Orientomysis mitsukurii ( Nakazawa, 1910 )

Fukuoka, Kouki & Murano, Masaaki, 2005, A revision of East Asian Acanthomysis (Crustacea: Mysida: Mysidae) and redefinition of Orientomysis, with description of a new species, Journal of Natural History 39 (9), pp. 657-708 : 680-682

Orientomysis mitsukurii ( Nakazawa, 1910)

Metamysis mitsukurii Nakazawa 1910: 250 , 251, Plate 8, Figures 9 , 11 , 13 , 18, 26.

Orientomysis mitsukurii: Derzhavin 1913: 202 ; Müller 1993: 245, 246 (list).

Neomysis mitsukurii: Illig 1930: 597 (key); W. Tattersall 1932: 317 (key).

Acanthomysis mitsukurii: Ii 1936: 589 (list), 600–603, Figures 56–66; Banner 1948: 87 (key); Gordan 1957: 337 (list); Ii 1964: 495–499, Figure 127; Mauchline and Murano 1977: 44 (list).

Type locality

Off Oarai, Ibaraki, central Japan; off Maisaka, Shizuoka, central Japan.

Material examined

One hundred and seventy males (4.7–7.3 mm), 23 immature males (4.6–4.8 mm), 202 females (5.3–7.6 mm) and 132 immature females (4.1–5.2 mm), 34 ° 54.89N, 138 ° 27.99E, Suruga Bay, central Japan, 20 m, bottom net, 8 July 1969, R / V Tansei-Maru cruise, NSMT-Cr 15573. Sixty males (6.0– 8.3 mm) and 207 females (5.8–8.2 mm), Tateyama Bay, Chiba, central Japan, 19 June 1978, NSMT-Cr 15574. Fourteen males (6.3–7.2 mm) and six females (5.8–6.7 mm), Tateyama Bay , Chiba, central Japan, 19 June 1978, NSMT-Cr 15575. Twenty males (6.4–8.2 mm), Tateyama Bay , Chiba, central Japan, 0.7–3 m, sandy beach, sledge net, 19 June 1980, NSMT-Cr 15576. Thirty-two males (6.2–9.1 mm), nine immature males (5.3–5.8 mm), 31 females (6.5–9.0 mm) and 32 immature females (5.2–6.3 mm), Ohno Bay , Iwate, northern Japan, 8 m, 31 July 1989, NSMT-Cr 15577. Twenty-one males (7.6–11.8 mm), 12 immature males (5.0–7.0 mm), 13 females (9.4–11.0 mm) and 12 immature females (6.6–7.4 mm), Ohno Bay , Iwate, northern Japan, 11 m, sledge net, 26 April 1991, coll. H. Yamada, NSMT-Cr 15578. Forty-three males (10.8–11.2 mm) and 151 females (8.0– 11.4 mm), Ohno Bay , Iwate, northern Japan, 4 m, sledge net, 12 June 1992, coll. H. Yamada, NSMT-Cr 15579 .

Remarks

Location of type specimens is unknown.

Orientomysis mitsukurii is readily distinguished from related species by the presence of a number of small spines on the abdominal somites ( Ii 1964).

Distribution

This species is distributed in Pacific coastal waters of Japan from Aomori to Miyazaki ( Nakazawa 1910; Ii 1936, 1964; Yamada et al. 1994; present study).

Along the Sanriku coast, northern Japan, this species predominates in mysid assemblages in waters shallower than 10 m deep, especially in depths of 7–10 m, in sandy bottom areas facing the open sea ( Yamada et al. 1994).

Orientomysis okayamaensis ( Ii, 1964) comb. nov. Acanthomysis okayamaensis Ii 1964: 504–506 , Figure 130; Mauchline and Murano 1977: 45 (list); Shen et al. 1989: 215, Figure 12 ; Müller 1993: 196 (list); Jo and Ma 1996: 815– 818, Figure 12 ; Wang and Liu 1997: 216; Liu and Wang 2000: 238–240, Figure 87.

Type locality

Atsu, mouth of Kojima Bay, Seto Inland Sea, western Japan.

Material examined

Syntype: one male (18.6 mm) and two females (19.4 mm and damaged), Atsu , mouth of Kojima Bay, Okayama, western Japan, 18 March 1936, Ii’s coll. no. 215 .

Others. One male (damaged) and two immature females (9.7 and 11.3 mm), Atsu, mouth of Kojima Bay , Okayama, western Japan, Ii’s coll. no. 216. Two females (damaged), Boryong, Chungchongnamdo, western Korea, plankton net, 1 April 1992, on loan from S.-G. Jo. One male (10.5 mm), 34 ° 24.709N, 135 ° 04.839E, Osaka Bay, central Japan, 40 m, bottom net, 16 June 1997, TR/ V Seiyo-Maru cruise, NSMT-Cr 15580 .

Remarks

Shen et al. (1989) and Jo and Ma (1996) noted the presence of dorsal spines on the telson, a character not mentioned in the original description by Ii (1964). The presence of these spines was confirmed in the type specimens.

Orientomysis okayamaensis is related to O. meridionalis and O. serrata . Differences among the three species are shown in Table VI.

Distribution

This species has been collected from Japanese embayments, Kojima Bay ( Ii 1964) and Osaka Bay (present study); Chinese coastal waters, Qingdao ( Shen et al. 1989) and the mouth of the Yangtze River ( Wang and Liu 1997); and West Korean coastal waters ( Jo and Ma 1996).

This species was collected from a depth of 30 m in the mouth of the Yangtze River ( Wang and Liu 1997) and from a depth of 40 m in Osaka Bay (present study) .

Figures

Figure 9. Orientomysis sagamiensis (Nakazawa, 1910). (A–J) Male (15.6 mm), NSMT-Cr 15598; (K) female (17.0 mm), NSMT-Cr 15598. (A) Third thoracic limb, posterior; (B) eighth thoracic limb, posterior; (C) penis, lateral; (D–H) first to fifth pleopods; (I) basal part of uropod, ventral; (J) uropod and telson, dorsal; (K) telson, dorsal.

Figure 11. Orientomysis tamurai (Ii, 1964) comb. nov. (A–D) Male (9.8 mm), NSMT-Cr 15599; (E) female (10.4 mm), NSMT-Cr 15599. (A) Penis, lateral; (B) fourth pleopod, posterior; (C) proximal part of uropod, ventral; (D, E) uropod and telson, dorsal.

Figure 12. Orientomysis arenaria sp. nov. (A, C–I) Male (9.6 mm), holotype, NSMT-Cr 15618; (B) female (17.8 mm), paratype, NSMT-Cr 15619. (A, B) Anterior part of body, dorsal; (C) antenna, ventral; (D) labrum, lateral; (E) mandible; (F) maxillule, posterior; (G) maxilla, posterior; (H) first thoracic limb, posterior; (I) second thoracic limb, posterior.

Figure 13. Orientomysis arenaria sp. nov. (A–J) Male (9.6 mm), holotype, NSMT-Cr 15618; (K) female (17.8 mm), paratype, NSMT-Cr 15619. (A) Third thoracic limb, posterior; (B) eighth thoracic limb, posterior; (C) penis, lateral; (D–H) first to fifth pleopods; (I) basal part of uropod, ventral; (J, K) uropod and telson, dorsal.