Research Article |
Corresponding author: Sergio I. Salazar-Vallejo ( savs551216@hotmail.com ) Academic editor: Christopher Glasby
© 2017 Naoto Jimi, Sergio I. Salazar-Vallejo, Hiroshi Kajihara.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Jimi N, Salazar-Vallejo SI, Kajihara H (2017) Designation of a neotype and redescription of Hesione reticulata von Marenzeller, 1879 from Japan (Annelida, Hesionidae). ZooKeys 657: 29-41. https://doi.org/10.3897/zookeys.657.11064
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The hesionid polychaete Hesione reticulata von Marenzeller, 1879 was described from Enoshima Island, Japan and has been recorded also from the Red Sea. Depending on researchers, it has been regarded as either a distinct species or synonymous with older established ones. The type specimen has been lost. In order to clarify its taxonomic status, H. reticulata is herein redescribed, illustrated, and a neotype is proposed based on recent material collected near the type locality. The diagnostic features include the presence of several dorsal, discontinuous longitudinal bands, interrupted by pale segmental spots; prostomium with tiny antennae; a tuberculated dorsal integument; acicular lobes double; and neurochaetal blades with guards approaching the distal tooth. The dorsal color pattern in life enables a clear distinction from similar species such as H. intertexta Grube, 1878 amongst others. Mitochondrial COI barcoding sequences are deposited in the DNA Data Bank of Japan. A key to Hesione species from Japan is also included.
Neurochaetal blades, parapodial features, pigmentation pattern, polychaetes, taxonomy
The hesionid polychaete Hesione reticulata von Marenzeller, 1879 is in need of redescription, in particular incorporating observations of the living pigmentation. This is because delimitation of the species from similar forms, such as H. splendida Savigny in Lamarck, 1818, H. pantherina Risso, 1826, and H. intertexta Grube, 1878, involves the color pattern on the dorsal surface, which unfortunately disappears immediately after fixation. Neither the original description (
Further, the morphological features of the currently valid Hesione species (after
The holotype specimen of H. reticulata was collected by the German naturalist Carl Koerbl on the east coast of Enoshima Island, Kanagawa, during his visit to Japan during 1875–1876. The type material was supposedly deposited in the Natural History Museum in Vienna by Richard von Drasche-Wartinberg (
Due to the uncertainties pertaining to some characters in H. reticulata, the taxonomic status of the species has been doubted by some researchers.
In this paper, H. reticulata is redescribed as a distinct species. We designate a neotype as there is no existing type material, and, moreover, there are apparently two different species occurring in Kanagawa Province, which closely resemble each other.
Photographs of the dorsal color pattern in the living state are also provided, as well as of other morphological characters, and the COI barcoding sequence on the basis of freshly-collected material from a place near to the type locality. The key to species of Hesione from Japan by
Four specimens were collected at a depth of 1 m by hand in Zaimokuza (35°18'02.9"N, 139°33'02.9"E), Kanagawa Prefecture, Japan. Two specimens were fixed in a 10% formalin sea water solution, later washed and preserved in 70% ethanol (NSMT Pol N-620, NSMT Pol 113205), the other two specimens were fixed and preserved in 70% ethanol (NSMT Pol 113206, NSMT Pol 113207). All specimens were anesthetized with menthol before fixation.
Live and preserved specimens were examined under stereoscopic microscopes (Leica MZ 16F and OLYMPUS BX51); photographs were taken with a digital camera (Nikon D5200). Morphology of chaetae and parapodial features were described from chaetigers 7–9. Neurochaetal blade length was measured from the level of the articulation membrane attachment to chaetal tip; the width was measured at the widest part and expressed as a length:width ratio or by indicating how many times the length corresponds to the width.
Tissue from the dorsal cirri was used for DNA extraction from the two specimens, NSMT Pol N-620 and NSMT Pol 113205. Methods for DNA extraction, PCR amplification, and sequencing followed athose of
Hesione
reticulata
von Marenzeller, 1879: 129–131, pl. 3, fig. 4;
Hesione
splendida
Hesione
pantherina
Hesione
intertexta
Northwestern Pacific, Japan. Neotype NSMT Pol N-620, and three paraneotypes NSMT Pol 113205, NSMT Pol 113206, NSMT Pol 113207, Zaimokuza (35°18'02.9"N, 139°33'02.9"E), rocky bottom, 1 m depth, 19 Mar. 2016, N. Jimi & H. Tanaka, coll. Paraneotypes (NSMT Pol 113205 – NSMT Pol 113207) 40–47 mm long, 4 mm wide).
Zaimokuza (35°18'02.9"N, 139°33'02.9"E), rocky bottom, 1 m depth.
Neotype (NSMT Pol N-620) complete. Body cylindrical, medially swollen (Fig.
Dorsal pigmentation pattern consisting of longitudinal, brownish, subcontinuous, irregular lines; no reddish brown longitudinal broken line on median line; single, irregularly-shaped spot (formed by absence of brown pigment, through which basement pale tan to wheat body color seen) on each chaetiger except 2nd, arranged mid-dorsally (larger anteriorly; reduced medially and posteriorly); and additional row of similar but smaller spots on lateral cushion on each side; silvery white spots absent. Cirrophores yellow; cirrostyles yellow to whitish; parapodial lobes whitish (Fig.
Integument smooth, annulated, giving impression of being tuberculated, especially along posterior region; longitudinal ridges absent in lateral cushions.
Prostomium heart-shaped, wider than long (Fig.
Tentacular cirri tapered, longest complete anterior cirri reaching chaetiger 5. Lateral cushions slightly projected, entire, with smooth surface.
Parapodia with dorsal cirrophore twice longer than wide, articulated (Fig.
Prepygidial segment with two cirri, three times as long as body width of previous chaetiger (chaetiger 16). Pygidium smooth, trapezoidal, as long as wide, cylindrical (Fig.
Venter without pigmentation, with longitudinal midventral depression.
Pharynx divided into three rings, with relative lengths 1.5:1.5:1; basal ring with similar pigmentation as anterior end (Fig.
Oocytes not visible.
(observed in paraneotypes NSMT Pol 113205–113207). Pharynx and esophagus thick, muscular, yellowish, continuing into darker, shorter stomach; enteric caeca extending anteriorly along two or three chaetigers (Fig.
Hesione reticulata Marenzeller, 1879, A (NSMT Pol N-620) B–C (NSMT Pol-113205) A Anterior end, dorsal view, six months after fixation B Medial part, ventral view after longitudinal dissection (*: enteric caecum, Ph: pharynx, St: stomach) C Same, close up after dissecting stomach, with a gastropod prey (St W: stomach wall). Scale bars: 1.5 mm (A); 1.2 mm (B); 0.6 mm (C).
Hesione reticulata Marenzeller, 1879, A–F (NSMT Pol N-620). A Chaetiger 8, right parapodium, anterior view B Chaetiger 9, right parapodium, anterior view, close-up of acicular lobe C Chaetiger 8, right parapodium, anterior view, close-up of acicular lobe (arrow points to lower tine) and neurochaetal bundle D Same, tip of neurochaetae (inset: blade tip) E Same, close-up of dorsal cirrophore F Same, close-up of cirrostyle distal region. Scale bars: 0.78 mm (A); 0.15 mm (B); 0.17 mm (C), 25 μm (D); 0.13 mm (E, F).
The nomenclatural status of Hesione reticulata von Marenzeller, 1879 has been unclear due to several reasons: there is no type material, some diagnostic features were not clarified in the original description, the species has been recorded from the Red Sea, and some authors have regarded it as a junior synonym of other species within the genus. Consequently, in order to comply with the International Code of Zoological Nomenclature (
The above description and illustrations will clarify the taxonomic status of H. reticulata (Art.75.3.1), and its diagnostic and differential features have been included in the description and illustrations (Arts 75.3.2, 75.3.2), and will be contrasted below. Our enquiries on the existence of type material of H. reticulata to Dr. Helmut Sattmann, Curator of Marine Invertebrates, in the Naturhistorisches Museum, Vienna, where Emil von Marenzeller used to work and produced all of his publications, indicate that type material is absent (Art. 75.3.4), probably destroyed or never deposited. The original collector was Carl Koerbl (
The neotype fits the original description and because it was recently collected, it even matches the general pigmentation pattern which is not long-lasting in ethanol. Further, as happens in some other species of Hesione, they are simultaneous hermaphrodites (
The original specimen was collected in the east coast of Enoshima (35°18'07"N, 139°29'00"E), and the neotype was found in Zaimokuza (35°18'02.9"N, 139°33'02.9"E), nearly four kilometers away, such that we are confident these two localities belong to the same ecological unit (Art. 75.3.6). The neotype of H. reticulata has been deposited in the National Science Museum, Tokyo, which holds the most important polychaete collection in Japan, and has a very important tradition in the scientific study of polychaetes from Japan and elsewhere (Art. 75.3.7).
Another taxonomic relevance of our study lies in the identification of the dorsal color pattern in the living state as a clear distinguishing feature between H. reticulata, H. intertexta, and H. cf. ehlersi sensu
The vivid images of the dorsal color pattern in H. reticulata, along with the COI barcoding sequence provided in this paper, will contribute to future taxonomic revision of the genus Hesione.
Hesione reticulata was regarded as a distinct species by
One of the important discoveries in our observation of the specimens of H. reticulata is that the acicular lobe in this species is doubled, comprised of the upper and lower tines, a character state that separates Hesione species in two groups, each with approximately the same number of species (SISV pers. obs.).
The record of H. reticulata by
Distribution. Hesione reticulata has so far been recorded only from Japan: Kanagawa (
(modified from
1 | Antennae present; eyes positioned centrally on prostomium | 2 |
– | Antennae absent; eyes displaced anteriorly | Hesione ? sp. |
2 | Neurochaetal blades with guard | 3 |
– | Neurochaetal blades without guard | H. splendida ? sensu Monro, 1931 |
3 | Dorsum with transverse bands; neurochaetal guards approaching subdistal tooth | 4 |
– | Dorsum with longitudinal bands; neurochaetal guards approaching distal tooth | 5 |
4 | Chaetiger 2 pale; dorsal pigmentation without spots; second tentacular cirri markedly longer than fourth | H. genetta Grube, 1867 |
– | Chaetiger 2 with a black band; dorsal pigmentation includes spots; second tentacular cirri as long as fourth | Hesione sp. |
5 | Longitudinal bands short; silvery white spot present mid-dorsally | H. intertexta Grube, 1878 |
– | Longitudinal bands long; silvery white spot absent | 6 |
6 | Dorsal cirrophores pale; neurochaetae with long blades in chaetigers 1–7; acicular lobe as long as chaetal lobe width; mid-dorsal reddish brown, subcontinuous line present | Hesione cf. ehlersi |
– | Dorsal cirrophores yellow; neurochaetae with long blades in chaetigers 1–3; acicular lobe shorter than chaetal lobe width; mid-dorsal reddish brown line absent | H. reticulata von Marenzeller, 1879 |
Dr Helmut Sattmann at the Natural History Museum in Vienna provided information about the collections studied by Emil von Marenzeller, and indicated there are no type specimens of H. reticulata. Mr Hayate Tanaka helped sampling at Zaimokuza and Enoshima, Japan. Drs Alexandra Rizzo, Yen-ling Lee, and Chris Glasby carefully read a previous draft and made positive recommendations to improve this final form, which was carefully line-edited by Nathalie Yonow.