Propeamussium jeffreysii (E.A. Smith, 1885 )

Dijkstra, H. H. & Maestrati, P., 2015, Pectinoidea (Bivalvia: Propeamussiidae and Cyclochlamydidae) from the southwestern Indian Ocean, African Invertebrates 56 (3), pp. 585-585 : 591-592

Propeamussium jeffreysii (E.A. Smith, 1885)

Fig. 1G, H

Amussium jeffreysii E.A. Smith, 1885: 310 , pl. 23, figs 2–2c; Knudsen 1967: 276, pl. 1, fig. 19. TYpe locality: Philippine Islands, E of Panay (9°26'N 123°45'E), - 686 m, live, blue mud, 25.i.1875

(Challenger, stn 210).

Propeamussium jeffreysii: Dijkstra 2001: 76 , figs 5–12; 2013: 13, pl. 1, figs 2a–d, pl. 4, figs 2a–b; Dijkstra

& Maestrati 2008: 83; 2012: 391.

Description: Shell fragile, up to 28 mm in height, more commonly 20–23 mm, slightly higher than wide, equilateral, inequivalve, weaklY inflated, left valve somewhat more than right, auricles equal, umbonal angle 100°–110°. Colour of left valve an orangebrown tint and semi-transparent, right whitish. Prodissoconch 200 µm high. Left valve has a delicate regular latticed sculpture in early growth stage, distinct near the umbo, but tends to be obsolete near the ventral margin. Anterior and posterior auricles are relativelY small, equal in size, with fine radial riblets, weaker on right valve. Right valve sculptured with fine regularlY spaced commarginal lirae. Internal riblets 10 with 2 auricular riblets, and a few (2–4) interstitial rudimentary riblets in late growth stage. Hinge line straight. Resilifer triangular. No byssal fasciole, byssal notch, or ctenolium. Type material examined: Lectotype (pr) NHMUK 1887.2.9.3313, designated by Dijkstra (2001: 76), 2 paralectotypes NHMUK 1887.2.9.3314-15. The marginal apron (prismatic calcite outer layer) of the right valves of the type material is damaged or broken off, due to its fragility.

Other material examined: NW MADAGASCAR: Between Nosy-Bé and Banc du Leven (12°38'S 48°14'E), - 420–436 m, live, campaign Miriky, stn CP3183, 26.vi.2009 ( MNHN) ; between Nosy-Bé and Banc du Leven (12°40'S 48°12'E), - 492–524 m, live, campaign Miriky, stn CP3184, 26.vi.2009 ( MNHN) ; between Nosy-Bé and Banc du Leven (12°38'S 48°10'E), - 560–576 m, live, campaign Miriky, stn CP3185, 26.vi.2009 ( MNHN) ; between Nosy-Bé and Banc du Leven (12°30'S 48°08'E), - 691–695 m, live, campaign Miriky, stn CP3187, 26.vi.2009 ( MNHN) ; between Nosy-Bé and Banc du Leven (12°26'S 48°13'E), - 578–580 m, live, campaign Miriky, stn CP3192, 27.vi.2009 ( MNHN) ; West of Cap d’Ambre (12°08'S 48°53'E), - 496–501 m, dead, campaign Miriky, stn DW3195, 28.vi.2009 ( MNHN) ; West of Cap d’Ambre (12°06'S 48°54'E), - 560–653 m, live, campaign Miriky, stn DW3200, 28.vi.2009 ( MNHN) ; between Nosy-Bé and Banc du Leven (12°44'S 48°12'E), - 442–491 m, live, campaign Miriky, stn CP3210, 29.vi.2009 ( MNHN) ; between Nosy-Bé and Banc du Leven (12°23'S 47°56'E), - 391–438 m, live, campaign Miriky, stn DW3217, 30.vi.2009 ( MNHN) ; between Nosy-Bé and Banc du Leven (12°46'S 48°11'E), - 430–488 m, dead, campaign Miriky, stn CP3223, 02.vii.2009 ( MNHN) ; West of Nosy-Bé (13°24'S 47°57'E), - 435–600 m, live, campaign Miriky, stn DW3231, 03.vii.2009 ( MNHN) ; Mahajamba Bay (14°50'S 46°57'E), - 340–446 m, live, campaign Miriky, stn CP3248, 07.vii.2009 ( MNHN) ; Majunga (15°22'S 46°00'E), - 493–750 m, live, campaign Miriky, stn CP3250, 08.vii.2009 ( MNHN) ; Majunga (15°22'S 45°58'E), - 850–900 m, live, campaign Miriky, stn CP3252, 08.vii.2009 ( MNHN) ; Mahajamba Bay (14°47'S 46°58'E), - 512–680 m, live, campaign Miriky, stn CP3285, 13.vii.2009 ( MNHN) ; in front of Narendry Bay (12°26'S 48°13'E), - 578–580 m, live, campaign Miriky, stn CP3292, 14.vii.2009 ( MNHN) . MOZAMBIQUE CHANNEL: NE region, Mayotte (12°46'S 44°58'E), - 475–510 m, dead, campaign Benthedi 1977, stn 61 ( MNHN) ; Mayotte (12°46.5'S 44°57.6'E), - 530–535 m, dead, campaign Benthedi 1977, stn DS 62, Sanders epibenthic sledge, RV Suroît, 29.iii.1977 ( MNHN) ; Mayotte, E Bandele reef (12°53.8'S 45°16.2'E), - 520–830 m, dead, campaign Benthedi 1977, stn 37 ( MNHN) ; Maputo transect (25°13'S 35°18'E), - 480–503 m, dead, campaign Mainbaza, stn CP3135, RV Vizconde de Eza , 10.iv.2009 ( MNHN) ; Maputo transect (23°31'S 35°50'E), - 446–475 m, dead, campaign Mainbaza, stn CP3142, RV Vizconde de Eza , 11.iv.2009 ( MNHN) ; Zambeze transect (19°34'S 36°45'E), - 352–357 m, live, campaign Mainbaza, stn CC3151, RV Vizconde de Eza , 13.iv.2009 ( MNHN) ; Zambeze transect (19°34'S 36°45'E), - 443–445 m, dead, campaign Mainbaza, stn CC3152, RV Vizconde de Eza , 13.iv.2009 ( MNHN) ; Zambeze transect (19°35'S 36°46'E), - 518–524 m, live, campaign Mainbaza, stn CC3153, RV Vizconde de Eza , 13.iv.2009 ( MNHN) ; Maputo transect (25°34'S 34°11'E), - 155–165 m, dead, campaign Mainbaza, stn CC3175, RV Vizconde de Eza , 17.iv.2009 ( MNHN) . MOZAMBIQUE: S region: Off Zavora , - 235–400 m, live, trawled, don. J. Rosado, 30.iii.1998 ( NMSA L4655 ) . S MADAGASCAR: Manantenina (24°24'S 47°34'E), - 502–504 m, live, expedition Atimo Vatae, stn DW3526, RV Nosy Bé 11, 01.v.2010 ( MNHN) ; Fort-Dauphin (25°19.8'S 47°00.9'E), - 77 m, dead, expedition Atimo Vatae, stn DW3536, RV Nosy Bé 11, 02.v.2010 ( MNHN) ; Fort-Dauphin (25°28'S 47°02'E), - 607–633 m, dead, expedition Atimo Vatae, stn CP3542, RV Nosy Bé 11, 03.v.2010 ( MNHN) ; E of Faux Cap (25°37'S 46°20'E), - 433–456 m, live, expedition Atimo Vatae, stn DW3564, RV Nosy Bé 11, 06.v.2010 ( MNHN) ; Fort-Dauphin (25°05.5'S 47°05.5'E), - 69–70 m, live, expedition Atimo Vatae, stn CP3569, RV Nosy Bé 11, 08.v.2010 ( MNHN) ; S Pointe Barrow (25°31'S 44°16'E), - 296–302 m, dead, expedition Atimo Vatae, stn CP3583, 10.v.2010 ( MNHN) ; S Pointe Barrow (25°35'S 44°15'E), - 821–910 m, dead, expedition ATIMO VATAE, stn CP3595, RV Nosy Bé 11, 12.v.2010 ( MNHN) . SOUTH AFRICA: Zululand: Off Matigulu River mouth (29°22.3'S 31°57.7'E), - 400 m, dead, mud, NMDP stn ZR12, dredged RV Meiring Naudé, 16.vi.1989 ( NMSA E8820 ) . Transkei: Off Mbashe River (32°22.8'S 29°00.8'E), - 450–500 m, dead, coarse sand, some mud, dredged NMDP, RV Meiring Naudé, stn Q14, 06.vii.1985 ( NMSA C9023 ) .

Distribution and habitat: Propeamussium jeffreysii is recorded throughout the Indo-West Pacific from southern Japan, Taiwan, East China Sea, South China Sea, and the Philippines ( Bernard, Cai & Morton 1993: 53; Hayami 2000: 913; Xu & Zhang 2008: 77; Dijkstra 2013: 13), eastwards to Wallis and Futuna, Vanuatu ( Dijkstra 2001: 78; Dijkstra & Maestrati 2012: 391) and Fiji ( Dijkstra & Maestrati 2008: 83), and westwards to the Maldive Islands, Gulf of Aden and southeastern Africa ( Knudsen 1967: 276). Now also recorded from the Mozambique Channel, northwestern and southern Madagascar, and South Africa (new record). Propeamussium jeffreysii is living on soft-bottom assembles of mud or muddy sand at a bathymetric range of - 80–797 m ( Dijkstra 2013: 13). Present material live at - 70– 900 m.

Remarks: Almost all morphological characters of the present material are identical to the type specimens from the Philippines. The colour of the type specimens is orange-brownish and of the present material somewhat paler. However, this coloration is also observed in material from the southwestern Pacific (MNHN). The commarginal sculpture on the left valve is somewhat more prominent on the type specimens than of the present material. However, the radial and latticed sculpture of the left valve is variable in prominence or even lacking in a few eroded specimens. The internal ribs are generally 10–11 in number (6–7 main ribs and additional short ribs laterally). The interstitial rudimentary riblets vary strongly (1–4) or are sometimes lacking. Soft parts, reproduction and diet are described by Knudsen (1967: 277).

In the original description of Amussium jeffreysii the right valve is the upper valve and the left valve the lower, in contrast to present descriptions.