Alitto RADS et al. (2019), Atlantic West Ophiothrix spp. in the scope of i...

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PLoS One 2019 Jan 01;141:e0210331. doi: 10.1371/journal.pone.0210331.

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Atlantic West Ophiothrix spp. in the scope of integrative taxonomy: Confirming the existence of Ophiothrix trindadensis Tommasi, 1970.

Alitto RADS , Amaral ACZ , de Oliveira LD , Serrano H , Seger KR , Guilherme PDB , Domenico MD , Christensen AB , Lourenço LB , Tavares M , Borges M .

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We re-describe and confirm the validity of Ophiothrix trindadensis Tommasi, 1970 (Echinodermata: Ophiuroidea). This is a native species from Brazil, however it lacked a type series deposited in scientific collections. The recognition of O. trindadensis was made possible using integrative taxonomy applied to many specimens from the type locality (Trindade Island) as well as from different locations along the Brazilian coast (Araçá Bay and Estuarine Complex of Paranaguá). Initially, 835 specimens were studied and divided into four candidate species (CS) inferred from external morphological characters. Afterwards, the CSs were compared using integrative taxonomy based on external morphology, arm microstructures morphology (arm ossicle), morphometry, and molecular studies (fragments of the mitochondrial genes 16S and COI). Analyses indicated CS1 and CS2 as O. trindadensis, and CS3 as O. angulata, both valid species. CS4 remains O. cf. angulata as more data, including their ecology and physiology, are needed to be definitively clarified. Our integrative investigation using specimens from the type locality overcame the lack of type specimens and increased the reliable identification of O. trindadensis and O. angulata.

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Species referenced: Echinodermata
Genes referenced: cux1 LOC115925415 LOC579609 LOC594261 otp ret

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	Fig 1. Schematic diagram of integrative taxonomy applied to Ophiothrix spp.(A) A priori classification inferred from morphological characters. (B) Morphological characters (B1) external morphology and (B2) arm microstructures morphology. (C) Morphometry: measurements and linear discriminant analysis (LDA). (D) Molecular characters: (D1) phylogenetic analyses (Maximum Parsimony, Bayesian Inference, and Maximum Likelihood) and (D2) genetic diversity and species delimitation test (genetic distances, AMOVA, haplotype network, bPTP). (E) Congruence framework of integrative taxonomy.
	Fig 2. Candidate species of Ophiothrix.(A, B) CS1 –MZUSP 1426, Trindade Island. (C, D) CS2 –MZUSP 1425, Trindade Island. (E, F) CS3 –ZUEC OPH 2811, Araçá Bay. (G, H) CS4 –ZUEC OPH 2783, Estuarine Complex of Paranaguá. as: arm spine; dap: dorsal arm plate; ds: disc spine; lds: longer disc spine; sds: small disc spine; vap: ventral arm plate; vap1: first ventral arm plate; vap2: second ventral arm plate. Scale bars: 0.5 mm.
	Fig 3. Axes 1 and 2 from linear discriminant analysis (LDA) based on 17 brittle stars’ characters.See S2 Table and S2 Fig for definitions of the morphological characters used for the morphometric analysis of Ophiothrix CSs. a: specimens from AB; g: specimen from TX-US; p: specimens from ECP; s: specimens from SC-US; t: specimens from TMV; X: Ophiothrix angulata from type locality (USNM).
	Fig 4. Cladogram inferred from the Bayesian analysis of 16S and COI sequences (concatenated).The numbers above the branches represent posterior probabilities. For the clades also inferred in the MP analysis, bootstrap values (%) are provided (below the branches). Branches are identified by individual codes (S3 Table) and their localities: AB: Araçá Bay, São Paulo, Brazil; ECP: Estuarine Complex of Paranaguá, Paraná, Brazil; EUR: Europe; SPSPA: São Pedro and São Paulo Archipelago, Brazil; TMV: Trindade and Martin Vaz Oceanic Archipelago; TX-US: Texas, United States. The scale bar represents the average nucleotide substitutions per site. Asterisks (*) indicate that the support value was lower than 0.7 (Bayesian Inference) or 70% (Maximum Parsimony), and a dash (-) indicates that the branch was not recovered in MP analysis.
	Fig 5. Median-joining haplotype network based on the concatenated matrix of 16S and COI gene sequences.Each circle represents one haplotype and their size is proportional to the number of individuals possessing it. SPSPA: Saint Peter and Saint Paul Archipelago, Brazil; TX-US: Texas, United States.
	Fig 6. Synthetic representation of the integrative taxonomy approach within the Ophiothrix CSs.dap: dorsal arm plates; lap: lateral arm plates.
	Fig 7. Ophiothrix trindadensis sample MZUSP 1425 (5.8 mm dd).(A) Dorsal view. (B) Ventral view. (C) Dental plate. (D) Abradial view of oral plate. (E) Adradial view of oral plate. (F) Detail of dorsal arm. (G) Detail of ventral arm. (H) Lateral arm plate–external side. (I) Lateral arm plate–internal side. (J-M) Vertebrae ossicle: (J) proximal surface. (K) distal surface. (L) dorsal surface. (M) ventral surface. ads: adoral shields; as: arm spine; cdp: cluster of dental papillae; dap: dorsal arm plate; d: dorsal; ddi: dorso-distal; ddmf: dorso-distal muscular fossae; di: distal; dk: distal keel; ds: disc spine; dp: dorso-proximal; kn: knob; lg: large groove; ma: madreporite; os: oral shields; otp: oral tentacle pore; p: proximal; pe: perforation; ribs: rib-like branching structures; ret: regular teeth; rs: radial shields; sh: small hole; v: ventral; vap: ventral arm plate; vdi: ventro-distal; vi: ventral interradius; vp: ventro-proximal; zd: zygocondyle; zp: zygosphene. Stereomicroscope photos (A, B, F, G), scale bar equal to 0.5 mm. SEM photos (C-E, H-M), scale bar equal to 100 μm.
	Fig 8. Ophiothrix trindadensis–juvenile with 2.1 mm of dd (MZUSP 1687).(A) Dorsal view. (B) Ventral view. (C) Detail of the oral view. (D) Detail of dorsal arm. (E) Detail of ventral arm. ads: adoral shields; as: arm spine; cdp: cluster of dental papillae; dap: dorsal arm plate; di: distal; os: oral shields; otp: oral tentacle pore; p: proximal; rs: radial shields; vap: ventral arm plate; vi: ventral interradius. Stereomicroscope photos, scale bar equal to 0.5 mm.
	Fig 9. Ophiothrix cf. angulata ZUEC OPH 2783 (6.4 mm dd).(A) Dorsal view. (B) Ventral view. (C) Dental plate. (D) Oral plate—abradial view. (E) Oral plate—adradial view. (F) Detail of dorsal arm. (G) Detail of ventral arm. (H) Lateral arm plate–external side. (I) Lateral arm plate–internal side. (J-M) Vertebrae ossicle: (J) proximal surface. (K) distal surface. (L) dorsal surface. (M) ventral surface. ads: adoral shields; as: arm spine; cdp: cluster of dental papillae; d: dorsal; dap: dorsal arm plate; ddi: dorso-distal; di: distal; dk: distal keel; ddmf: dorso-distal muscular fossae; dp: dorso-proximal; kn: knob; lds: longer disc spine; lg: large groove; ma: madreporite; os: oral shields; otp: oral tentacle pore; p: proximal; pe: perforation; ribs: rib-like branching structures; ret: regular teeth; rs: radial shields; sh: small holes; v: ventral; vap: ventral arm plate; vdi: ventro-distal; vi: ventral interradius; vp: ventro-proximal; zd: zygocondyle; zp: zygosphene. Stereomicroscope photos (A, B, F, G), scale bar equal to 0.5 mm. SEM photos (C-E, H-M), scale bar equal to 100 μm.

References [+] :

Alitto, Shallow-water brittle stars (Echinodermata: Ophiuroidea) from Araçá Bay (Southeastern Brazil), with spatial distribution considerations. 2018, Pubmed, Echinobase