Pteraster willsi, Clark, Roger N. & Jewett, Stephen C., 2011

Clark, Roger N. & Jewett, Stephen C., 2011, Three new sea stars (Asteroidea: Solasteridae & Pterasteridae) from the Aleutian Islands, Zootaxa 3051, pp. 1-13 : 9-11

Pteraster willsi sp. nov.

Figures 7, 14–20

Type locality. Alaska, Aleutian Islands, Rat Islands, West of Kiska Island (52° 02.066 N, 176° 27.04 E), 162 m.

Type material. Table 3 .

Description. Small, stellate form, Holotype ( Fig. 14 ); disc broad, rays relatively long, tapering, disc plump, inflated R = 30 mm, r = 22 mm R:r = 1.36, (range 1:1.3–1:1.9). Supradorsal membrane (Fig. 15), relatively thin, firm, papillose. Abactinal plates 4–5 lobed; paxillar columns (Fig. 16), short (height less than half the length of paxillar spines), relatively thick, crowned with 5–7 long, slender spines, the tips of which protrude through the supradorsal membrane, and are covered by a fleshy papilla. Madreporite small, spherical, located beneath the supradorsal membrane, near the osculum. Osculum conspicuous, closed by five palmate valves, each formed by 4 large robust spines, along the facing edge of a large stout paxillae bearing about 16 spines. Spiraculae small, very numerous.

Adambulacral plates (Fig. 17), with L-shaped series of 5–7 webbed spines, distal 3–4 sub-equal, arranged transversely to groove, proximal 1–3 much smaller, set along groove, and a long actinolateral spine, flattened and sometimes bifurcated at the distal end; immersed in actinal membrane. Actinolateral fringe relatively wide, tapering. Each half of jaw plate (Fig. 18), bears 6–7 slender, webbed, grading spines, not continuously webbed to the adjacent plate, and a single large, triangular suboral spine. Tube feet in two rows.

Color of living specimens: from deep water uniformly white, sometimes with orange-tipped ocular spine tips, shallow water specimens ( Fig. 19), uniformly bright orange.

Distribution. Known from the central and western Aleutians (Fig. 7), Kanaga Island (178°26’ W) to near Attu Island (172°57 E).

Habitat. Rocky and pebbly bottoms, rich in sponges and hydrocorals, 11–166 m with a bottom temperature of 3.7° to 6°C.

Etymology. It is with great pleasure that we name this species in honor of Dr. Irvin A. Wills (deceased) of John Brown University, Siloam Springs, Arkansas. For nearly four decades Dr. Wills served JBU as Professor and Head of the Department of Biology where he mentored thousands of biology students, including Stephen C. Jewett.

Reproduction. Like many Pteraster spp., P. w i l l s i sp. nov. broods its young in the nidamental chamber until they are developed enough to break through the supradorsal membrane, crawl away and fend for themselves (R = 4–5 mm) ( Fig. 20) (LACM 2007-118.002). This has been observed in many specimens, including several Paratypes (LACM 2007-118-002, LACM 1997-222.001, CASIZ 184727).

Remark. Pteraster willsi sp. nov. is similar to P. militaris , but differs in 1) smaller size and firmer, more rigid supradorsal membrane which lacks the convolutions, 2) large, trigonal suboral spines, and 3) fewer adambulacral spines, 3–4 compared to 6–9 in P. militaris . The two species are frequently found together in the same habitat.

A Paratype specimen from station AKALE07-0017 (LACM 2007-118.002) was apparently feeding on the (scavenged?) chela of the small lithode crab Dermaturus mandtii Brandt.

Figures

FIGURE 14. Pteraster willsi sp. nov. Holotype (LACM 2002 - 101.001). Whole animal, aboral view; bar = 1.0 cm. FIGURES 15 – 18. Pteraster willsi sp. nov. Paratypes (LACM 1997 - 222.001). Figure 15, Close-up, aboral surface; bar = 2.0 mm. Figure 16, Close-up, nidamental chamber, pseudopaxillae / spines and supradorsal membrane; Bar = 1.5 mm. Figure 17, Close-up, adambulacral area (ad = adambulacral spines; al = actinolateral spine); Bar = 1.0 mm. Figure 18, Close-up, oral region; bar = 3.0 mm.

Tables

TABLE 3. Type material: Pteraster willsi sp. nov.

Type	Deposition & No. of Collection Site Specimens	Collection Depth, m	Collection Date	Collector & Method
Holotype	LACM 2002- W of Kiska Island 101.001, dry 52°02.06 N, 176°27.97 E; NMFS 94-200201-77	162 m	16 June, 2002	R. N. Clark, trawled, R/V Vesteraalen
Paratype	LACM 2002- W of Kiska Island 101.002, 52°02.06 N, 176°27.97 E; 1 specimen, dry NMFS 94-200201-77	162 m	16 June, 2002	R. N. Clark, trawled, R/V Vesteraalen
Paratype	USNM 1153701, N of Kiska Island 1 specimen, dry 52°04.29 N, 177°15.33 E; NMFS 23-199701-199	130 m	31 July, 1997	R. N. Clark, trawled, R/V Dominator
Paratype	USNM 1153702, N of Agattu Island 1 specimen, dry 52°20.58 N, 173°31.64 E; NMFS 23-199701-231	86 m	6 August, 1997	R. N. Clark, trawled, R/V Dominator
Paratypes	CASIZ 184726, E of Kiska Island 2 specimens, dry 52°01.81 N, 177°43.57 E; NMFS 23-199701-196	110 m	31 July, 1997	R. N. Clark, trawled, R/V Dominator
Paratypes	CASIZ 184727, S of Attu Island 2 specimens, dry 52°29.30 N, 172°57.50 E; NMFS 23-199701-210	166 m	2 August, 1997	R. N. Clark, trawled, R/V Dominator
Paratypes	LACM 1997- SW of Buldir Island 222.001, 52°14.94 N, 175°14.90 E; 6 specimens, dry NMFS 23-199701-239	141 m	8 August, 1997	R. N. Clark, trawled, R/V Dominator
Paratypes	LACM 2007- Vega Bay, Kiska Island 118.002, 51°54.86 N, 177°26.86 E; 3 specimens, dry AKALE07-0017	14 m	29 June, 2007	R. N. Clark, scuba
Paratype	LACM 1997- S of Tanaga Island 179.003, 51°37.36 N, 178°26.46 W; 1 specimen NMFS 23-199701-135	163 m	14 July, 1997	R. N. Clark, trawled, R/V Dominator
Paratype	LACM 2007- Rat Island 120.001, 51°49.59 N, 178°16.67 E; 1 specimen, dry AKALE07-A0031	14 m	1 July, 2007	H. Chenelot, scuba
Paratype	UAF 8139, Little Sitkin Island 1 specimen, dry 51°58.20 N, 178°27.18 E; AKALE07-0045	11 m	1 July, 2007	R. N. Clark, scuba