Amphipholis squamata (Delle Chiaje, 1828)

Gondim, Anne I., Alonso, Carmen, Dias, Thelma L. P., Manso, Cynthia L. C. & Christoffersen, Martin L., 2013, A taxonomic guide to the brittle-stars (Echinodermata, Ophiuroidea) from the State of Paraiba continental shelf, Northeastern Brazil, ZooKeys 307, pp. 45-96 : 55-56

Amphipholis squamata (Delle Chiaje, 1828) Figure 5 g–l

Description.

Disk circular (dd = 1.08 to 2.47 mm). Covered by large, irregular, and only slightly imbricating scales (Fig. 5g). Sometimes with the central primary plate evident. Radial scales slightly longer than broad, contiguous, separated proximally by a small scale, with outer margin rounded and inner margin straight. Ventral interradius covered by strongly imbricating scales, which are smaller than dorsal scales (Fig. 5h). Distinct line of demarcation between the scales of the dorsal and ventral surface. Bursal slits long and broad (Fig. 5h). Oral shields fan-shape, distal margin enlarged and convex, slightly longer than wide (Fig. 5i). Adoral shields large, united proximally. Two oral papillae on each side of jaw angle, distal long and opercular (Fig. 5i). A pair of infradental papillae. Dorsal arm plate broader than long, proximal margin rounded and distal margin straight (Fig. 5j). Ventral arm plate pentagonal, twice as long as wide. Three arm spines conical, erect, serrate at tip (Fig. 5l). Two tentacle scales small, narrow and elongated.

Distribution.

Traditionally considered cosmopolitan, except for the extreme polar regions (but see remarks). Western Atlantic from Canada, United States, Mexico, the Antilles, Belize, Costa Rica, Panama, Colombia, Brazil, Uruguay, and Santa Cruz Province, Argentina ( Bernasconi 1965, Hendler et al. 1995, Hernández-Herrejón et al. 2008, Martínez 2008, Benavides-Serrato et al. 2011). In Brazil, from Pará, Maranhão, Ceará, Paraíba, Alagoas, Bahia ( Gondim et al. in press), Rio de Janeiro ( H.L. Clark 1915) and, São Paulo ( Borges et al. 2002). Intertidal to 1962 m. Found between 21 and 26m in present study.

Remarks.

Viviparous polychromatic species, presenting simultaneous hermaphroditism ( Nisolle 1990), bioluminescence and fluorescence ( Hendler 1996). Commonly found associated with algae and other biological substrates (sponges, cnidarians, bryozoans and molluscs). It may also be found on bottoms of sand, rock, seagrass beds, mangroves, estuaries, and in hypersaline waters. This species has been assigned at least 25 different names ( Poulin et al. 1998), now synonymyzed as Amphipholis squamata . A.M. Clark (1987) has proposed conservation of this name and the suppression of the older name Ophiura elegans (Leach, 1815). Amphipholis squamata is regarded as the only species of echinoderm distributed world-wide. This vast distribution area contrasts with a low dispersal potential due to the lack of a pelagic larval stage and an aggregative spatial distribution ( Féral et al. 2001). According to Fell (1946), the species extends its distribution by coastal migrations. However, Tortonese (1965) questioned the authenticity of a pandemic species. This species is known to have a strong inter- and intra-population variability among adult individuals for both phenotype and genotype, although the species seems to be anatomically uniform. Dupont et al. (2000) found that polychromatism and bioluminescence might be good indicators of variability of genotypes only at the intra-population level. Féral et al. (2001) confirmed that each color variety possesses its own luminous capabilities and that color varieties are genetically differentiated, although no clear genetic differences were demonstrated between colour varieties. The study of Sponer and Roy (2002) finally confirmed the existence of cryptic species and cryptic dispersal potential in New Zealand. The analysed specimen presented a small variation in the shape of the oral shield (see description) when compared with the specimens described by Thomas (1962), which presented diamond-shaped and wider than long oral shields. Thomas (1962) observed that the vertral surface of the disk was spinulose in two specimens from Puerto Rico (apparently belonging to this species). No specimen from the coast of Paraíba presents this character. According to Hendler (1996), the structure of the arm spines is the most reliable differential character in adult specimens.