Creopelates hoshinoi n. sp.

New Japanese name: Hoshino-no-wakizashi (Figs 1 B, 4, 5)

Type material. Holotype: postmetamorphic adult female (NSMT-Cr 23841) (dissected), ex Bryaninops yongei (Davis & Cohen) (Perciformes: Gobiidae), off Akinohama (34°47'N, 139°23'E), Izu-Oshima Island, Tokyo, North Pacific Ocean, Japan, 20 m depth, 6 January 2011, leg. O. Hoshino. Paratype: 1 postmetamorphic adult female (NSMT-Cr 23842), ex Bryaninops yongei (Davis & Cohen) (Perciformes: Gobiidae), off Akinohama (34°47'N, 139°23'E), Izu-Oshima Island, Tokyo, North Pacific Ocean, Japan, 30 m depth, 11 January 2012, leg. O. Hoshino.

Description of postmetamorphic adult female. Body (Fig. 4 A) 4.67 long, comprising cephalothorax, neck region and trunk; junction of neck and trunk curved. Cephalothorax (Fig. 4 A–C) longer than wide 0.48 × 0.32, bearing paired antennary processes with irregular processes and paired small posterolateral lobes; rostrum (Fig. 4 D) flat, bearing straight frontal margin. Neck region (Fig. 4 A) narrow, fringed with one pair of finely digitate lobes (Fig. 4 A–C). Trunk (Fig. 4 A, E) pyriform, longer than wide 2.44 × 0.88, with anterior end narrowing towards neck region (Fig. 4 E). Abdomen located between oviducal pores (Fig. 4 A, E, F). Egg-sac uniseriate, spirally coiled (Fig. 4 A).

Antennule (Fig. 4 G) unsegmented, bearing at least 14 setae along anterior margin: distal tip with 10 setae distally, 2 of which share common base, and 1 aesthetasc. Antenna (Fig. 5 A) 3-segmented, chelate, typical pennellid; proximal segment bearing pointed outer process; middle segment bearing one pointed protrusion serrated along inner medial margin; terminal segment claw-like with minute element on posterior surface. Mouth tube, maxillule, and maxilla located near base of antenna on anterior part of ventral surface of cephalothorax. Maxillule (Fig. 5 B) comprising one seta and lobe with two distal setae. Maxilla (Fig. 5 C) 2-segmented; proximal segment bearing single subterminal pointed process; terminal segment incompletely subdivided, with rounded distal part covered with small spinules. Maxilliped absent.

Legs 1 and 2 (Fig. 5 D, E) biramous. Legs 3 and 4 (Fig. 5 F, G) uniramous. Legs 1 to 4 evenly arrayed on posterior part of cephalothorax to neck region (Fig. 4 C). Armature formula of legs 1–4 as follows:

Protopod Exopod Endopod Leg 1 1–1 1–1; 7 0–1; 7 Leg 2 1–0 1–1; 7 0–1; 7 Leg 3 1–0 0–0; 6 Absent Leg 4 0–0 0–0; 5 Absent Protopods of legs 1–4 connected to respective intercoxal sclerites (Fig. 5 D–G).

Attachment site. The cephalothorax and neck of the copepod were embedded in the musculature of the host’s trunk dorsally behind the base of the pectoral fin, while its trunk and egg sacs remained external to the fish’s body wall (Fig. 1 B).

Variability of female morphology. The morphology of the female paratype is as in the holotype. The measurements of the paratype are as follows (n = 1): body length 4.10; cephalothorax length 0.34; cephalothorax width 0.24; trunk length 1.95; trunk width 0.63.

Remarks. Creopelates hoshinoi n. sp. differs from C. floridus and C. nohmijimensis in having cephalic lobes without fringed digitate fringes (vs. with digitate fringes in the latter species) and the neck region is fringed with one pair of finely digitate lobes (vs. about ten pairs of lobes).

Etymology. The specific name of the new species, hoshinoi, is dedicated to Mr. Osamu Hoshino, an outstanding professional diver working at Izu Oshima Island, who collected the type material.