Nagasawanus akinohama, Uyeno, Daisuke, 2015

Uyeno, Daisuke, 2015, Systematic revision of the pennellid genus Creopelates Shiino, 1958 (Copepoda: Siphonostomatoida) and the proposal of a new genus, Zootaxa 3904 (3), pp. 359-386 : 375-379

Nagasawanus akinohama n. sp.

New Japanese name: Naga-wakizashi for both the genus and the species ( Figs 11 A, 12, 13)

Type material. Holotype: postmetamorphic adult female (NSMT-Cr 23844) (dissected), ex Trimma grammistes (Tomiyama) ( Perciformes : Gobiidae ), off Akinohama (34°47'N, 139°23'E), Izu-Oshima Island, Tokyo, North Pacific Ocean, Japan, 3 April 2011, leg. O. Hoshino. Paratype: 1 postmetamorphic adult female (NSMT-Cr 23845), ex T. grammistes , off Akinohama (34°47'N, 139°23'E), Izu-Oshima Island, Tokyo, North Pacific Ocean, Japan, 30 m depth, 13 February 2011, leg. O. Hoshino; 1 postmetamorphic adult female (NSMT-Cr 23846), ex T. grammistes , off Akinohama (34°47'N, 139°23'E), Izu-Oshima Island, Tokyo, North Pacific Ocean, Japan, 40 m depth, 12 September 2013, leg. O. Hoshino.

Description of postmetamorphic adult female. Body ( Fig. 12 A) 6.89 long, comprising cephalothorax, neck region and trunk; junction of cephalothorax and neck bending through 90o; junction of neck and trunk curved. Cephalothorax ( Fig. 12 A–D) longer than wide 0.38 × 0.26, bearing paired antennary processes and rounded posterolateral lobes; antennary process with additional spherical protrusion and three rounded smaller protrusions; rostrum ( Fig. 12 E) narrow. Neck region ( Fig. 12 A) narrow, curved near junction to cephalothorax with subterminal bulging and posterior constricted part; second and third pedigers clearly segmented ( Fig. 12 D). Trunk ( Fig. 12 A, F) pyriform, longer than wide 2.58 × 1.00, with anterior end narrowing towards neck region. Abdomen conical, located between oviducal pores ( Fig. 12 A, F, G). Egg-sac uniseriate, coiled ( Fig. 12 A).

Antennule ( Fig. 12 H) unsegmented, bearing at least 17 setae on anterior margin: distal tip 11 setae distally, 2 of which sharing common base, and 1 aesthetasc. Antenna ( Fig. 13 A) 3-segmented, chelate, typical pennellid; proximal segment unarmed; middle segment bearing one pointed protrusion 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. 13 B) bilobate, composed of knob-like lobes; inner lobe bearing one seta; outer lobe bearing two setae. Maxilla ( Fig. 13 C) 2-segmented; proximal segment bearing single subterminal pointed process; terminal segment elongated claw, incompletely 2- segmented without ornamentation. Maxilliped absent.

Legs 1 and 2 ( Fig. 13 D–F) biramous. Legs 3 and 4 ( Fig. 13 G–I) uniramous. Legs 1 to 4 evenly arrayed along posterior part of cephalothorax to neck region ( Fig. 12 C). Armature formula of legs as for generic diagnosis.

Protopods of legs 1 to 4 connected to respective intercoxal sclerites ( Fig. 13 D, E, G, I).

Attachment site. The cephalothorax and neck of the copepod were embedded in the musculature of the host’s trunk behind the base of the pectoral fin and attached to the vertebrae, while its trunk and egg sacs remained external to the fish’s body wall ( Fig. 11 A).

Variability of female morphology. The morphology of the female paratypes are as in the holotype. The measurements of paratypes are as follows (n = 2): body length 8.11–9.32 (8.71 ± 0.86); cephalothorax length 0.35–0.42 (0.38 ± 0.05); cephalothorax width 0.28–0.34 (0.31 ± 0.04); trunk length 2.81–3.20 (3.00 ± 0.28); trunk width 1.11–1.24 (1.18 ± 0.09).

Etymology. The specific name of the new species, akinohama , refers to the type locality, Akinohama on Izu Oshima Island, North Pacific Ocean, Japan.

Figures

FIGURE 11. Postmetamorphic adult females of Nagasawanus akinohama n. gen. et n. sp. (A) and N. snufkini n. sp. (B, C) attached to their hosts. A, a specimen of Trimma grammistes (Tomiyama) infected by the paratype female (NSMT-Cr 23845), c = a female specimen of Cardiodectes asper Uyeno & Nagasawa, 2010, n = paratype female of N. akinohama n. gen. et n. sp.; B, a specimen of Trimma tevegae Cohen & Davis infected by a specimen of N. snufkini. C, coloration in life of a specimen attached to host’s body. Scale bars: A, C, 2 mm; B, 5 mm.

FIGURE 12. Nagasawanus akinohama n. gen. et n. sp., postmetamorphic adult female, holotype, NSMT-Cr 23844. A, habitus; B, cephalothorax and anterior end of neck region, dorsal; C, same, ventral; D, same, lateral; E, anterior part of cephalothorax with rostrum; F, trunk, ventral; G, posterior part of trunk, ventral; H, right antennule, anterior. Scale bars: A, F, 1000 µm; B – D, G, 250 µm; E, 50 µm; H, 30 µm.

FIGURE 13. Nagasawanus akinohama n. gen. et n. sp., postmetamorphic adult female, holotype, NSMT-Cr 23844. A, right antenna, anterior; B, left maxillule; C, left maxilla, anterior; D, right leg 1 with intercoxal sclerite, anterior; E, protopod of right leg 2 with intercoxal sclerite, anterior; F, rami of right leg 2 anterior; G, protopod of right leg 3 with intercoxal sclerite, anterior; H, exopod of right leg 3, anterior; I, left leg 4 with intercoxal sclerite, anterior. Scale bars: A, C, D – F, I, 30 µm; B, 10 µm; G, H, 20 µm.