INTRODUCTION

Enoshima, a small island (35°17'N, 139°28'E; circumference: 4 km, maximum height: 60 m; Fig. 1), is located near a sandy beach facing Sagami Bay, Fujisawa, Kanagawa Prefecture of central Honshu, Japan (Figs 1 and 2) that is now connected by a concrete bridge (approximately 400 m length) across a narrow shallow (Fig. 1). Geohistorically, Enoshima had been isolated since the last glaciation due to the retreating sea level, particularly during the Jomon transgression (Fujisawa Board of Education, 1995). In addition, stone tools from the Jomon period were discovered (Tamagawa Institute of Cultural Resources, 2019) on this island, which has been considered a holy place due to the Enoshima Shinto Shrine, a typical historical landmark present since the dawn of history (Hattori, 1979). Since the Edo period, Enoshima has been a famous sightseeing point near the Tokyo Metropolis, and after World War II, many amusement facilities, such as fishing areas, a yacht marina, restaurants, and souvenir shops, have been built. Enoshima was completely connected with the opposite sandy beach in 1897 by a coarse wooden bridge (Tamamuro, 1991; Fujisawa Board of Education, 1995); subsequently, many people have been able to visit there easily. Since the completion of the concrete bridge, recently, over 10 million people visited the island annually (Fujisawa City Tourist Association, 2022). Therefore, it is possible that some organisms have been introduced artificially and accidentally, particularly plants. The current climate of Enoshima is mild and relatively warm, and this island has various types of vegetation. Ever-green plants observed in warmer climate regions, such as marlberry (Ardisia japonica), chinkapin (Castanopsis sieboldii), Japanese tassel fern (Polystichum polyblepharum), red machilus (Machilus thunbergii), Japanese spindle (Euonymus japonicus), and cheesewood (Pittosporum tobira), are mainly present in the island's interior, including introduced species (Fujisawa City, 2003; Ministry of the Environment, Japan:  http://www.vegetation.jp/).

Fig. 1.

(a) Map indicating localities related to the activities of E. S. Morse during his first stay in Japan in 1877. Shaded areas outlined by green dotted lines roughly indicate the current distributions of Dymecodon pilirostris (Kobayashi & Kitahara, 1968; Ohdachi et al., 2015). Kanagawa Prefecture and Tochigi Prefecture are indicated by white dotted lines. (b) Area magnified in Fig. 2, corresponding to an illustration map drawn by Morse (1917a) himself.

Fig. 2.

(left) Illustration map drawn by Morse (1917a) himself according to “Japan, Day By Day” vol. I (p. 163, fig. 137) and (right) its corresponding area (b in Fig. 1), indicating the geographical settings of Tokyo, Yokohama, and Enoshima. Notes as “17 m” from Tokyo to Yokohama and”15 m” from Yokohama to Enoshima probably mean 17 miles and 15 miles, respectively. “Cape King” corresponds to Susaki (current Cape Sunosaki) of the Boso Peninsula according to Rittau (1880) and Akioka (1930).

The lesser Japanese shrew-mole, Dymecodon pilirostris (Soricomorpha, Talpidae, Scalopinae), was first described by Frederick W. True in 1886 as a new genus and a new species (True, 1886; Ohdachi et al., 2015) that differed from the greater Japanese shrew-mole, Urotrichus talpoides, in dentition and external morphology. According to the description, the collector was Edward S. Morse, and the type locality was recorded as “Yenosima, at the mouth of the Bay of Yeddo, Japan” (True, 1886). This type locality is thought to be the current Enoshima (Figs 1 and 2). In the Japanese Archipelago, D. pilirostris generally occurs in mountainous areas consisting of rocky terrains at relatively high altitudes; U. talpoides inhabits forests, bushes, and grasslands at lower to higher altitudes. Therefore, Enoshima is currently not included in the potential distribution of D. pilirostris, nor probably U. talpoides (Ohdachi et al., 2015; Fig. 1).

In Kanagawa Prefecture, there are records of D. pilirostris at the higher altitudes (> 900 m) of the Tanzawa Mountains, far from Enoshima (> 20 km) (Kobayashi & Kitahara, 1968; Kobayashi & Yamaguchi, 1971; Imaizumi et al., 1980; Hirotani, 2003; Yamaguchi, 2003; Fig. 1). Enoshima is separated from the Tanzawa Mountains by an alluvial plain, the Sagami Plain, which contains alluvial sediment mainly from the Sagami River. It is estimated that Enoshima and the Tanzawa Mountains are not related biogeographically (Kaizuka & Moriyama, 1969; Fig. 1). On the other hand, introduced mammals, such as feral cats (Felis catus) and squirrels (Callosciurus erythraeus), are found everywhere in Enoshima (Fujisawa City, 2003). The fauna and flora have been disturbed by introduced organisms and it is thought that the original environment of Enoshima is already lost, unfortunately. It has been considered that the vegetation and environment of Enoshima are not biogeographically and ecologically suitable for D. pilirostris. Therefore, it is difficult to establish whether D. pilirostris currently occurs in Enoshima. Hence, considering the overall distribution of D. pilirostris and the current local environment, geological context, geographic settings, and human history of Enoshima, the type locality – present-day Enoshima – appears doubtful, as suggested, for example by Imaizumi (1960).

If the type locality of D. pilirostris is wrong, why did such an error occur? Where is the actual type locality? In this paper, we try to elucidate the cause of the error about the type locality and estimate the more likely type locality based on the literature, especially related to Morse's activities during his stay in Japan.

RESEARCH METHODS

Morse traveled to several places – Hokkaido, northeastern Honshu, western Honshu, and Kyushu – during his several stays in Japan starting in 1877. However, according to Poole & Schantz (1942), the specimen of D. pilirostris collected by Morse was moved from the Boston Society of Natural History to the National Museum of Natural History on February 19, 1878. Morse therefore had only visited Japan once before this transfer. Because of these date constraints, we investigated his activities during his first stay in Japan, from June to November 1877 (Morse, 1917a, b, 1970a, 1983; Howard, 1935; Hattori, 1979; Yoshikawa, 1985; Isono, 1987; Moriya, 1988; Nakanishi, 2002; Konishi & Oka, 2005; Makino, 2009). In addition, we checked the storage condition of the type specimen of D. pilirostris deposited at the National Museum of Natural History, Washington DC, USA in order to estimate its state at the time when Morse obtained it.

RESULTS AND DISCUSSION

At the beginning of the description by True (1886), there is an important section: “Seven years ago, at the request of Prof. E. S. Morse, the authorities of the Boston Society of Natural History sent to the National Museum two specimens of mammals in alcohol, from Yenosima, at the mouth of the Bay of Yeddo, Japan. The bottle in which they were contained having been misplaced, they have remained unidentified until the present time. One of the specimens is a common house-rat, Mus decumanus; the other is an insectivore belonging to a genus hitherto undescribed. The latter specimen closely resembles Urotrichus talpoides in general appearance but differs in dentition as well as in proportions” (M. decumanus is currently synonymized with Rattus norvegicus according to Wilson & Reeder, 2005). This paragraph implies that these specimens had not been stored in the correct place for mammals at the National Museum of Natural History and had been deposited for seven years along with aquatic organisms that were collected by Morse mainly from Enoshima.

Table 1.

Main activities of E. S. Morse during the period of his first stay (1877) in Japan.

Continued

Morse, who brought these specimens into the United States, studied aquatic invertebrates and discovered the Shell Mounds of Omori in the Tokyo Metropolis in Japan (e.g., Morse, 1983; Table 1). During his first stay in Japan, he became a part-time professor at the University of Tokyo and introduced the evolutionary theory of Darwin in his lectures. In addition, he also collected aquatic organisms from rivers, lakes, and seas. Moreover, he politely recorded Japanese culture, traditions, and lifestyles in his diaries with clear illustrations; today, his publications are important and useful ethnologically (e.g., Morse, 1979). His diaries and writings suggest how he was punctilious and had tidy personality.

His main interest was studying lingulids (brachiopods), and he set up a marine laboratory station in Enoshima in 1877 (Morse, 1917a; Table 1). Thus, Morse collected many samples of aquatic organisms and brought them to the United States with the two mammalian specimens. Considering these evidences, True (1886) possibly erred in designing the type locality of D. pilirostris as Enoshima, where Morse collected his aquatic organisms.

True's type locality of D. pilirostris was, however, problematic in several ways. Morse's illustration (Morse, 1917a, 1970a; Fig. 2) shows that the present Tokyo Bay was described as the “Bay of Yedo,” and “Enoshima” was located on the shore of present Sagami Bay on the west side of the Miura Peninsula (Figs 1 and 2). Morse already knew the difference between the current Tokyo Bay and Sagami Bay at the time, as seen in Fig. 2. Therefore, at least, True's “mouth of the Bay of Yeddo” is apparently mistaken and is far from Enoshima. In addition, although Morse used “Enoshima” and “Yedo” in his spellings, True used instead “Yenosima” and “Yeddo” suggesting that he did not follow Morse's original descriptions and added confusion with actual localities.

If Enoshima is not the type locality of D. pilirostris, where could it be located? We estimated that Morse obtained the D. pilirostris specimen himself at another locality, possibly in a mountainous area, considering the current distribution pattern of D. pilirostris and the geographic features of Enoshima (Ohdachi et al., 2015; Fig. 1). We reveal his activities at the time of his first stay in Japan based on his diaries, related publications, and biography in Table 1 (Morse, 1917a, b, 1970a, b, 1971; Isono, 1987). During his first stay in Japan, his only travel was a visit to Nikko, a mountainous area of Tochigi Prefecture in eastern Honshu, which is included in the current distribution of D. pilirostris (Morse, 1917a, b, 1970a, b, 1971; Fig. 1). Except for this journey to Nikko, he spent the rest of his time around Tokyo, including Yokohama and Enoshima, which lay outside the distribution of D. pilirostris (Fig. 1). Therefore, he likely did not obtain the D. pilirostris specimen around Tokyo. In addition, if a person brought it to Morse, he would have noted the name of the collector, considering his fastidious personality, which is evident from his diaries. As there is no notice or description about the collector of the specimen, and it seems improbable to have been collected by someone else. The type specimen of the shrew-mole was most likely obtained by Morse himself, from a locality included in the distribution of D. pilirostris.

Fig. 3.

The type specimen of Dymecodon pilirostris stored at the Smithsonian Museum of Natural History. (a) bones (No. 22139). (b and c) Labels. (d) Body in alcohol with labels (No. 15291).

Although Lyon & Osgood (1909) and Poole & Schantz (1942) mentioned that the body of the type specimen of D. pilirostris was in rather bad condition, the type has been stored in relatively good condition based on our examination (Fig. 3). The skull and mandible are slightly broken (No. 22139), and the body (No. 15291) is preserved in ethanol. The belly fur is partially lost, but elsewhere it remained almost entirely (Fig. 3). On the basis of such good storage conditions, the specimen was probably obtained in a relatively fresh condition – at least without putrescence. In addition, considering the way of life in the late 1800s, including the absence of cooling systems such as refrigerators or ice makers and quick transportation methods, it would be impossible for a person to bring a shrew-mole in a fresh condition back to Tokyo from its neighboring areas from a mountainous area. Moreover, on the basis of Morse's activities, most of his travel from Tokyo to Nikko and its neighboring areas was by rickshaw or stagecoach. Only on July 3-4, he climbed Mount Nantai-san on foot and collected animals (insects and aquatic invertebrates) around Lake Chuzenji-ko. On July 5-6, he stayed in a house near the lake because of rainy weather (Table 1). Accordingly, he likely obtained the shrew-mole from there and quickly put it in a certain fixative. We therefore conclude that the type specimen must have been obtained in early July 1877 at or near Lake Chuzenji-ko in Nikko (Morse, 1917a, b, 1970a, b; Table 1).

As mentioned above, the type specimen of D. pilirostris is preserved in relatively good condition. There are five labels attached to the specimen, and, based on their handwriting patterns, those were written by four people (Fig. 3). Three of them (Fig. 3b-iii, c, d) seem to be relatively newer, and these descriptions are in accordance with those of True (1886); two (Fig. 3b-iii, d) seemed to be written by the same person. The other two labels (Fig. 3b-i, -ii) seem to have been written by different people. In one of them (Fig. 3b-ii), “United States” and “National Museum” were printed. The final label (Fig. 3b-i) also indicated the specimen Nos. “152910” and “22139” as the series of the National Museum of Natural History. Therefore, at least according to these five labels (Fig. 3b-i, -ii, -iii, c, d), the description seemed to be added after transportation from the Boston Museum of Natural History to the National Museum of Natural History. In addition, the expressions used in the specimen notebook (Fig. 4) are the same as those of True (1886). Thus, all of the descriptions in the type specimen labels and notes corresponds to those of True (1886), and there are no hints about the actual type locality of D. pilirostris in these descriptions.

Fig. 4.

The scanned record of the type specimen of Dymecodon pilirostris (No. 15291, indicated by a red-colored underline) in the specimen notebook, referred from the Mammal Collections, National Museum of Natural History ( http://n2t.net/ark:/65665/3eb485d00-46c2-494b-80ea-69f775cb7591), with magnifications and translations by the authors. This record is fundamentally the same as the description of True (1886). In column of “When collected.” at line No. 15921, the date given is “R. Feb. 19, 1878”; this was not the date of collection but the date that the type specimen of D. pilirostris was transferred from the Boston Society of Natural History to the National Museum.

Considering Morse's fastidious personality, it is expected that he must have noted or labeled the collecting locality for the D. pilirostris specimen at that time. However, unfortunately, his notice might have been lost during its transportation from Japan to the United States, or from the Boston Museum of Natural History to the National Museum of Natural History. In addition, around 1886 when D. pilirostris was described, True had worked as a curator of mammals in the United States National Museum from 1883 to 1909 ( https://sova.si.edu//record/SIA.FARU7181, accessed 2022-9-17). On the other hand, Morse revisited Japan in 1882 to 1883 to collect clay and ceramics with a devotion to Japanese culture history, and he became the president of the American Association for the Advancement of Science in 1886 (Dall, 1926). On the basis of the situation during this era, their scientific connections were likely poor, which may have misled True about the real origin of the specimen. Based on Morse's activities at the time of his first stay in Japan, we therefore suggest that the type locality of D. pilirostris should be corrected from “Enoshima (Yenoshima, at the mouth of the Bay of Yeddo, Japan)” to “Nikko (Nikko., Tochigi Pref., eastern Honshu, Japan)”, according to the recommendation 76A.2 in the article 76 of the International Code of Zoological Nomenclature (ICZN, 1999). Unfortunately, all of the people related to the type specimen are deceased and we cannot obtain further important evidence about the actual type locality from them. Hopefully, DNA from the type specimen will be analyzed to evaluate local variations that would additionally support our current interpretation of the type locality of this taxon.