japan and Korea ( Venmathi Maran and Ohtsuka 2008), but some discrepancies are observed between the present specimens and the specimen reported from China by Shen and Li (1959). The present female specimens lack prominent ridges on the genital complex, which are shown on the illustrations given by Shen and Li (1959), but not on specimens from India ( Pillai 1966). The present male specimen (3.54 mm) is larger than one from China (3.08 mm) ( Shen and Li 1959), but similar to others from India (3.50 mm) ( Pillai 1966), Japan (3.50 mm), and Korea (3.52 mm) ( Venmathi Maran and Ohtsuka 2008).

Distribution. Caligus undulatus was originally discovered in plankton samples from China ( Shen and Li 1959) and was subsequently found in Brazil ( Montú 1982), India ( Pillai 1966, 1985), Japan, and Korea ( Nagasawa et al. 2010). This species has been found most frequently in plankton, and it may have unique aspects to its life history.

Figures

Fig. 8. Three previously described species of Caligus found in plankton samples. A, Caligus orientalis Gusev, 1951, female (KMNH IvR 500,503), habitus, dorsal view; B, C. orientalis, male (KMNH IvR 500,504), habitus, dorsal view; C, C. rotundigenitalis Yu, 1933, male (XOB- PC12), habitus, dorsal view; D, C. undulatus Shen and Li, 1959, female (KMNH IvR 500,505), habitus, dorsal view; E, C. undulatus, male (KMNH IvR 500,506), habitus, dorsal view.Scale bars: 1mm (A–E), 0.5mm (C).