Caligus latigenitalis Shiino, 1954

Maran, B. A. Venmathi, Ohtsuka, Susumu & Jitchum, Pailin, 2012, Occurrence of Caligid Copepods (Crustacea) in Plankton Samples Collected from Japan and Ŋailand, with the Description of a New Species, Species Diversity 17 (1), pp. 87-95 : 89

Caligus latigenitalis Shiino, 1954

(Fig. 2A)

Caligus latigenitalis Shiino, 1954a: 21 ; Izawa and Choi 2000: 995; Izawa 2004: 329; Kim 1998: 653. Not Caligus latigenitalis Shiino 1960: 471 .

Caligus dieuzeidei Brain, 1933 : Shiino 1954b: 268; Lin et al. 1994: 253.

Material examined.On e adult (KMNH IvR 500, 511), the Suo-nada basin of the Seto Inland Sea, Japan, St. 2, 33°51 .3'N , 131°22.6'E, 25–26 m deep, 28 October 2010, sledge-net.

Description. M ale . Body (Fig. 2A) 4.45 mm long excluding setae on caudal rami. Cephalothoracic shield longer than wide, 2.84× 2.50 mm. Fourth pediger wider than long, 0.15× 0.28 mm. Genital complex wider than long, 0.78× 0.93 mm. Abdomen 2-segmented, longer than wide, 0.47× 0.19 mm, second segment longer than rst segment. Caudal ramus 0.18× 0.20 mm, more or less equal in length and width and armed with 3 long terminal setae, 3 short subterminal setae.

Armature on rami of legs 1–4 as in C. chiastos (see Table 1).

Remarks.A ccording to Izawa and Choi (2000), males of this species are larger than females (4.1–6.9 mm vs 3.22– 4.33 mm). ffiey recognized two size classes based on body length, a large class of 6.10± 0.45 mm and a small class of 4.58± 0.36 mm. ffie present adult male is 4.45 mm long and falls within the latter group. Our male specimen is morphologically similar to the descriptions of Izawa and Choi (2000), except for a minor di erence in the post-antennal process. It is weakly curved and pointed in our specimen, but well curved and less pointed in the description of Izawa and Choi (2000). ffiis minor di erence might be due to the large size (6.4 mm) of the specimen described by Izawa and Choi (2000).

Males of C. latigenitalis are characterized by a maxilliped with the myxal area of its stout corpus comprising three unequal protuberances. ffiis species is closely similar to Caligus acanthopagri Lin, Ho and Chen, 1994 in general body structure and the maxilliped; however, it di ers from C. acanthopagri in the accessory processes at the distal end of the exopod of leg 4, which are simple with a hyaline membrane in C. acanthopagri (cf. Lin et al. 1994; Ho and Lin 2004a), but strong and sharply indented marginally in C. latigenitalis ( Izawa and Choi 2000) .

Caligus latigenitalis was rst described by Shiino (1954a) based on a single female infecting black seabream Sparus macrocephalus (Basilewsky, 1855) (= Acanthopagrus schlegelii schlegelii Bleeker, 1854 ) collected at Momotori, Mie Prefecture, Japan. Shiino (1954b) also reported Caligus diezuedei Brian, 1933 infecting black seabream, but this was subsequently stated to be a misidenti ed C. latigenitalis (cf. Lin et al. 1994). Izawa and Choi (2000) suggested that specimens referred to C. latigenitalis by Shiino (1960) (hosts were starspotted smooth-hound sharks Mustelus manazo Bleeker, 1854 and brown guitar- sh Rhinobatos schlegelii Müller and Henle, 1841 , landed at Hazima, Japan) represented a species other than C. latigenitalis , although the speci c identity remains unclear.

Recently, this species was redescribed by Izawa and Choi (2000) and Izawa (2004) on the basis of adult females and males, including some chalimus stages. It has so far been reported from Japan and Korea (cf. Nagasawa et al. 2010), and commonly infects black seabream ( Shiino 1954a, b; Kim 1998; Izawa and Choi 2000; Nagasawa et al. 2010). ffiis is the rst record of the occurrence of C. latigenitalis in a plankton sample.