Amphiodia (Amphispina) loripes Koehler 1922, new combination
Creators: name: Stöhr, Sabine
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Ophiuroidea
Ophiurida
Amphiuridae
Amphiodia
Amphiodia loripes

description: Amphiodia (Amphispina) loripes (Koehler, 1922) new combination
Figure 13
Amphipholis loripes Koehler, 1922: 164, pl. 68, figs 4,5; A.M. Clark 1970: 29, 76, fig. 6a; Cherbonnier & Guille 1978:100– 101.
Material. Sta. NC00-38: 1 spm; sta. NC00-35: 5 spms; sta. NC00-44: 3 spms; sta. 1448: 1 spm (used for SEM).
Description. About 2 mm dd, disk round, high raised, ventral disk separated from proximal arms, but apparently without damage. Arms all broken, but longest more than 20 times dd. Dorsal disk covered by small, round, overlapping scales, which stand almost upright at the disk edge. Scale stereom a uniform meshwork of small holes and round bead-like structures. Radial shields bar-like, at least four times as long as wide, about 1/4 as long as dd, outer edges overlapped by disk scales; pairs separated proximally by a wedge of scales for up to half their length. At distal end of each radial shield, above genital plates, a spiny process points upwards. Proximalmost arm segments lack dorsal plates, covered instead by skin, which ruptured in the preparation process, but was undamaged originally. In vivo, the genital plates and ventral disk are attached to this part of the arms. Dorsal arm plates at their distal edge twice as wide as long, proximal and lateral edges forming a convex bow, distal edge straight; plates on consecutive joints touch barely. Four arm spines proximally, dorsalmost spine longest, longer than an arm joint; spines tapering gradually into a blunt tip, edges slightly rugose, longitudinal grooves running towards the tip from about mid-length. Distal arm spines slightly hook shaped with distal thorn, long open groove at one side, bordered by small thorns.
Ventral disk covered by scales similar to dorsal disk; bursal slits lined by bar-like genital plates, wich are exposed due to the raised disk. Oral shields elongated drop-shaped with acute proximal point and convex distal edge; one shield slightly larger, with hydropore to the side of its distal edge, marking it as the madreporite. Adoral shields wing-like flaring, reaching around the oral shield and separating it from the arm. Jaws narrow, bearing three oral papillae to either side; a small oval infradental to either side of the dental plate, a similar papilla at the oral plate and a low, wide papilla at the adoral shield, no buccal scale. Ventral arm plates pentagonal, slightly wider than long, with obtuse proximal angle, straight lateral edges, concave distal edge; consecutive plates not touching. Single elongated tentacle scale on ventral arm plate, as long as lateral edge of ventral plate.
Remarks. The Lifou specimens agree well with Koehler's (1922) original description and images and the description by Cherbonnier & Guille (1978). This species was described in the genus Amphipholis and still remained there until now, although Clark (1970) remarked on its affinities with Amphiodia and was undecided on its generic position. However, she had access only to the single type specimen that lacked the dorsal disk. The nature of the disk scalation and the presence of spiny processes were therefore unknown to her. Cherbonnier & Guille (1978) found complete specimens at Madagascar and for the first time described the dorsal disk including the spiny processes, but although they remarked on its great similarities with Amphiodia, they kept it in Amphipholis solely on the basis of the widened outer oral papilla. The extremely long arms, fine disk scalation, long, partially separated radial shields, the single elongated, ventrally placed tentacle scale, and the number and placement of the oral papillae all point to Amphiodia; the thorny processes distal to the radial shields are similar to those found in the subgenus Amphispina (Stöhr et al. 2010). The only character in common with Amphipholis is the widened third oral papilla, which is usually shorter in Amphiodia, but in A. loripes it is not as high and operculiform as in Amphipholis (see above) and the jaws appear longer and narrower as in that genus. Weighing the combined evidence it is highly likely that the distal papilla is a convergent rather than homologous structure. The subgenus Amphispina is characterized by spiny marginal scales, which are lacking in all known specimens of A. loripes. However, as Stöhr et al. (2010) have shown, this character is highly variable and the radial processes may be the only spiny scales present in some individuals of species of Amphispina. It is also likely that the marginal spines have been reduced completely in some species. Therefore, I propose to transfer A. loripes to Amphiodia (Amphispina).
description: Published as part of Stöhr, Sabine, 2011, New records and new species of Ophiuroidea (Echinodermata) from Lifou, Loyalty Islands, New Caledonia, pp. 1-50 in Zootaxa 3089 on page 30, DOI: 10.5281/zenodo.279037