Introduction
The class Ophiuroidea, the most diverse group within the phylum Echinodermata, comprises approximately 2,466 species (Stöhr et al., Reference Stöhr, O’Hara and Thuy2025). Its distribution is remarkably broad, ranging from equatorial to polar regions and from intertidal zones to abyssal depths (O´Hara et al., Reference O´Hara, Hugall, Thuy and Moussalli2014; Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018). The family Amphiuridae (Ljungman, 1867) the largest within the class, contains 477 species in 28 genera (Stöhr et al., Reference Stöhr, O’Hara and Thuy2025). Amphiuridae dominates tropical and temperate environments, inhabiting both shallow and deep zones (Stöhr Reference Stöhr2012). These organisms are characterized by their delicate structures and remarkably elongated arms (Hendler et al., Reference Hendler, Miller, Pawson and Kier1995; Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018). They inhabit soft sediments, where they constitute a component of the infauna and are typically present in substantial quantities (Hendler et al., Reference Hendler, Miller, Pawson and Kier1995; O’Hara and Byrne Reference O’Hara and Byrne2017).
In Colombia, studies on Ophiuroidea are limited, particularly on the family Amphiuridae, due to its high taxonomic complexity, morphological plasticity, and frequent misidentifications errors (Chagas Reference Chagas2018). Despite these challenges, 17 species of Amphiuridae, have been documented in the Colombian Caribbean corresponding to the genera Amphiura, Amphipholis, Ophionephthys, Amphiodia, Amphioplus, Ophiophragmus, Ophiostigma, and Microphiopholis (Benavides-Serrato et al., Reference Benavides-Serrato, Borrero-Pérez and Díaz Sánchez2011; Borrero-Pérez et al., Reference Borrero-Pérez, Benavides-Serrato, Campos, Galeano-Galeano, Gavio, Medina and Abril-Howard2019).
The genus Ophiophragmus is distinguished from other genera within the family Amphiuridae by a ring of papillae at the edge of the disc, constituting its most striking character (Chagas Reference Chagas2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020). The classification currently includes 18 species worldwide (Stöhr et al., Reference Stöhr, O’Hara and Thuy2025). Within the genus, Ophiophragmus luetkeni stands out for its intraspecific variations (Borges and Amaral Reference Borges, Amaral, Amaral, Rizzo and Arruda2005; Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020; Prata et al., Reference Prata, Stevenson, Silva, Lima and Christoffersen2020). For identification, the following distinctive characteristics are noted: (1) small, imbricated scales, approximately 17 between the middle-dorsal part and the edge of the disc, (2) radial shields that are longer than they are wide and separated by one to three scales, and (3) dorsal plates that may be fragmented on one or all of its arms (Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020).
Ophiophragmus luetkeni (Ljungman Reference Ljungman1872) has a wide distribution in the Atlantic Ocean, including the British Virgins Islands (type locality), the United States Virgin Islands, Trinidad and Tobago, and Brazil (Ljungman Reference Ljungman1872; Tommasi Reference Tommasi1970; Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020; Prata et al., Reference Prata, Stevenson, Silva, Lima and Christoffersen2020; ). This species occurs at low densities and, inhabits soft substrates such as sandy, silty, and muddy bottoms at depths ranging from the intertidal zone to 50 m (Borges Reference Borges2006; Alvarado and Solís-Marín Reference Alvarado and Solís-Marín2013; Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020; Prata et al., Reference Prata, Stevenson, Silva, Lima and Christoffersen2020). Although known to occur in tropical and subtropical Atlantic waters, its presence in Colombia had not been previously confirmed. This study documents the first record of O. luetkeni in the Colombian Caribbean, specifically in the shallow waters of the southern Gulf of Morrosquillo, a region characterized by soft substrates rich in organic matter (Quirós-Rodríguez Reference Quirós-Rodríguez2015; Nisperuza Pérez et al., Reference Nisperuza Pérez, Padilla Cantero and Quirós-Rodríguez2018). These findings, supported by comparisons with previous descriptions, confirm the species identity and significantly expand its geographic range, validating this new record for Colombia.
Materials and methods
Four specimens of O. luetkeni were collected at the Ahumadera locality, Cispatá Bay, Gulf of Morrosquillo region, Colombia (DMS, 9.40993 N, –75.79298 W) (Figures 1 and 2). This area is characterized by a precipitation regime with a unimodal bi-seasonal pattern, including dry and rainy seasons (Quirós-Rodríguez Reference Quirós-Rodríguez2015; Nisperuza Pérez et al., Reference Nisperuza Pérez, Padilla Cantero and Quirós-Rodríguez2018). The substrate is predominantly composed of soft sand, muddy bottoms, and seagrass meadows (Figure 2), with a generally flat relief not exceeding 10 m in depth (Quirós-Rodríguez Reference Quirós-Rodríguez2015).
Distribution map of Ophiophragmus luetkeni. Previous records are indicated by yellow triangles, while the new record from Colombia is marked with a red star.
Location where Ophiophragmus luetkeni is recorded for the first time for the Colombia (A) Overview of the Ahumadera- Bay of Cispatá, Córdoba; (B, C) soft bottoms (D) seagrasses.
Specimens were collected during field trips conducted by the Biology Program of the University of Córdoba, Colombia, between 2023 and 2024 at a depths between 0.5 and 1.5 m using a nucleator. After collection, the specimens were anesthetized using magnesium sulphate, then fixed and preserved using 75% ethanol following the methodology described by Martínez-Melo et al., (Reference Martínez-Melo, Ríos Jara, Solís Marín, Galván Villa, Buitrón Sánchez and Laguarda Figueras2018). The specimens were photographed and examined under a Luxeo 6Z stereoscope equipped with a built in digital camera. The specimens were compared with the original description of O. luetkeni and also with keys and descriptions from the studies by Alitto et al. (Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018), Chagas et al. (Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020), and Prata et al. (Reference Prata, Stevenson, Silva, Lima and Christoffersen2020). The specimens are stored at the Laboratory Zoological Collections (LZUC) at the University of Córdoba, Colombia.
For detailed studies of the arm ossicles using Scanning Electron Microscopy (SEM), a fragment of one arm, between the second and tenth segments, was used (Stöhr et al., Reference Stöhr, Conand and Boissin2008; Chagas Reference Chagas2018; Rosales-Contreras et al., Reference Rosales-Contreras, Laguarda-Figueras and Solís-Marín2021). The fragment was immersed in a solution of sodium hypochlorite (NaClO) to remove soft tissue (Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Rosales-Contreras et al., Reference Rosales-Contreras, Laguarda-Figueras and Solís-Marín2021). After disarticulation, the plates were dehydrated through a series of steps, including rinsing with running water, distilled water, and 95% ethanol. The disarticulated ossicles were then prepared and mounted for observation under a JEOL JSM-7100 F Scanning Electron Microscope.
Results
Class Ophiuroidea (Gray, 1840)
Order Amphilepidida (O’Hara, Hugall, Thuy, Stöhr & Martynov, Reference O’Hara, Hugall, Thuy, Stöhr and Martynov2017)
Family Amphiuridae (Ljungman, 1867)
Genus Ophiophragmus (Lyman, 1865)
Ophiophragmus luetkeni (Ljungman, 1872)
Amphipholis Lütkeni (Ljungman 1872: 636)
Ophiophragmus luetkeni Tommasi (Reference Tommasi1970): 31; Monteiro Reference Monteiro1987): 88; Borges and Amaral (Reference Borges, Amaral, Amaral, Rizzo and Arruda2005): 269; Borges (Reference Borges2006): 51; Manso et al., (Reference Manso, Alves and Martins2008): 193; Alitto et al., (Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018): 24; Chagas et al., (Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020): 13; Prata et al., (Reference Prata, Stevenson, Silva, Lima and Christoffersen2020): 7.
Type locality: Tortola Island, British Virgin Islands (United Kingdom) (Ljungman Reference Ljungman1872).
Examined material: Four specimens from the Ahumadera (DMS, 9.40993 N, 75.79298 W), Cispatá Bay, Colombia, between 0.5 and 1 m depth, collected by nucleator. LZUC-ECH 029, 1 specimen (disk diameter (dd): 8.2 mm), August 28, 2023; LZUC-ECH 030, 1 specimen (dd: 11.8 mm), August 28, 2023; LZUC-ECH 031, 1 specimen (dd: 8.5 mm), June 3, 2024; LZUC-ECH 032, 1 specimen (dd: 8.7 mm), November 9, 2024.
Description: (LZUC-ECH 030): Disc (dd: 8.5 mm) circular, covered with numerous imbricated scales, approximately 18 between the centrodorsal and disc margin (Figure 3A). Radial shields twice as long as wide, with a straight inner edge and a curved outer edge, pointed proximally, separated by one or two scales (Figure 3A). Disc margin with a fence of elongated and pointed papillae (Figure 3A, 3C). Ventral interradial area covered with numerous imbricated scales, smaller than those in the dorsal view (Figure 3B). Bursal slits long and narrow, extending over eight or nine arm segments (Figure 3B). Oral shield spearhead-shaped, slightly rounded distally and triangular proximally (Figure 3D). Madreporite larger than the oral shields, longer than wide, triangular proximally and rounded distally (Figure 3D). Adoral shields, wider distally and in contact proximally (Figure 3D). Adoral shield spine (AdShSp) rounded and larger than the second (2AdShSp), a pair of rectangular infradental papillae (IPa) at the apex of the oral plate (Figure 3D). Dorsal arm plates, three times as wide as long, rectangular, distally convex and with rounded lateral edges, contiguous, and some arms fragmented from the second segment (Figure 3E). Ventral arm plates, twice as wide as long, rectangular to square, straight distally, slightly pointed proximally, contiguous (Figure 3F). Two tentacle scales of similar size (Figure 3F). Lateral arm plates, with three pointed arm spines, all of same size (Figure 3F). Its coloration is brown.
Ophiophragmus luetkeni (LZUC- ECH 030, dd: 8.5 mm) (A) dorsal view of specimen; (B) ventral view of specimen; (C) radial shield; (D) jaw; (E) dorsal view of arm; (F) ventral view of arm. Abbreviations: Rs: radial shields; P: disk edge papillae; Vap-1: first ventral plate; Ma: madreporite; OSh: oral shields; AdSh: adoral shields; AdShSp: adoral shield spine; 2AdShSp: second adoral shield spine; IPa: infradental papillae; T: teeth; Dap: dorsal arm plates; Vap: ventral arm plates; Ts: tentacular scale; As: spine.
Disarticulated ossicles (LZUC-ECH 030): Dorsal arm plate twice as wide as long, proximal edge convex, distal margin concave (Figure 4A). Ventral arm plate twice as wide as long, proximal edge pointed and distal edge indented (Figure 4B). Lateral arm plates (Figure 4C, D) twice as long as wide, ventral portion protruding ventro-proximal. Three similar spine articulations on distal surface, distance between spine articulations increasing dorsalwards. Lobes separated, distal lobe larger than the ventral. Massive stereom and no sigmoid fold is present. Ventral surface with a large ridge.
Ophiophragmus luetkeni (LZUC- ECH 030) (A) dorsal arm plate; (B) ventral arm plate; (C, D) lateral arm plate; (E) proximal vertebra surface; (F) distal vertebra surface; (G) dorsal vertebra surface; (H) ventral vertebra surface. Abbreviations: d: dorsal; dp: dorso proximal; ddi: dorso distal; ddmf: dorso distal muscle pits; di: distal; dp: dorso proximal; p: proximal; v; ventral; vp; ventro proximal; vdi: ventro distal; vma: ventral muscle area; zd; zygocondile; zp: zygophene. SEM: scale: 100 µm.
Vertebrae zygospondylous without a keel. Proximal part of the vertebrae lacks a large groove in the dorso-distal muscular fossa (Figure 4E). Zygosphene converges dorsally with a pair of zygocondyles (Figure 4F). Muscular fossa in the dorso-distal region located anterior to distal edge of the zygocondyles (Figure 4G). Zygosphene extends beyond the ventral edge of the zygocondyles, forming a projection longer than the zygocondyles themselves (Figure 4H).
Taxonomic comments: Only two species of the genus Ophiophragmus had been recorded in the Colombian Caribbean, Ophiophragmus septus (Lütken, 1859) and Ophiophragmus pulcher (H.L. Clark, 1918) (Benavides-Serrato et al., Reference Benavides-Serrato, Borrero-Pérez and Díaz Sánchez2011; Alvarado and Solís-Marín Reference Alvarado and Solís-Marín2013; Borrero-Pérez et al., Reference Borrero-Pérez, Benavides-Serrato, Campos, Galeano-Galeano, Gavio, Medina and Abril-Howard2019). The presence of O. septus has been recorded for the Guajira ecoregion, specifically for Cabo of the Vela (Thomas Reference Thomas1962; Benavides-Serrato et al., Reference Benavides-Serrato, Borrero-Pérez and Díaz Sánchez2011), while O. pulcher has been recorded in the San Andres ecoregion, specifically in the San Andres, Providencia, and Santa Catalina regions (Borrero-Pérez et al., Reference Borrero-Pérez, Benavides-Serrato, Campos, Galeano-Galeano, Gavio, Medina and Abril-Howard2019). Another species that has been documented in the Colombian Caribbean region is Ophiophragmus riisei (Lütken, 1859) (Gondim et al., Reference Gondim, Alonso, Dias, Manso and Christoffersen2013), although it is currently classified under the genus Amphiodia (Stöhr et al., Reference Stöhr, O’Hara and Thuy2025). It is important to mention the necessity for a comprehensive revision of this species complex group (Gondim et al., Reference Gondim, Alonso, Dias, Manso and Christoffersen2013). According to the studies by Vélez (2003) and Chagas et al., (Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020), O. luetkeni is distinguished from O. pulcher and O. septus by a unique combination of morphologies. While it shares a circular disc with O. pulcher, it is distinguished by its imbricate dorsal scales (as opposed to their irregular scales in O. pulcher). The presence of elongated and pointed papillae on the disc margin is a distinctive feature of O. luetkeni. Additionally, the shape and early fragmentation of its dorsal arm plates contrast with the morphology and lack of fragmentation observed in O. pulcher, and with the contiguous plates and dark dorsal line present in O. septus. It is important to note that all examined specimens of O. luetkeni presented all or most of their arms with fragmented dorsal plates from the second and third segments. The main differences among the three Ophiophragmus species recorded for the Colombian Caribbean are summarized in Table 1. Ophiophragmus luetkeni is frequently misidentified as Ophiophragmus filograneus (Lyman, 1875), a species that is also distributed along the Atlantic coast, including Florida and Brazil (Thomas Reference Thomas1962; Alvarado and Solís-Marín Reference Alvarado and Solís-Marín2013). A distinguishing character that sets, O. filograneus apart is the presence of papilliform granules on the ventral disc, in contrast to the imbricate scales of O. luetkeni (Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020).
Differences between the three species of Ophiophragmus recorded for the Colombian Caribbean. Ophiophragmus luetkeni is a new record for Colombia
Remarks: Only four specimens of O. luetkeni were collected during the course of this study. Alitto et al. (Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018) and Chagas et al. (Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020) suggest that the species is frequently found at low densities. The low density and lifestyle of the species suggest that it is a gregarious species; however, it is recommended that more collections be made in this and other areas to confirm this hypothesis. Its typical habitat includes muddy, sandy, and silty bottoms with seagrasses (Borges and Amaral Reference Borges, Amaral, Amaral, Rizzo and Arruda2005; Manso et al., Reference Manso, Alves and Martins2008; Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020; Prata et al., Reference Prata, Stevenson, Silva, Lima and Christoffersen2020). In this study, the species was exclusively found in sandy bottoms.
Distribution: Atlantic Ocean: British Virgin Islands, United States (Virgin Islands), Trinidad and Tobago, and Brazil (Ljungman Reference Ljungman1872; Tommasi Reference Tommasi1970; Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020; Prata et al., Reference Prata, Stevenson, Silva, Lima and Christoffersen2020). The first record for the Colombian Caribbean, specifically in Cispatá Bay, the Ahumadera sector (Figures 1 and 2).
Bathymetry: Depths ranging from the intertidal to 50 m (Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020). In this study, the specimens were found between 0.5 and 1.5 m depth.
Discussion
The failure to establish diagnostic characters in certain genera within the family Amphiuridae has led to a state of confusion over time. For instance, O. luetkeni was initially described as Amphipholis lütkeni by Ljungman in 1872. Subsequently, research revealed that distinctive features of Ophiophragmus is the fence of papillae surrounding the margin of the disc (Fell Reference Fell1960). Consequently, a taxonomic reclassification of the species was needed, resulting in its reidentification as Ophiophragmus. Subsequent studies have been conducted to ascertain additional diagnostic characteristics that can differentiate Ophiophragmus from closely related genera, such as Amphipholis and Amphiodia (Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020).
Due to the tendency of amphiurid specimens to lose their discs under stress, reliable identification often requires the examination of additional diagnostic features, particularly the dorsal and ventral arm plates, as well as detailed arm microstructures. These microstructures not only offer insights into phylogenetic relationships but also serve as a robust foundation for taxonomic delimitation (Stöhr Reference Stöhr2024). However, the high degree of phenotypic plasticity observed in this group limits the utility of traditional morphological descriptions. Consequently, the integration of advanced imaging techniques, such as SEM, has become essential for accurate taxonomic resolution (Thuy and Stöhr Reference Thuy and Stöhr2011, Reference Thuy and Stöhr2016; Stöhr Reference Stöhr2024). In the case of O. luetkeni, detailed SEM analyses of arm joint microstructures – particularly the lateral arm plates – have revealed key characteristics that are critical for informed taxonomic assessment (Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020).
The characterization of external morphology, traditionally used in the taxonomy of Ophiuroidea, and the use of more modern tools such as SEM have been demonstrated to be highly effective in the systematic study and differentiation of species (O´ Hara et al., Reference O’Hara, Hugall, Thuy, Stöhr and Martynov2017; Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas Reference Chagas2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020). The implementation of these tools during the present study facilitated the identification and incorporation of new external and internal diagnostic characters for O. luetkeni. For example, the species exhibits small and imbricated scales on its disc, a circle of elongated, pointed marginal papillae, a pointed radial shield on the proximal part, and separation by one to three scales. In its ventral part, smaller scales are present, and fragmented dorsal plates are observed on most of its arms. The microstructures of the lateral plate generated additional information, including (1) articular tubercules of similar size, (2) the distance between the articular tubercules of the column increases dorsally, (3) lobes of equal size that increase in size towards the dorsal part, (4) stereoma without perforations, (5) internal surface with two separate central protuberances, (6) no additional dorsal structure on the inner surface, and (7) a single large perforation on the inner surface.
The new record of O. luetkeni in Colombia, specifically in the southern Gulf of Morrosquillo region, expands our knowledge of the country´s biodiversity, particularly within the context of the Colombian Caribbean. Previously, only two species of this genus had been reported in the region: O. septus and O. pulcher (Benavides-Serrato et al., Reference Benavides-Serrato, Borrero-Pérez and Díaz Sánchez2011; Borrero-Pérez et al., Reference Borrero-Pérez, Benavides-Serrato, Campos, Galeano-Galeano, Gavio, Medina and Abril-Howard2019). The new finding increases the total number of Ophiophragmus species documented in the Colombian Caribbean to three.
Ophiophragmus luetkeni inhabits specific habitats and it is frequently associated with sandy and muddy substrates, which provide optimal food resources (Alitto et al., Reference Alitto, Bueno, Guilherme, Di Domenico, Christensen and Borges2018; Chagas et al., Reference Chagas, Alitto, Serrano, Granadier, Guilherme and Borges2020; Prata et al., Reference Prata, Stevenson, Silva, Lima and Christoffersen2020). These substrates are consistent with the documented occurrences of other species within the genus and are fundamental for understanding its distribution and ecology. Consequently, it is recommended to increase the number of samplings in soft substrates, as these environments may contain a higher number of records and potentially new species.
Acknowledgements
The authors thank the Vice-Rectory for Research and Extension of the University of Córdoba (Colombia). Special recognition is extended to Tania Jiménez, Ramón Hernandez, Jorge Murcia, Nixón Londoño, Luis Pérez, Tomás Ladeuth, and the Association of Fishermen of Maritime Transport and Tourist Services of Cispatá (TURIMARPEC) for their support in the logistics of the field phase. We would also like to thank ITM campus Fraternidad, Medellín, especially Claudia Betancourt for her services in microscopy. We also thank the reviewers and the Editorial Committee for their valuable contributions.
Author contributions
JDSG and CANP drafted the manuscript and collected the O. luetkeni specimens. JAQR contributed to the writing of the manuscript and took photographs. TEP identified the collected material and contributed to the manuscript preparation.
Financial support
The authors thank the Vice-Rectory for Research and Extension of the University of Córdoba (Colombia) for funding this work (code SI-FCB-03-23).
Conflict of interest
The authors declare no conflict of interest.
Data availability
All relevant data are included in this contribution.
