Heikeopsis japonica, , H. TAIWANENSIS (SERENE & ROMIMOHTARTO, 1969)

Guinot, Danièle, 2023, A new subfamily classification of the highly diversified Dorippidae H. Milne Edwards, 1837 (Crustacea, Decapoda, Brachyura, Dorippoidea), using morphological, molecular and palaeotonlogical data, with special emphasis on its unique female reproductive system, Zoosystema 45 (9), pp. 225-372 : 273-274

STATUS OF NON- JAPANESE HEIKEOPSIS JAPONICA, H. TAIWANENSIS ( SERÈNE & ROMIMOHTARTO, 1969) , AND H. ARACHNOIDES ( MANNING & HOLTHUIS, 1986) :

A MAJOR PROBLEM

While the present revision was in progress, we noted that the syntype specimen of Dorippe japonica described by De Haan (1839: pl. 31, fig. 1; 1841: 122; reproduced by Holthuis & Sakai 1970: pl. 8 fig. 3, and by Holthuis & Manning 1990: fig. 34, as Heikea japonica ), and the crabs of the type series figured by Yamaguchi & Baba (1993: 304, fig. 90A, B, as Heikea japonica ), have all invariably very long and thin P2 and P3. A long-legged crab is also shown in the picture of Dorippe japonica represented by Suiken (pl. 6, figs 41, 42), see above. De Haan’s illustration ( Fig. 1A ) indeed shows very long and slender legs in accordance with the text (Pedes secundi 3” 4”’, tertii 3” 8”’ vix quater thorace longiores, i.e., “legs barely four times as long as carapace”). Likewise, the three dry specimens from Japan in the MNHN historical collection ( Fig. 1C ) have very slim and long P2 and P3. Typical japonica was depicted by Miyake (1983: 17, pl. 6, fig. 1, as Nobilum japonicum japonicum ) and by Takeda (1983: fig. p. 121, as Neodorippe japonica ). The crabs figured as japonica by Takeda (1982b: 93, coloured fig., as Neodorippe japonica ) are typical Heikeopsis japonica . There is no figure in Yamaguchi et al. (1976: 34, as Neodorippe (Neodorippe) japonica ), whereas the crab from the Amakusa Islands in Yamaguchi et al. (1987: 8, pl. 1, fig. 10, as Nobilum japonicum ) is a typical Heikea japonica . Note that figures in various papers of Sakai show either a crab with long, slender P2, P3 (e.g. Sakai 1937: 72, pl. 10, fig. 1, as Dorippe japonica , from Omoniti), or others that are not significant ( Sakai 1976: 61, pl. 22, fig. 1, as Neodorippe (Neodorippe) japonica ), but this can be attributed to a bias. Sakai (1956: 6, 24, fig. 7, as Dorippe japonica ) reproduces De Haan’s figure of Dorippe japonica .

In his key paper ‘Heike-gani, its Prosperity and Fossils’, Sakai (1985: 330, as Neodorippe japonica ) reproduces in his fig. 1 a typical Heikea japonica with long, slender P2 and P3; his fig. 2 shows the carapace of ‘Heikegani’ in Japan: from top left to right, Dorippe frascone , Paradorippe granulata , Heikeopsis japonica , and below Ethusa izuensis , E. minuta , E. quadrata , and Tymolus japonicus . His fig. 3 reproduces at the top a sketch taken from Shen (1932: fig. 6, as Dorippe japonica ; the indicated date 1835 is erroneous) and showing a crab with short, stout P2 and P3, from northern China: Sakai was thus quite conscious that this was a species distinct from the typical japonica ; the middle photo is listed as representing Dorippe polita from Shen (1932: fig. 4) (T. Naruse, pers. comm.).

Holthuis & Manning (1990: 80) note in their specific description of Heikeopsis japonica “Second and third legs slender, long, both reaching beyond front [of carapace] with distal end of merus” but, at the same time, they do not distinguish between the Japanese syntype specimen of De Haan (1839: pl. 31, fig. 1) and a North Chinese specimen with short, robust P2 and P3 by Shen (1932: fig. 6), whose figure they reproduce (Holthuis & Manning 1990: fig. 35). In fact, the Heikea japonica of Holthuis & Manning (1990) indiscriminately includes crabs from Japan, China, Korea, Vietnam, Paracels Islands and Taiwan, whether long- or short- legged.

Yet, earlier, Serène & Romimohtarto (1969: 13, as Neodorippe (Neodorippe) japonica ) had recognised Chen’s Chinese crab as a doubtful japonica , arguing that its P3 was less than 3 times the carapace length, unlike their specimens from Nagasaki and Vietnam that have the merus of P3 much longer than the carapace length, and just like the Japanese specimens with ‘slender legs’ “more than 3.4 times the length of the carapace” of Sakai (1937: 72, pl. 10, fig. 1, as Dorippe japonica ). Consequently, Serène & Romimohtarto (1969: 14, figs 21, 22, pI. 5A, B, D) established a variety of japonic a as Neodorippe (Neodorippe) japonica var. taiwanensis , based on two specimens from Keelung, Taiwan, with the P3 having a total length (coxa and basis-ischium excluded) 3.2 times the carapace length, thus much longer and slimmer than the japonica from China and almost similar to the typical japonica from Japan. However, Holthuis & Manning (1990: 87) concluded that the features used to distinguish H. japonica taiwanensis from H. japonica fell within the range of variation of this character in H. japonica , including Chinese representatives, and that the two species were synonymous. Furthermore, it is rather incomprehensible that Manning & Holthuis (1986: 364, fig. 1d, as Nobilum arachnoides ) at the same time described a new species, now Heikeopsis arachnoides , collected by the Challenger in 1875 from the same provenance ( Japan, Inland Sea) as H. japonica , and characterised by very long legs. Holthuis & Manning (1990: 72, figs 27, 28, as Heikea arachnoides ) continued in the same vein, separating the two species only by the size of P2 and P3 without mentioning any other substantial distinguishing features. H. arachnoides is clearly synonymous with H. japonica .

Subsequent carcinologists followed suit, but with some variations. Ng & Huang (1997: 267, figs 3E, 4A) identify a male from northeastern Taiwan as H. arachnoides , but regard three males and two females collected at the same site as H. japonica on the basis of a lower length of P3. In their Fauna Sinica, Chen & Sun (2002) distinguish two species: Heikea japonica ( Chen & Sun 2002: 222, fig. 94), with taiwanensis as synonym; and Heikea arachnoides ( Chen & Sun 2002: 220, fig. 93, pl. 1.4). In the Catalogue of crabs from Taiwan, Ng et al. (2017: 36), as previously in 2001 (p. 8), list two species: H. arachnoides and H. japonicum [sic], the latter being considered a senior synonym of Neodorippe (Neodorippe) japonica var. taiwanensis , all with long, slender legs and none with short, stout legs. In Hong Kong seas two species are recognised: one, along the Tolo Channel, identified with Heikeopsis arachnoides by its ambulatory legs with long meri, notably P3 meri 6.6 to 7.3 times longer than high; and a second, in western waters, as H. japonica , with shorter P3 meri, less than 6.3 times longer than high ( Wong et al. 2021: 10, fig. 11, pl. 2E and fig. 12, pl. 2F, respectively). The Heikeopsis japonica from Korea in Koh & Lee (2013: 19, pls 10-12) has P2 and P3 that are more or less long and slender.

The discrepancies in the use of ambulatory leg length by Holthuis & Manning (1990) is an issue that will require detailed study, also taking into account changes during the growth and possible sexual dimorphism. The use of the ambulatory leg length has been followed by other reserchers since then, but there are clearly problems. We have examined a large number of range specimens as well as the types, and it is clear that all specimens from Japan, Korea, Taiwan, Hong Kong and Vietnam have long to very long P2 and P3. However, those from northern mainland China ( Shen 1932: 11, figs. 6, 7a-e, as Dorippe japonica ; Chen 1986b: 123, fig. 5. 23-27, as Nobilum japonicum ) (see? Heikeopsis aff. japonica in our Material examined) have consistently shorter legs, but comparisons of their carapaces, pereopods and gonopods have so far not uncovered any significant differences; and initial genetic studies also do not show any patterns. The issue will have to be addressed separately (Guinot D., Ng P. K. L. & Naruse T., in progress).

Figures

FIG. 1. — A typical dorippid crab, Heikeopsis japonica (von Siebold, 1824), the iconic ‘samurai crab’ known in Japan as ’heike-gani’, whose carapace looks like a human face: A, the species represented by De Haan (1839: pl. 31, fig. 1, as Dorippe japonica) in Fauna Japonica: top, a female; below, chelae of a male; B, lectotype selected by Yamaguchi & Baba (1993: 300, fig. 90-A.a-2, as Heikea japonica) from type series material labelled “Types, Japan, 1823, Leg. P. H. von Siebold”, RMNH CRUS D 822 (see Fransen et al. 1997: 83); C, ♂ 25.0 × 27.3 mm, ♀ 23.5 × 26.7 mm, Japan, Chaffanjon, 174-96, E.-L. Bouvier det. 1899 Dorippe japonica, dry condition, MNHN-IU-2000-4091 (= MNHN-B4091).