Baseodiscus Mexicanus (Bürger, 1893)

n Baseodiscus mexicanus (Bürger, 1893)

istributio First record of D (Nemertea: 1* Heteronemertea) 2 from 2 Japanese waters raphic

g Hiroshi Kajihara , Ryuta Yoshida and Daisuke Uyeno eo 1 Hokkaido University, Faculty [email protected] Science, Department of Natural History Sciences. Kita-ku, N10, W8. 060-0810. Sapporo, Hokkaido, Japan. G

n 2 University of the Ryukyus, Graduate School of Engineering and Science. Senbaru 1, Nishihara, Nakagami. 903-0213. Okinawa, Japan. o

* Corresponding author. E-mail: otes N Abstract: The heteronemertean Baseodiscus mexicanus (Bürger, 1893) was previously known exclusively from the

B. mexicanus eastern Pacific, except for fragmentary records from Palau and Indonesia, which suggested a possible amphi-PacificBaseodiscus tropical mexicanusdistribution. is strikinglyA single specimen similar in of appearance to collecteda sympatric in Okinawa,moray eel, Japan, Gymnomuraena represents zebrathe first record of this species from Japanese waters and provides additional evidence for the occurrence of the species in the western Pacific. (Shaw, 1797) (Actinopterygii: Anguilliformes: Muraenidae), possibly indicating a relationship of mimicry between them.

Baseodiscus mexicanus (Bürger, 1893) is a large

encircling the body at irregular intervals (Coe 1940). heteronemertean in the family Valenciniidae (or Living among shells and corals (Coe 1944), it is apparently Baseodiscidae). Its known distribution is largelyet restricted al. the largest and most abundant nemertean found in the to the eastern Pacific: west coast of Mexico (Bürger 1893; tropical eastern Pacific (Coe 1905). Joubin 1905; Coe 1940; Salcedo Martínez 1988; specimenDuring of fieldwork B. mexicanus conducted by SCUBA diving off Cape Hochberg and Lunianski 1998), Panama (Coe 1905; Manza, On’na-son, west coast of Okinawa-jima, Japan, a 1940; 1944), Colombia (Hochberg and Lunianski 1998), (Figure 2A) was collected from Galapagos Islands (Coe 1944; Hochberg and Lunianski a crevice in coral growing on a rock mass (26°30’16” N, 1998), and Chile (Friedrich 1970). Reports from the 127°50’39” E) at a depth of 3–4 m, on 31 March 2012. The western Pacific are confined to a field guide by Colin specimen was fixed in 95% ethanol and deposited in the and Arneson (1995) containing a photograph taken in a Ryukyu University Museum, Fujukan, in Okinawa, Japan seagrass bed at Lighthouse Reef, Palau, and a museum (voucher RUMF-ZN-00001). catalogue by Chernyshev and Volvenko (2008), listing In life, the fully extended specimen was about 4 m long. a specimen collectedB. mexicanus in 1975 from Batu Moncho Bay, The background body color was dark brownish purple, Komodo Island, Indonesia (Figure 1). transversewith numerous cephalic white furrow bands encircling(Figure 2A). the In neck, our specimen, from the Individuals of are usually 20–80 cm, the rounded head is demarcated from the body by a but occasionally up to 2–4 m, in length and are readily identifiable by a distinctive coloration pattern consisting entire part of which numerous secondary furrows extend of a brownish-green, maroon, deep red, mahogany, or anteriorly. Numerous, small, black ocelli are distributed brownish-violet background with numerous white rings along the lateral sides of the head. There are neither horizontal cephalic slits nor a caudal cirrus. The mouth opens mid-ventrally just posterior to the first white band onA the trunk (Figure 2B). B

Figure 1. Baseodiscus mexicanus

Map showing the known distribution of et al. Figure 2. Baseodiscus mexicanus (Bürger, 1893). 1, Bürger (1893); 2, Coe (1905); 3, Joubin (1905); 4, Coe (1940); 5, Coe (1944); 6, Friedrich (1970); 7, Salcedo Martínez (Bürger, 1893), RUMF-ZN-00001, (1988); 8, Colin and Arneson (1995); 9, Hochberg and Lunianski (1998); photographs of living specimen (anaesthetized). A. General appearance. 10, Chernyshev and Volvenko (2008); 11, present study. B. Magnification of head, ventral view. 754 Kajihara et al. | First record of Baseodiscus mexicanus from Japan

B. mexicanus Acknowledgments: zebura-himomushi We thank Takeshi Sasaki and Tohru Naruse This is the first record of from Japanese for keeping the voucher specimen at RUMF; and Matthew H. Dick for waters (new Japanese name: [= “zebra Literaturereviewing the Cited English. ribbon-worm”]), providing further evidence for an amphi-B Zoologische Jahrbücher, Abteilung für Systematik, Ökologie und Pacificcingulatus tropical distribution. Although there are no reports Bürger,Geographie O. 1893. der SüdgeorgischeTiere und andere exotische Nemertinen. from the central Pacific, a similar, banded Baseodiscus species, . cingulatus (Coe, 1906), has been describedB mexicanus and inreported having 7(1): 207–240. In Chernyshev, A.V. andTrudy I.E. Uchebno-nauchnogo Volvenko. 2008. Catalogue Muzeya ofDal’nevostochnogo the nemerteans from Hawaii (Coe 1906; 1934; 1947). Gosudarstvennogo(Nemertini) of the Univesiteta. Zoological MuseumVol. 4. of FESU; p. 104–117 B.K. , however, differs from . Starostin (ed.). a light-coloredBaseodiscus body mexicanus with many narrow, reddish-brown Bulletin of the Museum of Comparative Vladivostok: Zoölogy at Harvard FESU Press. College Coe, W.R. 1905. Nemerteans of the west and northwest coasts of America. rings. Gymnomuraena 47: zebra exhibits a remarkable 1–318. Bulletin of the United States Fish resemblance to the zebra moray eel, Coe,Commission W.R. 1906. for Nemerteans 1903 of the Hawaiian Islands collected by the Steamer Albatross in 1902. Occasional Papers of the (Shaw in Shaw and Nodder, 1797) (Actinopterygii: Bernice P. Bishop Museum 23(3): 975–986. Anguilliformes:B mexicanus Muraenidae)G zebra (Figure occur in3), exactly possibly the Coe, W.R. 1934. New nemerteans from Hawaii. indicating a relationship of mimicry. Near Cape Manza in 10(8): 1–9. Allan Hancock Pacific Coe,Expeditions W.R. 1940. Revision of the nemertean fauna of the Pacific coasts of Okinawa, . and . North, Central, and northern South America. same habitat, with the latter species much more abundant 2(13): 247–322. Journal (Uyeno, pers. obs.). The distributions of these two species Coe,of W.R. the 1944. Washington Geographical Academy distribution of Sciences of the nemerteans of the Pacific coast of North America, with descriptions of two new species. broadly overlap; the moray eel is distributed from the Occasional Papers of the Bernice P. Bishop 34(2): Museum 27–32. Red Sea and eastern African coast to the Society Islands, Coe, W.R. 1947. Nemerteans of theTropical Hawaiian Pacific and invertebrates: Marshall Islands. A field north to the Ryukyu and Hawaiian Islands, and south to guide to the marine invertebrates occurring on tropical 19(3): Pacific 101–106. coral the Great Barrier Reef (Fricke 1999); it also occurs in the Colin,reefs, P.L. seagrassand C. Arneson. beds and 1995.mangroves central eastern Pacific: along southern Baja California, Fishes of the Mascarene. Beverly Islands Hills: (Réunion, Coral Reef Mauritius, Press. Mexico; and from Guatemala to northern Colombia, Rodriguez):296 p. an annotated checklist, with descriptions of new species Fricke, R. 1999. including the Galapagos (McCosker and Rosenblatt 1995). Sarsia . Future investigations of the ecology and toxicology of Königstein: Koeltz Scientific Books. 759 p. these animals may shed light on a possible coevolutionary Friedrich, H. 1970. Nemertinen aus Chile. 40(1): 1–80. Hochberg, F.G. and D.N. Lunianski. 1998. NemerteanHydrobiologia collections at the relationship between them. Santa Barbara Museum of Natural History: type specimens and vouchers for Wesley R. Coe’s 1940 publication. 365(1– 3):