Crossaster penicillatus Sladen, 1889

Mah, Christopher L., 2023, New Genera, Species, and observations on the biology of Antarctic Valvatida (Asteroidea), Zootaxa 5310 (1), pp. 1-88 : 45-47

Crossaster penicillatus Sladen, 1889

FIGURE 14 A–E

Crossaster penicillatus Sladen, 1889: 446 , pl. 70, 72; Koehler 1907: 141, 1908; H.L. Clark 1923: 295, 1926: 21; Fisher 1940: 180; Mortensen 1933: 273; A.M. Clark 1952: 197; A.M. Clark & Courtman-Stock 1976: 86; Atkinson & Sink 2018: 435.

Solaster penicillatus Bell, 1905: 249 .

Crossaster multispinus H.L. Clark, 1916: 66 , pl. 18; H.L. Clark 1946: 150; Rowe & Gates 1995: 113; O’Hara 1998: 182, pl. 1f.

Crossaster japonicus Fell, 1958: 17 , pl. 2; 1960: 64; McKnight 1993: 193 (non Fisher 1911).

Diagnosis

Arms 9–12, gradually tapering. Body stellate, R/r=2.0–3.3. Interradial arcs acute ( Fig. 14A ). Abactinal plates forming open reticulate mesh on disk and arms with skin present between lobate plates. Individual small plates present in skin filled regions ( Fig. 14A, B ). Abactinal paxillae with pointed spinelets, 4–15, each bearing hyaline tips. Central spinelets most elongate flanked by shorter similar spines. Marginal plates, approximately 15–18 per side (30–36 per interradius) at R>3.0, with smaller individuals (R=1.0–1.5) with 10–12 per side (20–24 per interradius). Marginal series apparently composed of inferomarginal plates, each series composed of a single, large paxillae each bearing spinelets, 10–30, mostly 10–20 (30 in relatively large individuals, R=5.2) widely spaced ( Fig. 14D ). Actinal intermediate region minimal, reticulate plates with skin forming open mesh. Actinal plates with 2–4 spinelets ( Fig. 14F ). Furrow spines 1–5, mostly 4 or 5 decreasing distally, basally webbed. Subambulacral spines 5–8, mostly 7 or 8 proximally decreasing in number to distal arm region, arranged in transverse series ( Fig. 14E, F ), each sitting on a curved convexity or crest of the adambulacral plate. Oral plate with 9–10 furrow spines with 3 spines projecting into the mouth, most elongate. Oral plates with distinct ridge, each oral plate surface bearing 2 to 4 elongate spines.

Color in life, dark pink to orange, sometimes with white highlights.

Comments

Specimens recorded here are the first records of this species from New Zealand waters. As indicated in the diagnosis, these individuals had widely spaced slender paxillae with 4–15 spines, 3–5 furrow spines, and 6–8 elongate subambulacral spines in a transverse array. These specimens were consistent with Sladen’s (1889) description of this species, varying in having greater arm number (n=10–12 versus 9 in the description).

Gut contents of specimens examined included fish vertebrae, sponge spicules and indeterminate organic debris, but possibly squid tissue.

Synonymy of Crossaster multispinus

Based on USNM specimens and comparisons of type specimen descriptions, Crossaster multispinus H.L. Clark, 1916 appears to be a synonym of Crossaster penicillatus Sladen, 1889 , together forming a widely distributed species occurring from Tasmania and New South Wales to the southern Indian Ocean.

O’Hara (1998) reported Crossaster multispinus from Macquarie Island with 15 long, sharp abactinal paxillar spinelets, 5 to 6 furrow spines and 7 subambulacral spines, at R=2.3, which is consistent with H.L. Clark’s (1916) original account for this species (with type R=4.0 cm) which indicated 8–15 long slender spines on each paxillae, 5– 8 furrow spines (7–8 proximally, 5–6 distally) and 7 to 9 subambulacral spines. O’Hara’s (1998) specimen differed in having 30 spines on the inferomarginal paxillae versus 12 to 15 on Sladen’s type. USNM 1122950 from New Zealand (R=5.2) displays inferomarginal paxillae with variably 10–30 spines suggesting there is some variation for this character. Sladen’s (1889: 446) description of Crossaster penicillatus indicates abactinal paxillae with “ten or more” spinelets, 4 to 5 furrow spines and 7 to 8 subambulacral spines for an individual with R= 3.4 to 3.6 cm. USNM 1122950 from New Zealand (R=5.2) identified as Crossaster penicillatus displays 3 to 5 furrow spines and 7 to 8 subambulacral spines. Sladen (1889) did not count the total number of marginal paxillae in description but a count of this character from his plate (LXX: fig. 5) suggests approximately 15–18 per arm side, compared to 16 on H.L. Clark’s description of Crossaster multispinus . The furrow spine count and the number of spines on the surface of each oral plate of C. multispinus is 14 and 8–10 respectively versus 9 and 7–8, respectively in Crossaster penicillatus . H.L. Clark’s type of C. multispinus was larger (R=4.0) than that of C. multispinu s (R=3.4–3.6), it is argued that these minor differences are explained as being size-related.

H.L. Clark’s (1916) original description of C. multispinus compared this species with the Northern Hemisphere Crossaster papposus . McKnight (2006) briefly compared C. multispinu s with C. penicillatus but misidentified C. multispinus , as outlined herein.

Figures

FIGURE 14. Crossaster penicillatus USNM 1122950. A. Abactinal surface. B. Closeup showing abactinal paxillae. C. Actinal surface. D. Abactinal-lateral view showing marginal paxillae. E. Actinal intermediate and adambulacral spination. F. Closeup of adambulacral spination showing furrow and subambulacral spines.