Creopelates shirakawai Uyeno, 2015, n. sp.

Creopelates shirakawai n. sp.

New Japanese name: Shirakawa-no-wakizashi (Figs 6 A, B, 7, 8)

Type material. Holotype: postmetamorphic adult female (NSMT-Cr 23843) (dissected), ex Diancistrus fuscus (Fowler) (Ophidiiformes: Bythitidae), off Awa (26°36'N, 127°55'E), Nago Bay, Okinawa Island, Japan, 5 m depth, 8 December, 2011, leg. N. Shirakawa.

Description of postmetamorphic adult female. Body (Fig. 7 A) 7.55 long, comprising cephalothorax, neck region and trunk; junction of neck and trunk curved. Cephalothorax (Fig. 7 A–C) round, 1.09 × 1.08, with paired vertically long antennary processes with rugged surface and paired posterolateral lobes with digitate fringes; rostrum (Fig. 7 D) not well developed, bearing straight frontal margin. Neck region (Fig. 7 A) narrow, fringed with series of less than ten pairs of finely digitate lobes; second and third pedigers clearly segmented (Fig. 7 B, C). Trunk (Fig. 7 A, E) pyriform, longer than wide 2.76 × 1.06, with anterior end narrowing towards neck region (Fig. 7 E). Abdomen conical, bearing median depression, located between oviducal pores (Fig. 7 A, E, F). Egg-sac uniseriate, coiled (Fig. 7 A).

Antennule (Fig. 7 G) unsegmented, bearing 18 setae along anterior margin: distal tip with 11 setae distally, 2 of which share common base, and 1 aesthetasc. Antenna (Fig. 8 A) 3-segmented, chelate, typical pennellid; proximal segment bearing blunt distal process on outer margin; middle segment bearing two small pointed protrusions along inner medial margin; terminal segment claw-like bearing small basal element on posterior surface. Mouth tube, maxillule, and maxilla located near base of antenna on anterior part of ventral surface of cephalothorax. Maxillule (Fig. 8 B) comprising one seta and lobe with two distal setae. Maxilla (Fig. 8 C) 2-segmented; proximal segment bearing single subterminal pointed process; terminal segment incompletely subdivided, with rounded distal part bearing spatulate fringe covered with small spinules. Maxilliped absent.

Legs 1 and 2 (Fig. 8 D–G) biramous. Legs 3 and 4 (Fig. 8 H, I) uniramous. Legs 1–4 evenly arrayed on posterior part of cephalothorax to neck region (Fig. 7 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. 8 E, G, H, I).

Attachment site. The cephalothorax and neck of the copepod were embedded in the musculature of the host’s trunk near the anus and attached to the vertebrae, while its trunk and egg sacs remained external to the fish’s body wall (Fig. 6 A, B).

Remarks. Creopelates shirakawai n. sp. differs from C. floridus, C. nohmijimensis and C. hoshinoi n. sp. in having antennary processes without digitate fringes and cephalic lobes with digitate fringes.

Etymology. The specific name “ shirakawai ” is dedicated to Mr. Naoki Shirakawa, an expert diver who finds remarkable animals. He collected the type specimen of this copepod.