Tetronarce Gill, 1862

Ebert, David A., White, William T., Ho, Hsuan-Ching, Last, Peter R., Nakaya, Kazuhiro, Séret, Bernard, Straube, Nicolas, Naylor, Gavin J. P. & De Carvalho, Marcelo R., 2013, An annotated checklist of the chondrichthyans of Taiwan, Zootaxa 3752 (1), pp. 279-386 : 341-342

Genus Tetronarce Gill, 1862

Pelagic torpedoes / dzḍé

Tetronarce Gill, 1862 . Type species: Torpedo occidentalis Storer, 1843 , by monotypy and original designation (name appears in key; Eschmeyer, 2013).

[Note: The nominal genus Torpedo is universally used for pelagic as well as near-shore benthic torpedoes, with two subgenera employed– Tetronarce for pelagic torpedoes and Torpedo for inshore, primarily benthic species. In accordance with modern practice (e.g. Carvalho, in press; Carvalho & Séret, in press), however, Tetronarce is used here as a full genus. We also note that Torpedo Duméril, 1806 takes priority over Torpedo Houttuyn, 1764 , which is commonly credited as the valid nominal genus, because the latter was not coined as a generic but as a specific name according to Welter-Schultes & Feuerstein (2008: 141)].

Tetronarce formosa ( Haas & Ebert, 2006)

Taiwanese pelagic torpedo / Ớ dzḍ

Torpedo formosa Haas & Ebert, 2006: 2 , Figs. 1-3. Holotype: CAS 223471 , immature male, 332 mm TL. Type locality: Ta-Shi Fish Market , Tashi, northeastern Taiwan, 24°53'N, 122°01'E, 9 April 1988.

Local Synonymy: Torpedo nobiliana: Chen & Chung, 1971:6 , fig. 4; Chen & Joung, 1993: 621, pl. 11, fig. 1; Torpedo formosa: Haas & Ebert, 2006: 2 , figs. 1-3; Shen & Wu, 2011:90, fig.

Taiwan voucher material: CAS 223471 (Holotype), 332 mm TL, immature male ; CAS 223472 (Paratype), 243 mm TL immature male ; CAS 223473 (Paratype), 242 mm TL female (all from Da-xi , northeastern Taiwan) ; NMMBP 2797 ; NMMBP 6199 ; NMMBP 6614, 282 mm TL, female; NMMBP 6648 ; NMMBP , 6649; NMMBP 6650 ; NMMBP 8131, 300 mm TL, male; NMMBP 9293 ; NMMBP 11594 ; NMMBP 15880, 465 mm TL, 540 mm TL, 890 mm TL, all female; NMMBP 16216, 219 mm TL, male.

Remarks: The separation of Tetronarce formosa from T. tokionis ( Tanaka, 1908) and T. nobiliana ( Bonaparte, 1835) , the latter speciesreported from Taiwan prior to Haas & Ebert (2006), is not straight forward, a circumstance widespread in the systematics of Tetronarce ( Carvalho et al., 2002) . Tetronarce formosa resembles T. tokionis most, not being as dark or purplish-black dorsally as T. nobiliana , but this character is highly variable, as are proportional measurements that depend on the state of preservation of material, which is frequently poor. Tetronarce formosa is reported to differ from T. tokionis in having a lighter dorsal color without darker hatch markings, disc ovate (longer than wide vs. more circular in T. tokionis ), a thinner disc, in lacking an emarginated caudal fin (present in T. tokionis ), and in having a shorter tail ( Haas & Ebert, 2006). We follow Haas & Ebert (2006) in recognizing only T. formosa and T. tokionis from Taiwan. A revision of Tetronarce has been in preparation for a while (Carvalho & Séret, in prep.), hindered by the lack of series of well-preserved specimens. The species is occasionally taken as bycatch, but it is of no commercial value.

Conservation status: Data Deficient.

Tetronarce tokionis ( Tanaka, 1908)

Japanese pelagic torpedo, Trapezoid torpedo / Φợdzḍ

Tetronarcine tokionis Tanaka, 1908: 2 , fig. Type locality: Tokyo fish market, Tokyo, Japan. Holotype: ZUMT 917 (apparently lost).

Local Synonymy: Torpedo tokionis: Chen & Joung, 1993: 621 , pl. 11, fig. 2; Shen & Wu, 2011: 90.

Taiwan voucher material: ASIZP 57914, 200 mm TL, female; ASIZP 62334, 175 mm TL, male; ASIZP 64633, 230 mm TL, female; ASIZP 65468, 240 mm TL, male; ASIZP 66221, 295 mm TL, male; ASIZP 70777, 220 mm TL, male; CAS 235419, 693 mm TL adult male, 24 May 2005 ; CAS 236519, 184 mm TL immature female, 9 May 1988 ; CAS236520 (2 spec.), 289 mm TL immature male, 230 mm TL immature female, 20 May 1988 (All material from ASIZP and CAS collected at Da-xi , northeastern Taiwan) .

Remarks: To our knowledge, very few specimens of this species are present in Taiwanese collections, even though a poorly preserved specimen possibly of this species is figured in Shen & Wu (2011, p. 90). Most known material of this species is in Japanese collections and is from Japan. Haas & Ebert (2006) mention four specimens collected from the Da-xi, northeastern Taiwan, that they used for comparison with T. formosa (three immature and one adult male that are deposited at the CAS). As mentioned above, separation between T. tokionis and T. formosa is difficult, especially after preservation. The species is commonly reported from adjacent regions ( Hatooka, 2013). Infrequently captured as by-catch, but of no commercial importance. It is not as common at the Da-xi market as T. formosa .

Conservation status: Data Deficient.