Eijiroh Nishi

Habitat use by the gnathiid isopod Elaphognathia discolor living in terebellid polychaete tubes

The pattern of habitat utilization by Elaphognathia discolor , a gnathiid isopod inhabiting terebellid polychaete tubes, was examined in bimonthly samples taken between June 2003 and April 2004 from Shizugawa Bay, north-eastern Japan. Nine species of terebellid polychaetes were obtained, and gnathiids were found in tubes of four terebellid species. Of the terebellids, Nicolea gracilibranchis was collected in each sample, while the other species were obtained only intermittently. Both larval and adult E. discolor inhabited the tubes of N. gracilibranchis throughout the year, with their prevalence in samples ranging from 57.1 to 80.0%. A large range of larval stages was found within N. gracilibranchis tubes, including the first larval stage and premature females, suggesting that this gnathiid species may use N. gracilibranchis tubes for resting and moulting throughout the larval period. The distribution of adult gnathiids within tubes significantly differed from random. Adult males rarely coexisted with other males in tubes, while several larvae and females often lived together. Groups of female gnathiids in polychaete tubes were usually attended by a single male, resembling the ‘harems’ observed in other gnathiids and suggesting that the mating system of E. discolor can be classified as semelparous harem polygynandry.

Chaetopterus and Mesochaetopterus (Polychaeta: Chaetopteridae) from the Galapagos Islands, with Descriptions of Four New Species

ABSTRACT. We provide descriptions of five species of Chaetopterus and two species of Mesochaetopterus (Annelida: Polychaeta: Chaetopteridae) based on collections during 2001–2007 and observations from the Galapagos Islands, Ecuador. Chaetopterus galapagensis sp. nov. is a large (ca. 18 cm long) worm that inhabits a U-shaped tube in soft sand substrates. It is characterized by 12 – 14 chaetigers in the anterior region and 7–8 teeth on uncini of region A neuropodia. Chaetopterus charlesdarwinii sp. nov. is of intermediate size (2 – 4.5 cm long) with 9 anterior region chaetigers and a characteristic brown band on the lateral side of the ventral shield and posterior side of anterior region notopodia. It inhabits irregularly curved tubes cemented to the underside of rocks. Worms may occur singly or aggregated, with up to 10 worms in a cluster. Chaetopterus aduncus sp. nov. is 8–10 cm in length, and is characterized by 10 – 11 anterior region chaetigers, characteristic J-shaped tube with one blind end, and prominent dorsal bulbous inflations in anterior region chaetigers. Chaetopterus longipes Crossland, 1904 is highly gregarious, frequently forming aggregations of hundreds of worms. It is especially common at the northern islands of Darwin and Wolf. Chaetopterus macropus Schmarda, 1861 is solitary, lives in a U-shaped tube on a sandy bottom, has 9 anterior region chaetigers and no brown bands in region-A. We compared the five Galapagos Chaetopterus species to other Pacific (Japanese and Australian) species of the genus in detail. We confirm the presence of Mesochaetopterus minutus Potts, 1914 in Galapagos, the only chaetopterid previously recorded from the archipelago. Mesochaetopterus ecuadorica sp. nov. is a large (12 – 20 cm long) solitary species with 2 middle region chaetigers, that inhabits a long, nearly straight tube with small perforations at the blind end. New taxa: Chaetopterus galapagensis Nishi, Hickman, & Bailey-Brock, Chaetopterus charlesdarwinii Nishi, Hickman, & BaileyBrock, Chaetopterus aduncus Nishi, Hickman, & Bailey-Brock, Mesochaetopterus ecuadorica Nishi, Hickman, & Bailey-Brock

Contribution to the knowledge of Syllidae (Annelida, Phyllodocida) from Japan with descriptions of three new species

Abstract The study of a collection of Japanese Syllidae (Polychaeta) from 18 different intertidal samples yielded a total of 16 genera and 31 species. Three new species of Syllis Lamarck, 1818 from Japan are described. Syllis multiannulata sp. nov. is mainly characterised by its cylindrical broad body with annulated segments, weakly articulated antennae and cirri, dorsal cirri originating from two different levels, the presence of pre‐ and postchaetal parapodial lobes and the pharynx being shorter than the proventricle. Syllis pilosa sp. nov. is characterised by the presence of two marked ciliary bands per segment, elongated bidentate compound chaetae, and a very long pharynx and proventricle. Syllis rubicunda sp. nov. has a broad cylindrical body with distinct colour pattern, long and thick dorsal cirri, bidentate chaetae, and the pharyngeal tooth slightly removed from the anterior margin. Two species, revealing previously unreported morphological features, are also described and illustrated (Amblyosyllis speciosa Izuka, 1912 and Odontosyllis undecimdonta Imajima and Hartman, 1964). Moreover, one species belonging to the genus Pionosyllis Malmgren, 1867, is described, but will remain unnamed until additional material becomes available. An emended diagnosis for Alcyonosyllis Glasby and Watson, 2001 and a new combination, Alcyonosyllis exiliformis comb. nov. are proposed. The generic name, Trypanoseta, Imajima and Hartman, 1964 is proposed to replace Geminosyllis, Imajima, 1966 and the species, Trypanoseta sp. is described. Additionally, four new species to Japanese waters are herein reported: Eusyllis assimilis Marenzeller, 1867, Nudisyllis tinihekea Knox and Cameron, 1970, Paraehlersia ehlersiaformis (Augener, 1913), Branchiosyllis exilis (Gravier, 1900) and Syllis armil‐laris (Müller, 1771). Finally, Eusyllis habei Imajima 1966 and Odontosyllis fulgurans japonica Imajima, 1966 are considered synonymous with E. lamelligera Marion and Bobretzky, 1875 and O. fulgurans (Audouin & Milne Edwards, 1833) respectively.

A New Species of Alcyonosyllis Glasby and Watson, 2001 (Polychaeta: Syllidae: Syllinae) from Shimoda, Japan, Commensal with the Gorgonian Melithaea flabellifera

Abstract A new species of Alcyonosyllis Glasby and Watson, 2001 (Polychaeta: Syllidae: Syllinae) is described from shallow water of Shimoda, Izu Peninsula, Japan. The worms were commensal with the gorgonian Melithae flabellifera (Kükenthal, 1909). Alcyonosyllis glasbyi n. sp. differs from all other species of the genus in having a single chaeta per parapodium. The genus is new to Japan.

Male Dimorphism in the Harem-Forming Gnathiid Isopod Elaphognathia discolor (Crustacea: Isopoda)

Previously unreported males of a gnathiid isopod were found in reproductive aggregations of the harem-forming gnathiid Elaphognathia discolor. Although the male gnathiids were small in size and morphologically different from E. discolor males, the male sexual organ, appendix masculina, was similar to that of E. discolor males, and possible conspecific larvae and females of the small male gnathiid were never found. In the laboratory, the small male gnathiids as well as male E. discolor successfully copulated with female E. discolor, and the development of embryos in female brood pouches was observed. Offspring of small male gnathiids develop to adults of E. discolor after molting three times, or small male gnathiids after molting two times. Thus, the small male gnathiid was concluded to be an alternative male form compared to the regular large male form of E. discolor. This male polymorphism was thought to have a genetic basis, since no small male specimens appeared in offspring of regular E. discolor males. Field sampling showed that a regular large male formed a harem composed of one large male and several females and never coexisted with other large males as previously reported. However, small males were often found together with large males. Therefore, small males are thought to be sneakers intruding into harems dominated by large males.

First whale fall chaetopterid; a gigantic new species of Phyllochaetopterus (Chaetopteridae: Annelida) from the deep sea off California

Abstract Phyllochaetopterus gigas, new species, was found living associated with a whale fall lying at 2892 meters depth in the Monterey Submarine Canyon, off California, U.S.A. The new species was found over a period of nine yr adjacent to, on, or in sediment lying over, the baleen of the whale fall. Phyllochaetopterus gigas is characterized by its large size (up to 30 cm preserved body length), long palps, coloration, and patterning of the ventral shield of the anterior region (region A), the presence of 4–6 large cutting chaetae on each parapodium of the fourth chaetiger (a4), the shape of these chaetae (with a pear-shaped head, some small lateral teeth on the edge), and presence of two middle-region (region B) chaetigers with foliose notopodia. The new species is compared to other Phyllochaetopterus species and appears to be, at least in part, a deposit feeder.

A new species of Spiochaetopterus (Chaetopteridae: Polychaeta) from the Iheya Seamount off Okinawa in East China Sea, Japan

ABSTRACT Spiochaetopterus iheyaensis, a new species of Chaetopteridae (Annelida: Polychaeta) is described from 6 specimens collected by the Deep-Sea Research Vehicle Shinkai 2000 from the deep sea at Iheya Seamount, off Okinawa, Japan. The species is characterized by the coloration of the ventral shield of the anterior region (region A), by having one or two pairs of large cutting chaetae on the fourth chaetiger (A4), and by the morphology of A4 modified cutting chaetae (with inflated semi-circular and pear-shaped in upper view, head lacking teeth), having 2 middle region (region B) chaetigers, and a slender, annulated tube. The new species is compared to Pacific Spiochaetopterus, particularly the ultrastructure of the A4 chaetae.

Neosabellaria vitiensis, n. sp. (Annelida: Polychaeta: Sabellariidae), from Shallow Water of Suva Harbor, Fiji

ABSTRACT A new species of the genus Neosabellaria Kirtley, 1994, is described from shallow-water locations of Suva Harbor, Fiji. Neosabellaria vitiensis Bailey-Brock, Kirtley, Nishi, & Pohler, n. sp., is a gregarious sabellariid; its tubes are constructed of sand and shell debris and form small “reefs” exposed during low tides. The new species is distinguished by the structure of opercular paleae in the middle row, which are shoe-shaped with circular tips, and paleae in the outer row, which have distal lateral teeth and denticulate median plume. Detailed morphological features of the new species are described and compared with other Pacific sabellariid species, particularly with most closely related N. clandestina (Menon & Sareen, 1966). Neosabellaria vitiensis is endemic to the Fiji Islands.

Two New Species of Spiochaetopterus (Annelida: Polychaeta) from Sagami Bay and Tokyo Bay, Central Japan with a Comparative Table of Species from Japanese and Adjacent Waters

Two new species of Spiochaetopterus (Chaetopteridae: Polychaeta), S. sanbanzensis, from Sanbanze, off Ichikawa and Funabashi Cities, Tokyo Bay, and S. izuensis from the shallow waters of Sagami Bay, were described. The most obvious difference is the number of segments in region A: 9 in S. sanbanzensis and 10 in S. izuensis. In addition, Spiochaetopterus sanbanzensis has elliptical light brown or blackish eye-spots, asymmetrical cordate specialized A4 chaetæ, and a color pattern consisting of many dispersed brown spots on both ventral and dorsal faces of region A. In Spiochaetopterus izuensis, a brown band extends from each eye-spot to the level of the A1 chaetae; the convex ventral edge of the head of the specialized A4 chaeta has an oblique section and the color pattern of the body is absent. A comparison is established between these two new species and other known species from Indo-Pacific Ocean

Sabellaria jeramae, a new species (Annelida:Polychaeta: Sabellariidae) from the shallow waters of Malaysia, with a note on the ecological traits of reefs

A new species of the genus Sabellaria Lamarck, 1818 (Annelida: Polychaeta: Sabellariidae) is described from the intertidal zone of Jeram, Selangor, Malaysia. Sabellaria jeramae n. sp. is a gregarious species that constructs large reefs several hundreds of meters long and 50-200 m wide. The new species is distinguished from other congeners by the character combination of the presence of a single kind of middle paleae with conspicuous morphology, and outer paleae with long frayed teeth. Morphological features of the species are described and compared to those of all congeneric species. We also compare the reef structure and geographical distribution of the new species to those of the members of the family Sabellariidae around the world, demonstrating the ecological traits of the reefs.