Isostichopus maculatus subsp. maculatus
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
Isostichopus maculatus
Isostichopus maculatus maculatus (greeff, 1882)

description: Isostichopus maculatus maculatus (Greeff, 1882)
Figs 1Z –H’, 3A–D, 4C, 5A, 9, 10C, 11C, 12–14; Tables 1–3
Stichopus maculatus Greeff, 1882: 158.
Stichopus maculatus – Théel 1886: 195. — Sluiter 1910: 333. — Ancona-López 1957: 7.
Isostichopus badionotus – Clark 1922: 55. — Cherbonnier 1975: 631–637, pl. 1a–c figs 1a–g, 2h–o. — Pawson 1978: 27–28, fig. 11m. — Pérez-Ruzafa et al. 1999: 54. — Entrambasaguas 2008: 134–138. — Entrambasaguas et al. 2008: 479–481.
Isostichopus cf. badionotus – Wirtz et al. 2020: 38.
Isostichopus maculatus maculatus – Borrero-Pérez et al. 2022: 180.
Isostichopus sp. ‘maculatus’ – Purcell et al. 2023: 146–147.
Original name
Stichopus maculatus Greeff, 1882.
Current status
Isostichopus maculatus maculatus (Greeff, 1882).
Name-bearing type
Neotype USNM E16150, neoparatype USNM E16151.
Type locality
English Bay, Ascension Island for the neotype, instead of Rolas Island, São Tomé for the holotype.
Diagnosis
White spots as white granules on the skin (Figs 1Z –H’, 14); table ossicles from top of the dorsal papillae in two shapes, large, regular Isostichopus tables 58–86 (x = 71) µm high (Fig. 2B) and modified “ maculatus ” tables 60–108 (x = 86) µm high (Figs 2D, 10C, 12C, 13A); distributed in the Mid and East Atlantic (Fig. 5A); mtDNA divergence from other species of the genus>8.2% in COI-Fr1 (barcoding region),> 9.5 in COI-Fr2 and>8.2% in 16S; between subspecies 1.4%, 1,9% and 0.4% respectively (Table 2).
Material examined
Neotype (here designated)
ASCENSION ISLAND • 1 spec. (L = 105 mm); Ascension Island, English Bay, Station number RBM-ASC21; 1971; R. Manning leg.; USNM E16150.
Neoparatype (here designated)
ASCENSION ISLAND • 1 spec. (L = 125 mm); Ascension Island, Southwest Bay, Station number RBM-ASC9; 1971; R. Manning leg.; USNM E16151.
Other material
EAST ATLANTIC – Cape Verde • 1 spec. (L = 55 mm); São Vicente Island, Mindelo; 16.889267° N, 25.000642° W; 24 Aug. 2015; P. Wirtz leg.; ImuCV1, only images and tissue (used) • 1 spec. (L = 85 mm); same data as for preceding; ImuCV2, only images • 1 spec. (L = 120 mm); same data as for preceding; ImuCV3, only images • 1 spec. (L = 110 mm); same data as for preceding; ImuCV4, only images • 1 spec. (L = 145 mm); Santiago Island, Tarrafal; 15.275056° N, 23.758656° W; 28 Oct. 2015; P. Wirtz leg.; ImuCV5, only images • 1 spec.; same data as for preceding; ImuCV6, only images • 1 spec.; same data as for preceding; ImuCV7, only images and tissue (used) • 1 spec.; same data as for preceding; ImuCV8, only images • 1 spec.; same data as for preceding; ImuCV9, only images • 1 spec. spotted dark pattern; same data as for preceding; ImuCV10, only images and tissue (used). – São Tomé and Príncipe • 3 specs; São Tomé; 0.273383° N, 6.476564° E; N. Vasco-Rodríguez leg.; only images • 5 specs; Ilha do Principe; 1.606606° N, 7.355° E; R. Haroun leg.; only images. – Senegal • 1 spec.; Dakar – Îles Madeleines; UF16295. – Sierra Leone • 1 spec.; 8.135025° N, 13.198139° W; P. Wirtz leg.; only images. – Liberia • 1 spec.; Kligba, Rivercess County; FAOLIB08 • 1 spec.; same data as for preceding; FAOLIB09 • 1 spec.; Artah Beach, Sasstow Grand Kru County; FAOLIB10. – Nigeria • 2 specs; 4.528551° N, 5.491359° E; fishermen leg.; only images. – Gabon • 1 spec.; Libreville; 0.393065° N, 9.427977° E; P. Wirtz leg.; only images.
MID ATLANTIC – Ascension Island • 2 specs (L = 70–90 mm); Pan Am Base; depth 12–14 m; K. Jourdan leg.; USNM E17246 • 1 spec. (L = 10 mm); English Bay, Station number ASC3A; 7.93° S, 14.4° W; 1 Jul. 1976; M. Jones leg.; USNM E16166 • 1 spec. (L = 35 mm); Porpoise Point NE Side, Station 80-28; 7.9017° S, 14.355° W; depth 10.7–12.2 m; 27 Jul. 1980; Ascension I Expedition, Grice Marine Biological Laboratory exped.; USNM E34268 • 1 spec.; English Bay, One Hook; 7.893231° S, 14.387247° W; 9 Nov. 2015; P. Wirtz leg.; ImuASI1, only images and tissue (used) • 1 spec.; same data as for preceding; ImuASI2, only images and tissue (used) • 1 spec.; same data as for preceding; ImuASI3, only images • 1 spec.; Georgetown Town Pier; 7.924708° S, 14.414214° W; 15 Nov. 2015; P. Wirtz leg.; ImuASI4, only images and tissue (used) • 1 spec.; same data as for preceding; ImuASI5, only images.
Description
EXTERNAL APPEARANCE. Medium species, up to 220 mm long (Greeff 1882), examined specimens 55– 145 mm long (n = 7, neotype: 150 mm long (contracted); neoparatype: 125 mm long). Body loaf-like, length/width ratio 3.3± 0.9 (n = 5, 1.6–4.3, neotype 1.6, paratype 2.6). Specimens convex or somewhat quadrangular in cross section; rounded in the anterior and posterior parts (Figs 12B, 14). Contracted neotype tapering posteriorly and anteriorly (Fig. 12A). Body wall firm and thick (2–5 mm thick in the neotype). Anus supra-terminal, circular and surrounded by large papillae. Mouth directed ventrally, encircled by a collar of large papillae (2–3 mm high in the neotype). Large peltate tentacles 20, about 5–6 mm long, and shield 5–6 mm wide, in the neotype partially retracted. Dorsal papillae medium to large, wart-like; conical in the neotype (up to 5 mm high and 3 to 5 mm wide at the base) and neoparatype, usually scattered irregularly, in some specimens, including neotype and neoparatype, arranged in two irregular rows along each flank, defining a slightly quadrangular shape; smaller papillae irregularly arranged, usually wart-like, sometimes rounded and low with a thin tip in live specimens. Dorsal papillae less obvious than lateral ones; lateral papillae conical and large, sharply defining the dorsal and ventral surface (Fig. 14). Papillae in preserved specimens conspicuous (Fig. 12A–B). Ventral surface densely covered with large cylindrical pedicels, arranged in three longitudinal rows barely visible, most retracted in the neotype, but most relaxed in the neoparatype (2–3 mm long, 1 mm wide) (Fig. 12A–B).
COLOR AND BODY WALL APPEARANCE. Body wall opaque and smooth, not translucent, nor rugose. Color extremely variable, four main color patterns (Figs 1, 14): (1) Uniform pattern (U) (Fig.1Z): uniform dark red, specimens of this color are rare. (2) Dark and white color pattern (DW) (Fig. 1 A’–D’): red, orange, or brown background with white irregular blotches of different shapes and sizes, arranged in longitudinal or transversal orientations; a dark line occasionally surrounding white blotches. The white irregular blotches with off-white spots as white granules, not rugose. (3) Light and sharp dark color pattern (LSD) (Fig. 1 E’–F’): lighter background in brown, beige, white, pink colors, and sharp darker irregular blotches in brown or brown-orange of different size and irregularly arranged. The lighter background area with white spots as white granules, not rugose; most lateral papillae with spiral lines from the base to the tip, which are darker than the background. (4) Dark green and light papilla pattern (DGL) (Fig. 1 G’–H’): dark green color with white spots as white granules in the background and light-yellow papillae, with darker green blotches in some specimens. DGL color pattern resembling the reticulated pattern color of I. fuscus, in live and preserved specimens. Preserved, neotype and neoparatype (Fig. 12A–B) with dark brown background with the biggest dorsal and lateral papillae conspicuous and lighter in a yellow-brown color; white granules present in the dorsal side; some papillae with a spiral line from the base to the tip; tentacles, ventral surface and pedicels of the same color as the dorsal and lateral papillae.
INTERNAL ANATOMY (based on USNM E16150, Neotype, and USNM E16151, neoparatype, specimens 105–125 mm long). Calcareous ring 14 mm in diameter, radial elements roughly quadrangular, 5 mm wide and 6 mm long, with four anterior small lobes, dorsal radial plates with posterior projections longer (1.5 mm long) than those of the ventral plates (0.5 mm long); interradial elements about half as wide as radial elements (3 mm wide), pointed anteriorly with concave posterior margin (Fig. 4C). Neotype and neoparatype stone canal irregularly helical, about 10 and 12 mm long respectively, including the ending flat, leaf-like 4 and 6 mm long madreporite, broken free in the neotype; stone canal in good condition, attached to the dorsal tegument in the neoparatype. Tentacle ampullae variable in size, 10 to 21 mm long in the neotype and about 8 to 16 mm in the neoparatype. One elongated Polian vesicle, about 17 mm long by 3.5 mm wide in the neotype and 21 mm by 4 mm in the neoparatype. Gonads in two tufts, one on either side of dorsal mesentery, branched in cylindrical tubes about 0.5–1 mm wide, extending 50 mm from the anterior to posterior body and filled with eggs 31–64 μm diameter in the neotype (Fig. 11C), and extending 24 mm and filled with sperm in the neoparatype (Fig. 11C). Longitudinal muscles divided, about 8 mm wide, attached to body wall medially in both neotype and neoparatype. Respiratory trees inserted near the anterior cloaca, arising from a common stem 12 and 11 mm long in the neotype and neoparatype respectively; then divided in a left tree about 67 and 72 mm long and a right tree about 50 and 60 mm long, extending along the intestine.
OSSICLES (based on USNM E16150 (neotype, SEM images); USNM E16151 (neoparatype); USNM E17246 (for mouth membrane); fifteen not collected specimens (only tissue for dorsal papillae), specimens 55–145 mm long).
Dorsal papillae with regular Isostichopus tables (Fig. 2A–B), modified maculatus tables (Fig. 2D), few C-shaped ossicles, perforated plates, and large rods (Fig. 13A). All types of ossicles present in all the sizes examined. Modified maculatus tables not common in some specimens, in which only large and stout regular Isostichopus tables are present. C-shaped deposits 54–90 (x = 69) µm long, not abundant even on the top of the papillae, but more common in the neoparatype; S-shaped ossicles not observed. Tables varying in shape from the top to the base of the papillae; at the top numerous modified maculatus tables 60–79 (x = 70) μm high and 66–116 (x = 96) µm across disc; spire very high, slightly or strongly constricted at the crown, composed of four pillars ending in only one large and blunt spine; two to three crossbeams connecting adjacent pillars; disc margins irregular and wide, having one rounded central perforation and a variable number of peripheral perforations, irregularly arranged, usually in two rings, 9 to 14 perforations in the inner ring, and 1 to 20 in the external ring; outer edge of disks with some blunt projections resulting from incomplete holes (Figs 10C, 13A). In addition to the neotype and neoparatype, four examined specimens from Ascension 55 to 145 mm long with modified “ maculatus ” tables at the top of the papillae. Presence of these tables not related to the size of the specimens, present in the smallest specimen (L = 55 mm, 73–94 (x = 86) μm high and 82–141 (x = 104) μm across the disc) and in one of the largest (L = 110 mm, 80–108 (x = 94) μm high and 89–140 (x = 114) μm across the disc) (Figs 9B–C, 10C). In one specimen from Ascension and 10 specimens from Cape Verde the most common tables at the top of the papillae regular Isostichopus tables, but larger and stouter, more square profile than those of the middle and the base of the papillae (top papillae: 58–86 μm high (x = 71 µm) and 62–95 (x = 80) μm across the disc) (Figs 9B–C, 10C). Toward the papilla base modified maculatus tables absent, regular Isostichopus tables present, more numerous and decreasing in size toward the base, the latter with sizes similar to tables from the body wall. Large, regular Isostichopus tables at the middle of the papillae (50–78 (x = 60) μm high and 51–67 (x = 59) µm across disc) composed of four pillars slightly constricted proximally to the disc; one crossbeam connecting adjacent pillars; pillars ending in triplets of spines forming a crown with a middle hole; disc margins smooth and wide, having one rounded central perforation and 8 to 12 peripheral holes, usually arranged in one simple ring; tables nearest to the top of the papillae with 4 to 7 extra perforations. Few perforated plates, located in the top of the papillae, with few large perforations, larger in the center, 104–121 µm across. Slightly curved rods 228–317 µm long, usually with quadrangular extentions distributed mostly in the central part, occasionally perforated (Fig. 13A).
Dorsal body wall with numerous tables and a few C-shaped ossicles (Figs 10C, 13A). Regular Isostichopus tables similar to those in the middle and the base of the papillae, but smaller, 38–51 (x = 43) µm high and 43–60 (x = 48) µm across the disc, usually with perforations arranged in one simple ring. Few C-shaped ossicles (49–58 µm), scarce in the neotype, more common in the neoparatype; S-shaped ossicles not observed.
Pedicels with tables, thin C-shaped rods, perforated plates, large, curved rods and end plates (Fig. 13B). Few C-shaped deposits 79–81 µm long in the neotype, but more common 47–78 μm long in the neoparatype. Numerous small, regular Isostichopus tables 24–35 (x = 29) μm high and 36–54 (x = 49) µm across the disc; shape of the tables similar to those from median dorsal papillae and body wall. Numerous elongated perforated plates (195–282 µm), with numerous perforations larger and elongated in the center of the plate; slightly curved rods (300–389 µm), usually with perforated central expansions; end plates 638 µm across.
Ventral body wall only with tables similar to those from pedicels, 32–41 (x = 37) µm high and 36–49 (x = 43) µm across disc; no C-shaped ossicles.
Tentacles with tables and rods (Fig. 13C). Few table ossicles 38–42 μm across disc; spire low, composed of four incomplete pillars that usually are not joined at the top, without crossbeams connecting adjacent pillars, discs having a big and not rounded central perforation, usually with four peripheral perforations, margins spinous and thin; some tables in the neoparatype (36–51 μm long) with complete single ring of holes when situated at the base of the tentacles. Numerous strongly curved spiny rods 50–284 µm long.
Mouth membrane with tables, C-shaped rods, and simple rods (Fig. 11C). Numerous large tables 71– 97 µm across disc; spire low, composed of four incomplete pillars that usually are not joined at the top and end in some small spines, without crossbeams connecting adjacent pillars; discs having a large and not rounded central perforation, appearing as four perforations from dorsal view, usually with one or two rings of holes irregularly arranged, margins spinous and thin; numerous C-shaped deposits (38–55 µm); numerous small rods (48–81 µm).
Longitudinal muscle with small rods (46–68 µm) (Fig. 13D). Thin C-shaped rods in the neoparatype (26– 38 μm), absent in the neotype. Posterior cloaca with spinous rods simple or bifurcated (110–192 µm); spinous, irregular plate-like branched rods, 84–203 µm across; no C-shaped deposits (Figs 11C, 13E). Anterior cloaca with large tables 83–137 µm high and 109–208 µm across the disc (Fig. 11C). Respiratory trees with spinous rods, simple or bifurcated (91–157 µm); no table ossicles (Fig. 13F). Intestine with cross-shaped rods, sometimes with bifurcated ends (48–91 µm long), spinose or smooth (Fig. 13G). Gonads, with delicate and long spiny rods (169–256 µm) (Figs 11C, 13H); a few table ossicles in the neotype, one table ossicle 50 μm across the disc, spire low and incomplete.
Distribution
Isostichopus maculatus maculatus was only known from Rolas Island, São Tomé and Príncipe, Gulf of Guinea in the East Atlantic. We extend its geographical distribution to the tropical and subtropical East and Mid Atlantic, as there are confirmed specimens from Ascension Island, Cape Verde Archipelago, São Tomé and Príncipe, Senegal, Sierra Leone, Liberia, Nigeria, and Gabon (Fig. 5A) (Cherbonnier 1975; Pawson 1978; Pérez-Ruzafa et al. 1999, 2003; Entrambasaguas 2008; Entrambasaguas et al. 2008, as I. badionotus; Wirtz et al. 2020, as Isostichopus cf. badionotus). Specimens recorded by Pawson (1978) from Ascension Island as I. badionotus are designated here as neotype and neoparatype of I. maculatus maculatus. Bathymetric distribution: intertidal to 40 m (Purcell et al. 2023).
Habitat
Isostichopus maculatus maculatus is common in shallow habitats in the Mid and East Atlantic as reported by Pawson (1978), Pérez-Ruzafa et al. (1999, 2003), Entrambasaguas (2008), Entrambasaguas et al. (2008), Wirtz et al. (2020) and Purcell et al. (2023). In Ascension, I. maculatus lives exposed on sand or rock but is not common intertidally (Pawson 1978). In the Cape Verde Archipelago it is reported that adults (L = 150–200 mm) live completely exposed on mud, sand or rock bottoms, although they can also be found in cracks or under rocks (Entrambasaguas 2008). The species was recorded at most islands in the Cape Verde Archipelago, but not at São Antao and Santa Luzia. Where present, I. maculatus maculatus was very abundant and was one of the species that “were well correlated with some variables indicating heterogeneous (with an important proportion of algal cover and sand) and/ or complex habitats (determined by small and medium-sized boulders)” (Entrambasaguas et al. 2008). Feeding activity begins in the afternoon and peaks before midnight. Juveniles are usually located under gravel or slabs of coral, in isolation or aggregated (Perez-Ruzafa et al. 1999; Entrambasaguas 2008). Purcell et al. (2023) found this this species on sandy or rocky substrates and refuging under rocks and in crevices in Cape Verde. Observations made in Ilha do Principe, São Tomé and Príncipe in April–June 2016, found it to be common in shallow marine habitats, composed of volcanic rocks; the individuals were in crevices during the day and moved to nearby soft bottoms during the night (R. Haroun pers. com.). In subsequent sampling efforts in October–November 2016, the species was rarer than in April– June. At one locality where specimens were common at 1–3 m depth during April–June, they were only encountered at 15–25 m in October–November. The probable reason was excessive fishing for sale to the Chinese market (R. Haroun pers. com.). In Liberia, this species occurs mostly on reefs with large boulders (Purcell et al. 2023).
Remarks
Even though specimens of the African coasts and its neighboring islands were not examined by Clark (1922), he synonymized Stichopus assimilis from Angola and Stichopus maculatus from São Tomé under S. badionotus. He considered that there was nothing in the original descriptions that would justify their status as separate species. We examined the holotype of S. assimilis at the Natural History Museum of London (ZOO 1873.7.29.1) and determined that it belongs to the genus Holothuria, subgenus Holothuria, considering external morphology and ossicles (Fig. 12E–G). Although the types of S. maculatus were not found, several elements of evidence allowed us to resurrect I. maculatus and to designate the specimen USNM E16150 as the neotype and USNM E16151 as neoparatype. English Bay, Ascension Island is the new type locality, according to article 76.3 of the ICZN Code (1999). Attempts to obtain specimens of I. maculatus maculatus from São Tomé, were not successful, and neither was the attempt to examine at the Muséum national d’Histoire naturelle, Paris, the specimen described by Cherbonnier (1975). Greeff’s (1882) original description of this species is short and not accompanied by drawings of ossicles. However, coloration was considered by Greeff as an important diagnostic character. He described it as chocolate-brown in the background with numerous larger irregular yellow spots, and whitish round spots as white granules. Although the coloration was highly variable in the specimens we examined, the “whitish round spots as white granules” were a common pattern (Fig. 14). Cherbonnier (1975) examined one specimen of Isostichopus collected near São Tomé, the original type locality of I. maculatus, and concluded that it corresponds with the description of Greeff, but he also agreed with Clark (1922) in accepting S. maculatus as a synonym of S. badionotus. Cherbonnier (1975) observed a perfect match of ossicles of the São Tomé specimen and the ossicles of S. badionotus, except for some large tables from its dorsal papillae, which were twice as large as tables of S. badionotus. This is the kind of tables considered here as modified “ maculatus ” tables. These tables had a slenderer spire or pillars with some rough edges and ended with some blunt spines instead of a regular crown (Cherbonnier 1975: 632, fig. 1a–c, e). mtDNA sequences from our specimens and their ossicles, including the specimens reported by Pawson (1978) from Ascension (designated here as neotype and neoparatype), indicated that the table differences reported by Cherbonnier (1975) are not due to intraspecific variability in I. badionotus, but to interspecific differences. Tables of dorsal papillae in I. maculatus maculatus are of two shapes, the regular Isostichopus tables and the modified “ maculatus ” tables (Figs 2A–B, D, 13A). The regular Isostichopus tables in this species are the largest in the genus (in height and disc diameter) (Figs 9B–C, 10C, 13A); they are similar in size to those of I. badionotus only in the body wall. The coexistence in the dorsal body wall of two kinds of tables can lead to confusion in identification. The regular Isostichopus tables are located in the middle and the base of the papillae and in the body wall, whereas the modified “ maculatus ” tables, when present, are located at the top of the papillae. Perhaps because of their location, and of their absence in some specimens, neither Pawson (1978), Pérez-Ruzafa et al. (1999), or Entrambasaguas (2008) have recorded them.
Examination of three specimens (and several without measurements) of I. maculatus maculatus, from 55 mm to 150 mm long, showed that ossicles become more abundant in the largest specimens. No dramatic changes in size and shape were observed in the modified “ maculatus ” tables during ontogeny, but fewer regular Isostichopus tables with smallest discs were observed in the 55 mm long specimens in comparison to those from 110 mm. Entrambasaguas (2008) described a higher and slightly tapered spire in a 19 mm juvenile (HO 1028), a very small size not examined by us. C-shaped rods in this subspecies are less abundant than in the other species of Isostichopus. C-shaped rods are fewer in the neotype and more frequent in the neoparatype.
Biology
Purcell et al. (2023) reported that this species is mostly nocturnal, hiding during the day and foraging at night. These authors also report a reproductive season in late summer, when seawater is warmest.
Conservation status
As a species previously synonymized with I. badionotus, and currently recognized as a subspecies of a different species, it has not been included in the IUCN Red List of Threatened Species. Nuno et al. (2015) recorded an increasing harvest of sea cucumbers in the eastern Atlantic for the international trade, but presented no details as to the species, locality, and removed quantities. It has been reported that I. maculatus maculatus is being illegally fished in Ilha do Principe, São Tomé, even though the government issued a law in November 2016 to completely ban the fishing of this species (R. Haroun pers. com.). Recently, the species was included in the FAO catalog of commercially important sea cucumbers of the world (Purcell et al. 2023, as Isostichopus sp. ‘ maculatus ’) as a high-value species in Asian dried seafood markets. Trading is reported in Liberia and Sierra Leone, where it is sold by fishermen for US $ 1.75 kg-1 for fresh sea cucumbers, and US $ 50–150 kg-1 for dried animals. Average price of dried I. maculatus maculatus in Hong Kong, China SAR markets ranged from US $ 930 to 1237 kg-1 (Purcell et al. 2023). In Liberia there has been a legal fishery by holders of government-issued fishing licenses since 2021. The sea cucumbers are harvested by hookah divers from inshore reefs, catching 130–150 kg per diver per night in 2016, declining to 50–60 kg per diver per night by 2021 (Purcell et al. 2023). In Cape Verde there has also been a legal fishery since 2021 when fishing and trading was permitted by government regulations. Records from December 2020 to April 2021 (when the fishery was illegal), reported harvests of 2.7 tons (average catch rate of 37 kg per diver per night). The species is now found at depths of 30 to 40 m, perhaps due to fishing pressure in shallow waters (Purcell et al. 2023). Potential fishery interest in the species has been reported in Nigeria (Fig. 14P) (Solís-Marín pers. com.). Conservation status of this subspecies is unknown. The current geographic distribution could be considered as restricted, which is a new criterion for its inclusion in the IUCN Red List.
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 41-49, DOI: 10.5852/ejt.2024.949.2641, http://zenodo.org/record/13710645