Amphilimna Verrill, 1899

Martynov, Alexander, 2010, Reassessment of the classification of the Ophiuroidea (Echinodermata), based on morphological characters. I. General character evaluation and delineation of the families Ophiomyxidae and Ophiacanthidae 2697, Zootaxa 2697, pp. 1-154 : 47-50

Genus Amphilimna Verrill, 1899

Figures 37–39

Amphilimna Verrill, 1899: 30

Type species: Ophiocnida olivacea Lyman, 1869 , by original designation

Diagnosis. The disk is covered with numerous small, uniform scales. A skin layer is not evident. The dorsal disk surface is covered with numerous long spinelets or granules. The radial shield and adradial genital plate are well defined. The articulation surfaces of both adradial genital plate and radial shield bear a distinct compact ball-like condyle. The abradial genital plate has a peculiar twisted shape. The oral frame bears few spiniform or square papillae, of which the distal (adoral shield papillae) are longer. The apical papillae are paired or tripled and conical. The jaws are moderately short and high. The adradial sides of the jaws distally bear a few sharp straight folds. The dental plate is entire (as in the type species) or transversally fragmented (in A. multispina ) and bears alternately placed non-perforated sockets. The teeth are rectangular and massive. Dorsal and ventral arm plates are well developed. Tentacle scales are placed on the lateral and ventral arm plates, the former spiniform and distinctly elongate. Arm spine articulations consist of two subparallel ridges each, often tapering and bottle-like distally. The spines are moderately long, not flattened, and solid. Most proximal spines under the disk are characteristically modified into wide scale-like structures. Distal hooks are absent. The vertebrae are distinctly keeled with zygospondylous articulation.

Remarks. Verrill (1899), when establishing the genus Amphilimna , placed it in the family Amphiuridae . This decision was then supported by Koehler (e.g. 1922a). Thomas (1967; 1975) considered Amphilimna within Ophiacanthidae , and Paterson (1985) further placed it in the subfamily Ophiotominae . A detailed discussion on the taxonomic problems of the placement of Amphilimna will be presented in a general discussion section below.

Material studied. Amphilimna olivacea ( Lyman, 1869) , ZMMU D-52, 2 specimens ( Figs 37B–F; H, I– L) ; Amphilimna multispina Koehler, 1922 , 6 paratypes, USNM E00026; ZMMU D-841, D-842, 3 specimens ( Figs 37M; 39) ; Amphilimna valida (H.L. Clark, 1939) , USNM E42872 , 1 specimen .

Number of species in the genus: 10.