Research Article |
Corresponding author: Francisco Alonso Solís-Marín ( fasolis@cmarl.unam.mx ) Academic editor: Yves Samyn
© 2019 Francisco Alonso Solís-Marín, Carlos Andrés Conejeros-Vargas, Andrea Alejandra Caballero-Ochoa, Julio Adrian Arriaga-Ochoa.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Solís-Marín FA, Conejeros-Vargas CA, Caballero-Ochoa AA, Arriaga-Ochoa JA (2019) Epitomapta simentalae sp. n., a new species of apodous sea cucumber from the Central Eastern Pacific coast of Mexico (Echinodermata, Holothuroidea, Apodida). ZooKeys 817: 1-9. https://doi.org/10.3897/zookeys.817.29406
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Epitomapta simentalae sp. n. occurs in depths of 4–10 m off the Mexican Central Pacific coast. It is distinctive in having twelve tentacles, each tentacle with two or three pairs of digits and four to six sensory cups, lacking papillae or oval bumps and in reaching a maximum length of 50 mm in life.
Epitomapta simentalae sp. n. fue recolectada a profunidades de entre 4–10 m en el Pacífico Central Tropical. Se distingue de sus congéneres por poseer doce tentáculos, cada tentáculo tiene dos o tres pares de dígitos, los cuales a su vez cuentan con cuatro a seis copas sensoriales, no posee papilas o protuberancias ovaladas sobre la superficie del cuerpo y por tener tallas desde los 4 hasta los 50 mm de largo total en ejemplares vivos.
Leptosynaptinae , Synaptidae , Taxonomy
Leptosynaptinae , Synaptidae , Taxonomía
Sea cucumbers of the family Synaptidae (order Apodida), while resolved as a non-monophyletic group in recent molecular analyses (
The genus is represented by three nominal species, including the new one described here. In
Specimens were collected by SCUBA diving (4–10 m depth). They were relaxed in a solution of 4% magnesium chloride and seawater. Fixation was made using 70% ethanol. Ossicles were extracted from the body wall (anterior, medium and posterior region) and tentacles. The tissue was dissolved in fresh household bleach [5–6.5%] in centrifuge tubes. After centrifugation at 1000 rpm for 10 minutes, bleach was pipetted off and the ossicles were rinsed and centrifuged with distilled water that was pipetted off afterwards. The same process was done with 70, 80, and 95% ethanol. Absolute ethanol was added to the ossicles, and finally a small aliquot was taken and placed to dry on a cylindrical double-coated conductive carbon tape stub. Then it was sputter coated with gold 2.5 kV in the ionizer Polaron E3000 for 3 minutes and photographed using a Hitachi S-2460N scanning electron microscope (SEM). Ciliated funnels were detached from the internal body wall using tweezers and dehydrated by critical point drying and placed on a carbon tape stub. Specimens were deposited at the following scientific collections: Colección Nacional de Equinodermos “Dra. Ma. Elena Caso Munoz”, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Ciudad de México and Smithsonian Institution, Natural History Museum, Washington, D.C., United States.
Abbreviations used in the text:
ICML-UNAM Colección Nacional de Equinodermos, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México;
USNM Smithsonian Institution, Washington, D.C., United States Natural History Museum.
Diagnosis.Synaptidae with 10, 11 or 12 pinnate tentacles, with one to nine digits on each side. Digits increase in size from base to tip of tentacle. Anchor plate develops from a rod which lies at a right angle to stock of developing anchor. Anchor plates with small number of holes, usually seven (6+1) in main part of the plate: six holes form a circle around a central hole. Articular end of plate usually has a “ledge” for contact with anchor keel. Anchor arms serrated, rarely naked, and without minute knobs on vertex (
Tentacles pinnate, usually 12. Digits from two to five pairs on each side (rarely two or none). Sense organs never in the form of pigment-eyes, but occur as minute cups on inner face of stalk of tentacles. Calcareous ring well developed. The radial pieces are not perforated for the passage of nerves, but with a notch in the anterior margin. Cartilaginous ring absent. Polian vesicle usually single. Stone canal single, unbranched. Ciliated funnels are of different shapes and are attached to the body wall, not to mesenteries. The calcareous deposits in the body wall are anchors, anchor plates and miliary granules; in the tentacles large rods. Stock of anchors finely toothed, but not branched; arms usually with teeth on the outer edge; vertex smooth. Anchor plates oval or somewhat elongated, with large central hole, surrounded by six large holes, usually more or less dentate, and two large and several small smooth holes at the narrow posterior end, but without an arched bow crossing the outer surface; at the broad end there are often additional dentate holes (modified from
Epitomapta tabogae Heding, 1928 (original designation).
Holotype ICML-UNAM 5.169.0, 19 mm total length (TL), Caleta, Acapulco Bay, Guerrero, Mexico, Pacific Ocean 16°49.812'N, 99°59.062'W, 10 m depth, 8 May 2008, coll. F. A. Solís-Marín.
Paratypes: USNM 1114315, 10 specimens, same data as the holotype; ICML-UNAM 5.169.1, 11 specimens, same data as the holotype; ICML-UNAM 5.169.2, 63 specimens, Caleta, Acapulco Bay, Guerrero, Mexico, Pacific Ocean 16°49.812'N, 99°59.062'W, 10 m depth, 28 October 2006, coll. F. A. Solís-Marín, Y. Yerye, Honey-Escandón, M., A. Martínez Melo; ICML-UNAM 5.169.3, 20 specimens, Caleta, Acapulco Bay, Guerrero, Mexico, Pacific Ocean 16°49'N, 99°59'W, 4 m depth, 2 March 2006, coll. F. A. Solís-Marín, C. S. Frontana Uribe; ICML-UNAM 5.169.4, 27 specimens, Caleta, Acapulco Bay, Guerrero, Mexico, Pacific Ocean 16°49'N, 99°59'W, 9 m depth, 27 September 2006, coll. F. A. Solís-Marín, B. Urbano, M. A. Torres; ICML-UNAM 5.169.5, 5 specimens, Caleta, Acapulco Bay, Guerrero, Mexico, Pacific Ocean 16°49'N, 99°59'W, 8 m depth, 21 March 2009, coll. F. A. Solís-Marín and J.A. Díaz-Jáuregui.
Caleta, Acapulco Bay, Guerrero, Mexico, Pacific Ocean 16°49.812'N, 99°59.062'W.
Body wall smooth, lacking papillae or oval bumps. Tentacles 12, each with two or three pairs of digits and a terminal digit; up to six sensory cups on each tentacle. One Polian vesicle. Stone canal single, unbranched. Anchor and anchor plates of one kind, large, anchors usually exceeding 120 µm in length, plates exceeding 100 µm in length. Miliary granules numerous, in form of C-shaped rods with enlarged ends and O-shaped ossicles present only in the longitudinal muscles. Tentacle ossicles curved spiny rods with perforated ends.
19 mm total length (TL).When preserved is uniformly whitish, body wall translucent when expanded (Fig.
Ossicles. Body wall deposits, anchors, and anchor plates of one kind (Fig.
Paratype variations. Specimens ranges from 4–43 mm TL. Sensory cups vary in number, fewer (2–3) in smaller specimens (4–15 mm TL).
Epitomapta simentalae sp. n. is named in honor of Dr Delia Rosalba Simental Crespo, a scientist, entrepreneur and echinoderm enthusiast, who supports research programs and marine expeditions providing passion, funding, equipment, and travel support to scientists who are involved in research and conservation efforts related to the echinoderms in the Mexican marine waters.
Epitomapta simentalae sp. n. occurs at 4–10 m depth, burrowed approximately 2 cm deep in in well-aerated quartz sand.
Epitomapta simentalae sp. n. is a gonochoric species; females have lecithotrophic eggs between 140 and 150 μm in diameter; ripe gonads occupy about 80% of the celomic cavity. Neither brooding nor external sexual dimorphism was observed.
Epitomapta simentalae sp. n. is very similar to its Caribbean congener E. roseola, differing in the number of pairs of digits present on the tentacles (2–4 in E. roseola and 2–3 in E. simentalae sp. n.), and in the number of sensory cups per tentacle (2–5 in E. roseola and 4–6 in E. simentalae sp. n.). In addition to the geographical distribution, E. simentalae sp. n. is smaller (<50 mm) than E. roseola (30–120 mm) (
Epitomapta simentalae sp. n. clearly differs from E. tabogae and E. roseola in lacking papillae or oval bumps all over its body wall; the number of sensory cups per tentacle (8–14 in E. tabogae and 4–6 in E. simentalae sp. nov), and in the number of pairs of digits present on the tentacles (5–6 in E. tabogae and 2–3 in E. simentalae sp. n.). Epitomapta tabogae is distributed throughout the Gulf of California (
The anchors of the body wall in E. simentalae sp. n. are similar in shape to those of E. roseola, but differ in size, being approximately 90–150 μm length and 70–90 μm width in E. simentalae sp. n. (Fig.
In Epitomapta simentalae sp. n. the anchor plates are 100 μm in length and 90 μm in width.
Epitomapta simentalae sp. n. is clearly distinguished from other species of the genus in lacking papillae or oval bumps in the body wall, a character that had been used to differentiate species of the genus by various authors (see
1 | Papillae or oval bumps present all over the body wall | 2 |
– | Papillae or oval bumps absent. With 2–3 pairs of tentacle digits, each tentacle with 4–6 sensory cups. Miliary granules “C” and “O”–shaped bodies; no papillae or oval bumps present in the body wall | E. simentalae sp. n. |
2 | Atlantic Ocean. With 7 pairs of tentacle digits, each tentacle with 2–5 sensory cups. Anchors of body wall exceed 120 μm in length (up to 150 μm). Miliary granules in the shape of small oval rings and very few C–shaped bodies | E. roseola |
– | Pacific Ocean. With 5–6 pairs of tentacle digits, each tentacle with 8–14 sensory cups. Anchors of body wall exceed 120 μm in length (up to 200 μm). Miliary granules in the shape of oval rings and very few C–shaped bodies | E. tabogae |
The authors thank Dr. Dave L. Pawson (Senior Scientist, Emeritus, Curator of Echinoderms, Smithsonian Institution) and Luciana Martins (Universidade de São Paulo, Museu de Zoologia), for the critical review of this paper. To the SCUBA group who collected the specimens: José Andrés Díaz-Jáuregui, C. Sarita Frontana Uribe, Magali Honey Escandón, Yuri Yerye, Brian Urbano, Alejandra Martínez Melo and Miguel Angel Torres. To Alicia Durán González (ICML, UNAM) for her technical support. Ma. Esther Diupotex (ICML, UNAM) prepared figure 1, Alejandra Martínez Melo prepared figures 2 and 4. We thank Scott D. Whittaker (SEM Lab, Smithsonian Institution) and Berenit Mendoza Garfias (Laboratorio de Microscopía Electrónica, IB, UNAM) for their technical support with the SEM work.