Fromia hemiopla Fisher 1913

Mah, Christopher L., Kogure, Yoichi, Fujita, Toshihiko & Higashiji, Takuo, 2024, New Taxa and Occurrences of Mesophotic and Deep-sea Goniasteridae (Valvatida, Asteroidea) from Okinawa and adjacent regions, Zootaxa 5403 (1), pp. 1-41 : 15-17

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

Figures

FIGURE 6. Fromia hemiopla USNM E9721 A. Abactinal surface. B. Abactinal, superomarginal plates showing tubercles and spines. C. Abactinal surface detail. D. Lateral view. E. Actinal surface. Scale bar: A, E=3.0 mm; B–C, D=1.0 mm.