Amphipholis squamata ( Delle Chiaje, 1828 )

Madeira, Patrícia, Kroh, Andreas, Cordeiro, Ricardo, De, António M., Martins, Frias & Ávila, Sérgio P., 2019, The Echinoderm Fauna of the Azores (NE Atlantic Ocean), Zootaxa 4639 (1), pp. 1-231 : 19-20

Amphipholis squamata ( Delle Chiaje, 1828)

( Fig. 5 )

Reports for the Azores:

Amphipholis squamata ( Delle Chiaje, 1828) — Ljungman 1872: 633–634; Barrois 1888: 32; $ Chapman 1955: 400; Tortonese 1965: 231–234, fig. 107; Marques 1980: 100; $ Marques 1983: 3, fig. 2; Pereira: 332; García-Diez et al. 2005: 48;

Amphipholis lineata $ Ljungman, 1872: 634 ; Barrois 1888: 32, 115;

Amphiura squamata L̹tken, 1859 — $ Barrois 1888: 73;

Amphiura squamata ( Delle Chiaje, 1828) — Barrois 1888: 115; $ Koehler 1898: 53;

Amphiura tenuispina Ljungman, 1865 — $ Koehler 1898: 53–55, pl. 6, figs. 22–23, 1909: 180.

Type locality: Mediterranean Sea.

See: Mortensen (1927a: 221–222, fig. 125; 1936: 292–293); Paterson (1985: 91, fig. 36).

Occurrence: present in all seas, cosmopolitan (absent in the polar areas; Tortonese 1965).

Depth: 0–1,962 m ( Hernández-Herrejon et al. 2008); AZO: 0–1,229 m ( Koehler 1909, herein).

Habitat: soft to hard substrates, common among algae and under rocks during low tide ( Mortensen 1927a); found also on the roots of floating Macrocystis ( Mortensen 1936) ; in the Azores they are also a common presence among algae ( Marques 1983).

Larval stage: brooding hermaphrodite species ( Mortensen 1927a); reproduces also through self-fertilisation ( Boissin et al. 2008a).

Material examined: DBUA-ECH 241 (Baixa do Porto, Lajes, FLS, AZO, c. 39°22’50”N, 31°10’00”W, 1990.10.29;1 spm, DD = 1 mm); DBUA-ECH 267(S„o Roque, SMG, AZO, c. 37°44’37”N, 25°38’19”W, 2012.11.16, intertidal; 5 spms, DD = 2 mm); DBUA-ECH 277 (FRM, AZO, c. 37°16’14”N, 24°46’52”W, 1990.06.08, 6–8 m; 1 spm, DD = 3 mm); DBUA-ECH 284 (Gorringe Bank, NE Atlantic, c. 36°40’N, 11°12’W, 2006; 1 spm, DD = 2 mm); DBUA-ECH 308 (Baixa do Porto, Lajes, FLS, AZO, c. 39°22’50”N, 31°10’00”W, 1990.10.27; 4 spms, DD = 1–2 mm); DBUA-ECH 312 (Lajes, PIX, AZO, c. 38°23’22”N, 28°15’04”W, 1994.08.07, 1 m; 4 spms, DD = 2–3 mm); DBUA-ECH 314 (off Ribeira das Tainhas, SMG, AZO, 37°42’04”N, 25°25’02”W, 2006.07. 24, 45–117 m; 1 spm, DD = 1 mm); DBUA-ECH 353 (Poços, SMG, AZO, c. 37°50’06”N, 25°40’10”W, 1996.07.08, intertidal; 5 spms, DD = 1–2 mm); DBUA-ECH 354 (Vila Franca do Campo, SMG, AZO, 37°41’39”N, 25°27’11”W, 2006.07. 21, 95–121 m; 1 spm, DD = 2 mm); DBUA-ECH 417 (Mosteiros, SMG, AZO, 37°53’52”N, 25°48’19”W, 2011.07.06, 10 m; 1 spm, DD = 1 mm).

Description: disc round to subpentagonal, covered on both sides by coarse and imbricated scales. Centrodorsal and surrounding primary plates distinct. Radial shields small, between 1/3 and 1/2 of the disc radius (length> breadth), contiguous throughout their whole length. Sharp limit between the scales of the dorsal and ventral side near the edge of the disc. Ventral interradial plates imbricate and slightly smaller than the dorsal plates. Two oral papillae on each side of the jaw forming a continuous series with the blunt block-like to conical infradental papillae; the distalmost oral papilla very broad. Oral shields rounded to triangular in small specimens, becoming more rhombic (produced inwards) in larger animals. Arms about three or four times the DD. Tentacle pores small, with two tentacle scales proximally decreasing to one on the distal part of arms. Dorsal arm plates separated, proximally fan-shaped (length <breadth), with round distal edge, becoming more square-like on distal arm (length Ξ breadth). Ventral plates with slight indentation in the distal edge, contiguous only on the proximal part of the arm. Large lateral arm plates, meeting along the longitudinal mid-line, both dorsally and ventrally. Four, further out three, short, conical arm spines. One specimen (DBUA-ECH 354) with a juvenile’s arm sticking out from a bursal slit. Colour in ethanol uniformly white.

Remarks: the specimens herein examined diverge slightly from what is described for the typical Amphipholis squamata , particularly regarding the shape and size of disc plates on the dorsal side. For example, the coarser plating, a well-defined central rosette and relatively larger radial shields are all features that agree with the description of A. tenuispina by Koehler (1898) based on animals collected by Hirondelle in the Azores (sta 198: 38°26’25”N, 28°38’56”W, 800 m). Mortensen (1927a) remarked on the existence of transitional stages that hardly support the maintenance of tenuispina as a separate variety of A. squamata even less as a separate species. In turn, Paterson (1985) stated that the primary plates are indistinguishable, except in smaller specimens. Future works will have to address the specific significance of A. squamata morphological variation throughout its geographical range. Molecular studies on A. squamata populations in New Zealand ( Sponer & Roy 2002) and in French Mediterranean coast ( Boissin et al. 2008b) indicate that A. squamata represents a cryptic species complex.

Figures

FIGURE 5. Amphipholis squamata (Delle Chiaje, 1828) (DBUA-ECH 354). Dorsal view (A); ventral view (B); detail of the disc and arm, dorsal view (C) and ventral view (D); arm of a young (indicated by white arrowhead) out of the adult bursae.