Fromia hemiopla Fisher 1913

FIGURE 6A–E

Fromia hemiopla Fisher 1913: 214; 1919: 377; A.H. Clark 1952: 286; Marsh & Fromont 2020: 232.

Diagnosis

Body stellate (R/r=2.6–2.8), arms relatively short, disk stout, small, triangular in outline, interradial arcs acute (Fig. 6A). Abactinal plates weakly convex covered by continuous granular cover (Fig. 6C). Superomarginal plates in gradually, regular series with no marginal alternation of sizes (Fig. 6D). Distalmost superomarginals with tubercular granules centrally located on each plate (Fig. 6B, D). Furrow spines, 3 to 4 flat, spatulate, subambulacral spines 2, short and thick, granules similar to actinal granules (Fig. 6E).

Comments

This species closely resembles Fromia milleporella, from which it differs in presence of distinct tubercles or spines on the distalmost marginal plates (Fig. 6B, D), presence of broad-based arms and more numerous abactinal pates across the arm base.

Accessory granules, especially around the armtips have been argued as being being phenotyptically variable (Mortensen, 1925). Phenotypic variation with response to the environment (e.g., wave motion) occurs in the asteriid sea star, Pisaster ochraceus (Hayne & Palmer 2013) . It is possible this is a variable character in Fromia hemiopla, and possibly synonymous with Fromia milleporella .

Occurrence

Okinawa, Ryukyu Islands, Japan. 3.0– 52 m.

Fiji, Marshall Islands, Samoa. 3.0–55.0 m

Material Examined

USNM E9721 Okinawa, Ryukyu Islands, Japan. Coll. L.J. Withington, 1960. 4 dry specimens. R=2.0 r=0.6 R=1.9 r=0.6 R=1.7 r=0.5 R=2.1 r=0.5.

USNM E45989 1 km WNW of Onna Village ( Horseshoe Cliffs), Okinawa, Ryukyu Islands, Japan. 26.5 127.848, 52.0 m. Coll. R.F. Bolland 24 May 1984. 1 dry spec. R=1.7 r=0.6.

USNM E45994 1.3 km ENE of Maeki-Zaki, Seragaki Beach, Okinawa, Ryukyu Islands, Japan. Walls and floor of surge channel near reef edge, 26.5067, 127.877, 3.0 m. Coll. R.F. Bolland, 25 Oct 1984. 1 dry spec. R=1.3 r=0.5.

USNM E 46008 Reef edge, 1 km WNW of Onna Village, Okinawa, Ryukyu Islands, Japan, 26.5, 127.848, 3–12 m. Coll. R.F. Bolland, 9 Aug 1981. 1 dry spec. R=2.5 r=0.7