Luidia atlantidea Madsen, 1950

Mezali, Karim, Khodja, Ihcene, Benarous, Ahlam, Lebouazda, Zineb & Soualili, Dina Lila, 2022, First record of Luidia atlantidea Madsen, 1950 (Echinodermata: Asteroidea Paxillosida: Luidiidae) in the Sidi-Medjdoub area-Mostaganem (West Algerian coast, Mediterranean Sea), Zootaxa 5124 (1), pp. 88-94 : 90

Luidia atlantidea Madsen, 1950

Figures 2–3 , Table 1

Luidia sarsi Studer, 1884: 43 .

Luidia africana Koehler, 1911:19 ; Doderlein, 1920: 288–289.

Luidia atlantidea Madsen, 1950: 192–198 , fig. 5, pl. 16, figs 1, 2; Nataf & Cherbonnier, 1973: 76–80; pl. I, B, pl. II, A, B, pl.

VII, 1–5, pl. IX, E, F; Clark & Downey, 1992: 10–11, figs 5b, 6b, 7p, pl. 2A; Clark, 1953: 393, 394; 1955: 22, 32; 1982:

168, fig. 3p.

Material examined. LPVCMRMS2019.401, LPVCMRMS2019.402, Mostaganem, Algeria, 36°0.032’N, 0°1.456’E, 53 m, February 2019, 2 specs .

Description. Two specimens, minor radius “r” 42.83 and 34.51 mm, wet weight 185.22 and 128.92 g respectively. Flat body, five slender arms from base to tip. Major radius “R max” 230.30 and 180.40 mm and average width 25.83 and 24.98 mm respectively. Abactinal side ( Figure 2A ) gray, paxillae white, marginal paxillae show white bands. Superomarginal paxillae squarish ( Figure 2C 1 & 2E 1 ), larger with 4 rows of spinelets, abactinal paxillae small and rounded ( Figure 2C2 & 2E2 ) with 3 rows of short and thick spinelets. Central paxillar spinelets larger and shorter than the peripheral ones. Actinal side beige ( Figure 2B ). Dorsolateral Inferomarginal plates with 3 rows of needle-like spines ( Figure 2F 1 ) black at the base and white at the tips, the central spines significantly larger than the peripheral ones. Ventrolateral inferomarginal plates with 3 alternating rows of white spines ( Figure 2F2 ) that decrease in size from the abactinal surface to the actinal surface. Adambulacral plates ( Figure 2G 1 ) with 3–4 smaller spines arranged perpendicular to the ambulacral groove with the spine adjacent to the ambulacral groove longer than the peripheral spines. Two long spines at the mouth plate ( Figure 2D ) directed toward the mouth followed by pedicellariae and shorter spines. Pedicellariae with two valves, numerous especially on the inferomarginal and adambulacral plates. Two rows of large podia. Madreporite small.

Gonad description. The largest specimen male (LPVCMRMS2019.401) and the smallest one female (LPVCMRMS2019.402). The gonads extend into the coelomic cavity, forming two rows of tufts on each side of the arm (ten in total), above the caeca pyloric. Color beige to cream for both sexes. Microscopically, gonads enclosed in two sacs (inner and outer) separated by the genital coelom. Testes ( Figure 3A ) composed of spermatogenic columns, spermatids attached to the top of the columns and the lumen where the spermatozoa accumulate. Ovaries ( Figure 3B ) with an elongated tubular shape. Oocytes of the same size (synchronous growth). Centric circular nuclei.

Distribution, abundance and habitat. Luidia atlantidea was first recorded from the western and northwestern African Atlantic coast from Morocco to Zaire including the Cape Verde Islands ( Clark 1953; Clark 1982; Clark & Downey 1992; Entrambasaguas 2008). It occurs between 10 and 80 m deep ( Clark 1982) and frequents rocky bottoms with gray mud, sand and calcareous algae, muddy sand, fragments of gastropod shells, mud with stones, sand with stones, fine sand ( Clark & Downey 1992). Recently, L. atlantidea has been reported in the Canary Islands ( Osaer & Narváez 2017) and in the Mediterranean Sea [northern Alboran Sea ( Gallardo-Roldán et al. 2015) and the Golf of Gabes ( Chammem et al. 2019)].

In the Mediterranean, studies on the ecology and biology of L. atlantidea are practically very few, even anecdotal. In fact, only Gallardo et al. (2015) and Chammem et al. (2019) recorded it at the Spanish and Tunisian water respectively, these authors affirmed the very low abundance of this species (generally <2 individuals per haul). Individuals of L. atlantidea were found at a greater depth range in the Mediterranean (0.9 – 95 m) (Gallardo et al. 2015; Chammem et al. 2019) than that reported by Clark (1982) in the Atlantic.

No conclusion can be taken on the invasive status of this species, in fact, according to Makhlouf & Shakman (2021), it is very difficult to identify invasive species in any country or region, because the species and their interactions with ecosystems are very complex.

Remarks. In the Mediterranean Sea, two species of the genus Luidia are documented, Luidia sarsii sarsii Düben & Koren in Düben, 1844 and Luidia ciliaris ( Philippi, 1837) . The differences that exist between the three species present in the Mediterranean Sea are summarized in the table 1.

Figures

FIGURE 1. Sampling station of Luidia atlantidea (indicated by the black circle).

FIGURE 2. Morphological characters of Luidia atlantidea Madsen, 1950 (fixed individual: LPVCMRMS2019.402) sampled in the region of Sidi-Medjdoub (Mostaganem). A. Abactinal surface. B. Actinal surface. C. Paxillae of the abactinal surface. 1. Large superomarginal paxillae. 2. Small abactinal paxillae. D. Mouth. E. Detail of abactinal paxillae. 1. Large superomarginal paxillae. 2. Small abactinal paxillae. F. Detail of an arm, lateral view. 1. Dorsolateral inferomarginal spines. 2. Ventrolateral inferomarginal spine. G. 1. Adambulacral plate.

FIGURE 3. Histological sections of the gonads of Luidia atlantidea. A. Testes. B. Ovaries. O. Oocytes. N. Nuclei. Sp. Spermatozoa. SC. Spermatogenic columns. Small black arrows indicate spermatids. Lu. Lumen. Scale bar = 100 µm.