Sinularia species

Benayahu, Yehuda, Ofwegen, Leendert Pieter van, Dai, Chang-feng, Jeng, Ming-Shiou, Soong, Keryea, Shlagman, Alex, Du, Samuel W., Hong, Prudence, Imam, Nimrah H., Chung, Alice, Wu, Tiana & McFadden, Catherine S., 2018, Psammoecus simonis Grouvelle 1892, Zoological Studies 57 (50), pp. 1-26 : 13-19

publication ID	https://doi.org/ 10.6620/ZS.2018.57-50
persistent identifier	https://treatment.plazi.org/id/0387FA5F-FFD2-FF96-8148-FAF5FD4CFA1A
treatment provided by	Felipe
scientific name	Sinularia species
status

Treatment

Identification of Sinularia species using pure

characteristic attributes (PuCAs)

A total of 27 nominal species of Sinularia plus at least one potentially new, undescribed species were identified based on the reconciliation of morphological with molecular data ( Table 1). Phylogenetic analyses of mtMutS plus igr1 + COI identified Sinularia specimens to clade and sub-clade (see McFadden et al. 2009) with high support (data not shown). Within sub-clades, however, distinct morphospecies often shared identical or nearly identical mtMutS sequences. Minimum pairwise genetic distances (Kimura 2-parameter) among morphospecies ranged from 0.5-1.1% among five species in sub-clade 4D, and from 0-1.8% among eleven species belonging to sub-clade 5C. Intraspecific genetic distances as high as 0.8% were observed in several morphospecies. As a result of this substantial overlap between intra- and interspecific genetic distances, there was no barcoding gap that could be used as a threshold value for delimiting species reliably. Morphospecies whose mtMutS sequences differed by just a single nucleotide (genetic distance ~0.1%) could, however, be distinguished unequivocally if that difference represented a pure characteristic attribute (PuCA). All 12 species belonging to clade 4 and 9 of 13 species belonging to clade 5 had simple or compound PuCAs that distinguished them from all other species ( Fig. 2). For example, the presence of a C at nucleotide position 245 of mtMutS is a simple PuCA that distinguished S. lochmodes ( Fig. 3A View Fig ) from all other species belonging to clade 5. Within sub-clade 5C, however, individuals of four morphospecies (S. abrupta: Fig. 3B, S. acuta View Fig : Fig. 3C, S View Fig . penghuensis: Fig 3D and S View Fig . slieringsi) could not be distinguished reliably using PuCAs as they often shared identical mtMutS haplotypes. In addition, some colonies identified morphologically as S. exilis had mtMutS haplotypes that were identical to those of S. erecta ( Figs. 2; 3E View Fig ). For those morphospecies that lacked diagnostic PuCAs or for which there was an unresolved incongruence between morphology and molecular barcode, the barcode nonetheless narrowed the initial identification to a small subset of species within a clade, after which we relied on morphological characters for the final species identification.

Phylogenetic relationship between

Sarcophyton and Lobophytum

The second-most speciose genera of soft corals found at Dongsha Atoll were the alcyoniids Lobophytum (7 species) and Sarcophyton (6

S. flexibilis 3

S. yamazatoi 1

S. querciformis 2

S. variabilis 4

S. heterospiculata 1

S. curvata 2

S. humilis 9

S. ceramensis 13

S. ovispiculata 2

S. pavida 3

S. scabra 1

S. tumulosa1 8

S. tumulosa2 8 011111222222333333444555555666667

614478244788111245037444567112291

Clade 5 N 0 7 3 4 6 8 4 5 9 9 2 5 0 1 5 2 0 8 0 8 5 0 7 9 9 1 1 2 8 0 8 0 1 S. humesi 4 G T A C C C C T A A T A A C C A G G G A A A A G A T G G C A G T A S. hirta 5 G C G C C C C T A A T A A C T G G G G A A A A G A C G G A G G T G S. capillosa 2 G C A C C T C T T A T A G C C G G G G A A A A G A C G G C G G T A S. densa 9 G C A C C C C T T A T A A C C G G G G A A A T G A C G G C G G T A S. erecta 3 G C A C C C C T C A C A A C C G G A A G A A A A A C G A C G G T A S. exilis 2 G C A T C C C T T A T A A C C G G G G A A A A G A C G G C G G T A S. lochmodes 10 G C A C C C C C T A T A A C C G G G G A A A T G A C G G C G G T A S. maxima 8 G C A C C C T T T A T C A C C G G G G A A A A G A C G G T G G C A S. abrupta 3 G C A C C C C T Y A T A A C C G G G G A A A A G A C G G C G G T A S. acuta 14 G C A C C C C T T A T A A C C G G R G A A A A G A C G G C G G T A S. penghuensis 11 G C A C C C C T T A T A A C C G G G G A A A A G A C G G C G G T A S. slieringsi 22 G C A C C C C T T A T A A C C G G G G A A A A G A C G G C G G T A S. wannanensis 15 G C A C C C C T C A T A A C C G G G G A A A A G A C G G C G G T A

species). The phylogenetic relationship between these two genera is currently unclear, as previous molecular analyses have divided their species among three distinct clades, each supported by diagnostic morphological characters ( McFadden et al. 2006). A combined analysis of mtMutS and COI sequences obtained for specimens from Dongsha unequivocally assigned individuals to each of these three previously designated clades (‘ Sarcophyton ’, ‘ Lobophytum ’ and ‘mixed’) ( Fig. 4 View Fig ).

However, six colonies identified as S. crassocaule and L. rigidum ( Fig. 3F View Fig ) belonged to a wellsupported, genetically distinct fourth clade that was sister to the [‘ Sarcophyton ’ + ‘ Lobophytum ’] clade; a reference specimen of S. crassocaule from Indonesia also belonged to this fourth clade, although it was genetically distinct from the S. crassocaule in Dongsha. Four species belonging to the ‘ Sarcophyton ’ clade (S. cinereum: Fig. 5A, S View Fig . elegans, S. nanwanensis: Fig. 5B, S View Fig . trocheliophorum: Fig. 5C, D View Fig ) were morphologically and phylogenetically distinct from one another and had unique barcode sequences that closely matched reference material of those species. Within the ‘ Lobophytum ’ clade, five species were identified based on morphology: L. catalai, L.

crassum: Fig. 5E, L View Fig . hirsutum, L. legitimum, and L. pauciflorum: Fig. 5F. View Fig Colonies identified as L. crassum, however, belonged to four genetically distinct sub-clades, each of which also included reference material previously identified as L. crassum as well as some other species ( Fig. 4 View Fig ). Two ‘mixed’ clade species were identified, S. ehrenbergi ( Fig. 6A View Fig ) and L. hsiehi ( Fig. 6B View Fig ). Barcode sequences for S. ehrenbergi varied slightly among individuals but most haplotypes

matched existing reference material of that species; we were unable to obtain sequence data from any specimens of L. hsiehi.

Other taxa

All other taxa were identified to the genus level based on a congruence of morphological characters and molecular barcodes. Species-level identifications were not possible, however, for the alcyoniid genera Klyxum and some Cladiella and for the majority of Nephtheidae genera as a result of the need for taxonomic revisions coupled with a lack of reference sequences with confirmed species IDs. Previous work has demonstrated that neither the mtMutS nor COI barcodes resolve species boundaries adequately in Klyxum and Cladiella ( Benayahu et al. 2012). Although the 28S rDNA barcode provides better resolution for species in those genera ( Benayahu et al. 2012), we encountered some incongruence between morphological and molecular identifications (data not shown) that limited our ability to assign species names with confidence to some specimens.

Both molecular and morphological data support the conclusion that the Nephtheidae genera Capnella, Lemnalia, Litophyton ( Fig. 6C View Fig ), Paralemnalia, and Stereonephthya are each represented by just a single species at Dongsha. No or only minimal (<0.2%) variation in mtMutS + igr1 + COI haplotypes were observed among specimens within any of those genera. Although all colonies of Dendronephthya also shared an identical mitochondrial haplotype, morphological differences suggested that 3-4 species may be present at Dongsha. Previous molecular work has shown that mitochondrial barcode markers may not exhibit sufficient variation to distinguish morphospecies of that genus ( Park et al. 2012).