Inachus bifidus Marion de Procé, 1822

Lee, Bee Yan, Low, Martyn E. Y. & Ng, Peter K. L., 2018, A nomenclatural review of the genus Schizophrys White, 1848 (Decapoda: Brachyura: Majoidea: Majidae), Raffles Bulletin of Zoology 66, pp. 12-22 : 14-16

Status of Inachus bifidus Marion de Procé, 1822 : reversal of precedence with junior synonym Mithrax asper H. Milne Edwards, 1831

Inachus bifidus was described from “baie Manille ” (Manila Bay, Philippines) by Marion de Procé (1822: 134). Since it was described, only Ng et al. (2008: 118) treated this name, listing it as a junior synonym of Schizophyrs aspera (H. Milne Edwards, 1831) . The original description given by Marion de Procé (1822: 134) is short and brief. No figures of Inachus bifidus are known and the type material of Inachus bifidus Marion de Procé (1822) is no longer extant (see Ng et al., 2008: 123). As described by Marion de Procé (1822), the species has 18 protuberances on the carapace, with the two posterior ones adjoining, and is taller than it is wide. In the Philippines, where this species is found, the only majoid species that matches this morphology is Schizophrys aspera (H. Milne Edwards, 1831) (see Griffin & Tranter, 1986: 254; Ng et al., 2008: 118). The locality also fits within the known distribution of Schizophrys aspera (H. Milne Edwards, 1831) (see Griffin & Tranter, 1986: 246). We are thus confident that Inachus bifidus Marion de Procé, 1822 , is a synonym of Schizophrys aspera (H. Milne Edwards, 1831) .

There is, however, a problem with priority. Ng et al. (2008: 123) commented that “[w]ith regards to Inachus bifidus Marion de Procé, 1822 , also from Manila, his description best fits the common Schizophrys aspera (H. Milne Edwards, 1834) and we also synonymise these. The types of both species are no longer extant (see discussion for Portunus tropicalis Marion de Procé, 1822 )”. Basically, Ng et al. (2008) had invoked Article 23.9.1.1 of the Code (1999) to reverse priority for Portunus tropicalis Marion de Procé, 1822 , and, by extension, Inachus bifidus Marion de Procé, 1822 . Their action, however, was invalid because they did not provide the requisite list of works using the junior name.

The present authors agree that while the Principle of Priority (Article 23 of the Code, ICZN, 1999: 24, 25) requires that the oldest available name for the taxon under consideration to be used, replacing the name Mithrax asper H. Milne Edwards, 1831 , with Inachus bifidus Marion de Procé, 1822 , will only cause nomenclatural instability as the former is in current and widespread use for a well-known and widely-distributed species of spider crab (see references cited below). We, therefore, formally invoke Article 23.9 of the Code ( ICZN, 1999: 27–29) that requires a reversal of precedence of a junior synonym when the senior synonym has not been used as a valid name after 1899 (Article 23.9.1.1) and the junior synonym “has been used for a particular taxon, as its presumed valid name, in at least 25 works, published by at least 10 authors in the immediately preceding 50 years and encompassing a span of not less than 10 years” (Article 23.9.1.2).

Since 1899, the species-group name Inachus bifidus Marion de Procé, 1822 , has not been used as a valid name for the taxon it denotes, which fulfils Article 23.9.1.1 of the Code. In the past 44 years, 30 publications by 45 different authors have used the name Mithrax asper H. Milne Edwards, 1831 , as the valid name for the taxon it denotes (viz., Takeda, 1973: 109; Griffin, 1974: 28; Griffin & Tranter, 1974: 181, 182; Lundoer, 1974: 5 (list); Sakai, 1976: 246, pl. 89 fig. 3; Serène et al., 1976: 16 (list); Griffin & Tranter, 1986: 245 (key), 245, 246, figs. 88a, 91g, h; Berry & Morgan, 1986: 60 (list); Dai & Yang, 1991: 152, 153, pl. 18 fig. 5, fig. 77 (5); Yamaguchi & Baba, 1993: 359; Morgan & Berry, 1993: 49 (list); Tirmizi & Kazmi, 1995: 135 (list), 139; Poupin, 1996: 27; d’Udekem d’Acoz, 1999: 190; Jones & Berry, 2000: 62 (table); Morgan, 2000: 117 (list), 120 (table); Siddiqui et al., 2000: 17, 28; Türkay, 2001: 285 (list); Ng & Ahyong, 2001: 87; Ng & Davie, 2002: 371 (list); Ghory & Siddiqui, 2007: 49 (list), 53 (table), 61 (list), figs. 3A–C, 8B, 16; Ng et al., 2008: 118 (list); Yeo et al., 2009: 181, 182 (table); Gokul & Venkataraman, 2010: 71, pl. 3 fig. t; Castro, 2011: 53, 54; El-Serehy et al., 2012: 3667–3671; Ghory, 2012: 121–124; Naderloo & Türkay, 2012: 36 (list); Tudge et al., 2014: 3, 5, 7, 9, 11, 13, figs. 2D, E, 3, 4; El-Serehy et al., 2015: 789–793). As such, all the requirements for Article 23.9.1.2 of the Code ( ICZN, 1999: 28) are fulfilled.

As both requirements of Article 23.9.1 are met and in accordance with Article 23.9.2, the name Mithrax asper H. Milne Edwards, 1831 (herein declared a nomen protectum) is considered a valid name and takes precedence over the subjective synonym Inachus bifidus Marion de Procé, 1822 (herein declared a nomen oblitum). Mithrax asper H. Milne Edwards, 1831 , remains the valid name for the taxon under consideration in the combination Schizophrys aspera (H. Milne Edwards, 1831) .