Photo images, 3D models and CT scanned data of loaches (Botiidae, Cobitidae and Nemacheilidae) of Japan

Abstract Background Loach is one of the major cypriniform ﬁshes in freshwater habitats of Japan; 35 taxa/clades have, until now, been recognised. Parallel to genetic studies, morphological examinations are needed for further development of loach study, eventually ichthyology and fish biology. Digital archiving, concerning taxonomy, ecology, ethology etc., is one of the progressive challenges for the open science of biology. This paper aimed to online publish photo images, 3D models and CT scanned data of all the known clades of loaches inhabiting Japan (103 individuals in total with several type specimens), contributing to ichthyology and public interest of biodiversity/biology. New information Photo images, 3D models and CT scanned data of all the known 35 taxa/clades of loaches inhabiting in Japan were online published at http://ffish.asia/loachesOfJapan and http://ffish.asia/loachesOfJapan3D.


Introduction
Loach is one of the major cypriniform fishes in freshwater habitats of Japan, being recognised with 23 described species/subspecies and 12 undescribed/undecided clades (Nakajima and Uchiyama 2017) (http://ffish.asia/loachesOfJapan). As well as molecular genetic research (Kitagawa et al. 2001a, Kitagawa et al. 2001b, Kitagawa et al. 2003b, Kitagawa et al. 2003a, Kitagawa et al. 2005, Suzawa 2006, Morishima et al. 2008, Saitoh et al. 2010, Kano et al. 2011, Shimizu et al. 2011, Kano et al. 2012, Nakajima 2016, Nakajima and Suzawa 2016, Nakajima and Uchiyama 2017, morphological examinations are needed for further development of loach study. Digital archiving of fish specimens is one of the progressive challenges in ichthyology for open science (Kanagawa Prefectural Museum of Natural History and National Museum of Nature and Science 1998, Berquist et al. 2012, Kano et al. 2013, Kano et al. 2016). This paper aimed to online publish photo images, 3D models and CT scanned data for all the known taxa/clades of loaches inhabiting Japan (http://ffish.asia/loachesOfJapan3D) for the advances of loach study and ichthyology and furthermore as a challenge of open science for public interests of biology.

Sampling methods
Study extent: Photo images and specimens of loaches of Japan were taken in the field and borrowed from museums (see "Collection data").

Figure 1.
A photo image of an individual of Parabotia curtus in a makeshift aquarium at a wild habitat.

Figure 2.
A photo image of Cobitis sakahoko in the wild, under cloudy water by volcanic ash of Mt. Kirishima.
Photo images, 3D models and CT scanned data of loaches (Botiidae, Cobitidae ... Sampling description: The specimens were generally captured by a hand-net in the field. All the specimens were fixed in 10% formalin and preserved in 70% ethanol. Step description: Photo images were taken in the field by capturing individuals (Fig. 1) (Kano and Nakajima 2014) and/or by snorkelling (Fig. 2). The formalin-fixed specimens were also photographed in the laboratory (Fig. 3) followed by CT scanning (Aloka Latheta Hitachi,Ltd.). 3D surface ( Fig. 4; CT value: -400 to -40) and skeletal (Fig. 5;CT value: 5 to 200) models were extracted from the CT data. The CT data (Figs 6,7) in raw file format were also stored and available on the web.     A movie for CT scanned data of Cobitis minamorii yodoensis (OMNH-P45848), changing the camera angle and CT value.

Geographic coverage
Description: Inland water habitats of Japan.

Taxonomic coverage
Description: This paper includes all the known 35 loach taxa/clades (103 specimens) in Japan, of which 12 clades have still been undescribed or are uncertain.
Type specimens: The dataset includes nine type specimens as below.
Twenty taxa of genus Cobitis have been hitherto known in Japan (Ikeda 1936, Okada and Ikeda 1939, Mizuno 1970, Kitagawa et al. 2003a, Kitagawa et al. 2003b, Suzawa 2006, Nakajima 2016, Nakajima and Suzawa 2016, Nakajima and Uchiyama 2017, although five taxa are still undescribed/undecided without scientific names: One from Cobitis matsubarae species complex and the other four from Cobitis biwae species complex. Cobitis sp. "yamato" complex Type A (sensu Kitagawa et al. 2003a; one of Cobitis matsubarae species complex), distributed exclusively in Nagato District (western Honshu, Yamaguchi Prefecture), has peculiar genetic traits (Kitagawa et al. 2003a) and which should be treated as a single clade (Nakajima and Uchiyama 2017). It has a similar morphology to Cobitis matsubarae, whilst Nakajima and Uchiyama (2017) indicated that the genetic traits were close to Cobitis magnostriata and Cobitis takenoi. Amongst the four types of Cobitis biwae species complex, it is unknown which of these corresponds to the scientific name "Cobitis biwae" (Kitagawa et al. 2003b, Nakajima andUchiyama 2017). Cobitis sp. BIWAE type A, also referred as "Western group (tetraploid form)" (Kitagawa et al. 2003b), is distributed amongst western Honshu, northern Shikoku, Awaji Island and eastern Kyushu. Cobitis sp. BIWAE type B, also referred to as "Western group (diploid form)" (Kitagawa et al. 2003b), is distributed in western Honshu and Okidougo Island. Cobitis sp. BIWAE type C, also referred to as "Eastern group" (Kitagawa et al. 2003b), is distributed between eastern Honshu and Sado Island. Cobitis sp. BIWAE type D, also referred to as "Kochi group" (Kitagawa et al. 2003b), inhabits the rivers flowing to Tosa Bay, southern Shikoku.
The situation about "Misgurnus anguillicaudatus" is rather complicated. Six taxa/clades of Misgurnus anguillicaudatus species complex has been hitherto known in Japan, namely "A", "B1", "B2", "Jindai", "IR" and "OK". Misgurnus sp. (Clade A) is a native loach clade of Japan, although the distribution is limited to northern parts such as Hokkaido and eastern Honshu (Morishima et al. 2008, Nakajima andUchiyama 2017). Misgurnus anguillicaudatu s (Clade B1) is another clade native to Japan and is widely distributed amongst Hokkaido (likely domestically introduced from Honshu), Honshu, Shikoku, Kyushu and several isolated islands (Morishima et al. 2008, Kano et al. 2011. Misgurnus anguillicaudatus (Clade B2) is a non-native clade introduced from mainland China and is also widely distributed amongst Honshu, Kyushu andSado Island (Morishima et al. 2008, Kano et al. 2011). Misgurnus anguillicaudatus (Jindai), so-called "Jindai-dojyô" in Japanese, meaning "God's vicarious loach" or "loach in God's era", is an unusual local population that is already extinct. The loach had been distributed exclusively in Shindo Zone (Iga City, Mie Prefecture) having been visibly discriminated from the sympatric M. anguillicaudatus (Clade B1) by its size: the body size of the loach sometimes reached more than 30 cm (Takeda 1978). The ecology of the loach also seemed to be different from M. anguillicaudatus (Clade B1) as the trials of artificial breeding of the loach were extremely difficult and in vain, while the breeding of M. anguillicaudatus (Clade B1) was much easier (Takeda 1978). No genetic information on the loach was unfortunately available at present as the few old specimens were all formalin-fixed. Misgurnus sp. IR is distributed amongst several islands of Amami Islands and Iriomote Island, the southern part of Japan, with peculiar genetic/morphological traits (Shimizu et al. 2011, Kano et al. 2012, Nakajima and Uchiyama 2017. Misgurnus sp. OK has been found from Okinawa and Yonaguni Islands in Japan (Shimizu et al. 2011, Nakajima andUchiyama 2017). The native distribution ranges of Misgurnus sp. IR and Misgurnus sp. OK are unknown.
Two Lefua species have still been left undescribed. Lefua sp. 1 is distributed amongst a narrow range of western Honshu, eastern Shikoku, Awaji Island and Shodo Island (Nakajima and Uchiyama 2017). Lefua sp. 2 is distributed in a limited area of Tokai region of Honshu, which is genetically discriminated from allopatric Lefua sp. 1 although the morphology of the two is rather similar (Nakajima and Uchiyama 2017).