Cobitis takatsuensis Mizuno 1970

Ito, Taiki, Suzawa, Yuzuru & Sato, Yoichi, 2024, Notes on type specimens of Rhinogobius flumineus (Mizuno 1960) (Perciformes: Gobiidae) and Cobitis takatsuensis Mizuno 1970 (Cypriniformes: Cobitidae) in Tokushima Prefectural Museum, Tokushima, Japan, Zootaxa 5446 (4), pp. 564-572 : 565-567

Cobitis takatsuensis Mizuno 1970

( Figs. 1–3 )

Holotype: TKPM-P 3006 , male, 53.4 mm SL, Kabatani-gawa River , Takatsu-gawa River System , Kakinoki, Kanoashi District, Shimane, Japan, 10 September 1970, N. Mizuno.

Paratypes: TKPM-P 3007 , 1 specimen, female, 70.0 mm SL, collected with holotype ; TKPM-P 3008 , 1 specimen, female, 53.1 mm SL, Ninotani-gawa River , tributary of Hikimi-gawa River , Takatsu-gawa River System , Shimane, Japan, 10 September 1970, N. Mizuno .

Remarks. Mizuno (1970) described Cobitis takatsuensis based on the holotype, five paratypes, and some non-types collected on 28 August 1970 and 10 September 1970 (N. Mizuno, personal correspondence). Mizuno (1970) noted that he had preserved the type specimens of the species in the “author’s collection”; registration numbers had not been individually allocated to the type specimens. When TKPM received Mizuno’s collection, the holotype and two paratypes were identified by one of us (Y. Suzawa) based on an interview with Prof. Mizuno, considering also the measurements declared in Mizuno (1970). Subsequently, TKPM-P registration numbers were assigned to the holotype and two paratypes.

Mizuno’s collection, as received by TKPM, includes two specimens ( TKPM-P 3009 , 2 specimens) of C. takatsuensis , excluding the holotype and two paratypes. According to the accompanying labels written by Prof. Mizuno, TKPM-P 3009 were collected from the Takatsu-gawa River System on the same date as the holotype. However, the SL of TKPM-P 3009 (female: 60.4 mm SL, male: 47.9 mm SL) does not match the SL of any paratypes described in Mizuno (1970). It is highly likely that these specimens are non-types, not paratypes.

The current whereabouts of the remaining three paratypes are unknown. According to an interview conducted by one of the authors (Y. Suzawa) with Prof. Mizuno, several paratypes were distributed among some Japanese ichthyologists. However, no information regarding the whereabouts of these paratypes is available. In search of the remaining three paratypes, we collected information from Hokkaido University Museum (HUMZ), Kyoto University (FAKU), National Museum of Nature and Science (NSMT), Osaka Museum of Natural History (OMNH), and Yokosuka City Museum (YCM). As a result, we found some specimens of C. takatsuensis collected on the same day and locality as the holotype and paratypes at YCM (YCM-P 20077: 22 specimens, YCM-P 20183: 1 specimen, and YCM-P 20186: 9 specimens) and HUMZ (HUMZ 52549–59: 11 specimens). Among these specimens, individual number 8 in YCM-P 20077 closely matches a paratype [= total length: 44.1 mm, SL: 37.9 mm, male in Table 2 of Mizuno (1970)] as described in Mizuno (1970) in terms of total length, SL, and sex. HUMZ 52549 exhibits bifurcation of the right-side third barbel and two barbels at the location of the left-side second barbel. These characteristics closely correspond to one of the paratypes mentioned in Table 1 of Mizuno (1970): “Abnormal barbels, which consist not only of two barbels at the location of second barbel but also of bifid third babel.” The SL of HUMZ 52549 measures 50.2 mm, which is slightly different from the SL of the paratype (= 54.8 mm) indicated by Mizuno (1970). The condition of HUMZ 52549 has deteriorated due to desiccation. The difference in the aforementioned SL values is thought to be attributed to variations in the condition of the specimen, i.e., it is likely that the specimen shrunk due to desiccation. Consequently, both individual number 8 in YCM-P 20077 and HUMZ 52549 are considered highly likely to be paratypes. The remaining paratype [= total length: 74.8 mm, SL: 65.4 mm, female in Table 1 of Mizuno (1970)] is likely included in either YCM-P 20077 or YCM-P 20186, or possibly within TKPM-P 3009, all of which contain relatively large female specimens. Alternatively, it may be held in other universities, museums, or private collections, warranting further exploration.

In Mizuno (1970), the vertebral counts of C. takatsuensis were not provided. Herein, we present the vertebral counts (abdominal + caudal) of the holotype and two paratypes as follows: TKPM-P 3006 : 25+17, TKPM-P 3007 : 25+18, TKPM-P 3008 : 26+17.

Figures

FIGURE 1. Holotype of Cobitis takatsuensis Mizuno 1970, TKPM-P 3006, 53.4 mm SL. Lateral (upper) and dorsal (lower) views.

FIGURE 2. Paratypes of Cobitis takatsuensis Mizuno 1970. (A) TKPM-P 3007, 70.0 mm SL. (B) TKPM-P 3008, 53.1 mm SL.

FIGURE 3. Soft X-ray negatives of holotype and two paratypes of Cobitis takatsuensis Mizuno 1970. (A) TKPM-P 3006, holotype, 53.4 mm SL. (B) TKPM-P 3007, paratype, 70.0 mm SL. (C) TKPM-P 3008, paratype, 53.1 mm SL.