Echinocyamus pusillus (Müller, 1776)

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 : 132-133

Echinocyamus pusillus (Müller, 1776)

( Fig. 32 )

Reports for the Azores:

Echinocyamus angulosus Leske, 1778 — $ Drouët 1861: 211;

Echinocyamus pusillus Gray 1825 — Agassiz 1872: 111–112, pl. 11, fig. 3, pl. 13, figs. 1–8, 1881: 226; p.p. $ Koehler 1898: 24;

Echinocyamus pusillus (M̹ller, 1776)— $ Simroth 1888: 231; Bell 1892: 160–161, pl. 16, figs. 8–9; $ Mortensen 1907: 31–33, fig. 2, pl. 12, figs. 4, 6, 9, 18–20, 22, 23, 26, 27, 29–31; $ Koehler 1909: 235–236, pl. 4, fig. 10; Koehler 1914b: 278; $ Nobre 1924: 89, 1930: 6, 1938: 122–123, fig. 29; Mortensen 1927a: 316–317, figs. 182–183; Grieg 1932: 42; Mortensen 1948: 178–183; $ Tortonese 1965: 346–348, fig. 164; $ Marques 1983: 6; $ Mironov & Sagaidachny 1984: 126–183; Pereira 1997: 334; $ Morton et al. 1998: 143, fig. 7.4L1; García-Diez et al. 2005: 51; Mironov 2006: 114; Schultz 2006: 317–318, figs. 597–598; $ Wirtz 2009: 48, fig. 1f; Micael & Costa 2010: 323; Madeira et al. 2011: 255, fig. 11; Micael et al. 2012: 3; Echinocyamus minutus ( Pallas, 1774) — Harvey 1956: 66.

See: Mortensen (1907, 1948).

Occurrence: Mediterranean Sea and northeast Atlantic, from Iceland and Scandinavia, along the European coasts to Sierra Leone ( Mortensen 1907, 1951a, Koehler 1909, H.L. Clark 1925), including the archipelagos of the Azores, Madeira ( Koehler 1909), Canaries ( Bacallado et al. 1985) and Cape Verde ( Cadenat 1938), and the Ampère, Gorringe and Meteor seamounts ( Mironov 2006).

Depth: AZO: 0–207(?1,250) m ( Koehler 1909, herein).

Habitat: lives buried in soft substrates, in sand, detritic and gravelly bottoms where it feeds on detritus and foraminifera ( Koehler 1898, Picton 1993).

Larval stage: planktotrophic ( Mortensen 1927a).

Fossil record: also reported from the Pliocene and Pleistocene outcrops of Santa Maria Island ( Madeira et al. 2011, 2017a).

Material examined: DBUA-ECH 011 (Água d’Alto, SMG, AZO, 37°42’55.48”N, 25°28’27.39”W, 2006.08, intertidal; 1 bt, TL = 7 mm); DBUA-ECH 036 (Água d’Alto, SMG, AZO, c. 37°42’55”N, 25°28’27”W, 2009.04.25, intertidal; 47 bts, TL = 4–8 mm); DBUA-ECH 037 (off Marina of Vila Franca do Campo, SMG, AZO, 37°41’42”N, 25°25’22”W, 2006.07. 17, 135 m; 1 spm, 15 bts, TL = 3–5 mm); DBUA-ECH 038 (Vila Franca do Campo, SMG, AZO, 37°41’34”N, 25°27’34”W, 2006.07. 19, 167–189 m; 16 bts, TL = 3–5 mm); DBUA-ECH 039 (Vila Franca do Campo, SMG, AZO, 37°41’39”N, 25°27’11”W, 2006.07. 21, 95–121 m; 70 bts, TL = 3–6 mm); DBUA- ECH 040 (Vila Franca do Campo, SMG, AZO, 37°41’52”N, 25°27’13”W, 2006.07. 24, 45–47 m; 11 bts, TL = 4–6 mm); DBUA-ECH 041 (off Praia da Vinha da Areia, SMG, AZO, 37°42’45”N, 25°25’24”W, 2006.07. 21, 14 m; 14 bts, TL = 4–6 mm); DBUA-ECH 042 (off Ribeira das Tainhas, SMG, AZO, 37°42’01”N, 25°25’14”W, 2006.07. 24, 98–108 m; 13 bts, TL = 3–5 mm); DBUA-ECH 043 (off Ribeira das Tainhas, SMG, AZO, 37°42’01”N, 25°25’01”W, 2006.07. 24, 117–145 m; 8 bts, TL = 3–5 mm); DBUA-ECH 044 (off Ribeira das Tainhas, SMG, AZO, 37°41’57”N, 25°25’08”W, 2006.07. 24, 144–198 m; 24 bts, TL = 4–7 mm); DBUA-ECH 045 (off Ribeira das Tainhas, SMG, AZO, 37°42’17”N, 25°25’09”W, 2006.07. 24, 34–63 m; 14 bts, TL = 3–5 mm); DBUA-ECH 046 (off Cais do Tagarete, Vila Franca do Campo, SMG, AZO, 37°42’07”N, 25°25’14”W, 2006.07. 25, 52 m; 1 spm, 32 bts, TL = 2–5 mm); DBUA-ECH 047 (off Cais do Tagarete, Vila Franca do Campo, SMG, AZO, 37°41’53”N, 25°25’15”W, 2006.07. 25, 180 m; 11 bts, TL = 3–6 mm); DBUA-ECH 048 (Vila Franca do Campo SMG, AZO, 37°41’17”N, 25°25’10”W, 2006.07. 25, 129–207 m; 4 bts, TL = 3–4 mm); DBUA-ECH 049 (off Praia da Amora, Ponta Garça, SMG, AZO, 37°42’43”N, 25°21’33”W, 2006.07. 26, 38 m; 2 bts, TL = 4 mm); DBUA-ECH 050 (off Praia da Amora, Ponta Garça, SMG, AZO, 37°41’57”N, 25°22’08”W, 2006.07. 26, 156–360 m; 2 bts, TL = 4 mm); DBUA-ECH 051 (off Praia de Água d’Alto, SMG, AZO, 37°42’24”N, 25°28’59”W, 2006.07. 26, 66 m; 62 bts, TL = 2–7 mm); DBUA-ECH 052 (off Vinha da Areia, Vila Franca do Campo, SMG, AZO, 37°42’37”N, 25°25’18”W, 2006.07. 26, 56 m; 58 bts, TL = 2–7 mm); DBUA-ECH 124 (S„o Roque, SMG, AZO, c. 37°44’37”N, 25°38’19”W, 2012.11.16, intertidal; 1 spm, TL = 2 mm); DBUA-ECH 129 (Rosto do C„o, S„o Roque, SMG, AZO, c. 37°44’37”N, 25°38’19”W, 1990.07.4, 9,5 m; 3 spms, TL = 5 mm); DBUA-ECH 183 (Baixa do Porto, Lajes, FLS, AZO, c. 39°22’50”N, 31°10’00”W, 1990.10.27; 1 bts, TL = 3 mm); DBUA-ECH 293 (Baia de Belém, S„o Roque, SMG, AZO, c. 37°44’37”N, 25°38’19”W, 1990.07.4, 8,6 m; 1 spm; TL = 5 mm); DBUA-ECH 311 (off Ribeira das Tainhas, SMG, AZO, 37°42’33”N, 25°25’53”W, 23 m; 2 spms, TL = 3 mm); DBUA-ECH 324 (Sabrina Bank, SMG, AZO, 37°52’23”N, 25°54’00”W, 2011.07.07, 140 m; 1 spm, 7 bts, TL = 3–4 mm); DBUA-ECH 367 (Vila Franca, SMG, AZO, 37°42’39”N- 25°27’26”W, 2006.07.21, 18– 20 m; 2 spms, TL = 5 mm); DBUA-ECH 370 (Vila Franca, SMG, AZO, 37°42’42”N- 25°24’38”W, 2006.07. 25, 17 m; 1 spm, TL = 4 mm); DBUA-ECH 373 (Islet of Via do Porto, SMA, AZO, c. 36°56’23”N, 25°10’16W ”, 7 m; 2 spms, TL = 3–4 mm); DBUA-ECH 383 (Horta, FAY, AZO, c. 38°31’51”N, 28°37’23”W, 2010.03.02; 1 spm, TL = 4 mm); DBUA-ECH 435 (Vila Franca do Campo, SMG, AZO, 37°41’41”N– 37°41’17”N, 25°25’26”W– 25°25’10”W, 2006.07. 25, 129–207 m; 1 spm, TL = 3 mm); EMEPC-LUSO L9D9B20(S1) (Gorringe Bank, NE Atlantic, 36°42’49”N, 11°09’54”W, 2009.09. 13, 130 m; 20 bts, TL = 2–5 mm).

Description: test small, flattened, variable in form; outline generally elongated oval, though among the smallest specimens frequently ellipsoid (width =66–74%TL; TL <3 mm) becoming more circular or subpentagonal in larger individuals (width =100%TL; TL Ξ 7 mm). Apical disc central to slightly posterior, with large genital pores and five small ocular pores. The lower half of the apical side locally depressed in larger individuals (TL = 7–8 mm). Oral area mostly flat; depression between the peristome and periproct particularly evident in the larger specimens (TL> 5 mm). Peristome circular to subpentangular, relatively concave; diameter of the peristome about 30–33%TL in smaller individuals (TL <3 mm) decreasing to 13–19%TL in larger specimens (TL Ξ 7 mm). Periproct ellipsoid to round, small (6–12%TL) lies halfway between the peristome and the posterior margin. Petals well developed, but not reaching the edge of the test; pore-series almost parallel, open distally, reaching ten pore pairs per column in the posterior ambulacra in the largest specimens (TL = 7–8 mm). Spines short, relatively uniform. Colour (in ethanol): test and spines white or cream, occasionally green.

Remarks: in general, the genus Echinocyamus shows a great deal of intraspecific morphological variation, often depending on the age and size of the animal. Mironov & Sagaidachny (1984) attempted to clarify the limits between intra and interspecific variability in several Echinocyamus species, constructing a diagnostic set made of several morphometric and meristic characters. The Azorean specimens herein examined showed as expected, high intraspecific variation, explained for the most part by differences in size of the specimens and thus dismissed as allometric variation (see remarks under E. grandiporus ).

The first report of this species in the archipelago comes from Drouët (1861) who noted they are quite common on the coasts of S„o Miguel. Barrois (1888) believed that Drouët confused E. pusillus with Echinocardium flavescens . The material reported by Drouët (1861) could not be located, thus making impossible to verify Barrois’ statement. However, we are inclined to believe Drouët’s original identification. In S„o Miguel, dead tests of E. pusillus are relatively easy to find in the intertidal, particularly on sandy beaches, among the debris left by the low tide ( Nobre 1930, personal observation). They are also a common presence among the material dredged in the Azores at depths up to 200 m. Also, the maximum recorded depth of this species was reported by Koehler (1909) based on dead tests collected by Princesse Alice in Azorean waters between 650 and 914 m (sta 2214: 39°26’10”N, 31°21’30”W) and 1,250 m (sta 1349: 38°35’30”N, 28°05’45”W). The recorded depths may not represent a real bathymetric limit but rather be biased by transportation, as Koehler remarked. The light but robust Echinocyamus tests make it possible to keep their overall integrity even long after the animal is dead. Unfortunately, many of the documented reports for this species do not provide any description of the specimens, thus making impossible to understand the real depth range of this species. Storage in the DBUA-ECH collection we have found living specimens to a maximum reported depth of 140 m. Even though it is more than likely that E. pusillus lives at higher depths, we have accepted this value as the maximum depth in the archipelago for this species at present. Additionally, Mironov (2006) referred to station 166 (Princesse Alice) where Koehler (1909) had reported E. pusillus as being located in the Mid-Atlantic Ridge to the north of the Azores. This station is not in Azores waters but in the western shores of France (47°26’30”N, 3°12’05”W). Apparently Mironov had confused the symbol representing the degree of latitude with a zero.

Figures

FIGURE 32. Echinocyamus pusillus (M̹ller, 1776) (DBUA-ECH 036-3: A–C; DBUA-ECH 036-5: G; L09D17S5: D–F; DBUA-ECH 129: H–I); Apical view (A, D, G, H); oral view (B, E, I); lateral view (C, F).