A New Species and a New Genus of the Family Pennellidae (Copepoda: Siphonostomatoida) Parasitic on North Pacific Lightfish Maurolicus japonicus (Actinopterygii: Stomiiformes: Sternoptychidae) Collected from Suruga Bay, Japan Author Yumura, Nanami Atmosphere and Ocean Research Institute, The University of Tokyo, 5 - 1 - 5 Kashiwanoha, Kashiwa, Chiba 277 - 8564, Japan E-mail: yumura. nanami @ s. nenv. k. u-tokyo. ac. jp & Fisheries Laboratory, Blue Carbon Innovation Division, Seto Inland Sea Carbon Neutral Research Center, Hiroshima University, 5 - 8 - 1 Minato-machi, Takehara, Hiroshima 725 - 0024, Japan & Corresponding author yumura.nanami@s.nenv.k.u-tokyo.ac.jp Author Nishikawa, Jun Department of Marine Biology, School of Marine Science and Technology, Tokai University, 3 - 20 - 1 Orido, Shimizu, Shizuoka 424 - 8610, Japan Author Ohtsuka, Susumu Fisheries Laboratory, Blue Carbon Innovation Division, Seto Inland Sea Carbon Neutral Research Center, Hiroshima University, 5 - 8 - 1 Minato-machi, Takehara, Hiroshima 725 - 0024, Japan text Species Diversity 2024 2024-02-29 29 1 81 90 http://dx.doi.org/10.12782/specdiv.29.81 journal article 10.12782/specdiv.29.81 2189-7301 10833370 C1C34CBC-A3B0-4A3D-B4AA-D872848EFA31 Pseudosarcotretes omorii sp. nov. ( Figs 2–4 ) Type-material. Holotype (NSMT-Cr 31576), one ovigerous female infecting Maurolicus japonicus (standard length 38 mm ) collected from the eastern beach of Miho Peninsula in Suruga Bay ( 34.9899ºN , 138.5214ºE ) on 9 February 2019 , cephalothorax partly dissected and mounted on a glass slide, body in a vial . Paratype 1 (NSMT-Cr 31577), from the same host fish as in the holotype ; paratype 2 (NSMT-Cr 31578) from another individual host (standard length 38 mm ) collected from the eastern beach of Miho Peninsula in Suruga Bay ( 34.9899ºN , 138.5214ºE ) on 3 February 2019 ; paratypes 3 and 4 (NSMT-Cr 31579, 31580), two copepodids from egg string of paratype 2; paratype 5 (NSMT-Cr 31581), from another individual host (standard length 46 mm ) collected from the eastern beach of Miho Peninsula in Suruga Bay ( 34.9846ºN , 138.5165ºE ) on 11 February 2019 . Type locality. The east coast of Miho Peninsula ( 34.9847ºN , 138.5164ºE ), Japan . Table 1. Pennellid species used in the phylogenetic analysis, with notes on host, sampling date and location, INSD accession numbers of the sequences studied, and references.
Species Host Order of host Sampling date Sampling location Accession No. Reference
Peniculisa shiinoi Izawa, 1965 Canthigaster rivulata (Temminck and Schlegel, 1850) Tetraodontiformes 28 September 2020 Uwajima of the Seto Inland Sea LC777454 Present study
Peniculus minuticaudae Shiino, 1956 Stephanolepis cirrhifer (Temminck and Schlegel, 1850) Tetraodontiformes 11 March 2019 Uwajima of the Seto Inland Sea LC586436 Yumura et al. (2022)
Peniculus ostraciontis Yamaguti, 1939 Thamnaconus modestus (Günther, 1877) Tetraodontiformes 9 August 2019 Off Wajima, Sea of Japan LC586437 Yumura et al. (2022)
Peniculus truncatus Shiino, 1956 Sebastes inermis Cuvier, 1829 Scorpaeniformes 3 March 2020 Teshima of the Seto Inland Sea LC777453 Present study
Haemobaphes pannosus Kabata, 1979 NA NA NA Off the coast of Gyeongsangbuk-do, South Korea KR048773 Baek and Hwang (unpublished)
Lernaeocera branchialis (Linnaeus, 1767) Cyclopterus lumpus Linnaeus, 1758 Scorpaeniformes 19 May 2001 Off the coast of Newfoundland, Canada AY627030 Lovy and Friend (2020)
Phrixocephalus vipereus Shiino, 1956 Branchiostegus japonicus (Houttuyn, 1782) Perciformes 23 June 2021 off Ishikawa, Sea of Japan LC650961 Yumura et al. (2022)
Cardiodectes sp. Parapercis sexfasciata (Temminck and Schlegel, 1843) Perciformes 28 May 2019 Off the Tanegashima, Pacific Ocean LC777455 Present study
Pseudosarcotretes omorii gen. et sp. nov. Maurolicus japonicus Ishikawa, 1915 Stomiiformes 9 February 2019 Suruga Bay LC777456 Present study
Lernaeenicus radiatus Lesueur, 1824 Centropristis striata (Linnaeus, 1758) Perciformes 18 July 2019 Off the coast of southern New Jersey, USA MN523342 Lovy and Friend (2020)
Lernaeenicus hemirhamphi Kirtisinghe, 1932 Hyporhamphus sajori (Temminck and Schlegel, 1846) Beloniformes 8 September 2019 Okayama of the Seto Inland Sea LC586441 Yumura et al. (2022)
Pennella sp. Cololabis saira (Brevoort, 1856) Beloniformes 5 October 2018 Off the Hokkaido, Pacific Ocean LC586438 Yumura et al. (2022)
Lernaeenicus ramosus Kirtisinghe, 1956 Epinephelus awoara (Temminck and Schlegel, 1842) Perciformes 21 May 2019 Off the Miyazaki, Pacific Ocean LC586439 Yumura et al. (2022)
Lernaeenicus ater Shiino, 1958 Jaydia lineata (Temminck and Schlegel, 1843) Perciformes 12 May 2019 Fukuyama of the Seto Inland Sea LC586440 Yumura et al. (2022)
NA, not available. Table 2. Segmentation and setation of legs of Pseudosarcotretes omorii gen. et sp. nov.
Life stage Leg Protopod Exopod Endopod
Adult female 1 1-0 0-1, 5 0-1, 7
2 0-0 0-1, 6 0-0, 7
3 0-0 0-0, 4 absent
Copepodid 1 0-0 I, 4 I, 4
2 0-0 II, 3 I, 5
Table 3. The differentiation of four pennellid genera.
Genus Cephalothoracic holdfast Proboscis Caudal rami Endopod of leg 3 Leg 4
Pseudosarcotretes gen. nov. A pair of lateral expansions Elongated Bilobate Absent Absent
Cardiodectes Wilson, 1917 Lateral lobes and mass of small processes Not forming Absent Absent Absent *
Protosarcotretes Ohtsuka, Lindsay, and Izawa, 2018 A pair of lateral expansions Not forming Bilobate Present Present
Sarcotretes Jungersen, 1911 A paired of bulbous swellings Elongated Absent or swelling Absent Vestige
* Except C. rubosus Leigh-Sharpe, 1934 . Fig. 2. Pseudosarcotretes omorii gen. et sp. nov. , ovigerous adult females, holotype (A–F), and paratype (1, NSMT-Cr 31577: G). A, Anteri- or part of cephalothorax, dorsal view; B, habitus, dorsal view (trunk twisted); C, pedigers 1–3, dorsal view; D, posterior part of trunk, lateral view; E, oral cone, lateral view; F, anterior part of trunk, dorsal view; G, anterior part of trunk, dorsal view. Abbreviations: oc, oral cone; pb, proboscis; sp, semicircular processes. Scale bars: A, D, F, G, 0.5 mm; B, 1mm; C, 0.1 mm; E, 0.05 mm. Host. Maurolicus japonicus Ishikawa , 1915. Attachment site. The cephalothorax, neck, and anterior part of the trunk of the parasite were embedded in the host’s musculature from posterior to right pectoral fin. Description. Ovigerous female. Body ( Fig. 2B ) comprising laterally expanded cephalothorax, relatively slim neck, and trunk with anterior part constricted and posterior cylindrical. Total length ca. 5.5–7.1mm from anterior tip of cephalothorax to posterior end of caudal ramus. Anterior part of trunk embedded into host tissue. Cephalothorax produced lateral paired semicircle holdfasts ( Fig. 2B ). First pedigerous somite incorporated into cephalosome ( Fig. 2C ). Oral cone ( Fig. 2E ) in the form of elongated proboscis; pair of semicircular processes on constricted area between proboscis and cephalothorax ( Fig. 2A ). Neck ( Fig. 2C ) consisting of pedigers 2 and 3, and anterior part of trunk, 0.2–0.3 mm in length. Trunk ( Fig. 2B ) 3.4–4.4mm in length, about 1.8 times as long as the cephalothorax and neck; abdomen moderately reduced ( Fig. 2D ); caudal ramus ( Fig. 3F ) bilobate; setae missing, probably due to stranding damages. Egg string ( Fig. 2D ) straight and uniseriate. Number of eggs per string ranging from 298 to 324. Antennule ( Fig. 3A ) incompletely two segmented, bearing middle seta; some elements possibly lost during dissection. Antenna subchelate ( Fig. 3B ), relatively wide, 3-segmented; second segment produced into robust process near anterior edge; third segment curved inward acting as subchela against preceding segment. Mandible ( Fig. 3E ) short, spatular, with three teeth. Maxillule ( Fig. 3C, D ) simple, inner lobe with one terminal seta; outer lobe absent. Maxilla not observed. Fig. 3. Pseudosarcotretes omorii gen. et sp. nov. , ovigerous adult females, holotype (A–F), and paratype (1, NSMT-Cr 31577: G–I). A, Antennule; B, antenna; C, maxillule, basal part; D, maxillule; E, mandible; F, caudal ramus; G, leg 1, anterior surface; H, leg 2, anterior surface; I, leg 3, anterior surface. Scale bars: A, 0.1 mm; B, 0.25mm; C, D, F, G–I, 0.05 mm; E, 0.01 mm. Legs 1 and 2 biramous ( Fig. 3G, H ); rami 2-segmented; leg 3 ( Fig. 3I ) uniramous; armature elements are shown in Table 2 . Male . Unknown. Copepodid dissected from pre-hatching egg. Body comprising cephalosome with incorporated first pedigerous somite, second and third free somites, 2-segmented urosomes, and caudal rami. Cephalothorax ( Fig. 4A ) ellipsoid, the tip of anterior slightly hollow, oral cone ( Fig. 4B ) weakly developed. Naupliar eyes conspicuously present. Second pedigerous somite about two-thirds length of third pedigerous somite; urosomite separated vaguely from caudal rami ( Fig. 4G ). Antennule ( Fig. 4D ) 2-segmented. Antenna ( Fig. 4C ) 3-segmented, proximal segment large, having blunt process at mid length, middle segment short, terminal segment curved inward to form subchela with serrate notch. Oral cone ( Fig. 4B ) short, slightly conical. Oral appendages rudimentary, invisible. Fig. 4. Pseudosarcotretes omorii gen. et sp. nov. , copepodids, paratypes (3 and 4, NSMT-Cr 31579, 31580), from the egg string of paratype (2, NSMT-Cr 31578). A, Habitus, dorsal view; B, oral cone; C, antenna; D, antennule; E, leg 1; F, leg 2; G, caudal rami; H, leg 3. Arrows showing bearing parts of leg 3. Scale bars: A, 0.2mm; B, H, 0.02mm; C–F, 0.05mm; G, 0.03 mm. Legs 1 and 2 ( Fig. 4E, F ) biramous, rami unsegmented; armature elements shown in Table 2 ; leg 3 ( Fig. 4H ) represented by single spine on posterior tip of third pedigerous somite. Variation . The number and shape of knobs on the anterior parts of body of adult females vary among specimens. While the holotype has a pair of wing-shaped knobs on the anterior end of trunk, paratype 1 bears two pairs of spherical knobs in addition to one hump near the constricted part ( Fig. 2F, G ). Etymology. The specific name is named in honor of the late Dr Makoto Omori , who deceased on 4 June 2022 , and had been making a great contribution to copepodology of Japan and keen to study the taxonomy and ecology of the pelagic shrimp Lucensosergia lucens (Hansen, 1922) in Suruga Bay.