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A new species of Ophiocoma (Echinodermata: Ophiuroidea) from Archipelago Trindade and Martin Vaz, Southeastern Atlantic, and redescription of Ophiocoma echinata

Published online by Cambridge University Press:  10 July 2023

Helena Serrano*
Affiliation:
University of Campinas, Institute of Biology, Museum of Biological Diversity – MDBio – Institute of Biology, State University of Campinas – Zoology Area (ZUEC), Campinas, São Paulo, Brazil
Cecília J. S. Damiano
Affiliation:
University of Campinas, Institute of Biology, Museum of Biological Diversity – MDBio – Institute of Biology, State University of Campinas – Zoology Area (ZUEC), Campinas, São Paulo, Brazil
Renata A. S. Alitto
Affiliation:
School of Education, University of São Paulo, São Paulo, Brazil
Pablo D. B. Guilherme
Affiliation:
Collegiate of Biological Sciences, University of Paraná, Paranaguá, Paraná, Brazil
Walter R. P. Cerqueira
Affiliation:
Department of Biological Sciences, University of Feira de Santana, Feira de Santana, Bahia, Brazil
Joel B. Mendonça
Affiliation:
Zoology Museum, University of São Paulo, São Paulo, Brazil
Marcos Tavares
Affiliation:
Zoology Museum, University of São Paulo, São Paulo, Brazil
Michela Borges
Affiliation:
University of Campinas, Institute of Biology, Museum of Biological Diversity – MDBio – Institute of Biology, State University of Campinas – Zoology Area (ZUEC), Campinas, São Paulo, Brazil
*
Corresponding author: Helena Serrano; Email: helenasrn92@gmail.com
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Abstract

The brittle stars of the family Ophiocomidae inhabit shallow waters and coral reefs of tropical regions. The species of Ophiocoma are difficult to identify due to high morphological variation, especially when different stages of development are observed. Here, based on morphological analyses, two Brazilian morphotypes of Ophiocoma were studied and characterized, Ophiocoma sp. NB (Northeastern Brazil) and Ophiocoma sp. TMV (Trindade and Martin Vaz Archipelago), and subsequently thoroughly analysed to confirm whether they were the same species or not. After the morphological studies, including external morphology, morphometry and microstructural characters, and analysis of molecular data, involving the 16S gene, it was concluded that Ophiocoma sp. NB and Ophiocoma sp. TMV do not correspond to the same species, the first being identified as Ophiocoma echinata (Lamarck, 1816) and the latter being a new species. This new species is characterized by two tentacle scales on the first arm segment and then one on all following segments, and the dorsalmost arm spines are robust and rounded, as wide as long or almost as wide as long.

Information

Type
Marine Record
Copyright
Copyright © The Author(s), 2023. Published by Cambridge University Press on behalf of Marine Biological Association of the United Kingdom
Figure 0

Figure 1. Study areas: Trindade Island and Martin Vaz Archipelago, Espírito Santo and Itapuã Beach, Bahia.

Figure 1

Figure 2. Main characters used in the description: (A) dorsal view; (B) ventral view; (C) detail of dorsal arm; (D) detail of ventral arm; (E) oral plate – abradial and adradial; (F) vertebrae ossicle – proximal surface; (G) vertebrae ossicle – distal surface; (H) vertebrae ossicle – dorsal surface; (I) vertebrae ossicle – ventral surface; (J) lateral arm plate – outer and inner side. 2° AdShSp, secondary adoral shield spine; AdSh, adoral shield; AdShSp, adoral shield spine; d, dorsal; DAP, dorsal arm plate; DASp, dorsalmost arm spine; ddi, dorso-distal; di, distal; dp, dorso-proximal; IPa, infradental papilla; LyOs, Lyman's ossicle; Osh, oral shield; p, proximal; TPa, tooth papilla; TSc, tentacle scale; v, ventral; VAP, ventral arm plate; vdi, ventro-distal; vp, ventro-proximal. Scale bar: stereomicroscope photographs A, 5 mm; B–D, 1 mm; SEM images E–J, 500 μm.

Figure 2

Figure 3. Main characters used in morphometry: (A) dorsal view; (B) detail of the oral view; (C) disc granules; (D) detail of the jaw; (E) detail of dorsal arm; (F) detail of ventral arm. dd, disc diameter; as_l, length of arm spine; as_w, width of arm spine; od, oral diameter; os_l, length of oral shield; os_w, width of oral shield; ads_l, length of adoral shield; ads_w, width of adoral shield; dap_l, length of dorsal arm plate; dap_w, width of dorsal arm plate; vap1_l, length of first ventral arm plate; vap1_w, width of first ventral arm plate; vap2_l, length of second ventral arm plate; vap2_w, width of second ventral arm plate; pp, oral papillae; ts_1, tentacle scale of first arm segment; ts_2, tentacle scale of second arm segment; ts_3, tentacle scale of third arm segment; ts_4, tentacle scale of fourth arm segment. Scale bar: stereomicroscope photographs A and C, 5 mm; B, D, E and F, 1 mm.

Figure 3

Table 1. Abbreviations and definitions of morphological characters measured for morphometric analysis

Figure 4

Table 2. GenBank access number for DNA sequences used for phylogenetic analyses

Figure 5

Figure 4. Linear discriminant analysis (LDA) analysis based on 20 morphological variables (described in Table 1) from two morphotypes: Ophiocoma sp. TMV and Ophiocoma sp. NB. (A) Histogram of the LDA scores; (B) density plot of the values of the discriminant function for the samples from different morphotypes. dd, disc diameter; disc_granule, granules of disc; as_l, length of arm spine; as_w, width of arm spine; as, arm spine of first segment; as2, arm spine of second segment; as3, arm spine of third segment; as10, arm spine of tenth segment; od, oral diameter; os_l, length of oral shield; os_w, width of oral shield; ads_l, length of adoral shield; ads_w, width of adoral shield; dap_l, length of dorsal arm plate; dap_w, width of dorsal arm plate; vap1_l, length of first ventral arm plate; vap1_w, width of first ventral arm plate; vap2_l, length of second ventral arm plate; vap2_w, width of second ventral arm plate; pp, oral papillae.

Figure 6

Figure 5. Boxplots generated by the LDA analysis of two morphotypes: Ophiocoma sp. TMV and Ophiocoma sp. NB. Boxplot of positive morphological variables: (A) vap2_w and (B) vap1_l; and negative (C) od and (D) os_l. od, oral diameter; os_l, length of the oral shield; vap1_l, length of first ventral arm plate; vap2_w, width of second ventral arm plate.

Figure 7

Figure 6. Phylogenetic reconstruction of the 16S gene obtained with Bayesian inference. The numbers above the branches represent posterior probabilities. For clades also inferred in the MP analysis, bootstrap values (%) are provided (below the branches).

Figure 8

Table 3. Genetic distance (%) between and within groups of 16S

Figure 9

Figure 7. Ophiocoma trindadensis sp. nov. Sample ZUEC OPH 3095 (19.3 mm dd). (A) Dorsal view; (B) ventral view; (C) detail of the oral view; (D) detail of the jaw; (E) detail of dorsal arm; (F) detail of ventral arm. 2° AdShSp, secondary adoral shield spine; AdSh, adoral shield; AdShSp, adoral shield spine; BS, bursal slits; DAP, dorsal arm plate; DASp, dorsalmost arm spine; IPa, infradental papilla; LyOs, Lyman's ossicle; Osh, oral shield; TPa, tooth papilla; TSc, tentacle scale; VAP, ventral arm plate. Scale bar: A and B, 10 mm; C–F, 1 mm.

Figure 10

Figure 8. Microstructural characters of Ophiocoma trindadensis sp. nov. Sample ZUEC OPH 3095 (19.3 mm dd): (A) radial shield – outer side; (B) adradial genital plate; (C) abradial genital plate; (D) dental plate – outer and inner side; (E) oral plate – adradial; (F) oral plate – abradial (highlighted muscle attachment area); (G) dorsal arm plate – outer side; (H) ventral arm plate – outer side; (I) dorsal arm spine; (J) vertebra – proximal surface; (K) vertebra – distal surface; (L) vertebra – dorsal surface; (M) vertebra – ventral surface; (O) lateral arm plate – spine articulations. Sample MZUSP 2768 (19 mm dd): (N) lateral arm plate – outer side; (P) lateral arm plate – inner side. d, dorsal; ddi, dorso-distal; di, distal; dp, dorso-proximal; hr, horizontal ridge; kn, knob; lb, lobes; maa, muscle attachment area; p, proximal; pk, protruding knobs; sck, sockets; sf, sigmoidal fold; slp, single large perforation; sp, septum; spr, spur; ts, tooth sockets; v, ventral; vdi, ventro-distal; vp, ventro-proximal. Scale bars: A–P, 500 μm.

Figure 11

Figure 9. Ophiocoma echinata. Sample ZUEC OPH 1538 (19.3 mm dd). (A) Dorsal view; (B) ventral view; (C) detail of the oral view; (D) detail of the jaw; (E) detail of dorsal arm; (F) detail of ventral arm. 2° AdShSp, secondary adoral shield spine; AdSh, adoral shield; AdShSp, adoral shield spine; BS, bursal slits; DAP, dorsal arm plate; DASp, dorsalmost arm spine; IPa, infradental papilla; LyOs, Lyman's ossicle; Osh, oral shield; TPa, tooth papilla; TSc, tentacle scale; VAP, ventral arm plate. Scale bars: A and B, 10 mm; C–F, 1 mm.

Figure 12

Figure 10. Microstructural characters of Ophiocoma echinata. Sample ZUEC OPH 1538 (19.3 mm dd): (A) radial shield – outer side; (B) genital plate – adradial; (C) genital plate – abradial; (D) dental plate – outer and inner side; (E) oral plate – adradial; (F) oral plate – abradial (highlighted muscle attachment area); (G) dorsal arm plate – outer side; (H) ventral arm plate – outer side; (I) dorsal arm spine; (J) vertebra– proximal surface; (K) vertebra – distal surface; (L) vertebra – dorsal surface; (M) vertebra – ventral surface. Sample ZUEC OPH 3072 (19.5 mm dd): (N) lateral arm plate – outer side; (O) lateral arm plate – spine articulation; (P) lateral arm plate – inner side. d, dorsal; ddi, dorso-distal; di, distal; dp, dorso-proximal; hr, horizontal ridge; kn, knob; lb, lobes; maa, muscle attachment area; p, proximal; pk, protruding knobs; sck, sockets; sf, sigmoidal fold; slp, single large perforation; sp, septum; spr, spur; ts, tooth sockets; v, ventral; vdi, ventro-distal; vp, ventro-proximal. Scale bar: A–E and I–P, 500 μm; F and G, 200 μm.

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