Asterinides Verrill

Figures 2d, 8f–i

Asterinides Verrill, 1913: 479.— Verrill, 1914: 263.— Verrill, 1915: 58.— Tommasi, 1970: 14–15.—A.M. Clark, 1983: 364.— Rowe, 1995: 33.— Campbell and Rowe, 1997: 131.— Clark and Mah, 2001: 335.— O’Loughlin, 2002: 291, 293.

Paxillasterina A.M. Clark, 1983: 373.— Clark and Downey, 1992: 193.—A.M. Clark, 1993: 227. New synonym.

Diagnosis. Rays 5 or 6; form subpentagonal or subhexagonal or discrete rays; abactinal plates in longitudinal series; extensive papulate areas, predominantly single papulae; abactinal plates singly notched; abactinal spinelets glassy, acicular to subsacciform, in tufts or subpaxilliform or on paxilliform columns; lacking pedicellariae; superomarginal plates with tuft of spinelets; inferomarginal plates with distal dense subpaxilliform tuft of larger spinelets; actinal spines subsacciform, thin; lacking superambulacral and superactinal plates, distal interradial margin supported by inward projecting tongues from abactinal and sometimes actinal plates.

Type species. Asteriscus folium Lütken, 1860 (original designation).

Other species. A. hartmeyeri (Döderlein, 1910); A. pilosa (Perrier, 1881) (junior synonym: A. lymani Perrier, 1881, by Clark and Downey, 1992); A. pompom (A.M. Clark, 1983).

Material examined. A. folium. Holotype. Atlantic Ocean, Virgin Is (ZMUC). Other material. Atlantic Ocean, Caribbean Sea, USNM E28573 (1); Gulf of Mexico, USNM 38811 (3); Bermuda, USNM 38236 (4).

A. hartmeyeri. Atlantic Ocean, Caribbean Sea, USNM E49050 (2).

A. pilosa. Atlantic Ocean, Caribbean Sea, USNM E17973 (2); Gulf of Mexico, USNM E13707 (1); Venezuela, USNM E28411 (1).

A. pompom. Atlantic Ocean, Caribbean Sea, USNM E47755 (4); E47866 (1).

Description with species variations. Rays predominantly 5 (folium, hartmeyeri, pompom) or 6 (pilosa), interradial margin straight to slightly to deeply (pilosa) incurved, subpentagonal or discrete rays (pilosa); body thick, sides of rays steep (folium, hartmeyeri, pilosa), or thin (pompom); size small (folium up to R = 20 mm) to very small (hartmeyeri up to R = 7 mm); lacking pedicellariae; gonopores abactinal; one fissiparous (pilosa, R up to 10 mm).

Abactinal surface uneven due to raised proximal edge of thick imbricating plates (folium) or paxilliform columns (pompom); abactinal plates in longitudinal series; denuded appearance dominated by singly notched plates, heart-shaped to crescentiform; papulate areas extensive; papulae predominantly single, large, up to 4 longitudinal series along each side of rays; doubly notched and papulate carinal series variably present for most of ray, or upper ray plates irregular (pilosa); papular spaces fairly large, sometimes up to 3 papulae and 3 secondary plates per space; disc bordered by series of 5 radial 5 interradial plates (folium), or not (hartmeyeri, pilosa); denuded plates with glassy convexities (folium, hartmeyeri) or irregular texturing (pompom); plates with apical ridge or dome; spination variable, up to 3 subpaxilliform tufts across each plate proximally, each tuft with up to 20 spinelets, single subpaxilliform tufts distally (folium), or tufts of spinelets (hartmeyeri, pilosa), or soft paxillar columns and rounded domes, each with up to 50 spinelets (pompom); spinelets glassy, acicular to subsacciform; superomarginal plates with central tuft or pompom of spinelets; inferomarginal series projects to form margin, plates bare proximally, prominent marginal tuft of larger spinelets, sometimes on elevations (folium, pompom).

Actinal interradial plates in longitudinal series (folium, pompom), sometimes oblique (folium), or oblique (hartmeyeri).

Actinal spines per plate: oral 4–7; suboral 1–10; furrow 3–5, webbed; subambulacral 2–4 or clusters (pilosa); adradial actinal plates with complete series of spines; actinal 1–4 or clusters (pilosa), webbed if more than 1; actinal interradial spines subsacciform, thin.

Lacking superambulacral and superactinal plates; distal interradial margin supported by internal contiguous tongue-like projections from abactinal and actinal plates (folium, pompom) or from abactinal plates only (hartmeyeri).

Distribution. W Atlantic, Florida, Bahamas, West Indies, Caribbean, Brazil; 0– 256 m.

Remarks. Molecular data are not available for any species of Asterinides, and this review is based on morphology. Rowe (1995) and Rowe and Campbell (1997) considered Asterinides to be a valid genus. Verrill (1913) referred Asteriscus folium Lütken, Asteriscus cepheus Müller and Troschel, 1842 and Asterina (Asteriscus) modesta Verrill, 1870 to his new genus Asterinides. O’Loughlin (2002) removed A. modesta to his new genus Meridiastra. A. cepheus is removed here from Asterinides to Aquilonastra. The genera Aquilonastra and Asterinides share many morphological similarities, such as the multiple spinelet tufts per plate in A. batheri (A. folium also) and paxillar columns in A. coronata (A. pompom also). But the generic morphological difference evident in this study is the presence of superambulacral and superactinal internal skeletal plates in Aquilonastra and absence in Asterinides.

A.M. Clark (1983) considered the paxillar columns on many abactinal plates of P. pompom to be of generic significance, but Clark and Downey (1992) noted some similarity between A. folium and P. pompom. Both papers considered the paxillar columns to be otherwise unknown among Asterinidae but Aquilonastra coronata has similar columns. Their presence in two otherwise well-defined genera, Asterinides and Aquilonastra argues against use of paxillar columns as a generic character. Paxillasterina is placed in synonymy with Asterinides.

The description of A. folium by O’Loughlin (2002) was of specimens up to R = 15 mm, and is superceded by the descriptive details here based on a specimen with R = 19 mm (USNM E28573). The earlier description referred to ad-disc interradial papular spaces, each with two lateral papulae separated by one or two secondary plates. In the larger specimen these spaces have up to three papulae and three secondary plates. Multiple spinelet tufts are evident on the abactinal plates of the larger specimen, but were not evident on smaller specimens. Clark and Downey (1992) discussed differences between A. folium and A. hartmeyeri recognising separate but similar species. Asterina hartmeyeri also belongs to Asterinides. Asterinopsis pilosa (Perrier, 1881) is assigned here to Asterinides since it shares the generic diagnostic morphological characters.