Mithrodia clavigera ( Lamarck, 1816 )

Cunha, Rosana, Tavares, Marcos & Jr, Joel Braga De Mendonça, 2020, Asteroidea (Echinodermata) from shallow-waters of the remote oceanic archipelago Trindade and Martin Vaz, southeastern Atlantic, with taxonomic and zoogeographical notes, Zootaxa 4742 (1), pp. 31-56 : 43-44

Mithrodia clavigera ( Lamarck, 1816)

Figures 4 B–D, 7

Asterias clavigera Lamarck, 1816: 562 [type locality: unknown, viz. Clark & Downey, 1992]

Mithrodia clavigera – Verrill, 1870: 289 ; Gondim et al. 2014: 26 , figs. 7f–i.

Trindade specimens. Brazil, Espírito Santo, Trindade Island, Enseada da Cachoeira, Farrilhões , 20°31’22.4”S, 29°19’52”W, 14.viii.2012, 10 m: 1 spm R=110, r=10 ( MZUSP 1175 ) ; 4.vii.2012, 18 m: 1 spm R=160, r=15 ( MZUSP 1176 ) . Ilha do Sul , 20°31’32”S, 29°19’28”W, 21.x.2014, 18 m: 1 spm R=220, r=25 ( MZUSP 1178 ) . Enseada do Príncipe, 20°31’36”S, 29°18’94”W, 21.x.2014, 19 m: 1 spm R=240, r=20 ( MZUSP 1177 ) .

Comparative material. Brazil, Paraíba, Projeto Algas–PB, 7º04’S– 38º41’W, 17.ii.1981, 26 m: 1 spm R=10, r=2 ( UFPB.ECH.880) .

Distribution. Circumtropical ( Engel et al., 1948; Clark & Rowe, 1971; Marsh, 1977; Jangoux, 1984; Clark & Downey, 1992; Alvarado & Solis-Marin, 2013). Brazil: Paraiba, Fernando de Noronha and Trindade Islands (present study), and Vitoria Trindade Seamounts Chain (Vitoria Bank) ( Bell, 1882; Tommasi, 1970; Gondim et al., 2014; present study). Depth range: 0–157 m ( Clark & Downey, 1992; present study).

Recognition characters. Small disc (20–50 mm). Five long, cylindrical, flat arms, tapering terminally. Seven rows of prominent spines, occasionally five, distributed longitudinally around arm. Abactinal and marginal skeleton similar to each other, composed of well-spaced polygonal primary plates connected by elongate secondary plates arranged in a reticulum. Abactinal plates covered by granules. Papular areas large and triangular. Spines squamous other than ambulacral and oral ones. Actinal plates with row of robust spines reaching to terminal region of arm, forming clusters of 2–3 spines; papular areas between plates. Ambulacral spines seven, rounded tip, connected by membrane; central spine largest, remaining spines decreasing in size towards edge of plate. One row of subambulacral spines similar to actinal ones, but smaller and thinner. Pedicellariae rare ( Clark & Downey, 1992; present study).

Color in life. Arms boldly banded dark brown or reddish and light, usually gray. Papular areas are brown to black ( Clark & Downey, 1992; Marsh, 1977). Trindade specimens ( Figures 4 B–D, 7A).

Habitats. This species has been found to inhabit hard substrates, such as crevices, reefs gravel, rocky bottoms, and rhodolith banks ( Abreu-Pérez et al. 2005; Gondim et al. 2014). More active during the night ( Guille et al., 1986). One specimen was observed and photographed in situ by Gabriela C. Zeineddine in Fernando de Noronha (in a rocky tide pool at Boldró beach, ix.2019, figure 4D), but released after collection. In Trindade M. clavigera was found in rocky bottoms or sheltered in rocky cavities, between 10 and 19 m ( Figures 4 B–D, 7A).

Comments. Mithrodia claviger a is the only species of three in the genus to occur in the Atlantic Ocean. Mithrodia victoriae Bell, 1882 , described from off the coast of southeastern Brazil (Vitoria Bank, Espírito Santo) has been placed by Clark & Downey (1992) under the synonymy of M. clavigera , who also called into question the status of M. bradleyi Verril, 1870 (EP) as a distinct species. Engel et al. (1948), warned that pedicellariae are not easily detected, described and illustrated the pedicellariae of M. clavigera based on specimens from Moluccas, Flores and Java ( Indonesia), and Haingsisi (Timor). However, pedicellariae have not been found neither in the specimen from Paraíba (northeastern Brazil) studied by Gondim et al. (2014), nor in the Trindade specimens (present study).

These are the first records of M. clavigera from the oceanic islands of Fernando de Noronha and Trindade. Previous to the oceanic insular waters, M. clavigera was known in the southwestern Atlantic from the northeastern Brazilian coast (Paraíba) and the Vitória Bank, Espírito Santo ( Figure 1 ).

Figures

FIGURE 1. A. Diagrammatic East-West oriented cross-section of the volcanic Vitoria-Trindade Seamount Chain. Brazil’s landmass in dark grey. B, C. Trindade and Martin Vaz islands, respectively. Photographs by J.B. Mendonça Jr.

FIGURE 4. A. Copidaster lymani A. H. Clark, 1948, Trindade Island, Enseada das Orelhas. B–D. Mithrodia clavigera (Lamarck, 1816). B, C. Trindade Island, Príncipe beach. D. Fernando de Noronha, tide pool at Boldró beach. Photograph by Gabriela C. Zeineddine. E. Oreaster reticulatus (Linnaeus, 1758), Trindade Island, Enseada dos Portugueses, Farol. F. Luidia alternata alternata (Say, 1825) Trindade Island, Ponta da Calheta.