Astrotoma manilense Döderlein, 1927

O’Hara, Timothy D., 2014, A new species of Sigsbeia and additional records of ophiuroids from the Great Australian Bight, Memoirs of Museum Victoria 72, pp. 131-140 : 135-136

Astrotoma manilense Döderlein, 1927

Astrotoma manilense Döderlein, 1927: 19-21 , pl. 1(1-1b). Astrotoma drachi .-- McKnight, 2000: 68, fig. 33, pl. 32.-- Okanishi

& Fujita, 2013: 569 [Non Astrotoma drachi Guille A, 1979 ].

Material examined. Great Australian Bight. 110 nm due W of Whidbey Point , 34° 65'S, 132° 51'E, 880-940 m, 1989: 2 ( SAM K2734 ) . -- 165 nm SW of Eucla , 33° 23'S, 126° 26.3'E, 391-398 m, 1988: 1 ( SAM K3105 ) . -- 75 nm ESE of Cape Arid , 34° 15'S, 124° 42'E, 920- 1120 m, 1989: 1 ( SAM K2732 ) . -- 105 nm SSE of Eucla , 33° 35'S, 129° 4'E, 860-931 m, 1989: 4 ( SAM K2731 ) . -- Adelaide Pearl : stn 15, 125 nm E of Cape Arid , 34° 3'S, 125° 31'E, 1011-1020 m, 1988: 1 ( SAM K2763 ) . -- Adelaide Pearl : stn 28, 125 nm S of Eucla , 33° 45'S, 129° 17'E, 999-1110 m, 1988: 3 ( SAM K2762 ) ; 1 ( SAM K2726 ) .-- 80 nm SW of Pearson Is , 35° 4'S, 133° 35'E, 900-960 m, 1989: 1 ( SAM K3106 ) . -- Margaret Phillipa 6: stn 4, South of Ceduna, 33° 48'S, 130° 33'E to 33° 42'S, 130° 31'E, 1040 m, 1984: 3 ( TMAG H1985 ) .

New South Wales. NZOI: stn U223, east of Newcastle , New South Wales, Australia, 32° 58.8'S, 152° 41.598'E, 1150 m, 1982: 1 ( NIWA 49781 ). -- K88-22: stn 01, east of Ulladulla , 35° 27'S, 150° 54'E, 1060-1123 m, 1988: 1 ( AM J22108 ) .

New Zealand. TAN0604: stn 133, Shipley Seamount , 41° 48.072'S, 179° 29.61'W to 41° 48.03'S, 179° 30.198'W, 1240-1275 m, 2006: 1 ( NIWA 42265 ) . -- TAN0705: stn 211, 9D19, 42° 39.28'S, 177° 12.792'W to 42° 38.88'S, 177° 12.462'W, 1377-1402 m, 2007, identified by Okanishi & Fujita (2013) as Astrotoma drachi : 1 ( NIWA 30980 ) . -- NZOI: stn I666, 47° 47.502'S, 178° 59.502'W, 1165 m, 1979, identified by McKnight (2000) as Astrotoma drachi : 1 ( NIWA 48404 ) ; 1 ( NIWA 48405 ) . -- TRIP1650: stn 23, 46° 45'S, 170° 3'E, 1036-1312 m, 2002: 1 ( NIWA 49785 ) . -- TRIP2124: stn 21, 49° 17'S, 176° 18'E, 1192-1300 m, 2006: 1 ( NIWA 75841 ) .

Distribution. Philippines (721 m), Japan (660-710 m), Great Australian Bight (391-1120 m), Eastern Australia (1060-1150 m), SE New Zealand (1036-1402 m).

Remarks. There is a large Astrotoma species present on the continental slope of southern Australia and New Zealand in 400- 1400 m. Specimens collected to date form three populations, in the Great Australian Bight, off New South Wales and off southeast New Zealand, including the Campbell Plateau and the Chatham Rise. The latter population was first reported by McKnight (2000) who referred one lot ( NZOI I666) to the species A. drachi Guille, 1979 without comment. This is one of three similar species of Astrotoma reported from a few specimens from the Philippines and Japan. The differences between these species are minor, slight modifications to the shape and density of the disc tubercles on the disc and the number of arm spines, and may be related to size, with the holotype of A. manilense measuring 31 mm d.d., A. drachi is 15 mm d.d., and A. deficiens Koehler, 1922 is 21 mm d.d..

Examination of a series of specimens from the Great Australian Bight indicates that there is some variation with growth. Smaller specimens (e.g. 2 specimens in SAM K2762; 10-12 mm d.d.) appear like A. drachi with 2 (rarely 3) arm spines, sparse disc tubercles, and granular suboral papillae. Larger specimens are like A. manilense (e.g., SAM K3106, K3105; 25 & 34 mm d.d.) with a variable (medium to dense) coating of stout hemispherical to cylindrical disc tubercles on the radial shields and interradial margin, 3 (rarely 4) arm spines and spiniform suboral papillae. Astrotoma deficiens may differ in predominantly having conical pointed disc tubercles.

Without examining a range of specimens from the Philippines, we are hesitant to formally synonymise any of these species. However, there is no evidence of multiple species in the Australian and New Zealand region and we refer all specimens to the species A. manilense , as this name has date priority and represents the adult form. We note that no specimens of Astrotoma have been found in the tropical southern hemisphere, including the densely sampled New Caledonian region. Thus, as defined here, A. manilense has a disjunct distribution, with at least four isolated populations. Molecular data is required to further investigate species boundaries in this genus. The species is adequately figured my McKnight (2000).

The only other species of Astrotoma is the type A. agassizii Lyman, 1875 from circum-Antarctica and southern South America. It differs from the other species in having a covering of fine granules on the disc. Astrotoma agassizii has been found to both brood young and have a pelagic larva ( Heimeier et al. 2010) and Hunter & Halanych (2008) also found several separate genetic lineages that may indicate cryptic speciation.