Cryptomya (Venatomya) elliptica ( A. Adams, 1851 )

Zhang, Jun-Long, Xu, Feng-Shan & Liu, Rui-Yu, 2012, The Myidae (Mollusca, Bivalvia) from Chinese waters with description of a new species, Zootaxa 3383, pp. 39-60 : 46-47

Cryptomya (Venatomya) elliptica ( A. Adams, 1851)

Figure 4 B–O

Sphenia elliptica A. Adams, 1851: 88 .

Cryptomya truncata Gould, 1861: 24 — Gould, 1862: 163; Johnson, 1964: 161.

Cryptomya elliptica ( A. Adams, 1851) — A. Adams, 1868: 366; Dunker, 1882: 178, pl. 7, figs. 17–19; Hedley, 1913: 275 –276, pl. 17, figs. 40–44; Beets, 1950: 17; Bernard et al. 1993: 107.

Mya elliptica ( A. Adams, 1851) — Sowerby, 1875: sp. 2, pl. I, fig. 2.

Cryptomya (Tugonella) elliptica ( A. Adams, 1851) — Lamy, 1927: 172 –173.

Cryptomya tachibanensis Yokoyama, 1927: 454 –455, pl. 52, fig. 5.

Venatomya truncata ( Gould, 1861) — Habe, 1951: 75, pl. 12, figs. 12–14; Habe, 1961: 140, pl. 63, fig. 12; Habe, 1968: 205, pl. 63, fig. 12; Habe, 1977: 279, pl. 59, figs. 1 & 2; Xu, 1986: 34; Xu 1997: 229; Xu & Zhang, 2008: 257, fig. 810; Xu, 2008: 589; Okutani, 2000: 1021, pl. 508, fig. 5; Kwon et al., 2001: 277, fig. 1134.

Cryptomya (Venatomya) elliptica ( A. Adams, 1851) — Lamprell & Stanisic, 1998: 5 –6, fig. 3a–d; Lamprell & Healy, 1998: 190, fig. 551; Huber, 2010: 461 (text-fig.).

Material examined. MBM264724 (1 articutate shell), Dalian, Liaoning Province, China, collected by Ma Xiutong et al. on May 31st, 1950; MBM264725 (3 articutate shells, 3 left valves, 1 right valve), Yanghe River estuary, Jiaozhou Bay, China, on November 17th, 1957; MBM264726 (7 articutate shells, 3 right valves), Yanghe River estuary, Jiaozhou Bay, China, collected by Ma Xiu-tong, on November 7th, 1951; MBM264729 (3 right valves) from Grabau-King Laboratory of Natural History, Peking, China, collection information not available; MBM264732 (1 articutate shell), Shazikou, Qingdao, China, collected by Zhang Gang-xuan, on August 23rd, 1956; MBM136090 (53 articutate shells, 1 left valve), in sand, Qinhuangdao, Hebei Province, China, collected by Wang, on September 16th, 1974; MBM136097 (1 articutate shell), Bohai Sea, Station 64055, 11m, sand, Agassiz trawl, Haiyan R/V, collected by Xu Feng-shan, on April 10th, 1964; MBM 300738 (2 articutate shells), no collection information; MBM264727 (1 articutate shell), Cangkou, Qingdao, China, collected by Zhang, on June 26th, 1958; MBM264728 (1 articutate shell), Cangkou, Qingdao, China, collected by Xuan, on July 30th, 1954; MBM264733 (1 articutate shell) Cangkou, Qingdao, China, collected by Zhang Xiu-ji, on July 22 th, 1955; MBM136084 (2 articutate shells), Cangkou, Qingdao, China, collected by Zhang Xiu-ji, on February 24th, 1955.

Distribution and habitat. Pliocene to Recent. China; Japan; Australia. In sand and mud, commonly in 5 to 20 cm deep burrows. Lives in macrosymbiotic association with thalassinoidean shrimps such as Upogebia major (De Haan) , U. yokoyai Makarov , U. carinicauda (Stimpson) and Nihonotrypaea japonica (Ortmann) (= Callianassa japonica Ortmann ) ( Itani & Kato 2002; Nara et al. 2008).

Type locality. Sydney, Australia.

Diagnosis. Length to 25 mm; shell chalky, compressed, elliptical when small but more oval when large; umbo small and low, situated subcentral and prosogyrate; sculpture of commarginal lines, with thin radial ribs on the posterocentral part of the shell and lacking on the anterocentral portion; with yellowish periostracum on the margin; left valve with a large chondrophore, right valve with a small resilifer; pallial sinus not reaching further anterior than posterior adductor scar; pallial line obscure.

Remarks. Most of Chinese and Japanese scientists recognized this species as Cryptomya (Venatomya) truncata Gould, 1861 or Venatomya truncata ( Gould, 1861) ( Habe 1951, 1961, 1968, 1977; Okutani 2000; Xu 1986, 1997, 2008; Xu & Zhang 2008), whereas Hedley (1913), Huber (2010), Lamprell & Healy (1998), and Lamy (1927) considered it synonymous with C. (Venatomya) elliptica . Unfortunately, the type material of C. (Venatomya) truncata Gould, 1861 , from the East China Sea (lat. 24°N) is apparently lost ( Johnson 1964) and Gould's (1861, 1862) brief description and lack of figures do not allow to designate a neotype; a comparison with the lectotype of Sphaenia [sic] elliptica A. Adams, 1851 , designated by Lamprell & Stanisic (1998), is not possible, therefore.

Taking into account the variability seen in our material and the figures of the Japanese species, we cannot detect a significant difference to the Australian C. (Venatomya) elliptica . Okutani (2000) described V. t r u n c a t a with radial ribs all over the shell, which coincides with figures in Habe (1977: pl. 59, figs. 1 & 2). According to Gould (1861), C. (Venatomya) truncata has only posterior ribs, as in C. (Venatomya) elliptica of A. Adams (1851) and in our own material (see also, Itani & Kato 2002). We also found that younger specimens have fragile and more elongate shells, but they become taller, thicker, and ventrally more convex during growth ( Fig. 4 B–E, 4F–I, 4J–O, for small, intermediate and large specimens, respectively).

Figures

FIGURE 4. A. Cryptomya (Cryptomya) busoensis Yokoyama, 1922 (from Xu, 1987: fig. 1 c). Scale bar = 5 mm. B – O. Cryptomya (Venatomya) elliptica (A. Adams, 1851). B – E. MBM 264725, length = 11.4 mm. B. Exterior of right valve. C. Exterior of left valve. D. Interior of right valve. E. Interior of left valve. Scale bar (B – E) = 5 mm. F – I. MBM 264726, length = 14.9 mm. F. Exterior of right valve. G. Exterior of left valve. H. Interior of right valve. I. Interior of left valve. Scale bar (F – I) = 5 mm. J – O. MBM 264727, length = 23.3 mm. J. Exterior of right valve. K. Exterior of left valve. L. Interior of right valve. M. Interior of left valve. Scale bar (J – M) = 5 mm. H. Hinge of left valve. Scale bar = 5 mm. O. Close up of surface sculpture. Scale bar = 5 mm.