Research Article |
Corresponding author: Shigenori Karasawa ( dojyoudoubutu@gmail.com ) Academic editor: Stefano Taiti
© 2016 Shigenori Karasawa.
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:
Karasawa S (2016) Eleven nominal species of Burmoniscus are junior synonyms of B. kathmandius (Schmalfuss, 1983) (Crustacea, Isopoda, Oniscidea). ZooKeys 607: 1-24. https://doi.org/10.3897/zookeys.607.8253
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Holotypes, paratypes, and specimens newly collected from the type localities (i.e., topotypes) of Burmoniscus aokii (Nunomura, 1986), B. boninensis (Nunomura, 1986), B. daitoensis (Nunomura, 1986), B. hachijoensis Nunomura, 2007, B. japonicus (Nunomura, 1986), B. kagoshimaensis Nunomura, 2003, B. murotoensis (Nunomura, 1986), B. okinawaensis (Nunomura, 1986), B. shibatai (Nunomura, 1986), B. tanabensis Nunomura, 2003, and B. watanabei (Nunomura, 1986) were examined in order to clarify their taxonomic status. Observation of 13 morphological characters that were purposed to show species-level diagnostic variations in the original descriptions suggests that all eleven nominal species are identical, and molecular analysis based on three gene fragments supports this suggestion. Additionally, the morphology of the carpus of pereopod 1 and of the endo- and exopodites of pleopod 1 of these species are consistent with those of B. kathmandius (Schmalfuss, 1983). The eleven above-mentioned species of Burmoniscus described from Japan are therefore relegated to junior synonyms of B. kathmandius, originally reported from Nepal.
COI, 12S rRNA, 16S rRNA, Japan, Philosciidae , taxonomy
The genus Burmoniscus Collinge, 1914 includes more than 100 nominal species, 14 of which have been recorded in Japan (
The objective of the present study was to redescribe the purportedly diagnostic morphological features of the type specimens, or of new material collected from the type localities (topotypes), of these eleven Burmoniscus species from Japan, and thus determine whether or not they are distinct from B. kathmandius.
Holotypes or paratypes were examined when possible; however, when such specimens were in poor condition or required dissection, new specimens collected from the type localities (topotypes) were examined instead. I was unable to collect specimens of B. aokii and B. boninensis from their type localities on Chichijima Island, so new specimens from another site on Chichijima Island were examined instead. In addition, because efforts to collect new specimens of B. hachijoensis from the type locality on Hachijojima Island failed, some specimens were collected from another site on this island. The type localities of the eleven species of Burmoniscus are illustrated in Figure
Map of type localities of the 11 Burmoniscus species. Daito: Minami-daitojima Island, Okinawa; Hachi: Hachijojima Island, Tokyo; Kago: Sata Town, Kagoshima; Kochi: Muroto City, Kochi; Ogasa: Chichijima Island, Ogasawara Islands, Tokyo; Oki: Naha City, Okinawa; Okinoe: Okinoerabujima Island, Kagoshima; Waka-1: Kainan City, Wakayama; Waka-2: Tanabe City, Wakayama; Waka-3: Shirahama Town, Wakayama.
Male specimens were used for morphological examination, except for pereopod 1 of B. aokii and B. boninensis and maxilla 1 of B. tanabensis, of which only female had these appendages unbroken. The antenna 1, maxilliped, genital papilla, endopodites and exopodites of pleopods 1 and 2, and pereonites 1–7 were unilaterally removed from the body of each specimen under a stereo microscope (SZH, Olympus Corp., Japan). These body parts were then placed in Hoyer’s mounting medium (
A single topotypic (or near-topotypic) material of the eleven species was used for molecular analysis, but a single specimen for B. aokii and B. boninensis was used. Total DNA was extracted from leg muscle using the Qiagen DNeasy Blood and Tissue Kit, according to the manufacturer’s protocol (Qiagen, Germany). Parts of the mitochondrial cytochrome c oxidase subunit I (COI) and mitochondrial 12S and 16S ribosomal RNA (rRNA) genes were amplified by polymerase chain reaction (PCR) using the following primers: LCO1490 and HCO2198 (
The sequences were aligned using the default settings in MUSCLE 3.5 (
Eye. The number of ommatidia varied considerably among the nominal species. Burmoniscus hachijoensis had the fewest ommatidia (12), but most species had more than 20 ommatidia (Suppl. material
Antenna 1. As re-described from newly collected topotypes (Fig.
Antenna 1. A specimen collected from Chichijima Island (including type localities of Burmoniscus aokii and B. boninensis),
Outer endite of maxilla 1. The outer endites of maxillae 1 of the eleven nominal species of Burmoniscus with which we are concerned all bore 10 setae, both simple and bifid. However, there was variation in the number of simple and bifid types among species. For example, B. shibatai and B. tanabensis had only simple setae, while other species had 2–6 bifid setae (Suppl. material
Maxilliped. This could be described on the basis of holotypes or paratypes (Fig.
Maxillipeds. A Burmoniscus aokii, holotype B B. boninensis, holotype C B. daitoensis, holotype D B. hachijoensis, holotype E B. japonicus, holotype F B. kagoshimaensis, holotype G B. murotoensis, holotype H B. okinawaensis, holotype I B. shibatai, holotype J B. tanabensis, holotype K B. watanabei, Paratype (Cr-5350). All specimens male. Scale bars: 50 µm.
Carpus of pereopod 1.
SEM photos of carpus of pereopod 1, with details of tip of longest seta. A specimen collected from Chichijima Island (including type localities of Burmoniscus aokii and B. boninensis),
Genital papilla. The morphological characteristics of the genital papilla of terrestrial isopods typically exhibit little variation among related species. In contrast, the original descriptions of the Japanese species of Burmoniscus (
Genital papilla. A Burmoniscus aokii, holotype B B. boninensis, paratype (Cr-5506) C B. daitoensis, holotype D B. hachijoensis,
Male pleopod 1 endopodite. The morphological characteristics of the tip of the endopodite of pleopod 1 have often been used as defining taxonomic characteristics for males of the genus Burmoniscus (e.g.,
Pleopod 1 endopodite. A Burmoniscus aokii, holotype B B. boninensis, paratype (Cr-5506) C B. daitoensis, holotype D B. hachijoensis, holotype E B. japonicus, holotype F B. kagoshimaensis, holotype G B. murotoensis, holotype H B. okinawaensis,
Male pleopod 1 exopodite. As with the endopodite, the morphological features of the exopodite of pleopod 1 in males are also important for the taxonomic differentiation of species of Burmoniscus (e.g.,
Pleopod 1 exopodite. A Burmoniscus aokii, holotype B B. boninensis, paratype (Cr-5506) C B. daitoensis, holotype D B. hachijoensis, holotype E B. japonicus,
Male pleopod 2 endopodite. The present reexamination of Japanese Burmoniscus has shown that the endopodite of male pleopod 2 of all the nominal species tapers towards the tip, although the extent of the curve at the tip varies among species (Fig.
Pleopod 2 endopodite. A Burmoniscus aokii, holotype B B. boninensis, paratype (Cr-5506) C B. daitoensis,
Male pleopod 2 exopodite. Depending on species, the exopodite of pleopod 2 has been described as semicircular, triangular, or round in the original descriptions (Suppl. material
Pleopod 2 exopodite. A Burmoniscus aokii, holotype B B. boninensis, paratype (Cr-5506) C B. daitoensis,
Pleon and pleotelson. The length of the pleon and the shape of the posterior part of the pleotelson were previously used as distinguishing taxonomic characteristics for B. japonicus and B. murotoensis, respectively (
Pleonites 3–5 and pleotelson. A Burmoniscus aokii, holotype B B. boninensis, paratype (Cr-5506) C B. daitoensis,
Epimera 7. The original descriptions did not describe epimera 7 explicitly (Suppl. material
Epimera 7. A Burmoniscus aokii, holotype B B. boninensis, holotype C B. daitoensis, holotype D B. hachijoensis, holotype E B. japonicus, holotype F B. kagoshimaensis, holotype G B. murotoensis, holotype H B. okinawaensis,
Uropods. Uropods vary in length and have been used as a taxonomic characteristic to distinguish among some species. Original descriptions have often compared the length of the endopodite and exopodite (Suppl. material
Median values and ranges of proportional length of uropodal exopodite, with respect to width of head, of Burmoniscus samples collected from type localities. The names of sampling sites are given in Figure
Noduli laterales. In the original descriptions, the position of the noduli laterales was used as a taxonomic characteristic to distinguish among B. boninensis, B. kagoshimaensis, B. murotoensis, B. okinawaensis, B. shibatai, and B. watanabei (
The d/c co-ordinate values of the noduli laterales. A specimens collected from Chichijima Island (including type localities of Burmoniscus aokii and B. boninensis),
The b/c co-ordinate values of the noduli laterales. A specimens collected from Chichijima Island (including type localities of Burmoniscus aokii and B. boninensis),
Molecular analysis. The total alignments of the three sequenced regions contained 1210–1243 bases. The 50% majority-rule consensus tree produced by the ML analysis is shown in Fig.
ML phylogenetic tree based on combined COI, 12S rRNA, and 16S rRNA sequence data. A specimen collected from a site on Chichijima Island was used in this analysis in lieu of specimens collected from the type localities of Burmoniscus aokii and B. boninensis. Bootstrap values exceeding 90% are shown at each relevant node.
Based mostly on examination of type specimens and topotypic (or near-topotypic) material, I have re-described the morphological features and re-calculated various indices that were originally used for diagnosing and differentiating the eleven Japanese nominal species of Burmoniscus. They all exhibited little variation among species, and errors in some of the original description could be demonstrated. Based on these findings, it can be concluded that the species-level classification of Japanese Burmoniscus by
The present study has largely settled the taxonomic problems concerning Brumoniscus species in Japan, but one problem still remains unsolved.
Permission for collecting terrestrial isopods from Kashima Island, Tanabe City, was obtained from the Board of Education in Tanabe, Wakayama Prefecture. I thank Dr. Toshio Kishimoto (Museum of Natural and Environmental History, Shizuoka) for collecting specimens, Dr. Hisashi Negoro (Toyama Science Museum) and Mr. Noboru Nunomura (Kanazawa University, Institute of Nature and Environmental Technology) for loaning the holotypes and paratypes, and Dr. Mark J. Grygier (Lake Biwa Museum) for reading a previous draft and improving the English. This work was supported by the Grant-in-Aid for Scientific Research (B), Grant Number 25281053 and Grant-in-Aid for Young Scientists (B) Grant Number 26830145.
Type localities, collection data of new specimens, and accession numbers
Data type: specimens data
Details of specimens used for morphological observation
Data type: specimens data
Summary of diagnostic features of each nominal species of Burmoniscus in Japan according to the respective original descriptions
Data type: measurement