LEIOPATHIDAE HAECKEL, 1896

Brugler, Mercer R., Opresko, Dennis M. & France, Scott C., 2013, The evolutionary history of the order Antipatharia (Cnidaria: Anthozoa: Hexacorallia) as inferred from mitochondrial and nuclear DNA: implications for black coral taxonomy and systematics, Zoological Journal of the Linnean Society 169 (2), pp. 312-361 : 335

LEIOPATHIDAE HAECKEL, 1896

The Leiopathidae is a monogeneric family consisting of eight species, including Leiopathes acanthophora Opresko, 1998 , L. bullosa Opresko, 1998 , L. expansa Johnson, 1899 , L. glaberrima (Esper, 1792) , L. grimaldi Roule, 1905 , L. montana Molodtsova, 2011 , L. secunda Opresko, 1998 , and L. valdiviae ( Pax, 1915) (see Opresko, 1974, 1998; Opresko & Baron-Szabo, 2001a; Molodtsova, 2011). The family is characterized by polyps having 12 complete mesenteries: six primary and six secondary. The corallum is generally irregularly branched, although in some species it may be flabellate, and is never pinnulated. Spines range from being small, conical, and acute, to spherical and multi-lobed; they lack surface ornamentation. On the larger branches and stem, spines are poorly developed and tend to be very much reduced in size and are often absent, rendering the skeleton very smooth when the tissue is removed. The polyps are irregularly distributed on all sides of the axis on larger branches and stem, and are roundish to compressed transversely in the direction of the axis (equally wide in the sagittal and transverse diameters, or slightly longer along the sagittal axis; tentacles 1.6–2.8 mm). Polyps can be extremely variable in size (0.5–2.0 mm in transverse diameter) and spacing (0.4–2.5 mm apart) on a single colony.

We sequenced 16 Leiopathes colonies for this study (but only ten at all three mt regions), revealing six different haplotypes. Based on identifications provided by the Yale Peabody Museum online database and D.M.O., two colonies identified as different species shared identical haplotypes [ L. cf. expansa (GR101-1) and L. cf. glaberrima (MAN206-1)] and three colonies identified as the same species had different haplotypes [ L. glaberrima (BEA107-2, BEA504-1, USNM 1086471)]. These results suggest that current characters used to delineate species within the Leiopathidae need to be re-evaluated. Without complete taxon sampling, the monophyly of the Leiopathidae could not be determined. Minimal genetic distances were observed among the six haplotypes: maximum distance for cox 3- cox 1: 2.18%, igrN: 0.16%, igrW: 0.47%; however, this conclusion is subject to change as additional taxa are incorporated. Among the three mt gene regions sequenced, igrW was able to differentiate the most haplotypes (N = 5), followed by cox 3- cox 1 (N = 3) and igrN (N = 2). Sinniger & Pawlowski (2009) reported the presence of a group I intron in the cox 1 gene of L. glaberrima . All Leiopathes we examined also contained the cox 1 intron, inserted at position 895. Comparing specimens USNM 1070976 and USNM 1086471 across the first 1275 bp of the cox 1 group I intron revealed four variable sites, thus increasing the number of Leiopathes haplotypes, or species, to seven. The intron was 1587 bp in length and was most variable over the final 312 bp. The final 312 bp of the cox 1 intron contained seven variable sites, revealing only six of the seven haplotypes that were revealed by the mt-contig + the 5 ′ -end of the cox 1 intron (the 312 bp segment was not able to differentiate P4-227-2 and USNM 1086471).

The cox 3- cox 1 phylogeny recovered the Leiopathidae as sister to Acanthopathes thyoides , although without support (BS: 43; BPP: 57). Thus, the position of the Leiopathidae within the Antipatharia could not be resolved with confidence. The Leiopathidae + Acanthopathes thyoides clade grouped sister to, or formed a polytomy with, the Cladopathidae + Schizopathidae clade (BS: 62.4; BPP: 100).