European Journal of Taxonomy 154: 1-7

http://dx.doi.org/10.5852/eit.2015.154

www. europeani ournaloftaxonomv. eu

2015 • Reuscher M.G.

ISSN 2118-9773

This work is licensed under a Creative Commons Attribution 3,0 License.

Research article

um:lsid:zoobank.org:pub:F9A2F05E-0F3A-4459-BB5F-FC8563DD683C

Amage imajimai sp. nov., a new species of Ampharetidae

(Annelida: Polychaeta) from Japanese waters

Michael G. REUSCHER

Harte Research Institute for Gulf of Mexico Studies, Texas A&M University - Corpus Christi, 6300

Ocean Drive, Unit 5869, Corpus Christi, Texas 78412-5869, USA.

E-mail: [email protected]

um:lsid:zoobank.org:author:CEE857C6-DB17-4C9B-BE81-D04AB815E909

Abstract. A new polychaete species of the family Ampharetidae, Amage imajimai sp. nov., is described

from deep waters of Sagami Bay, Japan. It is characterized by the possession of four pairs of branchiae,

twelve thoracic uncinigers, eleven abdominal uncinigers, and the lack of thoracic notopodial cirri.

The new species is named in honor of the renowned Japanese polychaetologist Minoru Imajima. An

identification key for all Amage species from Japanese waters is provided.

Keywords. Ampharetidae, Amage , new species, Sagami Bay, Japan.

Reuscher M.G. 2015. Amage imajimai sp. nov., a new species of Ampharetidae (Annelida: Polychaeta) from

Japanese waters. European Journal of Taxonomy 154: 1-7. http://dx.doi.org/10.5852/eit.2015.154

Introduction

In a recent study on Ampharetidae from Japan many new species and new records were discovered

(Imajima et al. 2012, 2013; Reuscher et al. 2015a, 2015b). In the last publication of the series (Reuscher

et al. 2015b), a list of all 58 ampharetid species recorded from Japan was provided. Six of these species

known to occur in Japanese waters belong to the genus Amage Malmgren, 1866: A. cf. adspersa

(Grube, 1863), A. auricula Malmgren, 1866, A. delus (Chamberlin, 1919), A. ehlersi Reuscher, Fiege &

Imajima, 2015, A. longitorus Reuscher, Fiege & Imajima, 2015 and A. scutata Moore, 1923. During the

examination of material from the National Museum of Nature and Science in Tsukuba (Japan), I was

able to identify another new species of Amage, which is described here. The new species was collected

at a depth of about 1000 m in Sagami Bay off the southeastern Honshu coast.

Material and methods

The specimens examined in this study were collected in Sagami Bay during a research cruise in July

1966. They were fixed in 7% formaldehyde seawater solution and preserved in 70% ethanol.

Preserved specimens were examined with an Olympus SZX7 stereo microscope and compound

microscopes of the models Leica DMLB and Olympus CX41. Pencil drawings were made using a

camera lucida, attached to the Leica DMLB.

European Journal of Taxonomy 154: 1-7 (2015)

The drawings were digitized with a Wacom Intuos drawing tablet and Adobe Illustrator, according to the

methods of Coleman (2003). Shadings were added in Adobe Photoshop. The “ID card” (Imajima et al.

2012) was prepared in Adobe Illustrator.

Abbreviations

cs = complete specimen

af = anterior fragment

Types and other specimens are deposited in the following institutions:

NSMT = National Museum of Nature and Science, Japan

SMF = Senckenberg Museum Frankfurt, Germany

Full details for the material deposited at Senckenberg can be found at http://sesam.senckenberg.de/ .

Results

Phylum Annelida Lamarck, 1809

Class Polychaeta Grube, 1850

Order Terebellomorpha Hatschek, 1893

Family Ampharetidae Malmgren, 1866

Subfamily Ampharetinae Malmgren, 1866

Genus Amage Malmgren, 1866

Amage Malmgren, 1866: 370.

Par amage Caullery, 1944: 94.

Egamella Fauchald, 1972: 295.

Mexamage Fauchald, 1972: 309.

Type species

Amage auricula Malmgren, 1866.

Diagnosis (emended)

Prostomium with middle lobe surrounded by inflated lobe, lacking glandular ridges. Buccal tentacles

smooth. Two to four pairs of cirriform branchiae. Segment II usually without chaetae, or exceptionally

with minute chaetae. Thorax with 9-14 uncinigers. Modified or intermediate segments absent. Abdomen

with rudimentary notopodia.

Remarks

The diagnosis was emended to accommodate the synonymy of the monotypic genus Egamella Fauchald,

1972 by Jirlcov (2011). Egamella has only two pairs of branchiae and nine thoracic uncinigers. This

synonymy needs to be confirmed by the examination of the type specimen of Egamella quadribranchiata

Fauchald, 1972.

REUSCHER M.G., New Amage species from Japan

Amage imajimai sp. nov.

urn:lsid:zoobank.org:act:CCA76C94-C953-418D-AFC9-DDBBD7D99C6D

Fig. 1A-G

Diagnosis

Four pairs of branchiae. Twelve thoracic uncinigers. Notopodia without ventral cirri. Eleven abdominal

uncinigers.

Etymology

The species is dedicated to the distinguished Japanese polychaete taxonomist Minoru Imajima.

Specimens examined

Holotype

JAPAN: SMF 24087, Sagami Bay, 35°00.9’ N, 139°35.7’ E - 35°00.7’ N, 139 o 36.0’ E, 990-1060 m,

KT-66-12, St. 7, Jul. 1966 (1 cs).

Paratypes

JAPAN: SMF 24086, same locality as holotype (3 cs); NSMT-Pol. P-600, same locality as holotype

(3 cs, 1 af).

Description

Length of holotype 3.2 mm, width 0.4 mm Prostomium with middle lobe bearing anterolateral frontal

horns, delimited by incision from inflated surrounding lobe (Fig. 1A); prostomium without glandular

ridges or eyes. Single tip of smooth buccal tentacle visible in buccal cavity. Four pairs of branchiae

in L-shaped arrangement in segments II-IV (Fig. IB), separated by wide median gap; all branchiae

detached from specimen, cirriform, without conspicuous ciliation or annulations; innermost branchiae

of anterior transverse row (1) originating from segment II, outermost branchiae of anterior transverse

row (2) originating from segment III, median branchiae of longitudinal row (3) originating from

segment IV, posterior branchiae of longitudinal row (4) originating from segment V (Fig. IB). Segment

II without chaetae. Notopodia with capillary chaetae from segment III, present in 15 chaetigers; first

three notopodia in close succession due to shortness of segments and slightly elevated above following

notopodia (Fig. 1C); first notopodia small, increasing in size from first to third pair; notopodial cirri

absent. Neuropodial tori with uncini from segment VI, present in 12 thoracic uncinigers; tori without

cirri. Continuous ventral shields conspicuous from anterior thorax to thoracic unciniger 9. Modified

notopodia or segments absent. Intermediate uncinigers absent. Eleven abdominal uncinigers with

small tuberculate rudimentary notopodia. Pinnules with minute tuberculate dorsal cirrus. Rudimentary

notopodia and pinnules connected by glandular fold. Pygidium with one pair of digitiform, ventrolateral

anal cirri. Left anal cirrus broken off. Thoracic uncini with 7 teeth in 2 staggered row over basal prow

and rostral tooth (Fig. 1D-E). Abdominal uncini with numerous teeth in several rows over basal prow

and rostral tooth. Tube parchment like with needle like spicules embedded.

Remarks

In four of the paratypes the buccal tentacles are better visible and clearly smooth. The tuberculate dorsal

cirri of the abdominal pinnules are much better developed in the larger paratype specimens (Fig. IF).

The anal cirri are longer and cirriform in the larger paratypes (Fig. 1G). However, they also seem to

break off easily as three of the six complete paratypes lack both anal cirri.

The two other Amage species with twelve thoracic uncinigers are A. benhami Reuscher, Fiege & Wehe,

2009 from the northeast Pacific and the Ross Sea and A. longitorus Reuscher, Fiege & Imajima, 2015

European Journal of Taxonomy 154: 1-7 (2015)

Fig. 1 . Amage imajimai sp. nov. A. Anterior end of holotype, dorsal view. B. “ID card”. C. Anterior

end of holotype, lateral view. D. Thoracic uncinus, lateral view. E. Thoracic uncinus, frontal view.

F. Abdominal uncinigers, lateral view (from paratype SMF 24086). G. Posteriormost abdominal

uncinigers and pygidium, ventral view (from paratype SMF 24086).

REUSCHER M.G., New Amage species from Japan

from Japan. The latter species differs from A. imajimai sp. nov. by the possession of only three pairs

of branchiae, the very long tori in the first two thoracic uncinigers and the larger number of abdominal

uncinigers (13). A. benhami differs from the new species by the presence of club shaped notopodial cirri

and the higher number of abdominal uncinigers (15-16).

Among the other Japanese Amage species A. auricula , A. delus , A. ehlersi and A. scutata have 11

thoracic uncinigers, A. cf. adspersa has 14 thoracic uncinigers. A. cf. adspersa, A. auricula and A.

delus differ from A. imajimai sp. nov. by the presence of notopodial cirri. A. scutata is unusual for the

presence of rudimentary notopodia in the anterior segments. A. imajimai sp. nov. has a higher count of

abdominal uncinigers (11) than A. auricula (8) and A. ehlersi (10) and a lower count than A. delus (12)

and A. longitorus (13).

Distribution

Sagami Bay on the Southeastern Pacific coast of Honshu, in 990-1060 m.

Identification key for Amage species from Japanese waters

1. 11 or 12 thoracic uncinigers.2

- 14 thoracic uncinigers. Amage cf. adspersa (Grube, 1863)

2.11 thoracic uncinigers.3

- 12 thoracic uncinigers.6

3. Anterior notopodia with notochaetae.4

- Anterior notopodia lacking notochaetae . Amage scutata Moore, 1923

4. Thoracic notopodia with ventral cirri.5

- Thoracic notopodia lacking ventral cirri. Amage ehlersi Reuscher, Fiege & Imajima, 2015

5. 8 abdominal uncinigers. Amage auricula Malmgren, 1866

- 12 abdominal uncinigers. Amage delus (Chamberlin, 1919)

6. 3 pairs of branchiae; anterior neuropodia conspicuously elongated; 13 abdominal uncinigers

. Amage longitorus Reuscher, Fiege & Imaj ima, 2 015

- 4 pairs of branchiae; anterior neuropodia not conspicuously elongated; 11 abdominal uncinigers

. Amage imajimai sp. nov.

Discussion

The variety of habitat types and complex interactions of different environmental gradients in the oceans

surrounding the Japanese islands attract a variety of species with different physiological and ecological

adaptations and thus form the basis of a diverse polychaete fauna. Japan has a wide variety of habitats

that are colonized by polychaetes, including bays, deep-sea trenches, hydrothermal vents, and cold

seeps, among others (e.g., Juniper & Sibuet 1987; Horilcoshi et al. 1990). The northern part of Japan

receives cold water from the Oyashio Current, whereas southern Japan is under the influence of the

warm Kuroshio Current (Imajima et al. 2012). Therefore, Japan’s polychaete fauna includes Arctic and

sub-Arctic species as well as tropical and subtropical species. In the recent series on Ampharetidae from

Japan (Imajima et al. 2012, 2013; Reuscher et al. 2015a, 2015b), 60% of the examined species were

new to science and the number of species known from Japan more than doubled. This shows that the

current knowledge of species diversity of ampharetid polychaetes from Japan is far from exhaustive and

more sampling effort is needed to complete the picture. Amage imajimai sp. nov. is the 59 th species of

the family Ampharetidae and the seventh species of the genus Amage recorded from Japan.

European Journal of Taxonomy 154: 1-7 (2015)

Of the other Amage species from Japan, A. delus and A. scutata are known only from northern Honshu,

A. cf. adspersa and A. imajimai sp. nov. have only been recorded from Sagami Bay, whereas A. auricula ,

A. ehlersi and A. longitorus have a wider distribution within Japanese waters.

Within Ampharetidae Amage is probably the most heterogeneous genus as it contains species with

two (if the genus Egamella is considered a junior synonym), three and four pairs of branchiae, with

nine ( Egamella ), eleven, twelve, and fourteen thoracic uncinigers, with and without notopodial cirri.

A revision is needed to determine if Amage can be upheld as a single genus, or if it should be split into

multiple genera.

Acknowledgements

Min oru Imajima (NSMT) is thanked for the loan of the specimens. I am grateful to Richard D. Kalke

and Fabio Moretzsohn (Harte Research Institute, Texas A&M University-Corpus Christi) for their

permissions to use their camera lucida. Paul A. Montagna (Harte Research Institute, Texas A&M

University-Corpus Christi) is thanked for his financial support through the Texas Research Development

Post-Doctoral Support Grant.

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Manuscript received. 14 August 2015

Manuscript accepted. 8 October 2015

Published on: 19 November 2015

Topic editor. Rudy Jocque

Desk editor. Kristiaan Hoe demakers

Printed versions of all papers are also deposited in the libraries of the institutes that are members of the

EJT consortium: Museum national d’Histoire naturelle, Paris, France; Botanic Garden Meise, Belgium;

Royal Museum for Central Africa, Tervuren, Belgium; Natural History Museum, London, United

Kingdom; Royal Belgian Institute of Natural Sciences, Brussels, Belgium; Natural History Museum of

Denmark, Copenhagen, Denmark.