A new species of Peniculus (Copepoda: Siphonostomatoida) parasitizing mesopelagic myctophid fish: first discovery of colonization of the genus in deep water

Peniculus hokutoae n. sp. is described on the basis of an ovigerous adult female parasitizing the caudal fin of the myctophid fish Symbolophorus evermanni (Gilbert, 1905), collected from Suruga Bay, Japan. This is the first record of parasitism by this genus on mesopelagic myctophid fish. The new species is easily distinguished from other congeners in: (1) the presence of a conical process anterior to the rostrum; (2) the secondary elongation of the first pedigerous somite; (3) the incorporation of the third and fourth pedigerous somites into the trunk; (4) the unilobate maxillule bearing two unequal apical setae; (5) the lack of any processes on the first segment of the maxilla. Four morphological patterns of the cephalothorax, neck and anterior parts of the trunk can be found in the genus. We infer that initial colonization of a mesopelagic myctophid fish as host is likely to have occurred when the diurnally-migrating myctophid host was feeding in near-surface waters at night and was exposed to infective stages of Peniculus.

Copepods (Cyclopoida) associated with top shells (Vestigastropoda: Trochoidea: Tegulidae) from coastal waters in southern Japan, with descriptions of three new species

Four species of copepods are described based on specimens of both sexes from tegulid top shells (Vestigastropoda) caught from coastal waters of southern Japan. Three species, including two undescribed and one known of the genus Panaietis (Copepoda: Cyclopoida: Anthessiidae) were found in the pharynx and esophagus of gastropods. Panaietis incamerata Stebbing, 1900, P. doraconis n. sp., and P. satsuma n. sp. are distinguished from its congeners by the dorsal plates on the first pedigerous somite, the genital somite, the shape of the spines on legs, the number of setae on legs 1 and 2, and the position and shape of leg 5. Pseudanthessius imo n. sp. (Cyclopoida: Pseudanthessiidae) was found in the mantle cavity of the host. This copepod differs from its congeners in the proportions of the caudal ramus, the armature and proportion of the antenna, the armature of the exopod and general shape of the endopod of leg 4, and the presence of a post-rostral process.

Description of Stephos grieveae sp. nov. (Calanoida, Stephidae) from an anchialine cave in the Adriatic Sea

A new species of stephid calanoids copepodStephos grieveaesp. nov. was collected from an anchialine cave on Mljet Island (Croatia). The new species can be distinguished from otherStephosspp. by a combination of the following features: last pedigerous somite slightly asymmetrical, female genital double-somite symmetrical in ventral view, about as long as wide, single operculum; antennules of both sexes are symmetrical, 24-segmented and very long, reaching almost to end of anal somite; antennal exopod 7-segmented; maxillule displays 13 armature elements on praecoxal arthrite; female fifth legs symmetrical, uniramous and 3-segmented, terminal segment very long armed with spinules distally along inner and outer margins, single small spine on anterior surface and spiniform process laterally; male fifth legs are uniramous and asymmetrically, right leg 4-segmented and left 5-segmented, segment 4 not swollen and segment 5 simple, crescent shaped and is connected to segment 4 at approximately one quarter of its length. The shorter part of segment 5 tapers into a heavy process, while the longer part forms a club-shaped, curved extension.

Two new species of Tortanus (Atortus) (Copepoda, Calanoida, Tortanidae) from the Andaman Islands

Two new species of the planktonic copepod genusTortanus, subgenusAtortus, are described from inter- to sub-tidal water of South Andaman Island, India. The new species are assigned to thetropicusgroup sensu Othman (1987) and distinguished from the other members of the group by the characteristic morphology of the pair of posterior dorsolateral processes on the fifth pedigerous somite in the female and the antennule and leg 5 in the male. An analysis of previous records of thetropicusspecies group indicates their sporadic occurrence combined with high species richness in Southeast Asia, suggesting future discovery of even more species by sampling with finer geographic and habitat coverage.

Description of the male of Prosaetes rhinodontis (Wright, 1876) (Crustacea, Copepoda, Siphonostomatoida), with a proposal to synonymize Cecropidae Dana, 1849 and Amaterasidae Izawa, 2008 with Pandaridae Milne Edwards, 1840

This report provides the first description of the male of Prosaetes rhinodontis (Wright, 1876) (Copepoda, Siphonostomatoida, Cecropidae) based on specimens collected from two whale sharks (Rhincodon typus Smith) held in sea pens off the west coast of Okinawa-jima Island, Japan. We argue that the morphology of P. rhinodontis contributes significantly to the blurring of familial limits between Cecropidae Dana, 1849 and Pandaridae Milne Edwards, 1840 and based on our detailed consideration of this matter we recommend that Cecropidae be recognized as a junior synonym of Pandaridae. Accordingly, we transfer P. rhinodontis, along with species of Cecrops Leach, 1816, Luetkenia Claus, 1864, Philorthagoriscus Horst, 1897, Orthagoriscicola Poche, 1902, and Entepherus Bere, 1936, to the Pandaridae. In addition, our critical evaluation of the morphological features of the adult female and copepodid I of Amaterasia amanoiwatoi Izawa, 2008 indicated that the establishment of Amaterasidae Izawa, 2008 to hold the species was unfounded because A. amanoiwatoi can be accommodated within Pandaridae. Thus, we transfer A. amanoitwatoi to Pandaridae and consider Amaterasidae to be a junior synonym of Pandaridae. Lastly, our comparisons of morphological and ecological attributes of A. amanoiwatoi, specimens of “Nesippus costatus? Wilson, 1924” (Pandaridae) reported by Lewis in 1964, and other pandarids (Pandaridae) revealed the first two taxa to be strikingly similar and suggested them to be congeners. Based on those results we propose Lewis’ specimens represent a new species, which we name Amaterasia lewisi n. sp. Within the Pandaridae, Amaterasia spp. seem to belong to the Dinemoura-group based primarily on their similarity to some Nesippus spp., while representatives of Prosaetes, Cecrops, Luetkenia, Philorthagoriscus, Orthagoriscicola, and Entepherus are more confidently considered members of the Dinemoura-group based on their shared possession of a narrow third pedigerous somite and dorsal plates on the fourth pedigerous somite in the adult female and a modified leg 3 terminal endopodal segment in the adult male.

Asterocheres siphunculus, a new species of Asterocheridae (Copepoda, Siphonostomatoida) associated with Eucidaris tribuloides (Lamarck, 1816) (Echinodermata, Echinoidea) in Brazil

Asterocheres Boeck, 1859 is the most speciose genus within the copepod family Asterocheridae Giesbrecht, 1899. Its main hosts are sponges, cnidarians, bryozoans, and echinoderms. Among the latter there are records of Asterocheres associations with some species of the echinoid genus Eucidaris Pomel, 1883. Despite the wide distribution of Eucidaris tribuloides (Lamarck, 1883) in the coastal waters of Brazil, no records exist as yet of any copepod associated with this species. Asterocheres siphunculus sp. nov. is described herein based on samples collected from E. tribuloides sampled from two different sites off the coast of Salvador city, Bahia state, in northeastern Brazil. The new species shares a 20-segmented antennule with 20 congeners, but differs from them by having a very short siphon that reaches the insertion of the maxilla, a very wide rostrum that occupies the entire area between the antennules, and a pedigerous somite 4 with pointed and narrow posterolateral corners and a concave posterior margin.

The skeletomusculature of siphonostomatoid copepods, with an analysis of adaptive radiation in structure of the oral cone

The skeletomusculature of a primitive siphonostomatoid copepod, Hyalopontius typicus , is described and compared with that of a relatively advanced siphonostomatoid, Lepeophtheirus pectoralis , an ectoparasite of flatfishes. The comparison is used to assess how adaptation to parasitism has affected the morphology and musculature of the appendages. Anatomy has been related to presumed function wherever possible, and functional interpretations are presented for the feeding apparatus of both species and for a range of other siphonostomatoids. The longitudinal trunk muscles of Hyalopontius are arranged in paired dorsal and ventral bundles, as in free-living copepods, but are smaller and less powerful. A further reduction takes place in Lepohtirus , and is presumably correlated with a limited swimming ability. The tagmosis of Hyalopontius is typically podoplean, with the prosome-urosome junction between fourth and fifth pedigerous somites. Hyalopontius possesses a cephalothorax comprising the cephalosome plus the first pedigerous somite. The tagmosis of Lepeophtheirus is modified and the prosomeurosome junction is no longer functional. In adult females the fourth pedigerous somite forms a waist-like region separating anterior cephalothorax from posterior genital complex. The shield-like cephalothorax comprises the cephalosome plus the first three pedigerous somites. The fifth pedigerous, genital and probably the first abdominal somites are fused to form a genital complex. The eudactylinid genus Bariaka is identified as one of the only two siphonostomatoids that possess a free genital somite, not incorporating the first abdominal somite. The structure and musculature of the sternal furca of Lepeophtheirus is described. It is concluded that the furca is an elaboration of the median intersomitic sclerite lying between the maxillipedal and first pedigerous somites. The musculature of the sternal furca is derived from the ventral longitudinal trunk muscles. The musculature of the cephalosomic appendages of siphonostomatoids is reduced compared with that of free-living copepods. The mandibles and maxillules increasingly lose any adduction-abduction movements. In Hyalopontius some adduction of the mandible is possible and extrinsic adductor muscles originating on the anterior cephalic tendon are retained. These are absent from Lepeophtheirus . The maxillules have no ventral extrinsic muscles in Hyalopontius and few dorsal muscles. In Lepeophtheirus there are no maxillulary muscles. The antennae, maxillae and maxillipeds are all basically subchelate and their intrinsic muscles are arranged in antagonistic extensor and flexor groups. These commonly insert on an apophysis that extends proximally from the base of the subchela. A pattern of homologies for the segmental composition of the limbs of the siphonostomatoids is established, based on evidence from their musculature. The inner lobe of the maxillule is homologous with the praecoxal arthrite of other copepods, the outer lobe with the rest of the palp. The proximal segment of the maxilla is the syncoxa. The distal claw represents the basis and its proximal endite, and there is no vestige of the endopod in any siphonostomatoid. The subchela of the maxilliped is derived from the endopod and the endopodal segments are often fused to each other and to the distal claw. The oral cone in a range of siphonostomatoid families is described. Adapdve radiation in feeding mechanisms mainly involves modification of the oral cone and maxillules, rather than of the appendages used for attachm ent to the host. In Hyalopontius , Pontoeciella and Entomopsyllus the oral cone is specialized for fluid feeding. There are efficient seals both around the distal opening of the cone and along the labrum -labium boundary. Suction pressure is produced by labral muscles concentrated in the proximal part of the cone. In Lepeophtheirus the oral cone is specialized for surface grazing and it lacks efficient sealing mechanisms distally and along the labrum -labium boundary. Food material is transported up the oral cone by sequential contraction of labral muscles. In adult Lernaeocera the oral cone acts as an enlarged oral disc forming a feeding seal distally. Suction is generated by oesophageal peristalsis. The musculature of the swimming legs of Lepeophtheirus is described. Several remotor muscles insert on the ventral body wall remote from the basal foramina of the swimming legs. These muscles probably function as a dorsoventral tensors, and assist in creating suction beneath the disc of the cephalothorax. The posterior sinuses on the rear margin of the cephalothorax function as outlet valves during swimming. They are opened and closed by sinus muscles derived from modified promotor muscles of the second swimming legs.

Sexual Dimorphism in Aegisthid Cephalosomic Appendages (Copepoda, Harpacticoida): A Reappraisal

The cephalosomic appendages, including the rostrum, are redescribed in the bathypelagic harpacticoid Aegisthus mucronatus Giesbrecht, 1891 (Aegisthidae). Profound sexual dimorphism was found in all cephalosomic appendages. For the first time reference is made to the presence of a mandible in the male and figures are given for the male maxillula. Distinct sexual differences are also observed in the structure of the labrum and the labium. The structure and ornamentation of the male antennula clearly shows that the Aegisthidae belong to the monophyletic group Cervinioidea, including also the Rotundiclipeidae and Cerviniidae. Brief comments are made on the nature of the first pedigerous somite, the structure of the anal somite and of the caudal rami. The occurrence of sexual dimorphism in postantennular cephalosomic appendages of harpacticoids is reviewed.

On the anatomy of the misophrioid copepods, with special reference to Benthomisophria palliata Sars

The misophrioids are a small but phylogenetically important order of copepods, comprising only three species, which exhibit a mosaic of characters drawn from both gymnoplean and podoplean lineages. The skeletomuscular system of Benthomisophria palliata is described in detail and comparative observations are made on B. cornuta and Misophria pallida . All were found to possess a carapace-like posterior extension of the cephalosome which completely encloses, both dorsally and laterally, the first pedigerous somite beneath. This structure is a posterior outgrowth of the maxilliped-bearing somite and is not derived from the tergite of the pedigerous somite that it encloses. It may represent a modification of the somitic hyaline frill common to many copepods. Its presence is apparently associated with the ability of Benthomisophria to gorge itself until virtually all the free space within the prosome is occupied by the gut. The gut contents of B. palliata reveal that it feeds on relatively large food particles. The probable feeding mechanism is inferred from the ranges of movement possible at each of the joints of the feeding appendages and from their musculature. The probable swimming mechanism is also inferred from similar data for the thoracic limbs. The skeletomusculature of other copepod groups is compared with that of Benthomisophria . The extrinsic muscles of the cephalic appendages and both the extrinsic and intrinsic muscles of the swimming legs were found to be relatively uniform throughout the Copepoda. The longitudinal trunk muscles and intrinsic muscles of the cephalic appendages were found to be more subject to modification during adaptive radiation in habit and feeding strategy respectively. Both species of Benthomisophria exhibit ornamentation of the integument. This is described and a strengthening role is attributed to the intricate system of lamellae and ridges present. Laterally on the cephalosome of Benthomisophria species are areas of funnel-shaped cone organs standing erect from the body surface and bearing a spherical globule of secretion distally. They are positioned so that the long setae of the reflexed antenna and mandibular palp sweep over them. It is concluded that the secretion is spread over the surface of the carapace-like structure by the setae. Its function may be protective. The gross anatomy of the other organ systems is described. The highly distensible gut has large lateral caecae which can expand to accommodate large amounts of food. The musculature of the hindgut is described, as is the postulated sequence of events during defaecation. Adult B. palliata possess paired antennary glands as the functional excretory organs. The maxillary gland is absent. In other copepod groups the maxillary gland is the functional excretory organ of the adult. The central nervous system is described. The complete absence of the nauplius eye throughout the life cycle of misophrioids is noted. The heart is absent from B. palliata . In Misophria pallida it is a barrel-shaped structure about 40 µm long, with weakly muscular walls. It has anterior and posterior ostia only and is suspended from the dorsal body wall by short muscle fibres. The reproductive system is described in both sexes. Male and female have paired gonads, ducts and genital openings. The oviducts open into cavities (genital antra) within the genital somite, which are closed off externally by the plate formed from the fused sixth legs. The male possesses relatively simple vasa deferentia which are poorly differentiated into functional zones. The phylogenetic position of the misophrioids is discussed. They exhibit an unusual combination of ancestral, unique and convergent characters which makes assessment of their affinities difficult. It is tentatively suggested that the Misophrioida, which merits ordinal rank, is more closely related to the Harpacticoida than to any other order.