Isostichopus Deichmann 1958
Creators: name: Borrero-Pérez, Giomar H.
name: Solís-Marín, Francisco A.
name: Lessios, Harilaos
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Holothuroidea
Synallactida
Stichopodidae
Isostichopus

description: Genus Isostichopus Deichmann, 1958
Type species
Stichopus badionotus Selenka, 1867
Description (after Deichmann 1958)
Medium to large species, length to 50 cm, body wall firm and thick. Highly variable coloration (Fig. 1). Body convex to quadrangular in cross-section. Large lateral papillae, usually sharply defining dorsum and ventrum (or bivium and trivium). Dorsal papillae irregularly arranged and in different sizes and shapes: wart-like, spiky, or with small points. Sole well developed, with three bands of cylindrical podia. Single stone canal attached to the mesentery; calcareous ring with massive radial pieces with posterior projections of different sizes, and narrow interradial pieces with projections pointed anteriorly and concave posterior margins (Fig. 4). Ossicles: dorsal papillae with tables; thin C- or S-shaped rods in varying numbers and sizes; large, curved rods with quadrangular projections, sometimes perforated in the middle (Fig. 2S); few perforated plates in the tip (Fig. 2U). Tables in a dense layer, low, squat, with a circular disc with 8 to 12 small holes, four pillars, single crossbeam, and a wreath of small spines at the crown (Fig. 2A–B); tables with reduced disc (Fig. 2C), additional holes in more than one ring (Fig. 20A), or larger and modified discs also present (Fig. 2D), mainly at the top of papillae. Dorsal body wall with tables and a few thin C- or S-shaped rods only. Ossicles in dorsal papillae and body wall change during growth, though drastic ontogenetic changes occurring only in I. macroparentheses. Pedicels with low tables with large and not rounded central perforation (Fig. 2E); thin C-shaped rods less frequent than in the dorsal papillae; large endplates (Fig. 2W); numerous perforated or supporting plates with numerous holes (Fig. 2V); slightly or strongly curved rods with broad perforated expansions in the middle (Fig. 2T); both plates and rods larger than those of dorsal papillae. Ventral body wall with only tables and a few C-shaped ossicles. Tentacles with strongly or slightly curved spiny rods in varying sizes (Fig. 2O) and small tables as those of the body wall, or modified with low and incomplete spires (Fig. 2F). Mouth membrane with thin C-shaped rods, simple rods, and large tables, not documented previously for the genus, with well-developed spire, composed of at least ten pillars joining at the top, forming very dense and thick crown of spines, without crossbeams; discs of the same width as the spire, or wider with several rings of holes and several central perforations (Figs 2H, 7D, 11, 16D). Longitudinal muscles containing C-shaped rods and simple rods. Posterior part of the cloaca with C-shaped, simple or bifurcated rods (Fig. 11); anterior part with simple, branched rods, irregular plate-like branched rods (Fig. 2R) and large tables, with well-developed and very dense and thick spire, some with circular spire, without clear crossbeams, wide discs with several rings of holes and several central perforations (Fig. 11). Respiratory trees with small tables as those of the body wall or strongly spinose straight or cross-shaped rods and large tridimensional spheres (Fig. 2X), not documented previously for the genus. Intestine with spinose or smooth ossicles in a cross shape (Fig. 2P). Gonads with delicate and long rods (Figs 2N, 11). Rosettes not present in Isostichopus.
Distribution
Tropical and subtropical shores of America and the west coast of Africa (Fig. 5).
Key to the species of the genus Isostichopus Deichmann, 1958
1. C-shaped ossicles> 90 µm on average and 2–3 times as long as the tables are high; disc tables in dorsal papillae and body wall completely reduced in adults (Figs 2C, 10E, 23A); tridimensional spheres and straight/spiky rods in the respiratory trees (Fig. 23F); color not variable, dorsal side light yellow-brown in background, with irregularly arranged blurred large and small darker brown spots (Fig. 24); distributed in the Gulf of Mexico and Caribbean Sea, confirmed in few localities (Fig. 5B), not a common species ................................................................. I. macroparentheses (Clark, 1922)
– C-shaped ossicles <90 µm on average; disc tables in dorsal papillae and body wall with complete ring of holes, not reduced in adults; color highly variable; common and abundant species ............ 2
2. Table ossicles from top of the dorsal papillae in two shapes (Figs 10C, 13A), large, regular Isostichopus tables 58–86 µm (average = 71 µm) (Fig. 2B) and modified “ maculatus ” tables 60– 108 µm (average = 86 µm) (Fig. 2D); whitish spot-like granules on the skin (Figs 1, 14); distributed in the Mid and East Atlantic (Fig. 5A) ................................. I. maculatus maculatus (Greeff, 1882)
– Table ossicles from top of the dorsal papillae only regular Isostichopus tables 29–70 µm (average = 47 µm) ............................................................................................................................................... 3
3. Large wart-like dorsal papillae (Figs 19, 21); table ossicles from top of the dorsal papillae only regular Isostichopus tables squarer than narrow in profile (Figs 10D, 20A); large tables with a circular spire well developed in the cloaca (Figs 11D, 19C, 20F); distributed in the East Pacific Ocean (Fig. 5B) ..................................................................................................................... I. fuscus (Ludwig, 1875)
– Dorsal papillae variable in size and shape; table ossicles from top of the dorsal papillae only regular Isostichopus tables square or narrow in profile; distributed in the West Atlantic Ocean ................. 4
4. Semi-translucent and rugose body wall; spiral lines in dorsal and lateral papillae (Figs 1, 17); worm-like rod ossicles in dorsal papillae (Figs 15B, 16A); calcareous ring with dorsal radial plates with short posterior projections (Fig. 4B) in large specimens (L = 185 mm); adult specimens living hidden during day associated with live corals, sponges, rubble, and rocks, exposed for only short time (Fig. 18) ........................................................................... I. maculatus phoenius (Clark, 1922)
– Opaque and smooth body wall; no spiral lines in dorsal and lateral papillae (Figs 1, 8); no worm-like rod ossicles in dorsal papillae (Fig. 7A); calcareous ring with dorsal radial plates with long posterior projections turned inwards (Fig. 4A) in larger individuals (L = 160–235 mm); adult specimens living exposed on muddy, sandy, rocky substrates, seagrass beds and mixed bottoms (Fig. 8) ................... ............................................................................................................. I. badionotus (Selenka, 1867)
description: Published as part of Borrero-Pérez, Giomar H., Solís-Marín, Francisco A. & Lessios, Harilaos, 2024, Understanding the color variability and resolving taxonomic confusion in the sea cucumber Isostichopus badionotus (Echinodermata, Holothuroidea): a revision of the genus Isostichopus, pp. 1-96 in European Journal of Taxonomy 949 (1) on pages 17-81, DOI: 10.5852/ejt.2024.949.2641, http://zenodo.org/record/13710645