Ophiomusium acuferum Lyman, 1875

Baker, Alan N., 2016, An illustrated catalogue of type specimens of the bathyal brittlestar genera Ophiomusium Lyman and Ophiosphalma H. L. Clark (Echinodermata: Ophiuroidea), Zootaxa 4097 (1), pp. 1-40 : 4

Ophiomusium acuferum Lyman, 1875 . Figures 1 a, b, c,

Ophiomusium acuferum Lyman, 1875 ; Borges & Campos, 2011. Ophiomusium sculptum Verrill, 1899

Holotype MCZ 427, off Barbados, 177– 219m.

Other material examined: 3 specimens BMNH 92-2-22-16 -18, Barbados, 133 m; 4 specimens USNM 21289, Mayaguez Harbour, Puerto Rico, 97–120 fms (as O. sculptum ); 9 specimens, USNM E513, E514, E4375, E4539, E4540, E4538, University of Iowa Barbados-Antigua Expedition Stations 4, 7, 15, 28, 44 49. The Yale Peabody Museum in Boston was searched for the types of O. sculptum , but none were located. Dr Marc Eleaume, Paris Museum has recently informed me that a syntype of this species in in their collection: MNHN 10284, ex- Albatross expedition.

Main Features: In the holotype, the periphery of marginal disc plates is raised and knobbly. All other disc plates have one or more tubercles, those adjacent to the marginal plates with a group of 3–4 tubercles concentrated at their distal corners. Those inside this ring (primaries) have one or two central tubercles. First dorsal arm plate raised and knobbly and separates the radial shields. Dorsal sides of the lateral arm plates are also knobbly. Small dorsal arm plates lie in a median longitudinal depression. Interradial marginal plates large, V-shaped, protuberant, and knobbly. Otherwise, the surface of all plates is smooth (micro-reticulate).

Ventral surface smooth, 2 pairs of exposed tentacle pores, 1 circular scale. Closely adjoining oral papillae. Sinuous genital slits run to the distal end of the first lateral arm plate. Oral shield, 2 genital plates, and a large interradial plate only in the ventral interradial area.

Ventral arm plates throughout, but very small distally. 3 small arm spines. On basal arm segments a longer spine is present on the dorsal side of each lateral arm plate, each side of the median groove. Lower down on the arm near the ventral margin, are two small spines the lowermost of which has a bifurcate tip and hollow core.

This species is conspecific with O. sculptum Verrill 1899 as identified in the USNM collections, including one specimen identified by Verrill himself, and others identified by H. L. Clark. These specimens compare well with Verrill’s original description and figures, except for the first ventral arms plates shown in his Figure 2 , Plate II, which are unlike any Ophiomusium in that they are extremely small (25% of arm width) and the exposed tentacle pores are located in the middle of the ventral faces of the lateral arm plates. Also, Verrill did not mention in his description of the type the presence of dorsal arm spines, which are present in the specimens he identified in the USNM. Verrill’s type specimen could not be located in the YPM.

Figures

FIGURE 2. Ophiomusium alecto USNM E 0005197: a, b, dorsal and ventral disc sectors. FIGURE 3. Ophiomusium altum RMNH V. Ech. O 2045: a, b dorsal and ventral disc sectors.